WO2017098385A1

WO2017098385A1 - Methods for producing syngas from carbon dioxide

Info

Publication number: WO2017098385A1
Application number: PCT/IB2016/057280
Authority: WO
Inventors: Aghaddin Mamedov; Clark Rea
Original assignee: Sabic Global Technologies B.V.
Priority date: 2015-12-07
Filing date: 2016-12-01
Publication date: 2017-06-15

Abstract

Methods for producing syngas from carbon dioxide are provided. Methods can include heating a feed stream including hydrogen (H₂) and carbon dioxide (CO₂) to a temperature from about 800°C to about 900°C to generate a heated feed stream. Methods can further include feeding the heated feed stream to an adiabatic reactor containing a Catofin catalyst to generate a product stream including syngas.

Description

METHODS FOR PRODUCING SYNGAS FROM CARBON DIOXIDE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. Provisional Application No. 62/264,245, filed December 7, 2015. The contents of the referenced application are incorporated into the present application by reference.

FIELD

[0002] The disclosed subject matter relates to methods for producing syngas from carbon dioxide.

BACKGROUND

[0003] Syngas, also known as synthesis gas, is primarily a mixture of carbon monoxide (CO) and hydrogen (H₂), and can also contain carbon dioxide (C0₂) and/or water (H₂0). Syngas can be a feedstock for producing higher hydrocarbons, such as fuels, for example in a Fischer- Tropsch process. Syngas can also be used to produce various chemicals, including olefins, methanol, ethylene glycol, and aldehydes, for example by oxo-synthesis (also known as hydroformylation) and carbonylation reactions. In these processes, the composition of the syngas, and particularly the stoichiometric ratio of H₂ and C0₂ in the syngas, can be important in determining which materials are produced.

[0004] Syngas can be produced from hydrocarbons, for example by methane steam reforming. However, there is interest in producing syngas from alternative feedstocks. For example, carbon dioxide can be converted to syngas. Certain methods for producing syngas from carbon dioxide are known in the art. For example, U.S. Patent No. 8,551,434 discloses a process for hydrogenating C0₂ to form syngas. The reaction is carried out adiabatically in the presence of a non-zinc catalyst and within a reactor containing nickel or iron components. International Patent Publication No. WO2015/069840 discloses a process for generating syngas from C0₂ in an adiabatic metal reactor using a metal oxide catalyst. [0005] However, there remains a need for improved methods of producing syngas from carbon dioxide. The present disclosure addresses these and other needs.

SUMMARY OF THE DISCLOSED SUBJECT MATTER

[0006] The disclosed subject matter provides novel methods for producing syngas from carbon dioxide.

[0007] In certain embodiments, an exemplary method of producing syngas from carbon dioxide (C0₂) includes heating a feed stream including hydrogen (H₂) and C0₂ to a temperature from about 800°C to about 900°C to generate a heated feed stream and feeding the heated feed stream to an adiabatic reactor containing a Catofin catalyst to generate a product stream including syngas.

[0008] In certain embodiments, H₂ and C0₂ can be present in the feed stream in a molar ratio (H₂/C0₂) of less than about 2 or less than about 1. In particular embodiments, the feed stream can contain H₂ and C0₂ in a molar ratio (H₂/C0₂) of about 0.67. In particular embodiments, the feed stream can be heated to a temperature of about 830°C. The Catofin catalyst can include chromium supported on alumina.

[0009] In certain embodiments, the product stream can contain syngas having H₂ and CO in a molar ratio (H₂/CO) of less than about 2 or less than about 1. The product stream can have a temperature from about 600°C to about 700°C. In particular embodiments, the product stream can have a temperature of about 660°C.

[0010] In certain embodiments, C0₂ conversion can be from about 35% to about 40%. The produced syngas can be used to generate olefins. Alternatively or additionally, the produced syngas can be used in an oxo-synthesis reaction. Alternatively or additionally, the produced syngas can be used in a carbonylation reaction.

