Patent Application
20080071120
In a preferred embodiment, the present invention accordingly provides a process as described in which the oxidic material comprises
(a) copper oxide in a proportion in the range 50≦x≦80% by weight, preferably 55≦x≦75% by weight,
(b) aluminum oxide in a proportion in the range 15≦y≦35% by weight, preferably 20≦y≦30% by weight, and
(c) iron oxide in a proportion in the range 1≦z≦30% by weight, preferably 2≦z≦25% by weight,
in each case based on the total weight of the oxidic material after calcination, where 80≦x+y+z≦100,in particular 95≦x+y+z≦100.
The process of the present invention and the catalysts of the present invention are distinguished by the fact that the addition of iron in the precipitation leads to a high stability of the shaped body used as catalyst.
In general, the amount of pulverulent copper, copper flakes or pulverulent cement or graphite or a mixture thereof added to the oxidic material is in the range from 1 to 40% by weight, preferably in the range from 2 to 20% by weight and particularly preferably in the range from 3 to 10% by weight, in each case based on the total weight of the oxidic material.
As cement, preference is given to using an alumina cement. The alumina cement particularly preferably consists essentially of aluminum oxide and calcium oxide, in particular it comprises from about 75 to 85% by weight of aluminum oxide and from about 15 to 25% by weight of calcium oxide. It is also possible to use a cement based on magnesium oxide/aluminum oxide, calcium oxide/silicon oxide and calcium oxide/aluminum oxide/iron oxide.
In particular, the oxidic material may further comprise a proportion of not more than 10% by weight, preferably not more than 5% by weight, based on the total weight of the oxidic material, of at least one additional component selected from the group consisting of the elements Re, Fe, Ru, Co, Rh, Ir, Ni, Pd and Pt.
In a further preferred embodiment of the process of the invention, graphite is added in addition to the copper powder, the copper flakes or the cement powder or the mixture thereof to the oxidic material prior to shaping to form the shaped body. Preference is given to adding such an amount of graphite that shaping to form a shaped body can be carried out more readily. In a preferred embodiment, from 0.5 to 5% by weight of graphite, based on the total weight of the oxidic material, is added. Here, it is immaterial whether the graphite is added to the oxidic material before or after or simultaneously with the copper powder, the copper flakes or the cement powder or the mixture thereof.
The present invention accordingly also provides a process as described above in which graphite in an amount of from 0.5 to 5% by weight, based on the total weight of the oxidic material, is added to the oxidic material or the mixture resulting from (ii).
In a preferred embodiment, the present invention therefore also provides a shaped body comprising
an oxidic material comprising
(a) copper oxide in a proportion in the range 50≦x≦80% by weight, preferably 55≦x≦75% by weight,
(b) aluminum oxide in a proportion in the range 15≦y≦35% by weight, preferably 20≦y≦30% by weight, and
(c) iron oxide in a proportion in the range 1≦z≦30% by weight, preferably 2≦z≦25% by weight,
in each case based on the total weight of the oxidic material after calcination, where 80≦x+y+z≦100, in particular 95≦x+y+z 100, metallic copper powder, copper flakes or cement powder or a mixture thereof in a proportion in the range from 1 to 40% by weight, based on the total weight of the oxidic material, and
graphite in a proportion of from 0.5 to 5% by weight, based on the total weight of the oxidic material,
where the sum of the proportions of oxidic material, metallic copper powder, copper flakes or cement powder or a mixture thereof and graphite makes up at least 95% by weight of the shaped body.
After addition of the copper powder, the copper flakes or the cement powder or the mixture thereof and, if desired, graphite to the oxidic material, the shaped body obtained after shaping is, if desired, calcined at least once for a period of generally from 0.5 to 10 hours, preferably from 0.5 to 2 hours. The temperature in this calcination step or steps is generally in the range from 200 to 600° C., preferably in the range from 250 to 500° C. and particularly preferably in the range from 270 to 400° C.
In the case of shaping using cement powder, it may be advantageous to moisten the shaped body obtained before calcination with water and subsequently to dry it.
When the shaped body is used as catalyst in the oxidic form, it is prereduced by means of reducing gases, for example hydrogen, preferably hydrogen/inert gas mixtures, in particular hydrogen/nitrogen mixtures, at from 100 to 500° C., preferably from 150 to 350° C. and in particular from 180 to 200° C., prior to being brought into contact with the hydrogenation solution. This is preferably carried out using a mixture having a hydrogen content in the range from 1 to 100% by volume, particularly preferably in the range from 1 to 50% by volume.
