Patent Application
20150175898
The invention relates to methods of converting oxygenate-containing feedstocks to olefins and/or aromatic hydrocarbons. The method includes a moving bed reactor the use of which enables a reduced amount of recycle, optionally with liquid quenching, particularly interstage liquid quenching.
A variety of industrial processes are known for conversion of low boiling carbon-containing compounds to higher value products. One such process, the so-called “MTG process”, converts methanol and/or dimethyl ether to gasoline-range products. The methanol and/or dimethyl ether are then converted in a series of reactions that results in formation of a hydrocarbon mixture that comprises aromatic, paraffinic, and olefinic compounds. This mixture may be separated into a liquefied petroleum gas (LPG) fraction and a high-quality gasoline fraction comprising aromatics, paraffins, and olefins. The typical MTG hydrocarbon product consists of about olefins and about 50-60% paraffins and 30-50% aromatics, e.g., xylenes, benzene, toluene, etc.
Conventionally, methanol is converted to liquid fuels using either a fixed or fluid bed reactor, and coking is typically not a significant problem in the process. Tubular fixed bed reactors immersed in molten salt have also been proposed. Depending on the design, such reactors have one or more of the following drawbacks, e.g., relatively inconsistent product yields, low methanol utilization, low selectivity to desired products, and low catalyst utilization.
Low catalyst utilization is typically due to catalyst deactivation to which fixed and fluid bed reactors are prone. One mechanism for deactivation mechanism is de-alumination of the zeolite by steam. This deactivation is permanent and determines the overall catalyst life. Steam deactivation is most pronounced at the outlet of the catalyst bed due to higher temperatures, water partial pressures, and lower coke levels which provides less protection for the catalyst from steam deactivation. The end of the catalyst life is determined by the overall activity of the catalyst and at such time the catalyst must be replaced even though the catalyst at the top of the fixed bed is still quite active. This results in only partial catalyst utilization, lower catalyst efficiency and higher catalyst costs.
Fixed bed and fluid beds reactors also suffer from undesirable temperature fluctuations. A fixed bed MTG process is typically run as an adiabatic process, with a significant temperature increase across the catalyst bed because of the exothermic nature of the methanol conversion reaction. Fluctuations in reactor temperature profiles require significant light gas recycle or internal cooling coils to control reactor outlet temperature. Light gas recycle is typically used, but requires significant capital investment in the form of high capacity compressors and heat exchanger systems.
Thus, there is still a need for methods for converting oxygenate-containing feedstocks, e.g., methanol, that address one or more of these deficiencies.
Aspects of the invention are based in part on the discovery that a moving bed reactor may be used in methanol conversion despite the lack of coking. Aspects of the invention additionally or alternatively are based at least in part on the discovery that, over the catalyst life cycle, a moving bed reactor process approximates the end of cycle performance of a fixed bed reactor, where product distribution is desirable. The invention is also based in part on the observation that a moving bed process provides higher feedstock utilization over the catalyst lifetime. The invention is also based in part on the understanding that the use of a moving bed reactor for a highly exothermic reaction can reduce process variability and costly gas recycle, particularly when coupled with liquid quenching of the product at one or more stages of the reaction.
Thus, in one aspect, embodiments of the invention provide a method for organic compound conversion, comprising: a) providing a first mixture comprising ≧10.0 wt % of at least one oxygenate, based on the weight of the first mixture; b) contacting said first mixture in at least a first moving bed reactor with a catalyst under conditions effective to covert at least a portion of the first mixture to a product stream comprising water, hydrogen, and one or more hydrocarbons; and c) separating from said product stream (i) at least one light stream and ii) at least one heavy stream, wherein the method is characterized by a recycle ratio of ≦5.0.
In another aspect, embodiments of the invention provide a method for organic compound conversion, comprising: a) providing a first mixture comprising ≧10.0 wt % of at least one oxygenate, based on the weight of the first mixture; b) contacting said first mixture in a first moving bed reactor with a first catalyst under conditions effective to covert at least a portion of the first mixture to a first product stream comprising a first amount of one or more hydrocarbons; c) contacting said first product stream in a second moving bed reactor with a second catalyst under conditions effective to covert at least a portion of the first product stream to a second product stream comprising water, hydrogen, and a second amount of one or more hydrocarbons; and d) separating from said second product stream (i) at least one light stream, and (ii) at least one heavy stream, wherein the method is characterized by a recycle ratio of ≦5.0.
In yet another aspect, embodiments of the invention provide methods for organic compound conversion, comprising: a) providing a first mixture comprising ≧10.0 wt % of at least one oxygenate, based on the weight of the first mixture; b) contacting said first mixture in a first moving bed reactor with a first catalyst under conditions effective to covert at least a portion of the first mixture to a first product stream comprising water, hydrogen, and a first amount of one or more hydrocarbons; c) contacting said first product stream in a second moving bed reactor with a second catalyst under conditions effective to covert at least a portion of the first product stream to a second product stream comprising water, hydrogen, and a second amount of one or more hydrocarbons; d) contacting said second product stream in a third moving bed reactor with a third catalyst under conditions effective to covert at least a portion of the second product stream to a third product stream comprising water, hydrogen, and a third amount of one or more hydrocarbons; and e) separating from said third product stream (i) at least one hydrocarbon-enriched hydrocarbon stream, and (ii) at least one heavy stream, wherein the method is characterized by a recycle ratio of ≦5.0.
Particular embodiments benefit from the combination of a moving bed reactor and ability to provide a liquid quench of the reactor effluent, particularly an interstage liquid quench where two or more reactors, or reaction zones, are employed.
The present process is useful for the conversion a first mixture comprising oxygen-containing organic compounds (i.e., “oxygenates”) into hydrocarbon products where the conversion is carried out by an exothermic catalytic reaction. In particular the catalytic conversion is conducted in a moving bed reactor, the use of which enables a process having a lower recycle ratio than conventional processes.
For the purposes of this invention and the claims thereto, the numbering scheme for the Periodic Table Groups is used as described in Chemical and Engineering News, 63(5), pg. 27 (1985).
As used herein references to a “reactor” shall be understood to include both distinct reactors as well as reaction zones within a single reactor apparatus. In other words and as is common, a single reactor may have multiple reaction zones. Where the description refers to a first and second reactor, the person of ordinary skill in the art will readily recognize such reference includes a single reactor having first and second reaction zones. Likewise, a first reactor effluent and a second reactor effluent will be recognized to include the effluent from the first reaction zone and the second reaction zone of a single reactor, respectively.
As used herein, the phrases “light stream” and “heavy stream” are relative. A “light stream” will generally have a mean boiling point lower than the mean boiling point of a “heavy stream.” Without limiting the foregoing definition, in some embodiments, the light stream may comprise a majority of molecules having 10 or fewer carbon atoms, e.g., 9 or fewer, 8 or fewer, 7 or fewer, 6 or fewer, 5 or fewer, 4 or fewer, 3, or fewer, 2 or fewer, 1 or fewer, or no carbon atoms.
