Isoalcohol synthesis

FIELD OF THE INVENTION
The present invention relates to the two stage synthesis of isobutanol and methyl butanols by passing synthesis gas over a novel first stage catalyst, then passing the product from that stage through a second stage containing novel noble metal loaded manganese, zinc, zirconium mixed oxide catalyst. Optionally, any ethanol and propanol produced are recycled to the second stage.
BACKGROUND OF THE INVENTION
Environmental and other concerns have increased the demand for oxygenated fuels components for internal combustion engines. For instance, methyl tert-butyl ether (MTBE), tert-amyl methyl ether (TAME), as well as ethyl tert-butyl ether (ETBE), are some potential high octane oxygenates for gasoline engines. This increases the demand for isobutylene for MTBE and ETBE production and 2-methyl butylene for TAME production. These olefins can be derived by dehydrating isobutanol and methyl butanols, respectively. Similarly, alcohols like isobutanol or methyl butanols can be etherified with methanol or ethanol directly over solid acid catalysts to yield their respective methyl or ethyl ethers which are suitable for use as diesel fuel oxygenates.
The lowest cost isobutylene is usually that recovered as a by-product during the catalytic cracking of heavy petroleum fractions. Another source of relatively low cost isobutylene is that produced by the dehydration of by-product tertiary butyl alcohol which arises from the oxidation of isobutane to a tertiary butyl hydroperoxide (TBHP), tertiary butyl alcohol (TBA) mixture, and the subsequent reaction of this mixture with propylene to produce propylene oxide. Once these supplies are used up, current technology requires that isobutylene be obtained by the on purpose isomerization and dehydrogenation of butanes. This technology yields relatively expensive isobutylene. Therefore, there is a need for a route to relatively inexpensive isobutylene. The conversion of synthesis gas to isobutanol and its subsequent dehydration is one such route, provide that: 1) the synthesis gas is derived from low cost carbon sources such as remote natural gas or refinery waste streams; 2) the synthesis gas production technology is cost effective; and 3) the synthesis gas conversion process does not require excessively high pressures, that is, pressures above about 1500 psig (10,000 kPa). The cost is reduced if the process can be operated below 1000 prig (6900 kPa). Another important factor is that the process converts relatively little of the syngas to low value alkanes like methane and ethane. Syngas, as used here, is a mixture having a hydrogen to carbon monoxide ratio of from about 0.1 to about 4.0, preferably about 0.4 to about 2.5, and most preferably from about 0.5 to about 1.5. The synthesis gas may contain up to 50% or more carbon dioxide with less than 10% preferred, excluding the partial pressure of any inert components like nitrogen, argon or methane that may be present.
Many different copper/zinc oxide based catalysts have been reported for the synthesis of methanol, ethanol, n-propanol, isobutanol mixtures, etc. from synthesis gas containing hydrogen and carbon monoxide. These catalysts usually produce primarily methanol but produce increasing amounts of higher alcohols as the reactor temperature is increased. However, as the temperature is increased to favor the production of higher alcohols, hydrocarbons like methane are also produced. The co-production of hydrocarbons limits the economically useful production of higher alcohols.
Catalysts for the production of methanol are described in U.S. Pat. No. 4,843,101. These catalysts contain 0.43 mole % CsOH, 29.97 mole % Cu and 69.70 mole % ZnO and are prepared by precipitating the hydroxy carbonate material aurichalcite, Cu.sub.1.5 Zn.sub.3.5 (OH).sub.6 (CO.sub.3).sub.2, at pH 6.8 from a nitrate or acetate solution of copper and zinc with sodium carbonate. The precipitate is recovered by filtration and washing and calcined to 350.degree. C. which converts the hydroxycarbonate precursor to metal oxides. These are pelletized and then reduced at 250.degree. C. at ambient pressure with a 2% H.sub.2 98% N.sub.2 gas mixture flowing at a rate of 1.0 to 1.5 liters per hour per gram of catalyst. The catalyst is removed under inert atmosphere and treated with an aqueous solution of CsOH under nitrogen at 50.degree. C. It is then dried under flowing nitrogen before use. At 75 atm pressure with 70% H.sub.2, 30% CO synthesis gas at 250.degree. C. flowing at a space velocity of 5000, this catalyst produced 455.6 g/kg of catalyst/hour methanol, 6.28 g/kg of catalyst/hour methyl formate and 1.61 g/kg of catalyst/hour ethanol.
In other work Klier, et al. in "Direct Synthesis of 2-Methyl-1-Propanol/Methanol Fuels and Feed Stocks," Final Technical Report, March 1988, DOE DE89 003390, reports that a catalyst that on a metals only atomic fraction basis was 0.291 Cu, 0.437 Zn, 0.243 Cr, 0.030 Cs gave about 82 g/l catalyst/hour of a ethanol, n-propanol, isobutanol mixture under 0.45 H.sub.2 /CO syngas at 1100 psig (7600 kPa) 310.degree. C. and a 3,260 V/V-hr. gas hourly space velocity.
J. C. Slaa, et al. reported in Catalysis Today 15 (1992) 129-143 the synthesis of higher alcohols over modified Cu/ZnO/Al.sub.2 O.sub.3 catalysts. They state that the alkali dopants are effective for increasing the synthesis of higher alcohols in the order of Li<Na<K<Rb<Cs. They found at 40 atmospheres (4000 kPa) that the optimum doping of K.sub.2 CO.sub.3 is between 0.5 and 1.0wt %.
European Patent Application 0 034 338 A2 (1981) by C. E. Hofstadt, K. Kochloefl, and O. Bock discusses a series of potassium promoted copper-zinc oxide/alumina catalysts containing various other metal oxides: Cr.sub.2 O.sub.3, MnO, ThO.sub.2, Co.sub.2 O.sub.3 or La.sub.2 O.sub.3. These catalysts all produce methanol, ethanol, n-propanol, isobutanol, etc. but the catalysts described in the European's patent are prepared differently than the catalysts of our invention and have different metal ratios and lower surface areas than our catalysts. The catalysts described in European Patent Application 0 034 338 A2 (1981) are significantly less active than the catalysts of our invention. Significantly, their preparation does not involve a coprecipitation step involving copper, zinc and lanthanum soluble salts and an alkali hydroxide precipitating agent in the effective absence of CO.sub.2.
For instance, in Example 3 of European Patent Application 0 034 338 A2, there is a catalyst that is 34.4% Cu, 32.9% ZnO, 16.4% Al.sub.2 O.sub.3, 3.0% K and 3.4% La.sub.2 O.sub.3 (0.420 Cu, 0.314 Zn, 0.250 Al and 0.016 La on a metals mole fraction basis as our catalysts are defined), that when operated at a space velocity of 2600 hr.sup.-1 at 350.degree. C. under 100 atm (about 1470 psi) of syngas containing 29.5% CO converted 8.28 moles CO/l of catalyst/hour. In contrast, a lanthanum containing catalyst prepared according to our invention when operated at a space velocity of 12,220 hr.sup.-1 at 321.degree. C. under about 1000 psig syngas containing about 51% carbon monoxide converted about 50.9 moles % CO/l of catalyst/hour.
There are a wide variety of other copper-based catalysts reported. For instance, Underwood, R. P.; Waller, F. J.; Weist, E. L.; "Development of Alternate Fuels From Coal-Derived Syngas," Liquefaction Contractors Review Meeting Proceedings, Sep. 3-5, 1991, pp. 65-85, report a promoted Cu-ZnO/Al.sub.2 O.sub.3, promoted with other elements, gave 97 g/l of catalyst/hour of C.sub.2.sup.+ liquids at 300.degree. C. from 0.45H.sub.2 /l CO syngas at 1015 psig (about 7000 kPa) and a 10,000 V/V-hr. gas hourly space velocity.
Catalysts based on zirconium oxide for the conversion of syngas to the isobutanol and methyl butanol have also been reported, (e.g., W. Keim and W. Falter, Catalysis Letters, Vol. 3, pp. 59-64, 1989 and M. Roper, W. Keim and J. Seibring, Federal Republic of Germany Patent Application No. 3524317 A1 and W. Falter and W. Keim 3810421 A1 . However these zirconium oxide based catalysts only achieve reliably high productivities of higher alcohols at pressures well in excess of 1500 psig. Since the capital cost of syngas compressors and the energy cost of operating such compressors are major factors in cost of production, isobutanol processes that require pressures higher than about 1500 psig are not economically favorable. The above referenced works on the synthesis of isobutanol from synthesis gas do not disclose the coupling of methanol with ethanol or methanol with ethanol and propanol to produce isobutanol.
Other catalysts, such as gamma alumina impregnated with inorganic base promoters such as a basic metal salt and a Group VIII metal, are disclosed, for example, in U.S. Pat. No. 3,972,952 for the vapor phase conversion of methanol and ethanol to higher linear primary alcohols (such as n-butanol and n-propanol) but no significant levels of isobutanol and 2-methyl butanol. U.S. Pat. No. 4,681,868 and U.S. Pat. No. 4,935,538 discloses that copper bismuth mixed metal oxide catalyst promoted with alkali couples n-propanol to C.sub.6 aldol products but does not disclose the conversion of methanol ethanol mixtures to isobutanol and 2-methyl butanol. U.S. Pat. No. 5,095,156 discloses that methanol and higher alcohols are coupled in the presence of magnesia, (MgO), and also discloses losses to methane, e.g., the wt. % selectivity of the water free products in Table 7 of the patent shows a selectivity to CO+CO.sub.2 ranging from 35.8% to 67.7% and selectivity to methane ranging from 6.9% to 12.6% where methanol conversion ranged from 7.6% to 90.6% and ethanol conversion ranged from 20.4% to 99.1%. Such reactions are also discussed W. Ueda et al. in Catalysis Letters, Volume 12, pp. 97-104, 1992, although Ueda gives no information of losses to methane.

BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 graphically represents a portion of the protocatalyst before full activation (1.5 cm=0.3 .mu.m). FIG. 2 graphically represents a portion of the activated catalyst after more than 80 hours under synthesis gas at 380.degree. C. (1.5 cm=0.3 .mu.m).

SUMMARY OF THE INVENTION
The present invention provides for a method of using first and second stage catalysts to produce methyl branched alcohols, specifically isobutanol and methyl butanols, along with methanol from synthesis gas. The present invention may suitably comprise, consist or consist essentially of the elements disclosed herein and may be practiced in the absence of an element or limitation not disclosed as required. The present invention includes the products produced by the processes disclosed herein.
DETAILED DESCRIPTION OF THE INVENTION
Environmental and other concerns have increased the demand for oxygenated fuels components for internal combustion engines. For instance methyl tert-butyl ether (MTBE), tert-amyl methyl ether (TAME) as well as ethyl tert-butyl ether (ETBE), are some potential high octane oxygenates for gasoline engines. This increases the demand for isobutylene for MTBE and ETBE production and 2-methyl butylene for TAME production. These olefins can be derived by dehydrating the corresponding methyl branched alcohols, isobutanol and 2-methyl butanol, respectively. These alcohols in turn can be synthesized by reaction of methanol and ethanol in the presence of synthesis gas and a catalyst. Furthermore, if this reaction is carried out in the presence of synthesis gas and an olefin such as ethylene, the olefin becomes incorporated into the product isobutanol or 2-methyl butanol and other similar methyl branched alcohols.
An embodiment of the invention provides for a first stage syngas to alcohol catalyst that consists of highly dispersed, alkali promoted lanthanum stabilized microcrystalline Cu.sub.2 O having a particle size of .ltoreq.6 nm, interspersed with metallic copper crystallites having a particle size of .ltoreq.25 nm, and zinc oxide crystallites having a particle size of .ltoreq.6 nm in the presence of a structural promoter such as alumina or chromia. This catalyst is obtained by reduction of the mixed Cu, Zn, Al, La oxyhydroxides precipitated from solution at a constant pH by alkali hydroxide at a temperature between about 30.degree. C. and 100.degree. C. in the essential absence of carbon dioxide. The precipitation pH is between 7.0 and 11.0, preferably between 7.2 and 9.0, most preferably between 7.5 and 8.5, and ideally at 8.2. The alkali hydroxide used may be selected from LiOH, NaOH, KOH, CsOH or mixtures thereof. NaOH is preferred. While the precipitation temperature may be between 30.degree. C. and 100.degree. C., a temperature between about 50.degree. C. and about 90.degree. C. is preferred and between 75.degree. C. and 85.degree. C. is most preferred. Ideally the precipitation is carried out with rapid effective mixing at a temperature between 79.degree. C. and 81.degree. C. After precipitation the precipitate may be optionally aged, that is, held in the essential absence of carbon dioxide in contact with the mother liquor (i.e., the solution from which it was precipitated) for 1 hour to more than 48 hours at a controlled temperature, typically the temperature of precipitation. The precipitate is washed in the essential absence of carbon dioxide with water until it is free of alkali, especially sodium. The washing may be done in a continuous manner or in a series of batch-wise steps. For instance, the precipitate may be recovered from the mother liquor by filtration, and the filter cake reslurried with high purity water and refiltered. This sequence may be repeated until the solids are sufficiently free of alkali. This unpromoted catalyst precursor should contain less than 1000 ppm alkali, preferably less than 100 ppm alkali and most preferably less than 20 ppm alkali. While we do not wish to be bound by any particular theory, we believe the presence of alkali during the drying and calcining of the unpromoted catalyst would interfere with the essential solid state chemistry that leads to the desired microstructure that is expressed after reduction. The washed precipitate is dried at up to 120.degree. C. and then calcined in air for more than three hours at a temperature from between 300.degree. C. to 700.degree. C. The calcined precipitate, after cooling, is then contacted with a solution of potassium, cesium, or potassium and cesium such that it contains after a second drying step from about 0.01 wt % to 0.91 wt % potassium and from about 3 wt % to about 6.5 wt % cesium. The carbonates are effective sources of potassium and cesium. The drying of the promoted catalyst is conducted in air at up to about 120.degree. C. After drying the promoted catalyst is recalcined at from 300.degree. C. to 700.degree. C. in air. The resulting catalyst precursor contains highly dispersed CuO crystallites of about up to 10 nm. The catalyst precursor is converted to an active catalyst by reducing inflowing gas containing hydrogen. The reduction step must be conducted in a manner which is conducive to the formation and preservation of the desired microstructure. Typically this entails a low temperature reduction step at about 140.degree. C. to about 180.degree. C. and a higher temperature reduction step at about 250.degree. C. to about 270.degree. C. The composition of this catalyst is about, on a metals only mole % basis, 45% to 55%, preferably 50% Cu; 10% to 20%, preferably 18% Zn; 10% to 25%, preferably 20% Al; and 5% to 15%, preferably 11% La. Promoted on a wt % basis between about 0% to 1%, preferably 0.91% K, and 3% to 6.5%, preferably 6.2% Cs usually from the carbonate. Rubidium may be substituted to some degree for the potassium and cesium, but it is usually not cost effective.