[0011] In certain embodiments, an exemplary method of producing syngas includes heating a feed stream including H₂ and C0₂ to a temperature from about 800°C to about 900°C to generate a heated feed stream, feeding the heated feed stream to an adiabatic reactor containing a Catofin catalyst, and removing a product stream including syngas from the reactor. The product stream can have a temperature from about 600°C to about 700°C. The syngas can include H₂ and CO in a molar ratio (H₂/CO) of about 1.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 depicts a method for producing syngas from carbon dioxide according to one exemplary embodiment of the disclosed subject matter.

DETAILED DESCRIPTION

[0013] The presently disclosed subject matter provides novel methods for producing syngas from carbon dioxide.

[0014] As used herein, the term "about" or "approximately" means within an acceptable error range for the particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined, i.e., the limitations of the measurement system. For example, "about" can mean a range of up to 20%, up to 10%, up to 5%), and or up to 1% of a given value.

[0015] For the purpose of illustration and not limitation, FIG. 1 is a schematic representation of a method for hydrogenating carbon dioxide to form syngas according to a non-limiting embodiment of the disclosed subject matter.

[0016] The method 100 can include heating a feed stream including hydrogen (H₂) and carbon dioxide (C0₂) 101. "Feed stream" as used herein can refer to a single feed stream or multiple feed streams, which can be combined before or during the hydrogenation reaction. For example, the feed stream can be a single mixture of H₂ or C0₂. Alternatively or additionally, multiple feed streams containing H₂ and/or C0₂ can be provided. The C0₂ in the feed stream can originate from various sources. For example, the C0₂ can be sourced from other chemical processes, e.g., as a waste product, and/or unconverted C0₂ can be recovered from the product stream and recycled to the feed stream. The H₂ in the feed stream can also originate from various sources, for example from gaseous streams from other chemical processes.

[0017] In certain embodiments, the flow rate of the feed stream can be from about 500 cc/min to about 4000 cc/min, from about 1000 cc/min to about 3000 cc/min, or about 2000 cc/min. For example, the flow rate of H₂ in the feed stream can be from about 100 cc/min to about 1500 cc/min, from about 500 cc/min to about 1200 cc/min, or about 800 cc/min. The flow rate of C0₂ in the feed stream can be from about 400 cc/min to about 2000 cc/min, from about 800 cc/min to about 1600 cc/min, or about 1200 cc/min. In certain embodiments, the flow rate of the feed stream can depend on the space velocity of the hydrogenation reaction. For example, the space velocity of the hydrogenation reaction can be from about 2800 to about 3500 h^"1.

[0018] The feed stream can include H₂ and C0₂ in a particular ratio. For example, the molar ratio of H₂ to C0₂ (H₂/C0₂) in the feed stream can be less than about 5, less than about 3, less than about 2, or less than about 1. In certain embodiments, the feed stream can contain H₂ and C0₂ in a molar ratio (H₂/C0₂) of about 0.67.

[0019] The method 100 can further include providing the heated feed stream to an adiabatic reactor 102. In certain embodiments, the feed stream can be heated to a temperature from about 500°C to about 1200°C, from about 700°C to about 1000°C, or from about 800°C to about 900°C. In particular embodiments, the feed stream is heated to a temperature of about 830°C. For example, the feed stream can be preheated prior to entering the reactor. Alternatively or additionally, the feed stream can be heated as it enters the reactor.

[0020] The feed stream can be provided at atmospheric pressure. Alternatively, the feed stream can be pressurized, e.g., to from about 1 bar to about 26 bar. [0021] In certain embodiments, the reactor can be a fixed bed reactor. For example, the reactor can be a quartz reactor having a diameter of about 1 inch to about 4 inches. The dimensions and structure of the reactor can vary depending on the capacity of the reactor. The capacity of the reactor can be determined by the reaction rate, the stoichiometric quantities of the reactants and/or the feed flow rate. The reactor can be operated under adiabatic conditions.

[0022] In certain embodiments, a catalyst can be loaded into the reactor. Catalysts for use in the presently disclosed subject matter can include a Catofin® catalyst (Clariant, Cr/Al₂0₃). In certain embodiments, the catalyst can include about 16 wt-% chromium (Cr) supported on alumina (A1₂0₃). In certain embodiments, catalyst loading can be from about 100 mL to about 800 mL, from about 300 mL to about 600 mL, or from about 400 mL to about 500 mL. In particular embodiments, catalyst loading is about 426 mL.