In a preferred embodiment, the shaped body of the invention is activated in a manner known per se by treatment with reducing media prior to use as catalyst. The activation is carried out either beforehand in a reduction oven or after installation in the reactor. If the reactor has been activated beforehand in the reduction oven, it is installed in the reactor and supplied directly with the hydrogenation solution under hydrogen pressure.
A preferred area of application of the shaped bodies produced by the process of the present invention is the hydrogenation of organic compounds containing carbonyl groups in a fixed bed. However, other embodiments such as a fluidized-bed reaction using catalyst material in upward and downward swirling motion are likewise possible. The hydrogenation can be carried out in the gas phase or in the liquid phase. The hydrogenation is preferably carried out in the liquid phase, for example in the downflow mode or upflow mode.
When the hydrogenation is carried out in the downflow mode, the liquid starting material comprising the carbonyl compound to be hydrogenated is allowed to trickle over the catalyst bed in the reactor which is under hydrogen pressure, forming a thin liquid film on the catalyst. On the other hand, when the hydrogenation is carried out in upflow mode, hydrogen is introduced into the reactor flooded with the liquid reaction mixture and the hydrogen passes through the catalyst as rising gas bubbles.
In one embodiment, the solution to be hydrogenated is pumped over the catalyst bed in a single pass. In another embodiment of the process of the present invention, part of the product is continuously taken off as product stream after passing through the reactor and, if desired, is passed through a second reactor as defined above. The other part of the product is combined with fresh starting material comprising the carbonyl compound and fed back into the reactor. This mode of operation will hereinafter be referred to as the circulation mode.
If the downflow mode is chosen as embodiment of the present invention, the circulation mode is preferred. Further preference is given to carrying out the hydrogenation in the circulation mode using a main reactor and an after-reactor.
The process of the present invention is suitable for the hydrogenation of carbonyl compounds such as aldehydes and ketones, carboxylic acids, carboxylic esters or carboxylic anhydrides to give the corresponding alcohols, with preference being given to aiphatic and cycloaliphatic, saturated and unsaturated carbonyl compounds. In the case of aromatic carbonyl compounds, formation of undesirable by-products by hydrogenation of the aromatic ring may occur. The carbonyl compounds may bear further functional groups such as hydroxy or amino groups. Unsaturated carbonyl compounds are generally hydrogenated to the corresponding saturated alcohols. The term “carbonyl compounds” used in the context of the invention encompasses all compounds containing a C═O group, including carboxylic acids and their derivatives. Of course, it is also possible to hydrogenate mixtures of two or more carbonyl compounds. Furthermore, each individual carbonyl compound to be hydrogenated can also contain more than one carbonyl group.
The process of the present invention is preferably used for the hydrogenation of aliphatic aldehydes, hydroxyaldehydes, ketones, acids, esters, anhydrides, lactones and sugars.
Preferred aliphatic aldehydes are branched and unbranched, saturated and/or unsaturated aliphatic C2-C30-aldehydes, which are obtainable, for example, by means of the oxo process from linear or branched olefins having internal or terminal double bonds. It is also possible to hydrogenate oligomeric compounds containing more than 30 carbonyl groups.
Examples of aliphatic aldehydes are:
Formaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, valeraldehyde, 2-methylbutyraldehyde, 3-methylbutyraldehyde (isovaleraldehyde), 2,2-dimethylpropionaldehyde (pivalaldehyde), caproaldehyde, 2-methylvaleraldehyde, 3-methylvaleraldehyde, 4-methylvaleraldehyde, 2-ethylbutyraldehyde, 2,2-dimethylbutyraldehyde, 3,3-dimethylbutyraldehyde, caprylic aldehyde, capric aldehyde, glutaraldehyde.
Apart from the short-chain aldehydes mentioned, long-chain aliphatic aldehydes as can be obtained, for example, by means of the oxo process from linear α-olefins, are also particularly suitable.
Particular preference is given to enalization products such as 2-ethylhexenal, 2-methylpentenal, 2,4-diethyloctenal or 2,4-dimethylheptenal.
Preferred hydroxyaldehydes are C3-C12-hydroxyaldehydes as are obtainable, for example, from aliphatic and cycloaliphatic aldehydes and ketones by aldol reaction with themselves or formaldehyde. Examples are 3-hydroxypropanal, dimethylolethanal, trimethylol-ethanal (pentaerythrital), 3-hydroxybutanal (acetaldol), 3-hydroxy-2-ethylhexanal (butyl aldol), 3-hydroxy-2-methylpentanal (propane aldol), 2-methylolpropanal, 2,2-dimethylolpropanal, 3-hydroxy-2-methylbutanal, 3-hydroxypentanal, 2-methylolbutanal, 2,2-dimethylolbutanal, hydroxypivalaldehyde. Particular preference is given to hydroxypivalaldehyde (HPA) and dimethylolbutanal (DMB).