A second embodiment is the use of this catalyst to convert synthesis gas to a mixture of C.sub.1 through C.sub.4 +isoalcohols. The C.sub.4 isoalcohol, and the isoalcohol produced in greatest abundance by this catalyst, is isobutanol also known as 2-methyl-1-propanol; and the C.sub.5 isoalcohol is 2-methyl-1-butanol which is sometimes called isoamyl alcohol. This catalytic reaction is governed by the synthesis of methanol which is equilibrium controlled and the thermodynamic constraints of which are well-known by those skilled in the art. The catalyst of this invention is exceptionally productive under economically attractive pressures of less than 1500 psig, especially under 1100 psig.
A third embodiment of this invention is the use of this first stage catalyst to produce feed components for the two stage conversion of synthesis gas into C.sub.4 and C.sub.5 isoalcohols. The C.sub.4 isoalcohol and the isoalcohol produced in greatest abundance by this catalyst is isobutanol also known as 2-methyl-1-propanol, and the C.sub.5 isoalcohol is 2-methyl-1-butanol which is sometimes called isoamyl alcohol. This first stage catalyst produces mixtures of alcohols from methanol through ethanol, n-propanol to isobutanol and 2-methyl-1-propanol along with of course accompanying amounts of water and carbon dioxide. This total mixture can be fed without separation directly to the second stage catalyst. Typically, the first stage is operated under about 1000 psig (about 6900 kPa) syngas pressure. The first stage may have several substages with interstage cooling, but the final exit temperature is typically about 320.degree. C. to 330.degree. C. The effluent gas is then passed through a furnace and heated to between about 340.degree. C. and 360.degree. C. before being fed to the second stage. The first stage catalyst of this invention is especially suited for this use because of its high productivity of C.sub.2 through C.sub.4 alcohols at temperatures and pressures close to that required for second stage operation. Its high productivity of C.sub.4 and C.sub.5 isoalcohols is a benefit since these alcohols pass through the second stage effectively unchanged.
Although we do not wish to be bound by any specific theory, we believe that the second stage catalyst produces isoalcohols by converting an equilibrium fraction of the feed alcohols to their aldehydes or surface adsorbed equivalent thereof and then causes these species to undergo an "aldol"-like addition. This aldol addition is in effect the addition of one aldehydic carbon to the carbon alpha to the other aldehyde group. This results in a molecule that has a carbon bearing an alcohol group separated by one carbon atom from the carbon atom bearing the aldehyde group. Then in a key step this molecule effectively dehydrates to form a transient alpha beta unsaturated aldehyde before being rehydrogenated to the saturated alcohol. While preformed isoalcohols might dehydrogenate to the aldehyde and undergo an aldol type addition, they cannot dehydrate since the carbon atom alpha to the carbon bearing the newly formed hydroxyl group is quaternary; that is, does not bear a hydrogen atom, thus reaction reverses.
This embodiment also provides for the use of a manganese, zinc, zirconium oxide containing alkali and noble metal containing second stage catalysts. The noble metal is selected from the group consisting of palladium and platinum with palladium preferred. Applicants have found that the composition and microstructure facilitate production of isobutanol and methyl butanols. The protocatalyst, on exposure to syngas at operating pressure and temperatures between about 360.degree. C. and 390.degree. C., undergoes a solid state reaction which rearranges its microstructure. This results in a more active and selective catalyst. Although the precursor (protocatalyst) has the overall global composition of the final catalyst, the microstructure of protocatalyst and final catalyst are different. These second stage catalysts are useful for converting methanol or ethanol alone or in combination with n-propanol to isobutanol and methyl butanols. The protocatalyst, upon treatment under synthesis gas between about 360.degree. C. and 390.degree. C., preferably about 380.degree. C., results in the formation of a catalyst having at least three phases. The composition of each phase is given on an atomic percentage basis excluding oxygen and noble metals. The first phase, A' in FIG. 2, which is largest in volume and available surface area, is about 60 to about 74 atomic % (on a metals only basis) zirconium (preferably tetragonal, cubic or mixtures thereof), about 21 to about 31 atomic % manganese, about 5 to about 9 atomic % zinc mixed oxide in the form of about <40 .ANG. to about 100 .ANG. crystallites with a ZrO.sub.2 -like structure that also contains a minor amount (<1%) of alkali. The noble metal is principally associated with this phase. The noble metal may be in the form of a noble metal, a noble metal-containing alloy or mixed metal clusters. The noble metal is highly dispersed, typically 75% to 100% dispersion. The second phase, B' in FIG. 2, is comprised of larger crystallites (from about 200 .ANG. to about 1000 .ANG. crystallites), with a concomitantly lower surface area. This phase has the composition and structure of a Zr -doped hetaerolite, where the Mn/Zn ratio is approximately 2 to 1, that is, about 65 to about 69 atomic % manganese, about 31 to about 35 atomic % zinc, and about 1 to about 5 atomic % zirconium in crystallites that may also contain a small amount (0.1 atomic %) of alkali metal. The third phase, C' in FIG. 2, which is present in an active catalyst, is zirconium doped manganese-zinc phase with a highly variable Mn-Zn ratio. These are relatively large Mn or Zn rich crystallites with a highly variable composition that can range from about 29 to about 55 atomic % manganese, about 13 to about 55 atomic % zinc and about 13 to about 35 atomic % zirconium and range in size from about approximately 1000 .ANG. to >4000 .ANG..
While not wishing to be bound by any particular theory, Applicants believe that the overall efficiency of the catalyst in converting methanol with ethanol, n-propanol and light (C.sub.2 to C.sub.3) olefins to the corresponding higher (iso) alcohols depends primarily on the available surface area of the first phase, and that one of the roles of zinc in this phase is to maintain the noble metal highly dispersed thereon. The presence of the other phases are important insofar as they help stabilize the desired active phase.
The protocatalyst is prepared by coprecipitating at an essentially constant pH of between 8 and 12, preferably between 8.5 and 10, a mixed manganese, zinc, zirconium oxyhydroxide with a base selected from the group of alkali hydroxides consisting of LiOH, NaOH, KOH, RbOH, CsOH and mixtures thereof at temperatures of about 0.degree. C. up to about 100.degree. C., with suitable regard given to the freezing and boiling points of the solutions used. Preferably, the temperature is between 50.degree. C. and 90.degree. C., most preferably between 60.degree. C. and 80.degree. C. The concentration, temperature and pH at which the co-precipitation is carried out may be varied within the disclosed ranges to produce the protocatalyst. Any soluble form of the transition metals manganese, zinc and zirconium, that are free of potential catalyst poisons, may be used. Manganese nitrate, zinc nitrate and zirconyl nitrate are the preferred starting materials. Constant effective stirring or blending of the solution is necessary during the precipitation. The precipitated solid is then preferably washed with water to remove the alkali salts and other soluble materials. If the conditions of catalyst usage require it, the solid then may be blended with a suitable binder such as "Cab-O-Si" or a silica or zirconia sol and extruded or formed in another suitable manner known to those skilled in the art.
Preferably, the mole ratio of Zr to the sum of the moles of Mn plus Zr is between about 0.41 and about 0.50, more preferably between 0.425 and 0.49, while the mole ratio of Zn to the sum of the moles of Mn and Zr is preferably between 0.29 and 0.40, more preferably between 0.30 and 0.39.
After an optional drying step, the precipitated solids are calcined, preferably in an oxygen containing gas such as air or oxygen, which is free of typical catalyst poisons, such as sulfur compounds. The solid is calcined at a temperature between about 360.degree. C. and about 440.degree. C. for one to 24 hours, preferably between 360.degree. C. and 425.degree. C. and most preferably between 370.degree. C. and 390.degree. C. After calcination, the solid is then cooled to room temperature and loaded with noble metal. Although the Applicants do not wish to be bound by any particular theory, it is believed that the catalyst is more effective if it does not contain strong acid sites which would result in the conversion of the methanol feed to dimethyl ether rather than to the desired higher alcohols by reaction with the corresponding reactants, e.g., ethanol, n-propanol. Hence, the noble metal compound or compounds used should not contain components which might engender acid sites. Materials such as ammonia or amine complexes of palladium or platinum, typically as the nitrate salts, are preferred. It is especially preferred if the amine complex of the noble metal is an ethanolamine complex. Such may be readily obtained by dissolving the noble metal salt (e.g. palladium nitrate) in water along with sufficient ethanolamine. A sufficient amount of ethanolamine is between about 9 to 36 times the molar amount of noble metal used. After noble metal loading, the material is dried either in air or under vacuum and is ready for activation. Depending on the noble metal precursor used, an optional air calcining step, as well as an optional pre-reduction or pre-reduction and passivation step as well-known by those skilled in the art, may be used.
The protocatalyst, thus obtained by coprecipitation and washing will have at least two phases in addition to the noble metal or any added binder support. The first phase, Phase A in FIG. 1, is a continuous phase containing small and often poorly crystalline particles of a manganese and zinc doped zirconium oxide (preferably tetragonal, cubic or mixtures thereof) phase having about 71 to about 91 atomic % (on a metals only basis) zirconium, about 10 to about 16 atomic % manganese and about 4 to about 8 atomic % zinc and also containing the noble metal and alkali. Embedded in this extensive phase is a second, distinct phase, Phase B in FIG. 1, of zirconium doped hetaerolite (Mn.sub.2 ZnO.sub.4) or hetaerolite-like crystallites (e.g., crystals that give a electron or x-ray diffraction pattern similar to Mn.sub.2 ZnO.sub.4) containing about approximately about 65 to about 69 atomic % manganese, about 31 to about 35 atomic % zinc and about 0 to about 5 atomic % zirconium. These hetaerolite phase crystallites range in size from approximately 500 .ANG. to about 2000 .ANG.. A few large (>0.2 micron sized) particles of ZnO, sometimes containing some Mn and alkali metal, are occasionally found in less than optimum preparations that are believed to be indicative of insufficiently rapid mixing and pH control during the precipitation step or non-optimum starting metal ratios.
The overall bulk composition of the protocatalyst or catalyst expressed as atomic ratios of the metallic elements a:Mn b:Zn c:Zr has values of between about 3 to about 5 for a, about 2 to about 3 for b, and about 3 to about 5 for c. On the same atomic ratio scale, the value for the alkali metal coefficient is typically less than 0.1. On this material 0.1 to 5 wt % palladium or about 0.2 to about 10 wt % platinum may be used with 0.2 to 2 wt % preferred and palladium preferred. Higher noble metal concentrations unnecessarily add to the cost of the catalyst without a significant benefit.
On reduction in hydrogen and exposure to synthesis gas at from about 360.degree. C. to 390.degree., typically 380.degree. C., the protocatalyst is transformed into an active final catalyst phase (synthesis gas treated catalyst), the composition of which was discussed above. The reduction step is typically carried out in a manner that results in a highly dispersed noble metal phase. A typical reduction sequence would include establishing a flow of dry, poison-free inert gas at low pressure through the bed of the protocatalyst at about at least 30 SCCM/cm.sup.3 of catalyst volume and heating the reactor to 100.degree. C. at 8.degree. C./minute or less until 100.degree. C. is achieved and holding for at least 20 seconds per cm.sup.3 of catalyst volume. Thereafter, hydrogen is gradually introduced (to minimalize catalyst decomposition) into the inert gas until the hydrogen partial pressure is between about 60 and about 80 kPa. The reactor temperature then is increased at about 8.degree. C./minute or less until 200.degree. C. is achieved, at which point the temperature is held for about 20 sec/cm.sup.3 of catalyst. The temperature is increased at 4.degree. C./min or less to 260.degree. C. and held while the partial pressure of hydrogen is increased up to about 1 atm. or 100 kPa and the hydrogen flow rate increased to about 300 SCCM/cm.sup.3 of catalyst. The catalyst is held under these conditions for at least about 3 min/cm.sup.3 of catalyst. This gentle reduction sweeps reaction products from the reactor The reactor temperature is then increased at a rate of 3.degree. C./minute or less until up to about 380.degree. C. to 400.degree. C. is achieved. The catalyst is typically held at that temperature for at least one hour before the introduction of synthesis gas and the increase in pressure to the operating range. It is often advisable to decrease the temperature to about 350.degree. C. before synthesis gas is introduced to avoid the occurrence of any destructive exotherms. If the temperature is decreased before the introduction of synthesis gas, it may be increased at a controllable rate back to about 380.degree. C. once the synthesis gas is introduced and flowing at operating pressure.
The synthesis gas used may have a hydrogen to carbon monoxide ratio of from about 0.1 to 4.0, preferably 0.4 to 2.5, and most preferably from about 0.5 to about 1.5. The synthesis gas may contain up to 50% or more carbon dioxide with less than 10% preferred. This synthesis gas may also contain light olefins, like ethylene or ethylene and propylene, during operation since the catalyst will incorporate a portion of these olefins into the higher alcohol product, but it is usually advisable to introduce these olefins to the catalyst after the catalyst has been operated under synthesis gas for several hours. Of course, the synthesis gas may also contain inert gases such as nitrogen, argon and relatively unreactive hydrocarbons like methane and ethane, etc.