As used herein the phrase “at least a portion of” means ≧0 to 100.0 wt % of the process stream or composition to which the phrase refers. The phrase “at least a portion of” refers to an amount ≦about 1.0 wt %, ≦about 2.0 wt %, ≦about 5.0 wt %, ≦about 10.0 wt %, ≦about 20.0 wt %, ≦about 25.0 wt %, ≦about 30.0 wt %, ≦about 40.0 wt %, ≦about 50.0 wt %, ≦about 60.0 wt %, ≦about 70.0 wt %, ≦about 75.0 wt %, ≦about 80.0 wt %, ≦about 90.0 wt %, ≦about 95.0 wt %, ≦about 98.0 wt %, ≦about 99.0 wt %, or ≦about 100.0 wt %. Additionally or alternatively, the phrase “at least a portion of” refers to an amount ≧about 1.0 wt %, ≧about 2.0 wt %, ≧about 5.0 wt %, ≧about 10.0 wt %, ≧about 20.0 wt %, ≧about 25.0 wt %, ≧about 30.0 wt %, ≧about 40.0 wt %, ≧about 50.0 wt %, ≧about 60.0 wt %, ≧about 70.0 wt %, ≧about 75.0 wt %, ≧about 80.0 wt %, ≧about 90.0 wt %, ≧about 95.0 wt %, ≧about 98.0 wt %, ≧about 99.0 wt %, or 100.0 wt %.
Ranges expressly disclosed include combinations of any of the above-enumerated values; e.g., 10.0 to 100.0 wt %, 10.0 to 98.0 wt %, 2.0 to 10.0, 40.0 to 60.0 wt %, etc.
As used herein the term “first mixture” means a hydrocarbon-containing composition including one or more oxygenates. Typically, the first mixture comprises ≧10.0 wt % of at least one oxygenate, based on the weight of the first mixture. Thus, the amount of oxygenate(s) in the first mixture may be ≧10.0 wt %, ≧about 12.5 wt %, ≧about 15.0 wt %, ≧about 20.0 wt %, ≧about 25.0 wt %, ≧about 30.0 wt %, ≧about 35.0 wt %, ≧about 40.0 wt %, ≧about 45.0 wt %, ≧about 50.0 wt %, ≧about 55.0 wt %, ≧about 60.0 wt %, ≧about 65.0 wt %, ≧about 70.0 wt %, ≧about 75.0 wt %, ≧about 80.0 wt %, ≧about 85.0 wt %, ≧about 90.0 wt %, ≧about 95.0 wt %, ≧about 99.0 wt %, ≧about 99.5 wt %, or about 100.0 wt %. Additionally or alternatively, the amount of oxygenate in the first mixture may be ≦about 12.5 wt %, ≦about 15.0 wt %, ≦about 20.0 wt %, ≦about 25.0 wt %, ≦about 30.0 wt %, ≦about 35.0 wt %, ≦about 40.0 wt %, ≦about 45.0 wt %, ≦about 50.0 wt %, ≦about 55.0 wt %, ≦about 60.0 wt %, ≦about 65.0 wt %, ≦about 70.0 wt %, ≦about 75.0 wt %, ≦about 80.0 wt %, ≦about 85.0 wt %, ≦about 90.0 wt %, ≦about 95.0 wt %, ≦about 99.0 wt %, ≦about 99.5 wt %, or ≦about 100.0 wt %. Ranges expressly disclosed include combinations of any of the above-enumerated values; e.g., ≧10.0 to about 100.0 wt %, about 12.5 to about 99.5 wt %, about 20.0 to about 90.0, about 50.0 to about 99.0 wt %, etc.
As used herein the term “oxygenate,” oxygenate composition,” and the like refer to oxygen-containing compounds having 1 to about 50 carbon atoms, 1 to about 20 carbon atoms, 1 to about 10 carbon atoms, or 1 to about 4 carbon atoms. Exemplary oxygenates include alcohols, ethers, carbonyl compounds, e.g., aldehydes, ketones and carboxylic acids, and mixtures thereof. Particular oxygenates methanol, ethanol, dimethyl ether, diethyl ether, methylethyl ether, di-isopropyl ether, dimethyl carbonate, dimethyl ketone, formaldehyde, and acetic acid.
In particular embodiments, the oxygenate comprises one or more alcohols, preferably alcohols having 1 to about 20 carbon atoms, 1 to about 10 carbon atoms, or 1 to about 4 carbon atoms. The alcohols useful as first mixtures may linear or branched, substituted or unsubstituted aliphatic alcohols and their unsaturated counterparts. Non-limiting examples of such alcohols include methanol, ethanol, propanols (e.g., n-propanol, isopropanol), butanols (e.g., n-butanol, sec-butanol, tert-butyl alcohol), pentanols, hexanols, etc., and mixtures thereof. In any embodiment described herein, the first mixture may be one or more of methanol, and/or ethanol, particularly methanol. In any embodiment, the first mixture may be methanol and dimethyl ether.
The oxygenate, particularly where the oxygenate comprises an alcohol (e.g., methanol), may optionally be subjected to dehydration, e.g., catalytic dehydration over e.g., γ-alumina. Further optionally, at least a portion of any methanol and/or water remaining in the first mixture after catalytic dehydration may be separated from the first mixture. If desired, such catalytic dehydration may be used to reduce the water content of reactor effluent before it enters a subsequent reactor or reaction zone, e.g., second and/or third reactors as discussed below.
In any embodiment, one or more other compounds may be present in first mixture. Some common or useful such compounds have 1 to about 50 carbon atoms, e.g., 1 to about 20 carbon atoms, 1 to about 10 carbon atoms, or 1 to about 4 carbon atoms. Typically, although not necessarily, such compounds include one or more heteroatoms other than oxygen Some such compounds include amines, halides, mercaptans, sulfides, and the like. Particular such compounds include alkyl-mercaptans (e.g., methyl mercaptan and ethyl mercaptan), alkyl-sulfides (e.g., methyl sulfide), alkyl-amines (e.g., methyl amine), alkyl-halides (e.g., methyl chloride and ethyl chloride). In particular embodiments, the first mixture includes one or more of ≧1.0 wt % acetylene, pyrolysis oil or aromatics, particularly C6 and/or C7 aromatics. Thus, the amount of such other compounds in the first mixture may be ≦about 2.0 wt %, ≦about 5.0 wt %, ≦about 10.0 wt %, ≦about 15.0 wt %, ≦about 20.0 wt %, ≦about 25.0 wt %, ≦about 30.0 wt %, ≦about 35.0 wt %, ≦about 40.0 wt %, ≦about 45.0 wt %, ≦about 50.0 wt %, ≦about 60.0 wt %, ≦about 75.0 wt %, ≦about 90.0 wt %, or ≦about 95.0 wt %. Additionally or alternatively, the amount of such other compounds in the first mixture may be ≧about 2.0 wt %, ≧about 5.0 wt %, ≧about 10.0 wt %, ≧about 15.0 wt %, ≧about 20.0 wt %, ≧about 25.0 wt %, ≧about 30.0 wt %, ≧about 35.0 wt %, ≧about 40.0 wt %, ≧about 45.0 wt %, ≧about 50.0 wt %, ≧about 60.0 wt %, ≧about 75.0 wt %, or ≧about 90.0 wt %. Ranges expressly disclosed include combinations of any of the above-enumerated values; e.g., 1.0 to about 10.0 wt %, about 2.0 to about 5.0 wt %, about 10.0 to about 95.0 wt %, about 15.0 to about 90.0 wt %, about 20.0 to about 75.0 wt %, about 25.0 to about 60 wt %, about 30.0 to about 50 wt %, about 35.0 to about 45 wt %, about 40.0 wt %, etc.
