Integrated process for producing aldehydes from synthesis gas

Abstract

A process for preparing aldehydes from synthesis gas includes introducing a first feed stream comprising hydrogen gas and a carbon-containing gas comprising carbon monoxide into a reaction zone of a first reactor, converting the first feed stream in the reaction zone in the presence of a first catalyst to a first product stream comprising C2 to C4 hydrocarbons, the first product stream further comprising carbon dioxide, removing water and C4 and higher hydrocarbons from the first product stream to form a second feed stream, and converting the second feed stream in the presence of a second catalyst in a second reactor to a second product stream comprising propionaldehyde. The propionaldehyde can be further converted to methyl methacrylate by oxidative esterification.

Description

[Technical Field]

[0001] This specification relates generally to a process for efficiently converting various carbon-containing streams to aldehydes via C2-C4 hydrocarbons. [Background technology]

[0002] For many industrial applications, hydrocarbons are used to produce, or are starting materials used to produce, plastics, fuels, and various downstream chemicals. C2-C4 hydrocarbons are particularly useful in downstream applications, such as the preparation of aldehydes and further products, such as methyl methacrylate (MMA). MMA is a valuable chemical intermediate for producing (meth)acrylic polymers and copolymers.

[0003] Various processes have been developed to produce lower hydrocarbons, including petroleum cracking and various synthetic processes. Synthesis gas, known as syngas, which is a combination of carbon monoxide and hydrogen gas, represents a flexible intermediate that can be obtained from the gasification of biomass, waste, or conventional fuels.

[0004] Synthetic processes for converting syngas to lower hydrocarbons are known. The Fischer-Tropsch process is used to convert syngas to a mixture of olefins along with long-chain paraffins. The Fischer-Tropsch process results in a broad product distribution, and the selectivity to lower olefins is typically relatively limited. Modifications of the Fischer-Tropsch process, such as the process disclosed in WO 2019 / 089206, have been developed to increase the selectivity to lower olefins.

[0005] However, there are at least two azeotropes in a typical syngas that prevent separation to an olefins plant, including ethylene / carbon dioxide and ethane / carbon dioxide. See Nagahama et al., Journal of Chemical Engineering of Japan, 7, 5, 1974, pp. 323-328. Separating carbon dioxide from olefins is a costly process. While extractive distillation can assist in breaking one or the other of these azeotropes, the presence of both azeotropes facilitates the use of non-distillative separations, such as amine scrubbing of CO2 in the syngas, for olefin operations.

[0006] Some of these processes involve co-feeding CO to the process to reduce the net CO selectivity (which can be negative) determined by subtracting the total CO in the feed stream from the CO in the product stream, however, this approach typically reduces the productivity of desired C2-C4 hydrocarbons.

[0007] Other processes, such as that disclosed in US Pat. No. 10,513,471, use special catalysts to minimize CO2 formation in a two-reactor process that converts syngas to C2 to C5 hydrocarbons.

[0008] U.S. Patent No. 10,676,419 discloses a two-stage catalytic process for converting syngas to acetic acid, acrylic acid, and / or propylene. In the first stage, the syngas is contacted with a first catalyst to produce a first product stream containing C2 and C3 olefins and / or C2 and C3 paraffins, and the first product stream is then contacted with an oxygen-containing second catalyst to produce acrylic acid and acetic acid.

[0009] Therefore, there is a need for processes and systems that can efficiently and in high yield produce aldehydes and / or methyl methacrylate from syngas. Summary of the Invention

[0010] One aspect of the invention relates to a process comprising: introducing a first feed stream comprising hydrogen gas and a carbon-containing gas comprising carbon monoxide into a reaction zone of a first reactor; converting the first feed stream in the reaction zone in the presence of a first catalyst to a first product stream comprising C2 to C4 hydrocarbons, the first product stream further comprising carbon dioxide; removing water and C4 and higher hydrocarbons from the first product stream to form a second feed stream; and converting the second feed stream in the presence of a second catalyst in a second reactor to a second product stream comprising propionaldehyde and / or butyraldehyde.