While the protocatalyst can be used directly after reduction in hydrogen, it tends to be more effective if treated or held under synthesis gas, typically from 24 to 96 hours at between 360.degree. C. and 390.degree. C., preferably 370.degree. C. to 390.degree. C., to allow the transformations (i.e., in microstructure to produce the final catalyst) to occur (see Example 23, Table 6 below).
It is important that the combination of the overall elemental composition and microstructure of the catalysts fall within the requirements described herein. Desirably, the result will be a catalyst having high isobutanol selectivity and productivity at relatively low pressures for this type chemistry (pressure, up to about 1500 psig (10,350 kPa)).
The operating pressures and temperatures in the process herein are a function of the methanol, hydrogen and carbon monoxide thermodynamics. If the temperature is too high relative to the synthesis gas pressure, methanol will be decomposed to synthesis gas. If the pressure is too high relative to the hydrogen partial pressure, too little dehydrogenation will occur and the rate of coupling will be slow. The ratio of methanol to ethanol, or methanol to ethanol and n-propanol can vary from 50:1 to 4:1, with a preferred range of 15:1 and 5:1, and a more preferred range of 12:1 and 6:1. If the amount of ethanol, or ethanol and propanol is insufficient, the productivity will be low. If the amount of these higher alcohols is excessive, products such as n-butanol from ethanol-ethanol coupling, and 2-methyl pentanol from n-propanol to n-propanol coupling will become significant. Depending on the H.sub.2 and CO partial pressures and their ratio, methanol and ethanol, or methanol, ethanol and n-propanol will be smoothly converted to isobutanol with some methyl butanols at temperatures in the range of about 330.degree. C. to 355.degree. C., and above H.sub.2 to CO ratios of about 0.8 to about 1.2, with combined partial pressures of about 5600 kPa to about 6600 kPa.
Conversion by this second stage catalyst is preferably greater than 50%, more preferably greater than 80%, most preferably greater than 90% of ethanol fed, and preferably above 70% more preferably above 80% of the n-propanol fed. Optionally any unconverted ethanol and n-propanol may be recycled.
Table A below gives the composition of the various phases on a metals mole percent basis.
TABLE A______________________________________Phase Mn Zn Zr______________________________________A 13 .+-. 3 6 .+-. 2 81 .+-. 10B 67 .+-. 2 33 .+-. 2 2.5 .+-. 2.5______________________________________
Phase A is composed of small, Mn doped crystallites of ZrO.sub.2 that are responsible for the majority of the protocatalyst surface area. These crystals also contain a small amount of Zn. Phase B consists of hetaerolite, Mn.sub.2 ZnO.sub.4, crystallites.
Table B describes the catalyst after treatment for more than 80 hours under synthesis gas at 380.degree. C.
TABLE B______________________________________Phase Mn Zn Zr______________________________________A' 26 .+-. 5 7 .+-. 2 67 .+-. 7B' 67 .+-. 2 33 .+-. 2 2.5 .+-. 2.5C' 42 .+-. 13 34 .+-. 21 24 .+-. 11*______________________________________ *Dense agglomerates of the C' type are all relatively rich in Mn and Zn but exhibit a wide range of Mn to Zn ratios.
Phase A' remains the high surface area phase composed of small (about 40 .ANG. to about 100 .ANG.) Mn-doped ZrO.sub.2 that have become enriched in Mn while their Zn content hasn't significantly increased. These small crystallites exhibited a high concentration of stacking faults and other defects consistent with the presence of dopant atoms. The diffraction patterns, obtained from these small crystallites, were broad and poorly formed. They were most consistent with that expected for cubic ZrO.sub.2 and differing only by the absence of the 102 reflection at 2.1 .ANG. from the pattern expected of tetragonal ZrO.sub.2. Monoclinic ZrO.sub.2 can be ruled out since many unique reflections expected for that structure were missing. Phase B' are hetaerolite crystallites as in the protocatalyst but are considerably fewer in number and smaller in size. As their diffraction pattern did not change, they gained little if any Zr during catalyst activation. The third phase, C', are dense crystallites, all relatively rich in Mn and Zn, which exhibit a wide range of Mn to Zn ratios.
EXAMPLE 1
This demonstrates the preparation and use of the first stage catalyst in a preferred embodiment.
A "metals" solution was prepared by dissolving 32.41 g of Cu(NO.sub.3).sub.2.2.5 H.sub.2 O, 14.34 g of Zn(NO.sub.3).sub.3.6H.sub.2 O, 21.67 g of Al(NO.sub.3).sub.3.9H.sub.2 O, and 13.86 g of La(CH.sub.3 COO).sub.3.1.5H.sub.2 O in 300 ml of deionized water at 53.degree. C. to which sufficient concentrated HNO.sub.3 was added to adjust the pH to 1.6. A base solution was prepared by dissolving 30.0 g of NaOH in 300 ml of deionized water. A 300 ml. portion of deionized water was added to a 1 l beaker and preheated to 80.degree. C. To this the "metals" and base solution were added simultaneously over the course of about an hour in such a manner as the pH was controlled at 8.2 and the temperature of the slurry maintained at 80.degree. C. After the addition of the "metals" solution was complete, the mixture was aged for an hour at 80.degree. C. During the entire period of "metals" solution addition and aging, the reaction mixture was sparged with nitrogen to prevent the formation of carbonates by reaction with atmospheric CO.sub.2. After aging, the precipitate was filtered and washed in a continuous fashion with 2 l of deionized water. Then the precipitate was air dried at room temperature to yield 33.08 g of solids. 1.07 g of this material were retained for analysis and the remaining 32.01 g were oven dried at 120.degree. C. for 12 hrs before being calcined in air for 3 hrs at 400.degree. C. The yield after drying and calcining was 23.33 g of solid. The powder x-ray diffraction pattern of both the air dried solid and the calcined material show only amorphous or very finely crystalline material present. The surface area of the calcined precipitate, as measured by argon BET, was 98.9 m.sup.2 /g. The bulk density of the calcined material was 1.61 g/cm.sup.3, thus the volumetric surface area of this material was 159 m.sup.2 /cm.sup.3. The catalyst was then impregnated with an aqueous solution of K.sub.2 CO.sub.3 and Cs.sub.2 CO.sub.3 to give a material that after air drying contained 0.91 wt % K and 6.2 wt % Cs.
2 cm.sup.3 of this material was then mixed with 4 cm3 of high purity low surface area alpha alumina and placed in a 0.4" (10.16 mm) internal diameter copper-lined reactor. After purging with inert gas to remove any traces of oxygen the catalyst was pressurized with flowing hydrogen to 5175 kPa (750 psig) and reduced for 1 hr at 149.degree. C. then for an additional hour at 260.degree. C. During the reduction, the hydrogen hourly space velocity was 6,000. After reduction the hydrogen was replaced with 1 to 1 H.sub.2 /CO synthesis gas and the pressure increased to 6210 kPa (900 psig) and the space velocity was increased to 12,000. Under these conditions of pressure and feed gas flow, the catalyst productivity was determined for three 4.5 hr periods at 260.degree. C., 288.degree. C., and 321.degree. C. respectively. The catalyst productivity is given in Table 1A. No activity decline was observed during this test.
After use, the catalyst was examined by powder x-ray diffraction, electron microscopy and selected area electron diffraction. Powder x-ray diffraction revealed the presence of crystalline phases consistent with metallic copper and zinc oxide. Electron microscopy and selected area electron diffraction revealed that were also regions of microcrystalline Cu.sub.2 O. Since the used catalyst was subjected to exposure to air after use and before analysis and such exposure would be expected to oxidize any finely dispersed metallic copper or Cu.sub.2 O to CuO we believe that the presence of highly disperse microcrystalline Cu.sub.2 O is due to the stabilizing effect of lanthanum. This is supported by the finding that as determined by the ratio of emitted x-rays from representative 17,500 nm.sup.2 regions of this used first stage catalyst the La/Cu ratio stayed more nearly the same than any other metal ratio. The presence of this highly disperse Cu.sub.2 O material is a unique feature of this catalyst that contributes to the high productivity and selectivity of this catalyst for the conversion of synthesis gas to C.sub.2 + alcohols.
TABLE 1A______________________________________Temperature .degree.C. 260 288 321CO Conversion (%) 12.88 21.41 23.29Productivities (g/hr/l of catalyst)methane 1.59 5.00 15.18Other hydrocarbons 1.78 13.44 38.47methanol 858.20 1132.68 715.35ethanol 28.72 62.31 47.40n-propanol 11.31 38.18 49.12isobutanol 2.71 24.10 77.25methyl butanols 2.80 13.40 29.66Other alcohols & oxygenates 11.04 33.49 64.03______________________________________
EXAMPLE 2
This example demonstrates the unexpected effect of the precipitating agent.
The current art recognizes either sodium carbonate or sodium bicarbonate as typical precipitating agents for the preparation of alcohol synthesis catalysts. We have found, unexpectedly, that catalysts with superior activity for higher alcohol synthesis result when sodium hydroxide is used as the precipitating agent instead of the carbonate or bicarbonate. This effect is shown in the table below. The catalysts were prepared by continuous coprecipitation, followed by filtering and washing the precipitate, drying at 120.degree. C., and calcining in air at 400.degree. C. for 3 hrs. During co-precipitation the mixture was sparged with nitrogen to prevent reaction with atmospheric CO.sub.2. The catalysts were reduced in hydrogen at 177.degree. C. for 1 hr followed by reduction at 260.degree. C. for 1 hr. The hydrogen space velocity was 6000/hr and the pressure was 750 psig (5,175 kPa). Testing followed reduction at approximately 13000/hr. space velocity, 925 psig (6383 kPa) pressure, and 1/l H.sub.2 /CO ratio synthesis gas.
TABLE 2______________________________________Precipitation Agent Na.sub.2 CO.sub.3 NaOHMetal Content Oxygen Free Mole FractionCu 0.67 0.68Zn 0.18 0.18Al 0.09 0.10Mg 0.05 0.03Precipitation pH 9 9Precipitation Temp (.degree.V) 50 50Precipitation Sparge N.sub.2 N.sub.2Catalyst Surface Area (m.sup.2 /g) 45.4 50.1Alkali 0.91 wt % K 0.91 wt % KPerformance at 321.degree. C.CO Conversion (%) 9.6 12.8Productivity (g/hr/l of catalyst)methane 3.4 4.5methanol 565.1 584.8ethanol 20.8 32.0n-propanol 9.6 22.1isobutanol 7.5 22.3n-butanol 2.5 5.3methyl butanols 0.5 0.8n-pentanol 1.6 3.4C.sub.2 through C.sub.5 alcohols 42.5 85.9______________________________________
The powder x-ray diffraction patterns for the uncalcined precipitates shows significant differences between the sodium carbonate and sodium hydroxide precipitated materials. The sodium carbonate precipitated material shows a complex diffraction pattern indicative of a crystalline hydrotalcite-type material. On the other hand, the sodium hydroxide precipitated material has a pattern with diffuse peaks and also shows the presence of copper oxide. Copper oxide is absent from the sodium carbonate precipitated material. Both materials show similar patterns after calcination except that larger crystals of zinc oxide are present in the sodium hydroxide precipitated material than in the sodium carbonate precipitated material.
EXAMPLE 3
This example shows the effect of composition and preparation on catalyst selectivity toward the desired higher alcohols. It compares a commercially prepared "copper-zinc oxide" low pressure methanol synthesis catalyst with alcohol synthesis catalyst of this invention prepared by NaOH precipitation.
TABLE 3______________________________________ CommercialCatalyst Methanol This Invention______________________________________Added Alkali 3.1 wt % Cs 3.1 wt % CsPrecipitation Agent -- NaOHMetal Content Oxygen free Mole FractionCu 0.65 0.50Zn 0.20 0.18Al 0.15 0.20La 0.00 0.11Precipitation pH 8.2Precipitation Temperature (.degree.C.) -- 80Precipitation Sparge -- N.sub.2Catalyst Surface Area (sq.m/g) 90 99Performance at 610.degree. F. (321.degree. C.)GHSV 12580 12590Pressure (psig) 925 925H.sub.2 /CO 0.99 0.95CO conversion (%) 19.0 20.5Productivity (g/hr/l of catalyst)methane 10.9 13.2methanol 720.7 672.4ethanol 57.6 28.8n-propanol 39.4 25.5isobutanol 27.8 82.4n-butanol 11.9 5.4methyl butanols 18.3 23.6n-pentanol 6.6 3.3C.sub.2 OH-C.sub.5 OH 161.6 169.0iROH/nROH 0.40 1.68______________________________________
The data above show the effect of optimization of the catalyst formulation and preparation on higher alcohol yields and selectivities. The comparison is with a commercial methanol catalyst alkalized with the same level of Cs (as Cs.sub.2 CO.sub.3). The isobutanol catalyst shows somewhat higher activity for higher alcohol synthesis and significantly higher selectivity to isoalcohols. The reduction and test procedures are the same as described under Example 1.
EXAMPLE 4
This example shows the effect of optimization on catalyst performance.
Optimization of the catalyst formulation and preparation procedure had a very profound effect on the catalytic performance of these materials. The variables investigated were: metals content and composition, precipitant, precipitation temperature, precipitation pH, type of gas sparge used during precipitation and level and type of alkalizing agent. The catalyst preparation and formulation were optimized through the use of a neural net model. Data from several preparations were used to train the model. The model was then used to predict optimum formulations and preparation procedures. Data from these formulations were subsequently used to retrain the net and the cycle was repeated. The result can be seen below where an early formulation is compared with the optimum achieved through neural net modeling.