The term “catalyst” as used herein refers to a composition of matter comprising a zeolite and optionally a Group 2-12 element of the Periodic Table. In this sense the term comprising can also mean that the catalyst can comprise the physical or chemical reaction product of the zeolite another compound such as the Group 2-12 element, a filler, and/or binder. The catalyst may be combined with a carrier to form a slurry.
The zeolite employed in the present catalyst composition generally comprises at least one medium pore aluminosilicate zeolite having a Constraint Index of 1-12. The Constraint Index may be ≦about 12.0, ≦about 11.0, ≦about 10.0, ≦about 9.0, ≦about 8.0, ≦about 7.0, ≦about 6.0, ≦about 5.0, ≦about 4.0, ≦about 3.0, or ≦about 2.0. Additionally or alternatively, the Constraint Index may be about ≧about 11.0, ≧about 10.0, ≧about 9.0, ≧about 8.0, ≧about 7.0, ≧about 6.0, ≧about 5.0, ≧about 4.0, ≧about 3.0, ≧about 2.0, or ≧about 1.0. In any embodiment, the Constraint Index may be 1.0 to about 10.0, 1.0 to about 8.0, 1 to about 6.0, 1 to about 5.0, 1 to about 3.0, 2.0 to about 11.0, 3.0 to 10.0, 4.0 to 9.0, or 6.0 to 9.0, etc. Constraint Index is determined as described in U.S. Pat. No. 4,016,218, incorporated herein by reference for details of the method.
Some useful catalysts compositions include a zeolite having a structure wherein there is at least one 10-member ring channel and no channel of rings having more than 10 members. Some such molecular sieves may be referred to as having a framework type or topology of EUO, FER, IMF, LAU, MEL, MRI, MFS, MTT, MWW, NES, PON, SFG, STF, STI, TUN, or PUN. Particularly useful zeolites have a BEA. MFI or MEL framework.
Non-limiting examples of zeolites useful herein include one or a combination of SAPO-5, SAPO-8, SAPO-11, SAPO-16, SAPO-17, SAPO-18, SAPO-20, SAPO-31, SAPO-34, SAPO-35, SAPO-36, SAPO-37, SAPO-40, SAPO-41, SAPO-42, SAPO-44, SAPO-47, and SAPO-56.
Particular other zeolites useful in embodiments of the invention include ZSM-5, ZSM-11; ZSM-12; ZSM-22; ZSM-23; ZSM-34, ZSM-35; ZSM-48; ZSM-57; and ZSM-58. Other useful zeolites may include MCM-22. PSH-3, SSZ-25, MCM-36, MCM-49 or MCM-56, with MCM-22. In any embodiment the zeolite may be ZSM-5 or ZSM-11. ZSM-5 is described in detail in U.S. Pat. No. 3,702,886 and RE 29,948. ZSM-11 is described in detail in U.S. Pat. No. 3,709,979. ZSM-5 is particularly useful.
The catalyst composition can employ the zeolite in its original crystalline form or after formulation into catalyst particles, such as by extrusion. A process for producing zeolite extrudates in the absence of a binder is disclosed in, for example, U.S. Pat. No. 4,582,815, the entire contents of which are incorporated herein by reference. Some processes utilize a hydrothermally stabilized catalyst composition.
Hydrothermally stabilized zeolite catalyst compositions are well-known and are typically stabilized by incorporation of a Group 15 element, particularly phosphorous. The Group 15 element can be incorporated after formulation of the zeolite (such as by extrusion) to form self-bound catalyst particles. Optionally, a self-bound catalyst can be steamed after extrusion. Such compositions are particularly useful where the reactor feed, e.g., first mixture provided to the first reactor, the first product stream provided to the second reactor, and/or the second product stream provided to the third reactor, includes a significant amount of water, e.g., ≧5 wt % H2O. While a hydrothermally stabilized catalyst may be used in any embodiment, such catalyst compositions are also particularly useful where the liquid quench medium is water.
In particular embodiments, the zeolite may be combined with 5.0 to 75.0 wt %, e.g., 10.0 to 65.0 wt %, 20.0 to 55.0 wt %, 25.0 to 45.0 wt %, or 30.0 to 40.0 wt %, of a binder. There are many different binders that are useful in forming the catalyst compositions used herein. Non-limiting examples of binders that are useful alone or in combination include various types of metal oxides, e.g., hydrated alumina, silicas, and/or other inorganic oxide sols. One preferred alumina containing sol is aluminum chlorhydrol. Upon heating, the inorganic oxide sol, preferably having a low viscosity, is converted into an inorganic oxide binder component. For example, an alumina sol will convert to an aluminum oxide binder following heat treatment.
Aluminum chlorhydrol, a hydroxylated aluminum based sol containing a chloride counter ion, has the general formula of AlmOn(OH)oClp.x(H2O) wherein m is 1 to 20, n is 1 to 8, o is 5 to 40, p is 2 to 15, and x is 0 to 30. In one embodiment, the binder is Al13O4(OH)24Cl7.12(H2O) as is described in G. M. Wolterman, et al., Stud. Surf. Sci. and Catal., 76, pages 105 144 (1993), which is herein incorporated by reference. In another embodiment, one or more binders are combined with one or more other non-limiting examples of alumina materials such as aluminum oxyhydroxide, boehmite, diaspore, and transitional aluminas such as α-alumina, β-alumina, γ-alumina. δ-alumina, ε-alumina, κ-alumina, and ρ-alumina, aluminum trihydroxide, such as gibbsite, bayerite, nordstrandite, doyelite, and mixtures thereof.
In some embodiments, the binder is an alumina sol, predominantly comprising aluminum oxide, optionally including some silicon. In yet another embodiment, the binder is peptized alumina made by treating an alumina hydrate, such as pseudobohemite, with an acid, preferably an acid that does not contain a halogen, to prepare a sol or aluminum ion solution. Non-limiting examples of commercially available colloidal alumina sols include Nalco 8676 available from Nalco Chemical Co., Naperville, Ill., and Nyacol AL20DW available from Nyacol Nano Technologies, Inc., Ashland, Mass.