[0011] Additional features and advantages are set forth in the Detailed Description below, and in part will be readily apparent to those skilled in the art from that description or will be learned by practicing the embodiments described herein, including the Detailed Description below and the claims.

[0012] It is to be understood that both the foregoing general description and the following detailed description are intended to describe various embodiments and provide an overview or framework for understanding the nature and character of the claimed subject matter. DETAILED DESCRIPTION OF THE INVENTION

[0013] It should be noted that as used herein, "synthesis gas" and "syngas" are utilized herein to refer to a mixture containing primarily hydrogen, carbon monoxide, and very often some carbon dioxide.

[0014] Reference will now be made in detail to an embodiment of a process that utilizes syngas to prepare C2-C4 hydrocarbons, which are further processed into aldehydes and / or methyl methacrylate.

[0015] Generally, it is desirable to achieve high productivity of desired C2-C4 hydrocarbons while simultaneously reducing the net selectivity of CO in syngas-to-hydrocarbon processes. A known method of reducing net selectivity of CO is by co-feeding CO. However, co-feeding additional CO to reduce net selectivity of CO also reduces productivity of desired C2-C4 hydrocarbons. However, the present inventors have recognized that the CO reactant can be regenerated by directly subjecting a product stream containing C2-C4 hydrocarbons and CO to a hydroformylation or oxo process to produce aldehydes, such as propionaldehyde, with CO either passing through as an inert or participating in the water-gas shift. Furthermore, any unreacted CO, hydrogen, and CO can be recycled back to the syngas feed stream for more complete carbon utilization.

[0016] For example, by eliminating the need to break any azeotropes formed with CO, such as ethylene / CO or ethane / CO, significant reductions in capital and operating costs can be achieved, in addition to the more complete carbon utilization that can be achieved if the CO is recycled back into the syngas feed stream.

[0017] In the process of the present invention, a first feed stream comprising hydrogen gas and a carbon-containing gas comprising carbon monoxide is introduced into the reaction zone of a first reactor. Preferably, the first feed stream comprises syngas. The syngas may comprise hydrogen and carbon monoxide, optionally supplemented with carbon dioxide depending on the concentration of carbon dioxide, if any, present in the syngas.

[0018] Hydrogen may be present in the first feed stream in an amount of 10.0 vol.% to 90.0 vol.% H, e.g., 20.0 vol.% to 80.0 vol.% H, or 30.0 vol.% to 70.0 vol.% H, based on the total volume of the first feed stream.

[0019] Carbon dioxide may be present in the first feed stream in an amount of 0% to 20.0% CO by volume, based on the total volume of the first feed stream. Any carbon dioxide present in the feed stream may be present in the syngas or may be recycled from the second product stream back to the first feed stream. Because the carbon dioxide produced in the first reactor can be used in downstream processes, there is no need to add unused carbon dioxide, such as co-fed carbon dioxide, to the first feed stream.

[0020] The first feed stream can have a CO2 / CO volume ratio of 0 to 1.50, e.g., 0.05 to 1.50, 0.25 to 1.50, or 0.50 to 1.50. Preferably, the CO2 / CO ratio is high enough so that there is enough CO2 present to convert carbon to C2 to C4 hydrocarbons.

[0021] The first catalyst may include any known catalyst for converting syngas to C2-C4 hydrocarbons. For example, the first catalyst may include a mixed metal oxide catalyst, or a bifunctional or hybrid catalyst including a mixed metal oxide catalyst and a microporous catalytic component, such as a zeolite component.

[0022] The mixed metal oxide catalyst component may be a bulk catalyst or a supported catalyst and may be prepared by any suitable method, such as coprecipitation, impregnation, etc. The mixed metal oxide catalyst may include, for example, cobalt (Co), manganese (Mn), copper (Cu), zinc (Zn), chromium (Cr), aluminum (Al), gallium (Ga), zirconium (Zr), and combinations thereof. It should be understood that any metal in the mixed metal oxide component mixture may exist in various oxidation states. It should also be understood that the designation of a particular oxide (e.g., Ga2O3) does not necessarily exclude the presence of additional or different oxides of a given metal.