TABLE 4______________________________________Catalyst Early Example Optimized______________________________________Precipitation Agent Na.sub.2 CO.sub.3 NaOHMetal Content Oxygen Free Mole FractionCu 0.69 0.50Zn 0.19 0.18Al 0.09 0.20La 0.00 0.11Mg 0.02 0.0Precipitation pH 7.0 8.2Precipitation Temp (.degree.C.) 50 80Precipitation Sparge CO.sub.2 N.sub.2Calcination Temperature (.degree.C.) 400 400AlkaliK, wt % 0.91 0.91Cs, wt % 0.0 6.2Catalyst Surface Area (sq.m/g) 90 99Performance at 610.degree. F.GHSV 13210 12590Pressure (psig) 925 925H.sub.2 /CO 0.98 0.95CO Conversion (%) 9.0 23.3Productivity (g/hr/l of catalyst)methane 2.6 15.2methanol 443.4 715.4ethanol 15.7 47.4n-propanol 7.7 49.1isobutanol 6.5 77.3n-butanol 2.2 12.1methyl butanols 4.0 29.7n-pentanols 0.0 8.2C.sub.2 OH-C.sub.5 OH 36.1 223.8iROH/nROH 0.43 0.92______________________________________
Despite the similarities of the two materials above, the effect of optimization was profound. The productivity of C.sub.2.sup.+ alcohols increased over six times and the selectivity to isoalcohols more than doubled.
EXAMPLE 5
This examples shows the effect of alkali. Alkalization of the catalysts is needed to increase selectivity to higher alcohols.
TABLE 5______________________________________Catalyst -- Optimized______________________________________Precipitation Agent NaOHMetal ContentCu 0.50Zn 0.18Al 0.20La 0.11Mg 0.0Precipitation pH 8.2Precipitation Temp (.degree.C.) 80Precipitation Sparge N.sub.2Calcination Temperature (.degree.C.) 400Alkali 99K, wt % 0.0 0.0 0.91Cs, wt % 3.1 6.2 6.2Performance at 610.degree. F. (321.degree. C.)GHSV 12590 12729 12590Pressure (psig) 925 925 925H.sub.2 /CO 0.95 0.94 0.95CO Conversion (%) 20.5 23.2 23.3Productivity (g/hr/lr of catalystmethane 13.2 14.8 15.2methanol 672.4 718.1 715.4ethanol 28.8 40.4 47.4n-propanol 25.5 39.0 49.1isobutanol 82.4 86.1 77.3n-butanol 5.4 9.4 12.1methyl butanols 23.6 29.3 29.7n-pentanols 3.3 6.3 8.2C.sub.2 OH-C.sub.5 OH 169.0 210.5 223.8iROH/nROH 1.68 1.21 0.92______________________________________
Cesium improves activity and productivity of isoalcohols while potassium increases productivity of normal alcohols. Methane productivity increases with increasing alkali content. The higher levels of Cs and K are preferred due to the higher productivity of higher alcohols.
EXAMPLE 6
This example shows the unique effect of lanthanum. The addition of lanthanum improves the productivity of higher alcohols and the selectivity to isoalcohols. Overall CO conversion is increased, as is the catalyst surface area.
TABLE 6______________________________________Catalyst Without La With La______________________________________Precipitation Agent NaOH NaOHMetal Content(Oxygen Free Mole Fraction)Cu 0.68 0.63Zn 0.18 0.17Al 0.10 0.09Mg 0.04 0.04La 0.00 0.06Precipitation pH 10.0 9.0Precipitation Temp (.degree.C.) 50 50Precipitation Sparge N.sub.2 N.sub.2Calcination Temperature (.degree.C.) 400 400AlkaliK, wt % 0.91 0.91Cs, wt % 0.0 0.0Catalyst Surface Area (sq. m/g) 40.1 71.9Performance at 610.degree. F.GHSV 12120 12250Pressure (psig) 925 925H.sub.2 /CO 0.96 0.95CO Conversion (%) 14.5 18.2Productivity (g/hr/l of catalyst)methane 5.0 10.7methanol 564.5 642.2ethanol 34.8 28.6n-propanol 28.1 21.5isobutanol 24.7 65.5n-butanol 6.9 4.7methyl butanols 11.6 21.0n-pentanol 4.4 3.2C.sub.2 OH--C.sub.5 OH 110.5 144.5iROH/nROH 0.49 1.49______________________________________
EXAMPLE 7
This examples compares lanthanum to other metals. The following table shows that lanthanum is superior to other metals in improving catalyst performance with regards to activity, productivity of higher alcohols, and selectivity to isoalcohols. Lanthanum is unique in that it simultaneously improves productivity to higher alcohols and improves selectivity to isoalcohols. All catalysts were precipitated with NaOH using a N.sub.2 sparge and calcined at 400.degree. C. The alkali level was 0 wt % K and 3.1 wt % Cs. The reactor pressure used to evaluate these catalysts was 925 psig (.apprxeq.6383 kPa). The reactor temperature was 610.degree. F. (321.degree.). Precipitation is abbreviated as PPT.
TABLE 7__________________________________________________________________________ Mn Cr V La Y Ce LaCatalyst PPT @ 30.degree. C. and pH 9.0 PPT @ 50.degree. C. pH__________________________________________________________________________ 10.0Metal Content,Oxygen Free Mole FractionCu 0.60 0.60 0.76 0.62 0.62 0.62 0.63Zn 0.18 0.18 0.06 0.19 0.15 0.15 0.17Al 0.10 0.10 0.10 0.10 0.09 0.09 0.09Mg 0.04 0.03 00 0.04 0.05 0.05 0.04Mn 0.09 -- -- -- -- -- --Cr -- 0.08 -- -- -- -- --V -- -- 0.04 -- -- -- --La -- -- -- 0.05 -- -- 0.06Y -- -- -- -- 0.08 -- --Ce -- -- -- -- -- 0.08 --PPT Ph 9.0 9.0 9.0 9.0 10.0 10.0 10.0PPT Temp. (.degree.C.) 30 30 30 30 50 50 50Catalyst S.A. (m.sup.2 /gm) 92.4 117.8 54.8 84.4 41.2 54.1 71.9GHSV 12590 12590 12580 12220 12250 12140 12220H.sub.2 /CO 0.94 0.96 1.00 0.95 0.95 0.95 0.96Performance at 610.degree. F., (321.degree. C.)CO Conversion (%) 17.0 17.0 12.3 18.3 14.0 14.0 18.4Productivities g/hr/l of catalystmethanol 734.7 623.1 471.2 590.5 529.2 530.8 611.0ethanol 32.5 57.6 15.6 40.7 37.0 34.6 32.2n-propanol 26.4 38.1 11.0 32.5 24.1 26.0 24.7i-butanol 43.0 21.7 4.5 48.2 21.6 27.6 55.7n-butanol 5.5 10.2 1.9 8.5 6.4 6.4 5.6methyl butanols 15.5 13.3 2.3 25.5 9.9 11.0 18.9n-pentanol 3.2 5.8 0.9 5.9 4.2 3.8 3.6C.sub.2 OH--C.sub.5 OH 126.1 146.7 26.1 161.3 103.2 109.4 140.8iROH/nROH 0.87 0.31 0.18 0.84 0.44 0.55 1.13__________________________________________________________________________
EXAMPLE 8
This example illustrates the use of a preferred first stage catalyst to provide a feed stream for the second stage catalyst.
An 18 g portion of the solid prepared in Example 1 is charged to a stainless steel die with a diameter of 2.54 cm and compressed under about 900 kg/cm.sub.2 (12,750 lb/in2) pressure in a hydraulic press. The resultant solid wafer is crushed and sieved to yield a granular material that is passed through a 60 mesh sieve (opening 250 .mu.m) and retained on a 100 mesh sieve (opening 150 .mu.m). 10 cm.sup.3 of this material were mixed with 20 cm.sup.3 of high purity acid washed and calcined crushed fused quartz. This inert diluent passed through a 40 mesh sieve (opening 425 .mu.m) but was retained on a 60 mesh sieve (opening 250 .mu.m). This mixture is charged to a copper lined and copper jacketed 304 stainless steel reactor tube with and internal diameter of 0.41 inches (1.04 cm). The reactor tube is so configured that the highly purified, iron carbonyl free synthesis gas contacts no materials of construction other than copper at elevated temperatures. After purging the reactor with purified argon to remove any traces of air the argon is replaced with hydrogen flowing at 6000 GHSV. The reactor is heated to 150.degree. C. and held there for an hour, then heated to 260.degree. C. and held for an hour. The hydrogen is then replaced with highly purified synthesis gas effectively free of sulfur compounds and metal carbonyls. The H.sub.2 /CO ratio in the synthesis gas is 1. The reactor inlet pressure is about 6400 kPa or about 930 psig, and the synthesis gas space velocity is about 12,000. The reactor temperature is progressively increased at 5.degree. C./hr until it is stabilized at about 320.degree. C. Under these conditions, the CO conversion is about 23.3% and the reactor productivity is about as follows:
TABLE 8______________________________________Productivities (g/hr)______________________________________methane 0.152Other hydrocarbons 0.385methanol 7.154ethanol 0.474n-propanol 0.491isobutanol 0.773methyl butanols 0.297Other alcohols & oxygenates 0.640______________________________________
EXAMPLE 9
Preparation of Second Stage Protocatalyst A with Ratio of Mn:Zn:Zr of 0.38:0.26:0.30
The protocatalyst was prepared by the constant pH precipitation of a mix oxyhydroxide of Mn, Zn and Zr by a 2 Molar LiOH solution. The Mn, Zn, Zr solution was prepared by dissolving in 500 ml of distilled water the following amounts of manganese, zinc and zirconyl nitrates that were obtained from Aldrich Chemical Company, Inc. of Milwaukee, Wis. 53233 USA. 0.3 Moles, 43.06 g, Mn(NO.sub.3).sub.2.6H.sub.2 O, (F.W. 287.04), 0.2 Moles, 29.70 g, Zn(NO.sub.3).sub.2.6H.sub.2 O (F.W. 297.47) and about 0.4 Moles, 46.25 g, ZrO(NO.sub.3).sub.2..times.H.sub.2 O (F.W. 231.23). The resulting solution was 0.9 Molar in transition metals. This solution was added over the course of 30 minutes, with constant stirring, to 600 ml of water held at 70.degree. C. The pH of this 600 ml was initially adjusted to pH 9.0 with LiOH. Over the course of the addition, the addition rate of the transition metal solution and of 2.0 Molar LiOH was controlled to maintain a pH of 9.0. Five minutes after the addition was complete, the pH was observed to drift down to about pH 7 and additional 2.0 Molar LiOH was added to restore pH 9.0. Stirring was continued overnight at 70.degree. C., during which time the suspension was concentrated by water evaporation. The precipitate was isolated by filtration. The filtrate had a pH of 6.26. The solids were resuspended in one liter of distilled water and stirred vigorously for 30 minutes, then recovered by filtration. The pH of the filtrate was 7.07. This washing step was repeated and the pH of the final filtrate was 6.20. It was dried overnight at 130.degree. C. The dried material was ground to a fine powder and calcined in air in a tube furnace, the temperature of which was raised from room temperature to 425.degree. C. over the course of two hours, held at 425.degree. C. for two hours, and allowed to cool to room temperature over the course of two hours. 13.79 g of dry material was recovered. 10 g of this material was treated with 10 ml of distilled water in which 0.0616 g of Pd(NO.sub.3).sub.2 was dissolved along with 15 drops of ethanolamine. After thorough mixing the slurry was dried in a vacuum oven for six hours. The Pd-loaded and dried catalyst was heated in air, with the temperature increased from ambient to 325.degree. C. over the course of one hour. The temperature was held at 325.degree. C. for three hours, then cooled over the course of one hour.
The BET surface area was 74.1 m.sup.2 /g, and elemental analysis showed mole fractions of the Mn, Zn, Zr and Li to be respectively 0.3841, 0.2592, 0.2954 and 0.0613. The wt % Pd was 0.24%.
The calcined protocatalyst was crushed to a fine powder; a portion of this solid was then compressed under about 880 kg/cm.sup.2 pressure using a stainless steel die 2.56 cm in diameter to form wafers which were then crushed and sieved to obtain a granular material that was retained on an 80 mesh sieve after passing through a 60 mesh sieve (that is, particles with an approximate size of about 180 .mu.m to about 250 .mu.m in diameter). 3.0 cm.sup.3 of this material, 3.9850 g, was mixed with 6 cm.sup.3, 7.1860 g, of 40-60 mesh (that is, about 250 .mu.m to 425 .mu.m in diameter), crushed, high purity, acid washed and calcined quartz as a diluent. The resulting mixture was charged to a copper-jacketed, copper-lined stainless steel reactor tube (net I.D. 0.41 inch, 1.0414 cm) equipped with a copper-jacketed 0.125 inch (0.3040 cm) outside diameter thermowell. This reactor was attached to a flow system by means of "VCR" fittings. The catalyst bed was flushed with high purity argon, and then 240 SCCM high purity hydrogen and 180 SCCM high purity argon under an exit pressure of 300 kPa were passed through the catalyst bed as it was heated to 240.degree. C. over the course of 120 minutes. After a one minute hold at 240.degree. C., the argon was turned off and the hydrogen flow rate was increased to 1200 SCCM. The catalyst bed was then heated to 260.degree. C. at 8.degree. C./min and held there for five minutes, then heated at 2.degree. C./min. to 400.degree. C. and held there for one hour, after which time the reactor was cooled to 350.degree. C. at 8.degree. C./minute and held at 350.degree. C. while gas composition was changed to synthesis gas and the system pressurized to about 6540 kPa at the outlet of the catalyst bed. Once synthesis gas flow was established, the catalyst bed could then be heated back to 380.degree. C. at 3.degree. C./min without overheating. The synthesis gas mixture used contained 44.0% carbon monoxide, 39.4% hydrogen, 10.0% argon and 6.6% carbon dioxide. It was held at 380.degree. C. for 92 hours before the temperature was decreased to 360.degree. C. and at 360.degree. C. for an additional 20 hours before the temperature was decreased to 340.degree. C. After 16 hours at 380.degree. C., a methanol ethanol water mixture was introduced and vaporized before the catalyst such that the gas composition entering the catalyst bed was approximately 44% CO, 39.4% H.sub.2, 6.6% CO.sub.2 and 10.0% Ar synthesis gas, into which was vaporized at a rate of 0.8 liquid hourly space velocity a mixture of 90.00 wt % methanol, 9.56 wt % ethanol and 0.44% water. The overall gas hourly space velocity was then about 8500 V/V/hr.