A process for converting an oxygenate-containing first mixture to a hydrocarbon stream containing aromatic molecules in the present of the catalyst described above will now be described.
Moving bed reactor 106 may be operated with a catalyst and under conditions to produce a product stream comprising water, one or more hydrocarbons, and hydrogen. In particular embodiments, the reactor 106 is operated at a weight hourly space velocity (WHSV, g oxygenate/g catalyst/hour) in the range of from 0.50 to 12.0 hr−1. The WHSV may be 0.5 to 11.0 hr−1, 0.5 to 10.0 hr−1, 0.5 to 9.0 hr−1, 0.5 to 7.0 hr−1, 0.5 to 6.0 hr−1, 0.5 to 5.0 hr−1, 0.5 to 4.0 hr−1, 0.5 to 3.0 hr−1, 0.5 to 2.0 hr−1, 0.5 to 1.0 hr−1, 1.0 to 11.0 hr−1, 1.0 to 10.0 hr−1, 1.0 to 9.0 hr−1, 1.0 to 7.0 hr−1, 1.0 to 6.0 hr−1, 1.0 to 5.0 hr−1, 1.0 to 4.0 hr−1, 1.0 to 3.0 hr−1, 1.0 to 2.0 hr−1, 2.0 to 11.0 hr−1, 2.0 to 10.0 hr−1, 2.0 to 9.0 hr−1, 2.0 to 7.0 hr−1, 2.0 to 6.0 hr−1, 2.0 to 5.0 hr−1, 2.0 to 4.0 hr−1, 2.0 to 3.0 hr−1, 3.0 to 11.0 hr−1, 3.0 to 10.0 hr−1, 3.0 to 9.0 hr−1, 3.0 to 7.0 hr−1, 3.0 to 6.0 hr−1, 3.0 to 5.0 hr−1, 3.0 to 4.0 hr−1, 4.0 to 11.0 hr−1, 4.0 to 10.0 hr−1, 4.0 to 9.0 hr−1, 4.0 to 7.0 hr−1, 4.0 to 6.0 hr−1, or about 0.50 hr−1.
Additionally or alternatively, the first mixture comprising the oxygenate is exposed in moving bed reactor 106 to a temperature ≧about 400° C. and a pressure ≧1 bar absolute. In any embodiment, the temperature may be ≧about 425.0° C., ≧about 450.0° C., ≧about 475.0° C., ≧about 500.0° C., ≧about 525.0° C., ≧about 550.0° C., ≧about 600° C., ≧about 650° C., or ≧about 700° C. Additionally or alternatively, the temperature of reactor 106 may be ≦about 425.0° C., ≦about 450.0° C., ≦about 475.0° C., ≦about 500.0° C., ≦about 525.0° C., ≦about 550.0° C., ≦about 600° C., ≦about 650° C., or ≦about 700° C. Ranges of temperatures expressly disclosed include combinations of any of the above-enumerated values. Such temperature ranges may be used in combination with a reactor pressure of about 2.0 to about 500.0 bar absolute. In particular embodiments, the pressure may be ≦about 10.0 bar absolute, ≦about 50 bar absolute, ≦about 75.0 bar absolute, ≦about 100.0 bar absolute, ≦about 125.0 bar absolute, ≦about 150.0 bar absolute, ≦about 175.0 bar absolute, ≦about 200.0 bar absolute, ≦about 250.0 bar absolute, ≦about 300.0 bar absolute, ≦about 350.0 bar absolute, ≦about 400 bar absolute, or ≦about 450 bar absolute. Additionally or alternatively, the pressure may be ≧about 5.0 bar absolute, ≧about 10.0 bar absolute, ≧about 50 bar absolute, ≧about 75.0 bar absolute, ≧about 100.0 bar absolute, ≧about 125.0 bar absolute, ≧about 150.0 bar absolute, ≧about 175.0 bar absolute, ≧about 200.0 bar absolute, ≧about 250.0 bar absolute, 300.0 bar absolute. Ranges and combinations of temperatures and pressures expressly disclosed include combinations of any of the above-enumerated values.
The product stream from reactor 106 is provided via a line 108 to first separation unit 110 for separation into (i) at least one aromatic-rich hydrocarbon stream 112, and (ii) at least one heavy stream 112. First separation unit 110 may be any suitable separation means, e.g., distillation tower, simulated moving-bed separation unit, high pressure separator, low pressure separator, flash drum, etc.
In any embodiment, the recycle ratio may be ≦5.0, e.g. ≦about 4.0, ≦about 3.0, ≦about 2.0, ≦about 1.0, ≦about 0.5. Additionally or alternatively, the recycle ratio may be 0, ≦about 0.25, ≦about 0.5, ≦about 1.0, ≦about 2.0, ≦about 3.0, ≦about 4.0, e.g., 0 to about 5.0, 0 to about 4.0, 0 to about 3.0, 0 to about 2.0, 0 to about 1.0, 0 to about 0.5, or 0 to about 0.25. As used herein the term “recycle ratio” refers to the ratio of the number of moles of gas recycled to the reactor to the total number of moles of oxygenate provided to the reactor. For example, the gas recycled to the reactor may be a stream comprising molecules having 5 or fewer carbon atoms. Due to the highly exothermic nature of the conversion process, such recycle ratios are not sufficient to control reactor temperature within acceptable limits for fixed or fluid bed reactors. The reduction in recycle ratio reduces or eliminates capitally-intensive equipment, e.g., compressors, heat exchangers, etc., needed to implement such higher recycle ratios.
Typically, light stream 112 can be sent for further processing, e.g., to recover the desired aromatic or olefinic molecules therein. In any embodiment, however, at least a portion of hydrocarbon-enriched light stream 112 may optionally be recycled to reactor 106 via recycle line 116, e.g., by combination directly or indirectly with the first mixture in line 102. In particular embodiments, ≧50.0 wt %, 50.0 to 100 wt %, 60.0 to 95.0 wt %, 70.0 to 90.0 wt %, 80.0 to 85.0 wt %, of the first mixture's aromatics can be the recycled aromatics, weight percents being based on the total amount of aromatics in the first mixture. Additionally or alternatively, at least a portion of light stream 112 may be provided via a line 118 to line 108 exiting reactor 106 to quench the product stream. Additionally or alternatively, a liquid quench medium can be provided via line 120. Liquid quench medium provided via line 120 may be any liquid suitable for quenching the reaction, e.g., at least a portion of the light stream, at least a portion of the heavy stream, one or more oxygenates, and/or water.