[0023] The hybrid catalyst system includes a mixed metal oxide catalyst component that converts a first feed stream to oxygenated hydrocarbons, and a microporous catalyst component (e.g., a zeolite component) that converts oxygenates to hydrocarbons. The microporous catalyst component may be selected from molecular sieves with 8-MR pore access and a framework type selected from the group consisting of the following framework types: CHA, AEI, AFX, ERI, LTA, UFI, RTH, RHO, LEV, and combinations thereof, where the framework type corresponds to the International Zeolite Association nomenclature. It should be understood that both aluminosilicate and silicoaluminophosphate frameworks may be used. Preferably, the molecular sieve has a chabazite (CHA) framework type. For example, the molecular sieve may be SAPO-34 silicoaluminophosphate with a chabazite (CHA) framework type.

[0024] These examples include, but are not limited to, CHA embodiments selected from SAPO-34 and SSZ-13, and AEI embodiments such as SAPO-18. Combinations of microporous catalyst components having any of the above framework types may also be used. It should be understood that the microporous catalyst component may have different ring-shaped pore openings depending on the desired product. For example, depending on the desired product, a microporous catalyst component having 8-MR to 12-MR pore openings may be used. However, to produce C2 to C4 hydrocarbons, a microporous catalyst component having 8-MR pore openings is preferably used.

[0025] The mixed metal oxide catalyst component and the microporous catalyst component of the hybrid catalyst may be mixed together by any suitable means, such as physical mixing, for example, shaking, stirring, or other agitation. Alternatively, the mixed metal oxide catalyst component and the microporous catalyst component may be present as a single combined catalyst. The mixed metal oxide catalyst component and the microporous catalyst component may be present in the reaction zone, typically in a catalyst bed, as a hybrid catalyst in a weight / weight (wt / wt) ratio (mixed metal oxide catalyst component:microporous catalyst component) ranging from 0.1:1 to 10:1, for example, from 0.5:1 to 9:1.

[0026] The mixed metal oxide catalyst component may be reduced in the reactor prior to exposure to the first feed stream by exposing the mixed metal oxide catalyst component to a conventional reducing gas, or alternatively, the mixed metal oxide catalyst component may be reduced in the reactor upon exposure to a reducing gas in the feed stream, such as H and CO.

[0027] The reaction conditions within the reaction zone of the first reactor are now described. A first feed stream is contacted with a first catalyst in the reaction zone of the first reactor under reaction conditions sufficient to form a first product stream comprising C2-C4 hydrocarbons. The first product stream may further comprise higher hydrocarbons, i.e., C5 or higher hydrocarbons. Preferably, the first product stream comprises primarily C2-C4 hydrocarbons, e.g., C2-C4 olefins. More preferably, the hydrocarbons in the first product stream consist essentially of C2-C4 olefins. As used herein, "consist essentially of C2-C4 olefins" means that the first product stream comprises at least 70% by volume of C2-C4 olefins, based on the total volume of hydrocarbons in the first product stream. Reaction conditions include temperatures in the reaction zone ranging from, for example, 300°C to 500°C, e.g., 380°C to 450°C, 380°C to 440°C, 380°C to 430°C, 380°C to 420°C, 380°C to 410°C, 380°C to 400°C, or 380°C to 390°C.

[0028] Reaction conditions also include a pressure in the reaction zone of, for example, at least 20 bar (20,000 kilopascals (kPa)), e.g., at least 25 bar (25,000 kPa), at least 30 bar (30,000 kPa), at least 35 bar (35,000 kPa), at least 40 bar (40,000 kPa), at least 45 bar (45,000 kPa), at least 50 bar (50,000 kPa), at least 55 bar (55,000 kPa), at least 60 bar (60,000 kPa), at least 65 bar (65,000 kPa), or at least 70 bar (70,000 kPa).