Analytical transmission electron microscopy was used to characterize the composition and structure of phases in protocatalyst A, and in the same after activation, and used as an alcohol coupling catalyst. The composition (Zr, Mn, Zn) was determined for regions as small as 4 nm (40 .ANG.) using a 200 kV accelerating voltage Philips CM20 field-emission transmission electron microscope equipped with energy-dispersive x-ray (EDX) analysis. Catalyst particles were embedded in an epoxy and then microtomed into about 500 .ANG.-thick slices in order to determine the morphologies of the large scale structures (about .ltoreq.1 .mu.m) while simultaneously making it possible to observe individual small Zr-rich and Mn-rich phases. Quantitative EDX analyses were carried out using macroscopic (about 5 .mu.m) sampling regions of the starting catalyst as standards for determining k-factors that were subsequently used for analysis of smaller regions in starting and treated catalysts. The small probe available in this field-emission instrument (about 2 nm diameter) made it possible to isolate the EDX signal from individual particles as small as 4 nm with efforts taken to minimize contributions from neighboring particles. Noble metals were located in Zr-rich regions using a Philips EM420ST TEM operated at 100 kV using large sampling regions in Zr-rich or Zr-depleted regions and energy-dispersive x-ray analysis.
Protocatalyst A was found by transmission electron microscopy to have at least two phases in addition to palladium metal. The first phase is a continuous phase containing small (about 40 .ANG. to 50 .ANG.) and often poorly crystalline (as evidenced by the broad electron diffraction lines) particles of a manganese and zinc doped zirconium oxide phase containing about 71 to about 91 atomic % (on a metals only basis) zirconium, about 10 to about 16 atomic % manganese and 4 to about 8 atomic % zinc on an metals only basis. On the basis of electron diffraction patterns, the zirconium dioxide is believed to have a cubic structure. Embedded in this extensive zirconium rich phase is a second, distinct phase of irregular hetaerolite (Mn.sub.2 ZnO.sub.4) or hetaerolite-like crystallites (e.g., crystals that give an electron or x-ray diffraction pattern similar to Mn.sub.2 ZnO.sub.4) containing approximately about 65 to about 69 atomic % manganese, about 32 to about 35 atomic % zinc and about 0 to about 5 atomic % zirconium. These range in size from about approximately 500 .ANG. to about approximately 2000 .ANG..
After activation and use the catalyst was found to have three phases in addition to palladium. The continuous, higher surface area, Zr rich phase had gained Mn and some Zn, while the hetaerolite-like crystallites had decreased considerably in size and number and a third phase of variable composition with variable Mn/Zn ratio had appeared. The first phase, which was largest in volume and available surface area, contained on a metals only basis about 60 to about 74 atomic % (on a metals only basis) zirconium, about 21 to about 31 atomic % manganese, about 5 to about 9 atomic % zinc in the form of about 40 .ANG. to about 100 .ANG. crystallites. Compared to the protocatalyst, these are enriched in Mn, while their Zn content was not significantly increased. These small crystallites exhibited a high concentration of stacking faults and other defects consistent with the presence of dopant atoms. The diffraction patterns obtained from these small crystallites were broad and poorly formed. Their diffraction patterns were most consistent with that expected for cubic ZrO.sub.2 and differing only by the absence of the 102 reflection at 2.1 .ANG. from the pattern expected of tetragonal ZrO.sub.2. Monoclinic ZrO.sub.2 can be ruled out since many unique reflections expected for that structure were missing. Embedded in this extensive zirconium rich phase are irregular hetaerolite (Mn.sub.2 ZnO.sub.4) or hetaerolite-like crystallites (e.g., crystals that give an electron or x-ray diffraction pattern similar to Mn.sub.2 ZnO.sub.4). These were smaller in size (200 .ANG. to approximately 1000 .ANG. across) and fewer in number than in the protocatalyst and contained approximately the same concentration of manganese, zinc and zirconium as in the protocatalyst, that is, about 65 to about 69 atomic % manganese, about 31 to about 35 atomic % zinc and about 0 to about 5 atomic % zirconium, and gave the same diffraction pattern as in the protocatalyst. A significant increase in Zr would be expected to alter this pattern as the Zr atom is significantly larger in diameter than either Mn or Zn. Also embedded in the continuous Zr rich phase of the active catalyst was a new phase consisting of dense crystallites all relatively rich in Mn and Zn but which exhibit a wide range of Mn to Zn ratios. This latter phase varies in size as well as composition ranging from about approximately 1000 .ANG. to >4000 .ANG. and from about 29 to about 55 atomic % manganese, about 13 to about 55 atomic % zinc and about 13 to about 35 atomic % zirconium. This phase is large enough to be clearly visible with a scanning electron microscope when a backscattered electron detector was used to obtain average atomic number images of the sample.
EXAMPLE 10
Preparation of Protocatalyst B with a Mn:Zn:Zr Ratio of 0.39:0.27:0.34
This example illustrates the preparation and activation of Catalyst B, a catalyst within the preferred scope of this invention. 0.3 moles, 43.06 g, Mn(NO.sub.3).sub.2.6H.sub.2 O, (F.W. 287.04), 0.2 moles, 29.70 g, Zn(NO.sub.3).sub.2.6H.sub.2 O (F.W. 297.47) and about 0.4 moles, 46.25 g, ZrO(NO.sub.3).sub.2..times.H.sub.2 O (F.W. 231.23) were dissolved in 500 ml distilled water to make solution TM. Similarly, 42 g of LiOH.H.sub.2 O were dissolved in one liter of distilled water to make a 1 Molar solution of LiOH designated solution B. At a relative rate of 2.7 for solution TM and 1 for solution B, these two solutions were added with rapid stirring to 600 ml of distilled water at 70.degree. C. such that the pH of the resultant slurry was maintained at 9.04.+-.0.2. The resultant light pinkish precipitate was allowed to cool to room temperature (ca 22.degree. C.) and settle overnight. On filtering off the supernatant, which had a pH of 8.59, a light brown solid was recovered. This was washed with three one-liter portions of distilled water. The pH of the filtrate from each washing was respectively 8.32, 8.15 and 7.56.
After drying in a glass container at 130.degree. C. in air for an extended period of time, 36 g of the dry material were calcined to 380.degree. C. in air. 15 g of the calcined material was then palladium loaded as follows: 376 mg of Pd(NO.sub.3).sub.2..times.H.sub.2 O were dissolved in 20 ml of distilled water along with 30 drops of ethanolamine. The solid and the solution were combined and mixed thoroughly and then dried in a vacuum oven for two hours prior to calcining. The dried solid was heated in air over the course of one hour to 380.degree. C., held at 380.degree. C. for one hour, and then cooled to room temperature over the course of one hour.
The resulting material had a surface area of 75.1M.sup.2 /g and the atomic fractions of Mn, Zn, Zr and Li were respectively 0.3857, 0.2706, 0.3428 and 0.0010.
The material had a Pd concentration of 1.21 wt %. A portion of this solid was then compressed using a stainless steel die to form a wafer which was then crushed and sieved to obtain a granular material that was retained on an 80 mesh sieve after passing through a 60 mesh sieve, that is the granules had a size range of about 180 .mu.m to about 250 .mu.m. 3.0 cm.sup.3 of this material, 3.3952 g, were mixed with 6 cm.sup.3, 8.0937 g, of 40-50 mesh crushed high purity, acid washed and calcined quartz as a diluent, that is, the irregular quartz chunks were from about 300 .mu.m to 425 .mu.m in diameter. The resulting mixture of catalyst and quartz granules was charged to a copper-jacketed, copper-lined stainless steel reactor tube (net I.D. 0.41 inch, 1.0414 cm), equipped with a copper-jacketed 0.125 inch (0.3040 cm) outside diameter thermowell. This reactor was attached to a flow system by means of "VCR" fittings. The catalyst bed was flushed with high purity argon, and then 240 SCCM high purity hydrogen and 180 SCCM high purity argon under an exit pressure of 300 kPa were passed through the catalyst bed as it was heated to 200.degree. C. over the course of 15 minutes. After a one minute hold at 200.degree. C., the catalyst bed was heated at 4.degree. C./min to 260.degree. C. During a one minute hold at 260.degree. C., the argon was turned off and the hydrogen flow rate was increased to 1200 SCCM. Under this condition, the reactor bed temperature was increased at 3.degree. C./min to 377.degree. C. without overheating. After 60 minutes at 377.degree. C., the temperature was decreased to 350.degree. C. and the gas composition changed to a carbon monoxide, hydrogen, argon, carbon dioxide, blend flowing at about 400 SCCM through the catalyst bed and the reactor pressure was slowly increased to 6500 kPa. The synthesis gas mixture used contained 44.0% carbon monoxide, 39.4% hydrogen, 10.0% argon and 6.6% carbon dioxide. Once this gas mixture was flowing through the system and the reactor pressure was stabilized at about 6550 kPa, the reactor temperature was increased to 377.degree. C. Under these conditions the temperature at the exit of the catalyst bed was about 380.degree. C. The resultant liquid produced from the synthesis gas was about 29.4% water, 67.3% identified organic compounds: methanol, methyl formate, ethanol, n-propanol, isobutanol, n-butanol, 3-methyl 2-butanol, 3-pentanol, 3-methyl-1-butanol, 2-methyl-1-butanol, 4-methyl pentanol, n-pentanol, 2,2-dimethyl 3-pentanone, 2-methyl-1-pentanol, and 2,4 dimethyl-3-pentanol and about 3.3% trace, unidentified organic compounds. The identified organics were 73.6% methanol, 19.6% isobutanol, 1.8% n-propanol, 1.3% methyl butanols and 3.7% other materials on a carbon basis.
EXAMPLE 11
This example illustrates the performance of Catalyst B within the preferred scope of this invention with a methanol, ethanol, water feed.
After the gas composition of Example 9 (at 380.degree. C.) was changed to 47.1% carbon monoxide, 42.2% hydrogen and 10.7% argon, a 90 wt % methanol, 9.56% ethanol and 0.44% water vapor was added to the gas mixture and fed to the catalyst. Under these conditions, 99.7% of the ethanol was converted to C.sub.3 + products through reaction with the methanol. Some methanol was also decomposed into hydrogen and carbon monoxide. In this case, the liquid produced was 11.4% water, 87.4% identifiable organic compounds: methanol, methyl formate, ethanol, n-propanol, isobutanol, n-butanol, 3-methyl-2-butanol, 3-pentanol, 3-methyl-1-butanol, 2-methyl-1-butanol, 4-methyl-pentanol, n-pentanol, 2,2-dimethyl-3-pentanone, 2-methyl-1-pentanol, and 2,4-dimethyl-3-pentanol and 1.2% trace materials. On a carbon basis, the produced liquid was 45.9% isobutanol, 35% methanol, 4.4% methyl butanols, 4.4% n-propanol, 1.7% 2-methyl-1-pentanol with about 0.13% ethanol and 7.8% miscellaneous organic compounds.
EXAMPLE 12
This example illustrates that Catalyst B, a catalyst within the preferred scope of this invention, produces very little unwanted hydrocarbon and is effective in converting a methanol, ethanol, water and n-propanol feed.
The reactor temperature in Example 11 was decreased from about 380.degree. C. to about 340.degree. C. and the liquid feed composition was changed to resemble the liquid produced without the methanol-ethanol vapor feed. Under these conditions, little, if any, methanol was decomposed into gas, and less than 0.1% of the carbon passing through the reactor was converted to hydrocarbon gas. The liquid composition was changed to about 87.2 wt % methanol, 7% ethanol and 5.8% n-propanol. Under these conditions, the ethanol conversion was 90.2% and the n-propanol conversion was 74.9%. The resultant liquid product contained 86.3% identified organic products: methanol, methyl formate, ethanol, n-propanol, isobutanol, n-butanol, 3-methyl-2-butanol, 3-pentanol, 3-methyl-1-butanol, 2-methyl-1-butanol, 4-methyl-pentanol, n-pentanol, 2,2-dimethyl-3-pentanone, 2-methyl-1-pentanol, and 2,4-dimethyl-3-pentanol, 8.9% unidentified organic products and 4.8% water. On a carbon basis, the liquid product contained about 67.7% methanol, 24.4% isobutanol, 2.6% methyl butanols along with 3.5% n-propanol and 1.4% ethanol.
Increasing the temperature of the reactor in Example 11 from 340.degree. C. to 350.degree. C. increased the ethanol conversion to 97.8% and the n-propanol conversion to 88% after over 190 hours on-line. The liquid produced contained on a carbon basis 62.1% methanol, 30.8% isobutanol, 2.1% methylbutanols, along with 0.4% ethanol and 1.9% n-propanol.
EXAMPLE 13
This example illustrates the incorporation of a light olefin, ethylene, into the alcohol product when ethylene is cofed to the second stage catalyst, along with methanol, ethanol, n-propanol and synthesis gas.
Under the final conditions of Example 12 (350.degree. C. and about 6550 kPa), the feed gas was changed to 44.0% carbon monoxide, 39.4% hydrogen, 10.0% argon and 6.6% polymer grade ethylene. Under these conditions about 25% of the ethylene fed was converted with 80% selectivity to liquids, 19% to ethane and 1% to higher hydrocarbons including n-butane and butenes. The liquid produced on a carbon basis was: 59.3% methanol, 32.4% isobutanol, 2.3% methyl butanols, 2.2% n-propanol, 1% 2-methyl-1-pentanol and 0.4% ethanol along with miscellaneous organic compounds. With an ethylene co-feed, the ethanol conversion was about 97.4% and the n-propanol conversion was about 86.2%. These values were comparable to, or slightly lower than, those without ethylene feed. With ethylene co-fed, the concentration of unidentified organic compounds in the liquid increased from 1.1% to 3.2%. Significantly, ethylene co-feed also increased the productivity of isobutanol by 7.8% and that of methyl butanols by 11%.
EXAMPLE 14
This example illustrates that this second stage catalyst within the scope of this invention converts very little of the carbon dioxide free synthesis gas and a methanol, ethanol, n-propanol liquid feed into undesirable byproducts.