Additionally or alternatively, at least a portion of heavy stream 114 exiting first separation unit 110 may be recycled to reactor 106, e.g., by combination, directly or indirectly, with line 102 via line 116. While processes having high conversion may not necessarily benefit from doing so, any oxygenates remaining in heavy stream 114 may be recovered therefrom. At least a portion of the recovered oxygenates may thereafter be provided to reactor 106.
With continuing reference to
In embodiments of the invention, first moving bed reactor 106 may be operated at a WHSV greater than or less than that of second moving bed reactor 202. In particular embodiments, the WHSV of the first moving bed reactor 106 can be greater than that of the second moving bed reactor 202. Although it is not critical, in any embodiment, the ratio of the WHSV of the second reactor 202 to the WHSV of the first reactor 106 may be ≧about 40.0, ≧about 35.0, ≧about 30.0, ≧about 25.0, ≧about 20.0, ≧about 15.0, ≧about 10.0, ≧about 5.0, ≧about 2.5, ≧about 2.0, or ≧about 1.5. Additionally or alternatively, the ratio of the WHSV of the second reactor 202 to the WHSV of the first reactor 106 may be ≦about 1.1, ≦about 1.5, ≦about 2.0, ≦about 2.5, ≦about 5.0, ≦about 10.0, ≦about 15.0, ≦about 20.0, ≦about 25.0, ≦about 30.0, ≦about 35.0, ≦about 40.0. Exemplary ranges of the ratio of the WHSV of the first reactor 106 to the WHSV of the second reactor 202 include about 1.1 to about 40.0, about 1.5 to about 35.0, about 2.0 to about 30.0, about 2.5 to about 25.0, about 5.0 to about 20.0, about 10.0 to about 15.0, about 30.0 to about 40.0, about 25.0 to about 40.0, about 20.0 to about 40.0, about 15.0 to about 40.0, about 10.0 to about 40.0, about 5.0 to about 40.0, about 2.5 to about 40.0, about 2.0 to about 40.0, about 1.5 to about 40.0, about 25.0 to about 30.0, about 20.0 to about 30.0, about 15.0 to about 30.0, about 10.0 to about 30.0, about 5.0 to about 30.0, about 2.5 to about 30.0, about 2.0 to about 30.0, about 1.5 to about 30.0, about 1.1 to about 30.0, etc.
The second product stream may be directed from second moving bed reactor 202 via line 204 to separation unit 110. As described with respect to
As described with respect to
With continuing reference to
In embodiments of the invention, second moving bed reactor 202 may be operated at a WHSV greater than or less than that of third moving bed reactor 302. In particular embodiments, the WHSV of the second moving bed reactor 202 is greater than that of the third moving bed reactor 302. Although it is not critical, in any embodiment, the ratio of the WHSV of the second reactor 202 to the WHSV of the third reactor 302 may be ≦about 40.0, ≦about 35.0, ≦about 30.0, ≦about 25.0, ≦about 20.0, ≦about 15.0, ≦about 10.0, ≦about 5.0, ≦about 2.5, ≦about 2.0, or ≦about 1.5. Additionally or alternatively, the ratio of the WHSV of the second reactor 202 to the WHSV of the third reactor 302 may be ≧about 1.1, ≧about 1.5, ≧about 2.0, ≧about 2.5, ≧about 5.0, ≧about 10.0, ≧about 15.0, ≧about 20.0, ≧about 25.0, ≧about 30.0, ≧about 35.0, ≧about 40.0. Exemplary ranges of the ratio of the WHSV of the second reactor 202 to the WHSV of the third reactor 302 include about 1.1 to about 40.0, about 1.5 to about 35.0, about 2.0 to about 30.0, about 2.5 to about 25.0, about 5.0 to about 20.0, about 10.0 to about 15.0, about 30.0 to about 40.0, about 25.0 to about 40.0, about 20.0 to about 40.0, about 15.0 to about 40.0, about 10.0 to about 40.0, about 5.0 to about 40.0, about 2.5 to about 40.0, about 2.0 to about 40.0, about 1.5 to about 40.0, about 25.0 to about 30.0, about 20.0 to about 30.0, about 15.0 to about 30.0, about 10.0 to about 30.0, about 5.0 to about 30.0, about 2.5 to about 30.0, about 2.0 to about 30.0, about 1.5 to about 30.0, about 1.1 to about 30.0, etc.
The third product stream may be directed from third moving bed reactor 302 via line 304 to separation unit 110. As described with respect to
The processes described herein may be used to manufacture a variety of hydrocarbon compositions from the oxygenate-containing first mixture. For example, product stream exiting the first reactor, second and/or third reactors may comprise one or more olefins, typically having from 2 to 30 carbon atoms, 2 to 8 carbon atoms, 2 to 6 carbon atoms, or 2 to 4 carbons atoms, e.g., ethylene, propylene, butene-1, pentene-1,4-methyl-pentene-1, hexene-1, octene-1, and decene-1, preferably ethylene, propylene, butene-1, pentene-1,4-methyl-pentene-1, hexene-1, octene-1, and isomers thereof. Other non-limiting examples of olefin monomer(s) can include unsaturated monomers, diolefins having 4 to 18 carbon atoms, conjugated or nonconjugated dienes, polyenes, vinyl monomers, and cyclic olefins.
Additionally or alternatively, the product stream exiting the first, second and/or third reactor may comprise ≧about 30.0 wt % of paraffinic molecules, e.g., n-, iso-, and cyclo-paraffins, based on the weight of hydrocarbons in the product stream. In particular embodiments, the amount of paraffinic molecules in the hydrocarbon may be about 30.0 to about 100.0 wt %, about 40.0 to about 100.0 wt %, about 50.0 to about 100.0 wt %, about 60.0 to about 100 wt %, about 70.0 to about 100.0 wt %, about 80.0 to about 100.0 wt %, about 90.0 to about 100.0 wt %, about 95.0 to about 100 wt %, about 30.0 to about 95.0 wt %, about 40.0 to about 95.0 wt %, about 50.0 to about 95.0 wt %, about 60.0 to about 95 wt %, about 70.0 to about 95.0 wt %, about 80.0 to about 95.0 wt %, about 90.0 to about 95.0 wt %, about 30.0 to about 90.0 wt %, about 40.0 to about 90.0 wt %, about 50.0 to about 90.0 wt %, about 60.0 to about 90 wt %, about 70.0 to about 90.0 wt %, about 80.0 to about 90.0 wt %, about 30.0 to about 80.0 wt %, about 40.0 to about 80.0 wt %, about 50.0 to about 80.0 wt %, about 60.0 to about 80 wt %, about 70.0 to about 80.0 wt %, about 30.0 to about 70.0 wt %, about 40.0 to about 70.0 wt %, about 50.0 to about 70.0 wt %, about 60.0 to about 70.0 wt %, about 30.0 to about 60.0 wt %, about 40.0 to about 60.0 wt %, about 50.0 wt %, about 30.0 to about 40.0 wt %, about 30.0 to about 50.0 wt %, or about 40.0 to about 50.0 wt %. In some embodiments the product stream may comprise molecules having about 8 to 20 carbon atoms, particularly from 10 to about 15 carbon atoms. Such compositions may be useful in diesel fuel compositions.