Preferred ketones are acetone, butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, cyciohexanone, isophorone, methyl isobutyl ketone, mesityl oxide, acetophenone, propiophenone, benzophenone, benzal-acetone, dibenzalacetone, benzalacetophenone, 2,3-butanedione, 2,4-pentanedione, 2,5-hexanedione and methyl vinyl ketone.
Furthermore, carboxylic acids and derivatives thereof, preferably those having 1-20 carbon atoms, can be reacted In particular, the following may be mentioned:
carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, n-valeric acid, trimethylacetic acid (“pivalic acid”), caproic acid, enanthic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, acrylic acid, methacrylic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, cyclohexanecarboxylic acid, benzoic acid, phenylacetic acid, o-toluic acid, m-toluic acid, p-toluic acid, o-chlorobenzoic acid, p-chlorobenzoic acid, o-nitrobenzoic acid, p-nitrobenzoic acid, salicylic acid, p-hydroxybenzoic acid, anthranilic acid, p-aminobenzoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid;
carboxylic esters such as the C1-C10-alkyl esters of the abovementioned carboxylic acids, in particular methy formate, ethyl acetate, butyl butyrate, dialkyl esters of phthalic acid, isophthalic acid, terephthalic acid, adipic acid and maleic acid, e.g. the dimethyl esters of these acids, methyl (meth)acrylate, butyrolactone, caprolactone and polycarboxylic esters, e.g. polyacrylic and polymethacrylic esters and their copolymers, and polyesters, e.g. polymethyl methacrylate or terephthalic esters, and other industrial plastics; in these cases, the reactions carried out are, in particular, hydrogenolyses, i.e. the reaction of esters to form the corresponding acids and alcohols;
fats;
carboxylic anhydrides such as the anhydrides of the abovementioned carboxylic acids, in particular acetic anhydride, propionic anhydride, benzoic anhydride and maleic anhydride;
carboxamides such as formamide, acetamide, propionamide, stearamide, terephthalamide.
It is also possible for hydroxycarboxylic acids, e.g. lactic, malic, tartaric or citric acid, or amino acids, e.g. glycine, alanine, proline and arginine, and peptides to be reacted.
As particularly preferred organic compounds saturated or unsaturated carboxylic acids, carboxylic esters, carboxylic anhydrides or lactones or mixtures of two or more thereof are hydrogenated.
The present invention therefore also provides a process as described above in which the organic compound is a carboxylic acid, a carboxylic ester, a carboxylic anhydride or a lactone.
Examples of these compounds are, inter alia, maleic acid, maleic anhydride, succinic acid, succinic anhydride, adipic acid, 6-hydroxycaproic acid, 2-cyclododecylpropionic acid, the esters of the abovementioned acids, for example the methyl, ethyl propyl or butyl ester. Further examples are γ-butyro-lactone and caprolactone.
In a very particularly preferred embodiment, the present invention provides a process as described above in which the organic compound is adipic acid or an ester of adipic acid.
The carbonyl compound to be hydrogenated can be fed to the hydrogenation reactor either alone or as a mixture with the product of the hydrogenation reaction, and can be fed in in undiluted form or using an additional solvent. Suitable additional solvents are, in particular, water and alcohols such as methanol, ethanol and the alcohol formed under the reaction conditions. Preferred solvents are water, THF and NMP; particular preference is given to water.
The hydrogenation both in the upflow mode and in the downflow mode, in each case preferably in the circulation mode, is generally carried out at from 50 to 350° C., preferably from 70 to 300° C., particularly preferably from 100 to 270° C., and a pressure in the range from 3 to 350 bar, preferably in the range from 5 to 330 bar, particularly preferably in the range from 10 to 300 bar.
In a very particularly preferred embodiment, the catalysts of the present invention are used in processes for preparing hexanediol and/or caprolactone, as are described in DE 196 07 954, DE 196 07 955, DE 196 47 348 and DE 196 47 349.
High conversions and selectivities are achieved in the process of the present invention using the catalysts of the present invention. At the same time, the catalysts of the present invention have a high chemical and mechanical stability.