A second 3.0 cm.sup.3 (3.1215 g) sample of 60 to 80 mesh (180 .mu.m to 250 .mu.m) granules of Protocatalyst B were blended with 6.0 cm.sup.3 (6.8880 g) of acid washed and calcined high purity fused quartz crushed and sieved to 40 to 60 mesh (250 .mu.m to 425 .mu.m). This mixture was charged into a copper-jacketed, copper-lined stainless steel reactor tube (net I.D. 0.41 inch, 1.0414 cm) equipped with a copper-jacketed 0.125 inch (0.3040 cm) outside diameter thermowell. This reactor was attached to a flow system by means of "VCR" fittings. The catalyst bed was flushed with high purity argon, and then 240 SCCM high purity hydrogen and 180 SCCM high purity argon under an exit pressure of 300 kPa were passed through the catalyst bed as it was heated to 200.degree. C. over the course of 30 minutes. Then, after a one minute hold at 200.degree. C., it was heated to 260.degree. C. over the course of 30 minutes. After one minute at 260.degree. C., the argon was turned off and the hydrogen flow rate was increased to 1200 SCCM. The catalyst bed was then heated to 377.degree. C. over the course of about 50 minutes, then held there for one hour, after which time the reactor was cooled to 350.degree. C. at 2.degree. C./min and held at 350.degree. C. while gas composition was changed to synthesis gas and the system pressurized to about 6540 kPa at the outlet of the catalyst bed. Once synthesis gas flow was established, the catalyst bed could then be heated back to 380.degree. C. in the catalyst bed at 3.degree. C./min without overheating. Once the catalyst reached 380.degree. C. under synthesis gas flowing at 400 SCCM, it was "on-line" and the run time clock was started. The synthesis gas mixture used contained 47.5% carbon monoxide, 42.5% hydrogen and 10.0% argon. After 41 hours on-line, a mixture of 87.41% methanol, 6.42% ethanol, 5.85% n-propanol and 0.32 wt % water was vaporized into the synthesis gas above the catalyst bed at the rate of 2.4 cm.sup.3 of liquid at 0.degree. C. per hour. The catalyst bed was held at 380.degree. C. for 64 hours before the temperature was decreased to 350.degree. C.
After 70 hours on-line at a catalyst bed temperature of 350.degree. C. and a feed synthesis gas composition of 47.10 mole % CO, 42.17 mole % H.sub.2 and 10.73 mole % Ar as an internal standard, the carbon monoxide conversion was about 1.8%. This was determined using a gas chromatograph that alternately sampled feed and product gas streams. All the gas feeds to the experimental reactor are controlled with electronic mass flow controllers working with a constant feed and back pressure. Thus the flow of the individual gases and of the mixed gas feed to the reactor is effectively constant. Thus, the Molar ratio of carbon monoxide to argon in the feed and product should be constant in the absence of reaction. If a carbon monoxide-consuming reaction occurs over the catalyst, then the ratio of feed carbon monoxide, CO.sub.f, to feed argon Ar.sub.f must equal the ratio of product carbon monoxide, CO.sub.p, plus carbon monoxide consumed, CO.sub.c, to product argon, Ar.sub.p, that is:
CO.sub.f /Ar.sub.f =(CO.sub.p +CO.sub.c)/Ar.sub.p or CO.sub.c =(Ar.sub.p CO.sub.f --Ar.sub.f CO.sub.p)/Ar.sub.f
A gas chromatograph was used to alternately sample feed and product gas. The carbon selectivity of this converted gas was found to be about 39.2% to carbon dioxide, 60.8% to hydrocarbon gases and effectively none to liquids using the carbon bookkeeping convention that carbon from converted carbon monoxide is first assigned to the observed net carbon dioxide (excess of CO.sub.2 in the exit gas over that fed), then to the observed hydrocarbon gases. The balance of the consumed carbon is then assigned to the liquid product, that is:
Moles of CO converted-(moles CO.sub.2 produced+moles carbon as hydrocarbon gases)=moles CO converted to liquid.
The carbon distribution of the hydrocarbon gases was: 28.8 C % ethylene, 24.7 C % propylene, 18.8 C % isobutylene, 12.4 C % methane, 11.8 C % ethane, 2.3 C % propane and 1.2 C % isobutane. This composition suggests that most of these gases, with the exception of the methane, arose from the dehydration of the alcohols fed (or produced), forming olefins, with the subsequent hydrogenation of some of these olefins to form paraffins. These data also show that the losses to methane are on the order of 0.2% of the carbon passing through the reactor. The liquid product produced at the same time as above the gaseous products (that is, the liquid collected between 68.5 and 71 hours on-line) contained about 7 wt % water and 93 wt % organic products, of which 99% were identifiable. The breakdown of these organic products on a carbon percent basis is as follows: 62.41 C % methanol, 30.23 C % isobutanol, 2.08 C % n-propanol, 1.96 C % methyl butanols, 0.90 C % ethanol, 0.88 C % 2-methyl pentanol, 0.09 C % n-butanol and about 1.45 C % miscellaneous organic products. This represents about 95.1% ethanol conversion, 88.7% n-propanol conversion. On a methanol, water free basis, the C.sub.2 + liquid products were about 80 wt % isobutanol, 6 wt % n-propanol, 5 wt % methyl butanols, 3.0 wt % ethanol and about 6 wt % other products.
EXAMPLE 15
This example demonstrates the performance of second stage catalyst within the scope of this invention for the incorporation of a light olefin, ethylene, into the liquid product produced from carbon monoxide and hydrogen.
After 77 hours on-line, the gas composition over the catalyst in Example 14 was changed to 43.7mole % CO, 39.1 mole % H.sub.2, 9.9 mole % Ar and 7.3 mole % polymerization grade ethylene. After 89 hours, the liquid feed was turned off and the behavior of the thoroughly activated, lined-out catalyst under the ethylene containing synthesis gas was monitored by gas chromatography using argon as an internal gas standard as above. Using the carbon bookkeeping convention that ethylene could be converted to only ethane or liquid products and that CO could be converted to CO.sub.2, liquids or hydrocarbon gases except ethane and ethylene, the following results were obtained: Under these conditions 16.2% of the ethylene fed was converted to products. The carbon selectivity to ethane was 72.3 carbon % and the selectivity to liquid products 27.7 carbon %. At the same time, the CO conversion averaged 4.3 mole %. Of this, 92.7% on a carbon basis was converted to liquid products, 2.7 C % to carbon dioxide and the balance, 7.3 C % to hydrocarbon gases (except for ethane and ethylene). The breakdown of the hydrocarbon gases on a carbon % basis was as follows: 31.04 C % n-butane, 27.09 C % methane, 10.84C % propylene, 9.74C % isobutylene, 6.79C % isopentene, 6.25 C % propane, 3.79C % isopentane, 2.53 C % n-butenes, 1.19C % n-pentane, and 0.11 C % isobutane, along with about 0.63 C % hexenes and hexanes. The liquid product was about 5% water and 95% organic products by weight. The organic products on a carbon % basis were derived 72.7% from the CO that was converted and 27.3% from the ethylene that was converted. It is believed that the carbon derived from the incorporated ethylene is in the C.sub.2 + products, especially in the C.sub.4 + products. The composition of the liquid products on a carbon basis was: 90.02 C % methanol, 5.81 C % isobutanol, 0.37 C % methyl-butanols, 0.35 C % n-propanol, 0.18 C % 2 methyl-1-pentanol, 0.08 C % ethanol and 0.07 C % n-butanol, with the balance of the carbon in other miscellaneous oxygen-containing organic products.
EXAMPLE 16
This example further illustrates the incorporation of an olefin, ethlyene, into the liquid product derived from synthesis gas and a methanol, ethanol, n-propanol liquid feed.
After 165 hours on-line, the 87.41% methanol, 6.42% ethanol, 5.85% n-propanol and 0.32 wt % water liquid feed was once again vaporized into the synthesis gas (43.7 mole % CO, 39.1 mole % H.sub.2, 9.9 mole % Ar and 7.3 mole % polymerization grade ethylene) above the catalyst bed at the rate of 2.4 cm.sup.3 of liquid (at 0.degree. C.) per hour.
Under these conditions, 8.1% of the ethylene was converted with a carbon selectivity of 26.2% to ethane and 73.8% to "liquid products" with the same convention for carbon book keeping as above. Similarly, 2.5% of the carbon monoxide fed was consumed, being converted with a carbon selectivity of 72.5% to liquids, 21.4% to carbon dioxide and 6.1% to hydrocarbon gases except for ethane and ethylene. The breakdown of the hydrocarbon gases produced was on a carbon % basis as follows: methane 24.58 C %, propylene 20.79C %, n-butane 19.63 C %, isobutylene 18.04 C %, propane 6.60 C %, isopentene 4.92 C %, isopentane 2.24 C %, n-butenes 2.07 C %, n-pentane 0.82 C % and isobutane 0.31 C %.
The liquid product was about 4% water and about 96% organic products. 66.2% of the carbon in these products was derived from the feed methanol, 13.6% from the feed ethanol and propanol, 10.6% from the feed ethylene and 9.6% from the feed carbon monoxide. These organic products contained on a carbon % basis: 63.24% methanol, 27.21% isobutanol, 3.96% n-propanol, 1.96% methyl butanols, 1.00% ethanol, 0.83% 2-methyl pentanol and 0.16% n-butanol with about 1.64% miscellaneous products.
EXAMPLE 17
Preparation of Protocatalyst C with a Mn:Zn:Zr Ratio of 0.42:0.29:0.29
In 500 ml of distilled water 21.53 g Mn(NO.sub.3).sub.2.6H.sub.2 O, 14.85 g Zn(NO.sub.3).sub.2.6H.sub.2 O(F.W. 297.47) and 23.12 g ZrO(NO.sub.3).sub.2..times.H.sub.2 O were dissolved. This solution was added over the course of 30 minutes, with constant stirring, to 600 ml of water held at 70.degree. C. The pH of this 600 ml was initially adjusted to pH 9.0 with LiOH. Over the course of the addition, the addition rate of the transition metal solution and of a 21.0 g/l solution of LiOH was controlled to maintain a pH of 9.0. On addition of the transition metal solution and lithium hydroxide, the precipitate slurry was brown from the outset. Stirring was continued for five hours at 70.degree. C. The suspension was allowed to settle overnight at room temperature without stirring. The precipitate was isolated by filtration, then washed three times by resuspension and stirring in a liter of distilled water for an hour at room temperature, followed by filtering to recover the solids for further resuspension. The washed solids were dried overnight at 130.degree. C. The dried material was ground to a fine powder and calcined in air in a tube furnace, the temperature of which was raised from room temperature to 425.degree. C. over the course of two hours, held at 425.degree. C. for two hours and allowed to cool to room temperature over the course of two hours. 16.35 g of dry material was recovered. 15.0 g of this material were treated with 15 ml of distilled water in which 0.0939 g of Pd(NO.sub.3).sub.2..times.H.sub.2 O (assay 39.95 wt % Pd) was dissolved along with 15-20 drops of ethanolamine. After thorough mixing, the slurry was dried in a vacuum oven at 80.degree. C. overnight. The Pd-loaded and dried catalyst was heated in air with the temperature increased from ambient to 325.degree. C. over the course of one hour. The temperature was held at 325.degree. C. for three hours, then cooled over the course of one hour.
The BET surface area was 72.1 m.sup.2 /g, and elemental analysis showed mole fractions of the Mn, Zn, Zr and Li to be respectively 0.4202, 0.2914, 0.2884 and 0.0613. The wt % Pd was 0.24%.
EXAMPLE 18
Preparation of Second Stage Protocatalyst D with a Mn:Zn:Zr Ratio of 0.40:0.28:0.32
In 500 ml of distilled water 21.53 g, Mn(NO.sub.3).sub.2.6H.sub.2 O, 14.85 g, Zn(NO.sub.3).sub.2.6H.sub.2 O and 23.12 g, ZrO(NO.sub.3).sub.2..times.H.sub.2 O were dissolved. This solution was added over the course of 30 minutes, with constant stirring to 600 ml of water held at 70.degree. C. The pH of this 600 ml was initially adjusted to pH 9.0 with LiOH. Over the course of the addition, the addition rate of the transition metal solution and of a 21.0 g/500 ml solution of LiOH was controlled to maintain a pH of 9.0. On addition of the transition metal solution and lithium hydroxide, the precipitate slurry was lighter in color than similar precipitations conducted at 70.degree. C. Stirring was continued for five hours at 25.degree. C. The suspension was allowed to settle for about 60 hours at room temperature without stirring. The precipitate was isolated by filtration, then washed three times by resuspension and stirring in a liter of distilled water for an hour at room temperature, followed by filtering to recover the solids for further resuspension. The washed solids were dried overnight at 130.degree. C. The dried material was ground to a fine powder and calcined in air in a tube furnace, the temperature of which was raised from room temperature to 425.degree. C. over the course of two hours, held at 425.degree. C. for two hours, and allowed to cool to room temperature over the course of two hours. 15.25 g of dry material were recovered. 15.0 g of this material were treated with 15 ml of distilled water in which 0.0940 g of Pd(NO.sub.3).sub.2..times.H.sub.2 O (assay 39.95 wt % Pd) was dissolved along with 15-20 drops of ethanolamine. After thorough mixing, the slurry was dried in a vacuum oven at 130.degree. C. for two hours. The Pd-loaded and dried catalyst was heated in air with the temperature increased from ambient to 325.degree. C. over the course of one hour. The temperature was held at 325.degree. C. for three hours; then cooled over the course of one hour.
The BET surface area was 78.8 m.sup.2 /g, and elemental analysis showed mole fractions of the Mn, Zn and Zr to be respectively 0.4023, 0.2823, and 0.3154. The wt % Pd was 0.25%.
EXAMPLE 19
(Comparative)
Preparation of Catalyst E with a Mn:Zn:Zr Ratio of 0.54:0.29:0.17 that is outside the preferred range.