Additionally or alternatively, the product stream exiting the first, second and/or third reactors may comprise ≧about 30.0 wt % of aromatics, based on the weight of said hydrocarbons in the product stream. In particular embodiments, the amount of aromatics in the hydrocarbon may be about 30.0 to about 100.0 wt %, about 40.0 to about 100.0 wt %, about 50.0 to about 100.0 wt %, about 60.0 to about 100 wt %, about 70.0 to about 100.0 wt %, about 80.0 to about 100.0 wt %, about 90.0 to about 100.0 wt %, about 95.0 to about 100 wt %, about 30.0 to about 95.0 wt %, about 40.0 to about 95.0 wt %, about 50.0 to about 95.0 wt %, about 60.0 to about 95 wt %, about 70.0 to about 95.0 wt %, about 80.0 to about 95.0 wt %, about 90.0 to about 95.0 wt %, about 30.0 to about 90.0 wt %, about 40.0 to about 90.0 wt %, about 50.0 to about 90.0 wt %, about 60.0 to about 90 wt %, about 70.0 to about 90.0 wt %, about 80.0 to about 90.0 wt %, about 30.0 to about 80.0 wt %, about 40.0 to about 80.0 wt %, about 50.0 to about 80.0 wt %, about 60.0 to about 80 wt %, about 70.0 to about 80.0 wt %, about 30.0 to about 70.0 wt %, about 40.0 to about 70.0 wt %, about 50.0 to about 70.0 wt %, about 60.0 to about 70.0 wt %, about 30.0 to about 60.0 wt %, about 40.0 to about 60.0 wt %, about 50.0 wt %, about 30.0 to about 40.0 wt %, about 30.0 to about 50.0 wt %, or about 40.0 to about 50.0 wt %. In some embodiments the product stream may comprise aromatic molecules having about 5 to 20 carbon atoms, particularly from 5 to about 12 carbon atoms, particularly 8 to about 20 carbon atoms, particularly those having 1 to 2 aromatic rings.
In any embodiment, the aromatics comprise ≧10.0 wt % paraxylene, based on the weight of the aromatics. Thus, the amount of paraxylene in the aromatics of the hydrocarbon component of the product stream may be ≧10.0 wt %, ≧about 20.0 wt %, ≧about 30.0 wt %, ≧about 40.0 wt %, ≧about 45.0 wt %, ≧about 50.0 wt %, ≧about 55.0 wt %, ≧about 60.0 wt %, ≧about 65.0 wt %, ≧about 70.0 wt %, ≧about 80.0 wt %, ≧about 90.0 wt %, ≧about 95.0 wt %, or about 100.0 wt %. Additionally or alternatively, the amount of para-xylene in the aromatics portion of the hydrocarbon of the product stream exiting reactor 106 may be ≦about 12.5 wt %, ≦about 20.0 wt %, ≦about 30.0 wt %, ≦about 40.0 wt %, ≦about 45.0 wt %, ≦about 50.0 wt %, ≦about 55.0 wt %, ≦about 60.0 wt %, ≦about 65.0 wt %, ≦about 70.0 wt %, ≦about 80.0 wt %, ≦about 90.0 wt %, ≦about 95.0 wt % or ≦about 100%. Ranges of temperatures expressly disclosed include combinations of any of the above-enumerated values, e.g., about 10.0 to about 95.0 wt %, about 20.0 to 80.0 wt %, about 30.0 to about 70.0 wt %, about 40.0 to about 60.0 wt %, about 10.0 to about 50.0 wt %, about 20.0 to about 60.0 wt %, about 30.0 to about 50.0 wt %, etc.
In any embodiment, the hydrocarbons of the product stream comprises a relatively small amount of durene; e.g., 0 to about 30.0 wt %, 0 to about 25.0 wt %, 0 to about 20.0 wt % 0 to about 15.0 wt % 0 to about 10.0 wt %, 0.0 to about 5.0 wt %, 0 to about 2.5 wt %, 0 to about 1.0 wt %, 1.0 to about 30.0 wt %, 1.0 to about 25.0 wt %, 1.0 to about 20.0 wt %, 1.0 to about 15.0 wt %, about 1.0 to about 10.0 wt %, about 1.0 to about 5.0 wt %, about 1.0 to about 2.5 wt %, about 2.5 to about 30.0 wt %, about 2.5 to about 25.0 wt %, about 2.5 to about 20.0 wt %, about 2.5 to about 15.0 wt %, about 2.5 to about 10.0 wt %, about 2.5 to about 5.0 wt %, about 5.0 to about 30.0 wt %, about 5.0 to about 25.0 wt %, about 5.0 to about 20.0 wt %, about 5.0 to about 15.0 wt %, about 5.0 to about 10.0 wt %, about 10.0 to about 30.0 wt %, about 10.0 to about 25.0 wt %, about 10.0 to about 20.0 wt %, about 10.0 to about 15.0 wt %, about 15.0 to about 30.0 wt %, about 15.0 to about 25.0 wt %, about 15.0 to about 20.0 wt %, about 20.0 to about 30.0 wt %, about 20.0 to about 25.0 wt %, about 25.0 to about 30.0 wt %.
One of the products in the product stream exiting reactor 106 can typically include hydrogen. Preferably, hydrogen can be present in an amount ≧0.05 wt %. Thus, the amount of hydrogen may be ≦about 10.0 wt %, about 5.0 wt %, ≦about 4.0 wt %, ≦about 3.0 wt %, ≦about 2.0 wt %, ≦about 1.0 wt %, ≦about 0.50 wt %, ≦about 0.40 wt %, ≦about 0.30 wt %, ≦about 0.20 wt %, ≦about 0.10 wt %, or 0.05 wt %. Additionally or alternatively, the amount of hydrogen can be in some embodiments ≧about 5.0 wt %, ≧about 4.0 wt %, ≧about 3.0 wt %, ≧about 2.0 wt %, ≧about 1.0 wt %, ≧about 0.50 wt %, ≧about 0.40 wt %, ≧about 0.30 wt %, ≧about 0.20 wt %, ≧about 0.10 wt %, or 0.05 wt %. Ranges of hydrogen content expressly disclosed include combinations of any of the above-enumerated values, e.g., 0.05 wt % to about 5.0 wt %, about 0.10 to about 4.0 wt %, about 0.2 to about 3.0 wt %, about 0.4 to about 2.0 wt %, or about 0.5 to about 1.0 wt %.