The present invention therefore provides quite generally for the use of pulverulent metallic copper or pulverulent cement or a mixture thereof as additive in the production of a catalyst for increasing both the mechanical stability and the activity and selectivity of the catalyst.
In a preferred embodiment, the present invention provides for the use as described above of such a catalyst comprising copper as active component.
The mechanical stability of solid-state catalysts and specifically the catalysts of the present invention is described by the parameter lateral compressive strength in various states (oxidic, reduced, reduced and suspended under water).
The lateral compressive strength was determined for the purposes of the present patent application by means of a “Z 2.5/T 919” instrument of Zwick (Ulm). In the case of both the reduced catalysts and the used catalysts the measurement were carried out under a nitrogen atmosphere so as to avoid reoxidation of the catalysts.
Production of the Catalyst
A mixture of 12.41 kg of a 19.34% strength copper nitrate solution, 14.78 kg of an 8.12% strength aluminum nitrate solution and 1.06 kg of a 37.58% strength iron nitrate×9H2O solution was dissolved in 1.5 l of water (solution 1. Solution 2 comprises 60 kg of a 20% strength anhydrous Na2CO3. Solution 1 and solution 2 are introduced via separate lines into a precipitation vessel which is provided with a stirrer and contains 10 l of water heated to 80° C. The pH was brought to 6.2 by appropriate adjustment of the feed rates for solution 1 and solution 2.
While keeping the pH constant at 6.2 and maintaining a temperature of 80° C., all of solution 1 was reacted with sodium carbonate. The suspension formed in this way was subsequently stirred for another 1 hour, with the pH being increased to 7.2 by occasional addition of dilute nitric acid or sodium carbonate solution 2. The suspension was filtered and washed with distilled water until the nitrate content of the washings was<10 ppm.
The filter cake was dried at 120° C. for 16 hours and subsequently calcined at 300° C. for 2 hours. The catalyst powder obtained in this way is precompacted with 1% by weight of graphite. The compact obtained is mixed with 5% by weight of Cu flakes from Unicoat and subsequently with 2% by weight of graphite and pressed to form pellets having a diameter of 3 mm and a height of 3 mm. The pellets were finally calcined at 350° C. for 2 hours.
The catalyst produced in this way has the chemical composition 57% CuO/28.5% Al2O3/9.5% Fe2O3/5% Cu.
The lateral compressive strength in the oxidic state was 117 N and in the reduced state was 50 N, as shown in Table 1.
Dimethyl adipate was hydrogenated continuously in the downflow mode with recirculation (feed/recycle ratio=10/1) at a WHSV of 0.3 kg/(l*h), a pressure of 200 bar and reaction temperatures of 190° C. in a vertical tube reactor charged with 200 ml of catalyst 1. The experiment was carried out for a total time of 7 days. GC analysis found ester conversions of 99.9%, a hexanediol selectivity of 97.5% in the reaction product at 190° C. After removal from the reactor, the catalyst was found to be still completely intact and had a high mechanical stability. The experimental results are summarized in Table 1.
The comparative catalyst was produced by a method analogous to that for catalyst 2, but without the addition of the iron nitrate solution: 14.5 kg of a 19.34% strength copper nitrate solution and 14.5 kg of an 3.12% strength aluminum nitrate solution (solution 1) are precipitated by means of sodium carbonate solution in a manner analogous to catalyst 1.
The catalyst produced in this way has the chemical composition 66.5% CuO/28.5% Al2O3/5% Cu. The lateral compressive strength in the oxidic and reduced states is shown in Table 1=
Dimethyl adipate was hydrogenated continuously in the downflow mode with recirculation (feed/recycle ratio=10/1) at a WHSV of 0.3 kg/(l*h), a pressure of 200 bar and reaction temperatures of 190° C. in a vertical tube reactor charged with 200 ml of catalyst 2. The experiment was carried out for a total time of 7 days. GC analysis found ester conversions of 80.2% in each case and hexanediol contents of 86.6% in the reaction product at 220° C. and 240° C., respectively. After removal from the reactor the catalyst was found to be still completely intact and had a high mechanical stability. The experimental results are summarized in Table 1.
The data in Table 1 below show that the catalysts of the present invention have considerably higher hydrogenation activities, i.e. higher conversions of dimethyl adipate, at 190° C. than the comparative catalyst, and also give higher selectivities to the desired product i.e. higher contents of the target products hexanediol in the output from the reactor.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2004 033 554.0 | Jul 2004 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP05/07339 | 7/7/2005 | WO | 00 | 1/5/2007 |