In 500 ml of distilled water 0.10 moles, 28.70 g, Mn(NO.sub.3).sub.2.6H.sub.2 O, 0.05 moles, 11.56 g ZrO(NO.sub.3).sub.2..times.H.sub.2 O and 0.05 moles, 14.87 g, Zn(NO.sub.3).sub.2.6H.sub.2 O were dissolved, making a solution that was 0.4 Molar in transition metals. A LiOH solution was prepared by dissolving 21.0 g of LiOH in 500 ml distilled water. The transition metal solution was added over the course of 30 minutes, with constant stirring, to 600 ml of water held at 70.degree. C. The pH of this 600 ml was initially adjusted to pH 9.0 with LiOH. Over the course of the addition, the addition rate of the transition metal solution and of 1.0 Molar LiOH was controlled to maintain a pH of 9.04.+-.1.0. Five minutes after the transition metal solution addition was complete, the pH dropped to about 7.0 and more LiOH solution was added to bring it back up to 9.0. The precipitate was a light tanish brown in color. Stirring was continued overnight at 70.degree. C., during which time the suspension was concentrated by water evaporation. The precipitate was isolated by filtration. The filtrate had a pH of 6.26. The solids were resuspended in one liter of distilled water and stirred vigorously for 30 minutes, then recovered by filtration. The pH of the filtrate was 7.07. This washing step was repeated and the pH of the final filtrate was 6.20. The solid appeared to get darker in color and more difficult to filter as the washing proceeded. The solid was dried overnight at 130.degree. C. and 13.91 g of a black material were recovered. The dried material was ground to a fine powder and calcined in air in a tube furnace, the temperature of which was raised from room temperature to 425.degree. C. over the course of two hours, held at 425.degree. C. for two hours and allowed to cool to room temperature over the course of two hours. 13.79 g of dry material were recovered. 10 g of this material were treated with 10 ml of distilled water in which 0.0616 g of Pd(NO.sub.3).sub.2..times.H.sub.2 O (Johnson Matthey) were dissolved along with 15 drops of ethanolamine. After thorough mixing, the slurry was dried in a vacuum oven for 6 hours. The Pd-loaded and dried catalyst was heated in air with the temperature increased from ambient to 325.degree. C. over the course of one hour. The temperature was held at 325.degree. C. for three hours, then cooled over the course of one hour.
The BET surface area was 59 m.sup.2 /g, and elemental analysis showed mole fractions of the Mn, Zn, Zr and Li to be respectively 0.5390, 0.2892, 0.1674 and 0.0044. The wt % Pd was 0.24%.
EXAMPLE 20
(Camparative)
Preparation of second stage Catalyst F with a Mn:Zn:Zr Ratio of 0.27:0.22:0.51 that is outside the preferred range.
In 500 ml of distilled water 28.42 g Mn(NO.sub.3).sub.2.6H.sub.2 O, 23.05 g Zn(NO.sub.3).sub.2.6H.sub.2 O and 74.79 g ZrO(NO.sub.3).sub.2..times.H.sub.2 O were dissolved. The LiOH solution used to precipitate this was prepared by dissolving 42.0 g of LiOH.H.sub.2 O (F.W. 41.96) in a liter of distilled water. The transition metal nitrate solution, added over the course of 30 minutes, with constant stirring, to 600 ml of water held at 70.degree. C. The pH of this 600 ml was initially adjusted to pH 9.0 with LiOH. Over the course of the addition, the addition rate of the transition metal solution and of 1.0 Molar LiOH was controlled to maintain a pH of 9.0. Stirring was continued for five hours at 70.degree. C. The suspension was then allowed to settle and cool overnight. The tan-brown gelatinous precipitate was isolated by filtration. The solid was washed three times by resuspension in one liter of distilled water and 30 minutes of vigorous stirring prior to filtration. The recovered solids were dried overnight at 130.degree. C., leading to the recovery of 45.5 g of material. The dried material was ground to a fine powder and 20.0 g was calcined in air in a tube furnace, the temperature of which was raised from room temperature to 425.degree. C. over the course of two hours, held at 425.degree. C. for two hours and allowed to cool to room temperature over the course of two hours. 13.46 g of cooled, calcined material were recovered. This material was treated with 10 ml of distilled water in which 0.0939 g of Pd(NO.sub.3).sub.2 was dissolved along with 15 drops of ethanolamine. After thorough mixing, the slurry was dried in a vacuum oven at 110.degree. C. for six hours. The dried material was then calcined in air as follows: the temperature was increased from room temperature to 325.degree. C. over the course of an hour, then held at 325.degree. C. for three hours before cooling to room temperature over the course of two hours.
The BET surface area was 112.2 m.sup.2 /g, and elemental analysis showed mole fractions of the Mn, Zn, Zr and Li to be respectively 0.2663, 0.2184, 0.5116 and 0.0037. The wt % Pd was 0.22%.
EXAMPLE 21
Preparation of Catalyst G with a Mn:Zn:Zr Ratio of 0.46:0.29:0.25 that is outside the preferred range.
In 500 ml of distilled water 21.53 g Mn(NO.sub.3).sub.2.6H.sub.2 O, 17.94 g Zn(NO.sub.3).sub.2.6H.sub.2 O and 21.55 g ZrO(NO.sub.3).sub.2..times.H.sub.2 O were dissolved. This solution was added over the course of 30 minutes, with constant stirring, to 600 ml of water held at 70.degree. C. The pH of this 600 ml was initially adjusted to pH 9.0 with LiOH. Over the course of the addition, the addition rate of the transition metal solution and of 1.0 Molar LiOH was controlled to maintain a pH of 9.0. Stirring was continued for five hours at 70.degree. C. The suspension was then allowed to settle and cool overnight. The pale light gray-brown precipitate was isolated by filtration. The filtrate had a pH of 8.72. The solids were resuspended in one liter of distilled water and stirred vigorously for 30 minutes, then recovered by filtration. The pH of the filtrate was 8.04. This washing step was repeated three times and the pH of the filtrates were 7.58, 7.80 and 8.45, respectively. The recovered solids were dried overnight at 130.degree. C., leading to the recovery of 13.5 g of material. The dried material was ground to a fine powder and calcined in air in a tube furnace, the temperature of which was raised from room temperature to 425.degree. C. over the course of two hours, held at 425.degree. C. for two hours and allowed to cool to room temperature over the course of two hours. The material was treated with 20 ml of distilled water in which 0.0814 g of Pd(NO.sub.3).sub.2 was dissolved along with 15 drops of ethanolamine. After thorough mixing, the slurry was dried in a vacuum oven for six hours. The dried material was then calcined in air as follows: the temperature was increased from room temperature to 325.degree. C. over the course of an hour, then held at 325.degree. C. for three hours before cooling to room temperature over the course of two hours.
The BET surface area was 100 m.sup.2 /g, and elemental analysis showed mole fractions of the Mn, Zn, Zr and Li to be respectively 0.4634, 0.2891, 0.2475 and >0.0001. The wt % Pd was 0.23%.
EXAMPLE 22
Preparation of Catalyst H with a Mn:Zn:Zr Ratio of 0.37:0.38:0.25 that is outside the preferred range.
In 500 ml of distilled water 43.06 g Mn(NO.sub.3).sub.2.6H.sub.2 O , 44.55 g Zn(NO.sub.3).sub.2.6H.sub.2 O and 34.69 g ZrO(NO.sub.3).sub.2..times.H.sub.2 O were dissolved, making a solution that was 0.90 Molar in transition metals. This solution added over the course of 30 minutes, with constant stirring to 600 ml of water held at 70.degree. C. The pH of this 600 ml was initially adjusted to pH 9.0 with LiOH. Over the course of the addition, the addition rate of the transition metal solution and of 42.0 g LiOH.H.sub.2 O/liter was controlled to maintain a pH of 9.0. Stirring was continued for five hours at 70.degree. C. The suspension was allowed to cool and settle overnight. The precipitate was isolated by filtration. The filtrate had a pH of 9.43. The solids were resuspended in one liter of distilled water and stirred vigorously for 30 minutes, then recovered by filtration. The pH of the filtrate was 8.98. This washing step was repeated twice. The pH of the second filtrate was 8.61 and that of the final filtrate was 7.72. The solids were dried overnight at 130.degree. C. 35.63 g of dried, brownish black solid were recovered. This material was ground to a fine powder. A portion of this material was calcined in air in a tube furnace, the temperature of which was raised from room temperature to 425.degree. C. over the course of two hours, held at 425.degree. C. for two hours and allowed to cool to room temperature over the course of two hours. 20.16 g of cooled calcined solids were treated with 10 ml of distilled water in which 0.1263 g of Pd(NO.sub.3).sub.2 was dissolved along with 20 drops of ethanolamine. After through mixing, the slurry was dried in a vacuum oven for six hours. After drying, the Pd-loaded solids were calcined in air, the temperature of which was raised from room temperature to 425.degree. C. over the course of two hours, held at 425.degree. C. for two hours and allowed to cool to room temperature over the course of two hours. The resulting material had a bulk atomic ratio of Mn to Zn to Zr to Li of 0.3675, 0.381, 0.2491 and 0.001476 respectively.
EXAMPLE 23
Preparation of Catalyst I with an Mn:Zn:Zr:Li ratio of 0.25:0.00:0.65:0.10 that is without Zn and thus outside the preferred range.
In 500 ml of distilled water 41.0 g of 50% Mn(NO.sub.3).sub.2.6H.sub.2 O solution and 58.0 g ZrO(NO.sub.3).sub.2..times.H.sub.2 O were dissolved. This solution was added at the rate of 200 drops/minute to 1000 mls of distilled water, the pH of which had previously been adjusted to 9.0 through the drop-wise addition of 2.0 Molar LiOH solution. The pH of the mixture was maintained at 9.0 through the continuous addition of 2.0 Molar LiOH solution. The mixture temperature was maintained at about 70.degree. C. throughout the addition. The slurry containing the precipitate was aged overnight at 70.degree. C. The solids were then recovered by filtration and the filtrate had a pH of 6.98. The solids were resuspended in one liter of distilled water and stirred vigorously for 30 minutes before filtering. The filtrate had a pH of 6.36. The washing step was repeated and the final filtrate had a pH of 6.01. The gelatinous brownish maroon solid was dried overnight at 130.degree. C. 19.25 g of solids were recovered. These were finely ground and calcined at 425.degree. C. as in example above. 5 g of this solid were loaded with Pd as above. The Pd-loaded and dried catalyst was heated in air with the temperature increased from ambient to 325.degree. C. over the course of one hour. The temperature was held at 325.degree. C. for three hours, then cooled over the course of one hour.
This material had a surface area of about 206 m.sup.2 /g, and the ratio of mole fraction of Mn, Zr and Li respectively was 0.2467, 0.6487 and 0.1041. The Pd loading was 0.23 wt %.
EXAMPLE 24
Preparation of Catalyst J with a Mn:Zn:Zr:Li ratio of 0.33:0.00:0.63:0.04 that is without Zn and thus outside the preferred range.
In 500 ml of distilled water 41.1 g Mn(NO.sub.3).sub.2.6H.sub.2 O, and 115.6 g ZrO(NO.sub.3).sub.2..times.H.sub.2 O were dissolved and added drop-wise to 500 ml of water adjusted to pH 9.0 with LiOH. 42.0 g of LiOH.H.sub.2 O dissolved in 1000 ml of water was simultaneously added drop-wise (at about 1 drop per second) to the initial 500 ml so as to attempt to maintain a constant pH of 9.0. The temperature of the slurry was between about 60.degree. C. and about 65.degree. C. during the precipitation. The pinkish brown slurry was stirred overnight at 65.degree. C. The recovered precipitate was washed three times with two liters of distilled water and air dried for about 60 hours before calcining.
20 g of the solid were loaded with Pd as follows: 0.1240 g of Pd(NO.sub.3).sub.2.2H.sub.2 O were dissolved in 20 ml of water along with 24 to 30 drops of ethanolamine. This was thoroughly mixed with 20.0 g of the calcined mixed oxide and dried in a 130.degree. C. vacuum oven for three hours prior to calcination. The Pd-loaded and dried catalyst was heated in air with the temperature increased from ambient to 325.degree. C. over the course of one hour. The temperature was held at 325.degree. C. for three hours, then cooled over the course of one hour.
This material had a surface area of about 92 m.sup.2 /g, and the ratio of mole fraction of Mn, Zr and Li respectively was 0.3293, 0.6288 and 0.0418. The Pd loading was 0.24 wt %.
EXAMPLE 25
Preparation of Catalyst K, ZnMn.sub.2 O.sub.4, a composition outside the scope of this invention with a Mn:Zn:Zr Ratio of 0.68:0.32:0.00.
In 500 ml of distilled water 57.41 g Mn(NO.sub.3).sub.2.6H.sub.2 O and 29.70 g Zn(NO.sub.3).sub.2.6H.sub.2 O were dissolved, making a solution that was 0.6 Molar in transition metals with a pH of 2.32. This solution was added over the course of 30 minutes, with constant stirring to 600 ml of water held at 70.degree. C. along with a 2.0 Molar LiOH solution. The pH of this 600 ml was initially adjusted to pH 9.0 with LiOH. Over the course of the addition, the addition rate of the transition metal solution and of 2.0 Molar LiOH was controlled to maintain a pH of 9.0. Stirring was continued for five hours at 70.degree. C., then left unstirred to cool overnight. A creamy white gel resulted. The precipitate was isolated by filtration. The filtrate had a pH of 7.27. On resuspension the solid darkened to orange brown. The filtrate from this washing had a pH of 7.79. After the second washing the recovered air-dried orange brown powder was calcined directly, the temperature of which was raised from room temperature to 425.degree. C. over the course of two hours, held at 425.degree. C. for two hours and allowed to cool to room temperature over the course of two hours. 13.79 g of dry material were recovered. 14.81 g of this material were treated with 10 ml of distilled water in which 0.0927 g of Pd(NO.sub.3).sub.2 was dissolved along with 15 drops of ethanolamine. After thorough mixing, the slurry was dried in a vacuum oven for 1.25 hours, then calcined in air. Over the course of an hour, the temperature was increased from room temperature to 325.degree. C., then held at 325.degree. C. for three hours before cooling to room temperature over the course of two hours.