In any of the embodiments described, the at least one light stream 112 may be separated by any suitable means into a gas stream comprising C5− hydrocarbons and hydrogen, at least a portion of the gas stream may, but need not, be recycled if desired at an acceptable recycle ratio, and a product-enriched stream, e.g., comprises ≧about 30 wt %, ≧about 35 wt %, ≧about 40 wt %, ≧about 50 wt %, ≧about 60 wt %, ≧about 70 wt %, ≧about 80 wt %, about ≧90 wt %, C5+ hydrocarbons, based on the weight of the product-enriched stream. The C5− hydrocarbons comprise may ≧about 30 wt %, ≧about 35 wt %, ≧about 40 wt %, ≧about 50 wt %, ≧about 60 wt %, ≧about 70 wt %, ≧about 80 wt %, about ≧90 wt %, aromatic hydrocarbons. Thus, some embodiments may be described as further comprising separating from the at least one light stream 112 at least one aromatic-enriched hydrocarbon stream and at least one aromatic-depleted hydrocarbon stream.
In embodiments designed to utilize features of the invention to produce olefins, the at least one light stream may comprise ≧30 wt %, ≧about 35 wt %, ≧about 40 wt %, ≧about 50 wt %, ≧about 60 wt %, ≧about 70 wt %, ≧about 80 wt %, or ≧about 90 wt %, of one or more olefins, based on the weight of the light stream. Thus, some embodiments may be described as further comprising separating from the at least one light stream at least one olefin-enriched stream and at least one olefin-depleted stream.
Products may also comprise mixtures of the above-recited compositions. While some specific compositions are expressly described as being recovered from the light stream, the skilled person will understand that product mixtures may be isolated in a variety of ways from various separation processes and optionally be recombined to provide a desired product mixture, e.g., jet fuel compositions, diesel fuel compositions, gasoline fuel compositions, etc.
The embodiments of the invention are illustrated in the following additional embodiments.
A method for organic compound conversion, comprising: a) providing a first mixture comprising ≧10.0 wt % of at least one oxygenate, based on the weight of the first mixture; b) contacting said first mixture in at least a first moving bed reactor with a catalyst under conditions effective to covert at least a portion of the first mixture to a product stream comprising water, hydrogen, and one or more hydrocarbons; and c) separating from said product stream (i) at least one light stream and ii) at least one heavy stream, wherein the method is characterized by a recycle ratio of ≦5.0.
A method for organic compound conversion, comprising: a) providing a first mixture comprising ≧10.0 wt % of at least one oxygenate, based on the weight of the first mixture; b) contacting said first mixture in a first moving bed reactor with a first catalyst under conditions effective to covert at least a portion of the first mixture to a first product stream comprising a first amount of one or more hydrocarbons; c) contacting said first product stream in a second moving bed reactor with a second catalyst under conditions effective to covert at least a portion of the first product stream to a second product stream comprising water, hydrogen, and a second amount of one or more hydrocarbons; and d) separating from said second product stream (i) at least one light stream, and (ii) at least one heavy stream, wherein the method is characterized by a recycle ratio of ≦5.0.
A method for organic compound conversion, comprising: a) providing a first mixture comprising ≧10.0 wt % of at least one oxygenate, based on the weight of the first mixture; b) contacting said first mixture in a first moving bed reactor with a first catalyst under conditions effective to covert at least a portion of the first mixture to a first product stream comprising water, hydrogen, and a first amount of one or more hydrocarbons; c) contacting said first product stream in a second moving bed reactor with a second catalyst under conditions effective to covert at least a portion of the first product stream to a second product stream comprising water, hydrogen, and a second amount of one or more hydrocarbons; d) contacting said second product stream in a third moving bed reactor with a third catalyst under conditions effective to covert at least a portion of the second product stream to a third product stream comprising water, hydrogen, and a third amount of one or more hydrocarbons; and e) separating from said third product stream (i) at least one hydrocarbon-enriched hydrocarbon stream, and (ii) at least one heavy stream, wherein the method is characterized by a recycle ratio of ≦5.0.
The method of any of the previous embodiments, further comprising contacting the first, second, and/or third product streams with a liquid phase quench medium.
The method of any of the previous embodiments, wherein one or more of the first, second and/or third catalysts comprises a phosphorous-stabilized catalyst.
The method of any of the previous embodiments, wherein the first mixture, the first product stream, and or the second product stream comprises ≧about 5 wt % H2O and the catalyst comprises a phosphorous-stabilized catalyst.
The method of any of the previous embodiments, further comprising separating from the at least one light stream a gas stream comprising C5− hydrocarbons and hydrogen and a product-enriched stream.
The method of any of the previous embodiments, wherein the at least one light stream comprises ≧30 wt %, ≧about 35 wt %, ≧about 40 wt %, ≧about 50 wt %, ≧about 60 wt %, ≧about 70 wt %, ≧about 80 wt %, about ≧90 wt %, C5+ hydrocarbons, based on the weight of the light stream.
The method of embodiment 8, wherein the C5+, hydrocarbons comprise ≧about 30 wt %, ≧about 35 wt %, ≧about 40 wt %, ≧about 50 wt %, ≧about 60 wt %, ≧about 70 wt %, ≧about 80 wt %, about ≧90 wt % aromatic hydrocarbons, based on the weight of the C5+ hydrocarbons.
The method of embodiment 9, further comprising separating from the at least one light stream at least one aromatic-enriched hydrocarbon stream and at least one aromatic-depleted hydrocarbon stream.
The method of any of embodiments 1-7, wherein the at least one light stream comprises ≧30 wt %, ≧about 35 wt %, ≧about 40 wt %, ≧about 50 wt %, ≧about 60 wt %, ≧about 70 wt %, ≧about 80 wt %, about ≧90 wt %, of one or more olefins, based on the weight of the at least one light stream.
The method of embodiment 11, further comprising separating from the at least one light stream at least one olefin-enriched hydrocarbon stream and at least one olefin-depleted hydrocarbon stream.
The method of any of the previous embodiments, wherein the recycle ratio is ≦about 4.0, ≦about 3.0, ≦about 2.0, ≦about 1.0, ≦about 0.5, ≦about 0.25, about 0.
The method of any of the previous embodiments, wherein a second moving bed reactor is in fluid communication with the first moving bed reactor, preferably in direct serial fluid communication with the first moving bed reactor.
The method of embodiment 14, wherein a space-time velocity of the at least one oxygenate in the first moving bed reactor is greater than a space time velocity of the at least one oxygenate in the second moving bed reactor.
The method of any of the previous embodiments, wherein a third moving bed reactor is in fluid communication with the second moving bed reactor, preferably in direct serial fluid communication with the second moving bed reactor.
The method of embodiments 16, wherein a space-time velocity of the at least one oxygenate in the second moving bed reactor is greater than a space time velocity of the third moving bed reactor.
The method of any of embodiments 2-17, wherein the first and second catalysts are the same or different.
The method of any of embodiments 3-18, wherein the first and third catalysts are the same or different.