[0029] The reaction conditions also include a gas hourly space velocity in the reaction zone 101 of, for example, at least 2500 hr, such as at least 3000 hr, for example at least 3600 hr, such as at least 4200 hr, for example at least 4800 hr, such as at least 5400 hr, for example at least 6000 hr, for example at least 6600 hr, or for example at least 7200 hr.

[0030] The first product stream comprises C2-C4 hydrocarbons and further comprises carbon dioxide. The carbon dioxide present in the first product stream is not removed from the product stream. The first product stream may also contain unreacted carbon monoxide and hydrogen, and C2-C4 paraffins.

[0031] Water is removed from the first product stream. Additionally, C4 and higher hydrocarbons are also removed from the first product stream to form a second feed stream, which is fed to the second reactor. Depending on the desired aldehyde, C3 hydrocarbons may be removed along with the C4 and higher hydrocarbons. Alternatively, the C3 hydrocarbons may be sent overhead as part of the second feed stream for conversion to butyraldehyde in a hydroformylation or oxo process in the second reactor. Butyraldehyde can be used to make n-butanol or 2-ethylhexanol. Catalysts for this process include, but are not limited to, (organo)phosphines, phosphites, or bidentate ligand complexes containing Group VIII and Group VIIIB metals.

[0032] The second feed stream contains carbon dioxide and unreacted hydrogen and carbon monoxide in addition to C2 hydrocarbons and optionally C3 hydrocarbons. The second feed stream is converted to a second product stream in the presence of a second catalyst in a second reactor. The second feed stream is subjected to a hydroformylation reaction or an oxo process in the second reactor to form aldehydes from the hydrocarbons present in the second feed stream. If the C3 hydrocarbons are removed from the first product stream along with the higher hydrocarbons, the primary product of the second reactor will be propionaldehyde. If the C3 hydrocarbons are not removed from the first product stream, the product of the second reactor will primarily comprise a mixture of propionaldehyde and butyraldehyde. Carbon dioxide present in the second feed stream either passes through the second reactor as an inert or participates in the water-gas shift reaction to form carbon monoxide.

[0033] The second product stream comprises the produced aldehydes and may also comprise paraffins. The second product stream further comprises carbon dioxide and any unreacted hydrogen and carbon monoxide. The aldehyde products can be separated from the second product stream, and additional separation can remove any paraffins from the remaining carbon dioxide, carbon monoxide, and hydrogen. Preferably, the carbon dioxide, carbon monoxide, and hydrogen are recycled to the first reactor and combined with the first feed stream entering the first reactor.

[0034] The propionaldehyde from the second product stream can be further reacted to form methyl methacrylate by oxidative esterification using any known method. For example, propionaldehyde can be converted to methacrolein in the presence of formaldehyde. Methacrolein can then be converted to methyl methacrylate.