The BET surface area was 35.7 m.sup.2 /g, and elemental analysis showed mole fractions of the Mn, Zn and Li to be respectively 0.6766, 0.3230 and 0.0001. The wt % Pd was 0.21%.
Table 9 shows the composition and surface area of catalysts. Composition is by relative atomic fraction of the metallic elements in the mixed metal oxide phase(s) of the catalyst analyzed in the protocatalyst. "MMF" means metal mold fraction. Preferred versions of our patent are designated A, B, and C.
TABLE 9__________________________________________________________________________Catalyst Composition Surface AreaMn Zn Zr Li Zr/ Zn/ BETMMF MMF MMF MMF (Mn + Zr) (Mn + Zr) m.sup.2 /g__________________________________________________________________________A 0.3841 0.2592 0.2954 0.061255 0.4347 0.3815 74.1B 0.3857 0.2706 0.3428 0.000963 0.4706 0.3714 75.1C 0.4202 0.2914 0.2884 -- 0.4288 0.3838 72.1D 0.4023 0.2823 0.3154 -- 0.4395 0.3933 78.8E 0.5390 0.2892 0.1674 0.004428 0.2370 0.4094 59.0F 0.2663 0.2184 0.5116 0.003681 0.6577 0.2808 112.2G 0.4634 0.2891 0.2475 -- 0.3482 0.4067 100.0H 0.3675 0.3819 0.2491 0.001476 0.4040 0.6194 --I 0.2467 0.0000 0.6487 0.104117 0.7253 0.0000 206.2J 0.3293 0.0000 0.6288 0.041848 0.6563 0.0000 91.9K 0.6766 0.3230 0.0000 0.0001 0.0000 0.4773 35.7L 0.4165 0.2925 0.2910 -- 0.5000 0.5000 67.9__________________________________________________________________________
EXAMPLE 26
Table 10 is a comparison of the performance of second stage catalysts within the scope of this present invention with Catalyst E, a composition outside the scope of the present invention. Reaction conditions were 3.00 cm.sup.3 of 60 to 80 mesh catalyst volume in the copper-lined reactor tube, about 6500 kPa, 44% CO, 39.4% H.sub.2, 6.6% CO.sub.2 and 10.0% Ar synthesis gas, into which was vaporized at a rate of 0.8 liquid hourly space velocity a mixture of 90.00 wt % methanol, 9.56 wt % ethanol and 0.44 % water. Contact time is in seconds. Temperature is in .degree.C. iBuOH=isobutanol, MBuOH=methyl butanols, nPrOH=n-propanol, EtOH=ethanol. Others=other liquid products, including: n-butanol, n-pentanol, methyl pentanols, etc. CNV=ethanol conversion.
TABLE 10__________________________________________________________________________Catalyst C.sub.2 + Liquid ProductMn:Zn:Zr Reactor Contact CNV Composition, Weight %Atomic Fractions Temp. Time % iBuOH MBuOH nPrOH EtOH Others__________________________________________________________________________A 380 9.5 99.5 75 4 10 0.3 110.384:0.259:0.295 360 13.6 98.0 76 7 8 0.7 92M LiOH, 70.degree. C. ppt 340 13.3 94.6 75 8 5 4 8 320 13.2 61.9 36 5 20 30 9C 380 12.6 99.5 72 7 6 0.4 150.420:0.291:0.288 340 13.5 91.5 66 12 11 6 51M LiOH 70.degree. C. pptD 380 12.6 99.4 72 7 8 0.4 130.402:0.282:0.315 340 13.5 86.4 59 10 14 10 71M LiOH 25.degree. C. pptE 380 14.4 98.8 81 5 2 0.8 100.384:0.286:0.164 360 13.1 83.6 67 7 7 12 81M LiOH 70.degree. C. ppt 340 13.5 81.8 56 7 16 13 7__________________________________________________________________________
EXAMPLE 27
Table 11 is a further comparison of preferred second stage catalysts to other Pd loaded Mn:Zn:Zr mixed oxide catalysts. Reaction conditions were 3.00 cm.sup.3 of 60 to 80 mesh catalyst volume in the copper lined reactor tube, about 6500 kPa, 44% CO, 39.4% H.sub.2, 6.6 % CO.sub.2 and 10.0% Ar synthesis gas, into which was vaporized at a rate of 0.8 liquid hourly space velocity a mixture of 90.00 wt % methanol, 9.56 wt % ethanol and 0.44% water. Temperature is in .degree.C. iBuOH=isobutanol, MBuOH=methyl butanols, nPrOH=n-propanol, EtOH=ethanol. Others=other liquid products, including: n-butanol, n-pentanol, methyl pentanols, etc. CNV=ethanol conversion.
TABLE 11__________________________________________________________________________ C.sub.2 + Liquid Product Composition, Weight %Catalyst T.degree. C. CNV iBuOH MBuOH nPrOH EtOH Others__________________________________________________________________________A 380 99.5 75 4 10 0.3 110.384:0.259:0.295 360 98.0 76 7 8 0.7 92M LiOH, 70.degree. C. ppt 340 94.6 75 8 5 4 8 320 61.9 36 5 20 30 9C 380 99.5 72 7 6 0.4 150.420:0.291:0.288 340 91.5 66 12 11 6 51M LiOH 25.degree. C. pptD 380 99.4 72 7 8 0.4 130.402:0.282:0.315 340 86.4 59 10 14 10 71M LiOH 70.degree. C. pptE 380 98.8 81 5 2 0.8 100.384:0.286:0.164 360 83.6 67 7 7 12 81M LiOH 70.degree. C. pptF 380 99.6 74 7 5 <1 130.266:0.218:0.512 340 77.7 48 8 16 17 11G 380 99.5 70 7 7 <1 150.463:0.289:0.247 350 72.0 41 9 19 22 8H 380 95.7 72 6 7 <1 140.367:0.382:0.249 340 82.6 48 9 16 16 11__________________________________________________________________________
EXAMPLE 28
Table 12 is a comparison of Mn:Zn:Zr catalysts to catalysts lacking either Zn or Zr. Reaction conditions were 3.00 cm.sup.3 of 60 to 80 mesh catalyst volume in the copper-lined reactor tube, about 6500 kPa, 44% CO, 39.4% H.sub.2, 6.6% CO.sub.2 and 10.0% Ar synthesis gas, into which is vaporized at a rate of 0.8 liquid hourly space velocity a mixture of 90.00 wt % methanol, 9.56 wt % ethanol and 0.44% water. Contact time is in seconds. Temperature is in .degree.C. iBuOH=isobutanol, MBuOH=methyl butanols, nPrOH=n-propanol, EtOH=ethanol. Others=other liquid products, including: n-butanol, n-pentanol, methyl pentanols, etc. CNV =ethanol conversion
TABLE 12__________________________________________________________________________ C.sub.2 + Liquid Product Composition, Weight %Catalyst T.degree. C. CNV iBuOH MBuOH nPrOH EtOH Others__________________________________________________________________________A 380 99.5 75 4 10 0.3 110.384:0.259:0.295 360 98.0 76 7 8 0.7 92M LiOH, 70.degree. C. ppt 340 94.6 75 8 5 4 8 320 61.9 36 5 20 30 9I 380 99.5 72 5 9 0.3 130.247:0.000:0.649 360 94.5 73 6 6 4 1 340 59.8 36 6 21 32 4J 380 97.4 74 6 6 2 120.25% Pd 360 86.0 63 6 11 10 90.329:0.629 340 56.6 36 5 17 35 6K 380 93.9 72 7 9 4 7ZnMn.sub.2 O.sub.4 340 28.7 17 0 20 63 00.677:0.323:0.000__________________________________________________________________________
EXAMPLE 29
Table 13 is a comparison of the preferred second stage catalysts of this invention, Pd on Mn:Zn:Zr mixed oxide catalysts, to literature catalysts. Reaction conditions were 3.00 cm.sup.3 of 60 to 80 mesh catalyst volume in the copper lined reactor tube, about 6500 kPa, 44% CO, 39.4% H.sub.2, 6.6% CO.sub.2 and 10.0% Ar synthesis gas, into which was vaporized at a rate of 0.8 liquid hourly space velocity a mixture of 90.00 wt % methanol, 9.56 wt % ethanol and 0.44% water. Temperature is in .degree.C. iBuOH=isobutanol, MBuOH=methyl butanols, nPrOH=n-propanol, EtOH=ethanol. Others=other liquid products including n-butanol, n-pentanol, methyl pentanols etc. CNV=ethanol conversion.
TABLE 13__________________________________________________________________________ C.sub.2 + Liquid ProductCatalyst Hrs on Composition, Weight %MMF; Mn:Zn:Zr T.degree. C. Line CNV iBuOH MBuOH nPrOH EtOH Others__________________________________________________________________________A 380 87 99.5 75 4 10 0.3 110.384:0.259:0.295 360 111 98.0 76 7 8 0.7 92M LiOH, 70.degree. C. ppt 340 120 94.6 75 8 5 4 8 320 135 61.9 36 5 20 30 9CeC.sub.2 Alfa 380 119 82.1 56 4 21 12 7 360 143 32.6 16 3 19 59 3MgO 380 2 88.1 70 2 18 8 1 380 28 65.4 40 2 30 27 12__________________________________________________________________________
EXAMPLE 30
Table 14 shows the impact of time under syngas at about 380.degree. C. on the conversion of a second stage protocatalyst into a catalyst. Reaction conditions: 3.00 cm.sup.3 of 60 to 80 mesh catalyst volume in the copper lined reactor tube, about 6500 kPa, 44% CO, 39.4% H.sub.2, 6.6% CO.sub.2 and 10.0% Ar synthesis gas, into which is vaporized at a rate of 0.8 liquid hourly space velocity a mixture of 90.00 wt % methanol, 9.56 wt % ethanol and 0.44% water. Temperature is in .degree.C. Hours is hours at 380.degree. C. under syngas. iBuOH=isobutanol, MBuOH=methyl butanols, nPrOH=n-propanol, EtOH=ethanol. Others=other liquid products, including: n-butanol, n-pentanol, methyl pentanols etc. CNV=ethanol conversion.
TABLE 14__________________________________________________________________________ C.sub.2 + Liquid ProductCatalyst Composition, Weight %MMF; Mn:Zn:Zr T.degree. C. Hrs CNV iBuOH MBuOH nPrOH EtOH Others__________________________________________________________________________A 380 87 99.5 75 4 10 0.3 110.384:0.259:0.295 360 111 98.0 76 7 8 0.7 92M LiOH, 70.degree. C. ppt 340 120 94.6 75 8 5 4 8 320 135 61.9 36 5 20 30 9C 380 89 99.5 72 7 6 0.4 150.420:0.291:0.288 340 112 91.5 66 12 11 6 5C 340 18 85.4 57 9 13 11 100.420:0.291:0.2881M LiOH 70.degree. C. ppt__________________________________________________________________________
EXAMPLE 31
This example illustrates the two step conversion of synthesis gas into isobutanol and methyl butanols using the novel first and second stage catalysts of this invention. Two reactors are arranged in series, connected by a steam jacketed copper-lined gas transfer tube. At the inlet of the second reactor there is a line leading to a pump and reservoir such that additional liquid can be added and vaporized. The second reactor tube is connected to a liquid product knockout section cooled to -10.degree. C.
The first reactor is charged with 10 cm.sup.3 of catalyst and 20 cm.sup.3 of inert high purity crushed fused quartz as in Example 8. It is brought on-line as in Example 8 with its product gas going to vent until the second reactor in the series as ready to receive it. Sufficient catalyst is prepared as in Example 9 to charge the copper-lined and jacked reactor tube with an I.D. of 1.04 cm (0.41 inches) with 10 cm.sub.3 of protocatalyst. The protocatalyst is reduced and activated under synthesis gas thus converting to the catalyst as in Example 9. After activation, its temperature is decreased to 350.degree. C. and the effluent stream from the first reactor, the composition of which is shown in Table 8 is allowed to flow over the catalyst in the second reactor such that its exit pressure was about 900 psig or about 6200 kPa. With the first reactor fed 1 to 1 hydrogen/CO synthesis gas at a space velocity of 12,000, the liquid product from the second reactor produced at a rate of 995 grams/liter of catalyst volume/hour has the following composition in wt %: 70.0% methanol, 0.5% ethanol, 1.2% n-propanol, 17.5% isobutanol, 4.2% methyl butanols and 6.6% other compounds, primarily oxygenates including n-butanol and methyl pentanols. This liquid represents 94.8% of all the carbon containing products other than CO.sub.2, with the balance being 1.5% methane and 3.7% C.sub.2 through C.sub.5 hydrocarbons. Of the C.sub.2 + liquids, the isobutanol methyl butanol fraction represents 72 wt %.
EXAMPLE 32
In this example, the two reactors are charged and operated as in Example 29, but the liquid product is distilled into a methanol fraction, an ethanol, n-propanol fraction and an isobutanol, methyl pentanol and heavier fraction. The ethanol, n-propanol fraction is then fed via a feed pump into the second stage reactor such that it is vaporized and mixed with the effluent from the first stage reactor before contacting the second stage catalyst. In this example with ethanol and n-propanol recycled, the isobutanol productivity increased 10.3% from 174 g/l hour without recycle to 192 g/l hour recycle and similarly the productivity of methyl butanols increased 5.7% from 41.9 g/l hour without recycle to 44.9 g/l/hour. The liquid product minus the recycled ethanol and n-propanol is produced at a rate of 998 g/l hour and contains in wt % 69.7% methanol, 19.2% isobutanol, 4.4% methyl butanols and 6.7% others.

Number	Name	Date
3972952	Clark	Aug 1976
4681868	Budge et al.	Jul 1987
4843101	Klier et al.	Jun 1989
4935538	Budge et al.	Jun 1990
5095156	Radlowski et al.	Mar 1992

Number	Date	Country
1159435	Dec 1983	CAX
034338A2	Aug 1981	EPX

Isoalcohol synthesis

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J. C. Slaa et al., Catalysis Today, 15 (1992) 129-148.
Wilhelm Keim et al., Catalysis Letters 3 (1989) 59-64.
Wataru Ueda et al., Catalysis Letters 12 (1992) 97-104.