The method of any of embodiments 3-19, wherein the second and third catalyst are the same or different.
The method of any of embodiments 2-20, wherein the second amount of one or more hydrocarbons is greater than the first amount of one or more hydrocarbons.
The method of any of embodiments 3-21, wherein the third amount of one or more hydrocarbons is greater than the first and/or second amount of one or more hydrocarbons.
The method of any of the previous embodiments, where one or more of the catalyst compositions comprises a hydrothermally stabilized zeolite catalyst composition, e.g., phosphorous-stabilized catalyst composition, and the liquid quench medium provided to one or more of the first, second, and/or third reactors comprises water.
After pressurizing and vaporization, methanol can be provided to a first stage of a dehydration (DME) reactor having an alumina catalyst therein to form an equilibrium mixture of methanol, dimethyl ether, and water. The reactor can be operated at a reactor inlet temperature of 310-320° C. and a pressure of about 26 bar. Approximately 15-20% of the heat of reaction can be released in this first step.
In the fluid bed configuration, the DME reactor effluent should typically be cooled to moderate the temperature rise over a second-stage dehydration reactor before passing into multiple, parallel fixed-bed conversion reactors containing a ZSM-5 to convert the methanol and dimethyl ether to hydrocarbons and water. WHSV can be about 1.6. The inlet temperature of the conversion reactor can be ˜350-370° C., the inlet pressures can be about 19-23 bar. The reactor outlet temperature can be ˜410-420° C. About 85% of the reaction heat can be released in the conversion.
The conversion of methanol to hydrocarbons and water can be virtually complete and essentially stoichiometric. The reaction is typically highly exothermic with an adiabatic temperature rise. The fixed-bed process can often require a gas recycle to absorb the heat of reaction keeping the catalyst temperature within an acceptable temperature range. The recycle, however, can dilute the concentration of reactants in the reactor feed, thereby slowing the reaction rate. This dilution effect may be overcome by raising the reaction pressure.
After being cooled, the effluent from the MTG conversion reactor can be separated into three phases: gas, liquid water, and liquid hydrocarbons. The gas phase can contain mostly light hydrocarbons, hydrogen, CO and CO2. Most of the gas can be recycled with the aid of a recycle compressor to the ZSM-5 conversion reactor. The water phase, which can contain trace amounts of oxygenated organic compounds, can be treated in a biological wastewater treatment plant. The hydrocarbon product containing mainly raw gasoline, dissolved hydrogen, carbon dioxide and light hydrocarbons (C1-C4) can be sent first to the de-ethanizer. The de-ethanizer bottom product can be sent to the stabilizer where C3 and part of the C4 components can be removed overhead to the fuel gas system. C4 and C5 components can be withdrawn as a side stream. The bottom product can be fed into a gasoline splitter where it can be separated into light and heavy gasoline fractions. Each stream can be cooled and stored. The heavy gasoline fraction, which typically contains durene, can be passed to the heavy gasoline treatment (HGT) reactor. In the HGT process, the heavy MTG gasoline, comprising primarily aromatics, can be processed over a multifunctional metal acid catalyst. The following reactions can occur: disproportionation, isomerization, transalkylation, ring saturation, and dealkylation/cracking. The durene content can be reduced to less than 2 wt %.
Methanol can be preheated, vaporized and sent to a dense, fluid bed reactor. The fluid bed reactor can contain a catalyst that converts methanol to hydrocarbons. The reaction is typically exothermic and heat can be removed from the reactor by generating steam within tubes immersed horizontally in the fluid bed. The catalyst can be continuously regenerated by burning off coke in air in a separate regenerator vessel. The hot reactor effluent can generate high pressure steam before final catalyst removal. The reactor effluent can be recycled to heat the methanol feed before cooling in air and thereafter being provided to a three phase separator. The water can be sent to a treatment plant and the gas can be compressed and sent along with the liquid hydrocarbon to a de-ethanizer. The bottoms of the de-ethanizer can feed a debutanizer to produce C3 and C4 feed to an alkylation unit. The C5+ gasoline fraction can be blended with alkylate and butane to give finished gasoline. Optionally, the heavy fraction of the gasoline can be treated to reduce durene content.
After pressurizing and vaporization, methanol can be provided to a first moving bed reactor. Because the reaction is typically highly exothermic, the first reactor can be relatively small. Catalyst can move down from the first reactor to a second, larger moving bed reactor and the vapor phase effluent can be cooled before entering the second reactor. Thereafter, the vapor phase effluent from the second reactor can be provided to a third reactor larger than the second reactor. Catalyst can move from the second reactor to the third reactor. Back mixing can be minimized, thereby minimizing staging concerns associated with fluid-bed reactors. WHSV can be highest in the first reactor, decreasing in the second and third reactors. The system can have low pressure drop so as to reduce/minimize the recycle compressor cost. The moving bed reactor can be operated at minimum recycle (approaching zero). Methanol can be provided between reactors as an interstage quench. The interstage quench along with different WHSV for each reactor is believed to control catalyst aging and can optimize the reactor in addition to allowing a recycle ratio that decreases in the second and third reactors.
Table 1 compares the products and methanol utilization for the configurations of Examples 1-3. Data in Table 1 are indicative of performance at the beginning of the catalyst life. Data for Example 2 are estimated from known relationship between fixed-bed and fluid bed processes. Data for Example 3 are estimated from end of catalyst cycle of the fixed bed performance since the moving bed approximates the asymptotic limit of end of life, fixed bed conditions. The results show that the moving bed can provide a more desired product distribution and higher methanol utilization.
Embodiments described herein and recited in the claims appended hereto may have one or more of the following advantages compared to fixed or fluid bed reactor processes: reduced capital expenditure, reduced catalyst deactivation due to coking, reduced steam deactivation at the reactor outlet, higher methanol utilization, more consistent product yield, higher selectivity to desired products, and/or higher catalyst utilization. All documents described herein are incorporated by reference herein for purposes of all jurisdictions where such practice is allowed, including any priority documents and/or testing procedures to the extent they are not inconsistent with this text, provided however that any priority document not named in the initially filed application or filing documents is NOT incorporated by reference herein. As is apparent from the foregoing general description and the specific embodiments, while forms of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited thereby. Likewise, the term “comprising” is considered synonymous with the term “including” for purposes of Australian law. Likewise whenever a composition, an element or a group of elements is preceded with the transitional phrase “comprising,” it is understood that we also contemplate the same composition or group of elements with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “is” preceding the recitation of the composition, element, or elements and vice versa.
This application claims the benefit of U.S. Provisional Application Nos. 61/918,984, 61/918,994, and 61/919,013, each filed on Dec. 20, 2013, the entire contents of each of which are hereby incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 61918984 | Dec 2013 | US | |
| 61918994 | Dec 2013 | US | |
| 61919013 | Dec 2013 | US |