[0035] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Accordingly, this specification is intended to cover all such modifications and variations of the various embodiments described herein, provided they come within the scope of the appended claims and their equivalents. The present invention includes the following aspects. [Aspect 1] A process comprising: introducing a first feed stream comprising hydrogen gas and a carbon-containing gas comprising carbon monoxide into a reaction zone of a first reactor; reacting the first feed stream in the reaction zone in the presence of a first catalyst with C 2 ~C 4 converting the hydrocarbon-containing first product stream to a first product stream comprising carbon dioxide; said first product stream to water and 4 removing said hydrocarbons to form a second feed stream; converting the second feed stream in the presence of a second catalyst in a second reactor to a second product stream comprising propionaldehyde; The process includes: [Aspect 2] 2. The process of embodiment 1, wherein the carbon dioxide from the first product stream exiting the second reactor is recycled to the first feed stream. [Aspect 3] 3. The process of any one of aspects 1 to 2, further comprising recycling unreacted hydrogen and carbon monoxide to the first feed stream. [Aspect 4] Aspect 4. The process of any one of aspects 1-3, wherein the second product stream further comprises butyraldehyde. [Aspect 5] water and C from the first product stream 4 The step of removing hydrocarbons comprises removing C from the first product stream. 3 Aspect 4. The method of any one of aspects 1-3, further comprising removing hydrocarbons. [Aspect 6] Aspect 6. The process of any one of aspects 1-5, further comprising removing the propionaldehyde from the second product stream. [Aspect 7] Aspect 7. The process of any one of aspects 1-6, further comprising removing any paraffin from the second product stream. [Aspect 8] Aspect 8. The process of any one of aspects 1-7, further comprising converting the propionaldehyde to methyl methacrylate by oxidative esterification. [Aspect 9] Aspect 9. The process of any one of aspects 1 to 8, wherein the reaction zone operates at a pressure of at least 20 bar. [Aspect 10] The mixed metal oxide catalyst component is ZrO 2 10. The process of any one of embodiments 1 to 9, comprising: [Aspect 11] The mixed metal oxide catalyst component is ZrO 2 and Ga 2 O 3 11. The process of any one of aspects 1 to 10, comprising: [Aspect 12] 12. The process of any one of embodiments 1 to 11, wherein the microporous catalyst component is a molecular sieve having 8-MR pore openings. [Aspect 13] 13. The process of any one of aspects 1 to 12, wherein the microporous catalyst component is a molecular sieve having a chabazite (CHA) framework. [Aspect 14] 14. The process of any one of aspects 1 to 13, wherein the microporous catalyst component is SAPO-34. [Aspect 15] C 2 ~C 4 The hydrocarbon is C 2 ~C 4 15. The process of any one of embodiments 1 to 14, wherein the olefin consists essentially of olefins.

Claims

1. A process comprising: introducing a first feed stream comprising hydrogen gas and a carbon-containing gas comprising carbon monoxide and carbon dioxide into a reaction zone of a first reactor, said first feed stream having a CO2 / CO volume ratio of 0.25 to 1.50; reacting the first feed stream in the reaction zone in the presence of a first catalyst with C ２ ~C ４ converting a first product stream comprising hydrocarbons, said first product stream further comprising carbon dioxide; water and C from the first product stream ４ removing said hydrocarbons to form a second feed stream; converting the second feed stream in the presence of a second catalyst in a second reactor to a second product stream comprising propionaldehyde; The process includes:

2. 10. The process of claim 1, wherein the carbon dioxide from the first product stream exiting the second reactor is recycled to the first feed stream.

3. 3. The process of claim 1 or 2, further comprising recycling unreacted hydrogen and carbon monoxide to the first feed stream.

4. 4. The process of any one of claims 1 to 3, wherein the second product stream further comprises butyraldehyde.

5. water and C from the first product stream ４ The step of removing hydrocarbons comprises removing C from the first product stream. ３ The method of any one of claims 1 to 3, further comprising removing hydrocarbons.

6. 6. The process of any one of claims 1 to 5, further comprising removing the propionaldehyde from the second product stream.

7. 7. The process of any one of claims 1 to 6, further comprising removing any paraffin from the second product stream.

8. 8. The process of any one of claims 1 to 7, further comprising converting the propionaldehyde to methyl methacrylate by oxidative esterification.

9. The process of any one of claims 1 to 8, wherein the reaction zone operates at a pressure of at least 20 bar.

10. The process of claim 1, wherein the first catalyst comprises a mixed metal oxide catalyst component or a hybrid catalyst comprising a mixed metal oxide catalyst component and a microporous catalyst component.

11. The mixed metal oxide catalyst component comprising ZrO ２ or ZrO2 and Ga2O3.

12. The process of claim 10 or 11, wherein the microporous catalyst component is a molecular sieve having 8-MR pore openings.

13. The process of claim 10, wherein the microporous catalyst component is a molecular sieve having a chabazite (CHA) framework.

14. The process of any one of claims 10 to 13, wherein the microporous catalyst component is SAPO-34.

15. C ２ ~C ４ The hydrocarbon is C ２ ~C ４ The process of any one of claims 1 to 14, consisting essentially of olefins.