[0023] The contact time for contacting the feed stream with the catalyst can depend on a number of factors including, but not limited to, the temperature, the pressure, the amount of catalyst, and the flowrate of reactants, i.e., C0₂ and H₂, in the feed stream. In certain embodiments, the feed stream can contact the catalyst for from about 1 second to about 10 seconds.

[0024] The method 100 can further include removing a product stream including syngas from the reactor 103. In certain embodiments, the reactor is operated adiabatically such that the temperature of the product stream when it exits the reactor is less than the temperature of the feed stream. For example, the product stream can have a temperature from about 300°C to about 1000°C, from about 500°C to about 800°C, or from about 600°C to about 700°C. In certain embodiments, the product stream can have a temperature of about 660°C.

[0025] The product stream can be formed by the hydrogenation of C0₂ in the feed stream. For example, C0₂ and H₂ in the feed stream can react to form carbon monoxide (CO) and water (H₂0) in a reverse water gas shift reaction. The reverse water gas shift reaction is illustrated by:

C0₂ + H_{2 <}→ CO + H₂0 (Formula 1)

[0026] The reverse water gas shift reaction is equilibrium-driven, and can be performed under conditions resulting in only partial conversion of C0₂ and H₂. Thus, the hydrogenation of C0₂ by the reverse water gas shift reaction can result in a product stream containing C0₂ and H₂, as well as CO and H₂0. In certain embodiments, H₂0 can be separated from the product stream, e.g., by condensation.

[0027] In certain embodiments, C0₂ conversion can be from about 10% to about 65%>, from about 20% to about 55%, from about 30% to about 45%, or from about 35% to about 40%). The amount of C0₂ in the product stream can be from about 25 mol-% to about 65 mol-%, from about 35 mol-% to about 55 mol-%, or from about 40 mol-% to about 50 mol- %. In certain embodiments, the amount of C0₂ in the product stream is about 45 mol-%. The amount of H₂ in the product stream can be from about 10 mol-% to about 50 mol-%, from about 20 mol-% to about 40 mol-%, or from about 25 mol-% to about 35 mol-%. In certain embodiments, the amount of H₂ in the product stream is about 27 mol-%. The amount of CO in the product stream can be from about 5 mol-% to about 45 mol-%, from about 15 mol-%) to about 35 mol-%, or from about 20 mol-% to about 30 mol-%. In certain embodiments, the amount of CO in the product stream is about 27 mol-%.

[0028] The ratio of H₂ and CO in the product stream can be manipulated by varying process conditions, e.g., reaction conditions, catalyst type or amount, or the ratio of H₂ to C0₂ in the feed stream. Although it is possible to adjust the H₂ to CO ratio in the syngas of the product stream after the hydrogenation reaction, e.g., by a subsequent reverse water gas shift reaction or by mixing the syngas with another gaseous stream, it can be desirable to generate a product stream which contains a suitable H₂ to CO ratio for a downstream use. [0029] In certain embodiments, the product stream can contain H₂ and CO in a molar ratio (H₂/CO) of less than about 3, less than about 2, or less than about 1.5. For example, the product stream can contain H₂ and CO in a molar ratio (H₂/CO) of about 1.

[0030] In certain embodiments, the method can include separating at least some C0₂ from the CO and H₂ in the product stream to produce purified syngas. In certain embodiments, unconverted C0₂ in the product stream can be recovered and recycled to the feed stream. By way of example, C0₂ can be separated by a process including absorption by an amine.

[0031] The syngas produced by the presently disclosed methods can be suitable for use in oxo-synthesis reactions, e.g., to produce aldehydes. Alternative or additionally, the syngas can be suitable for use in carbonylation reactions, e.g., to produce ketones, aldehydes, and/or organic acids. Alternatively or additionally, the syngas can be suitable for olefins synthesis, e.g., by using a Fischer-Tropsch process or via an alcohol intermediary, such as methanol or ethanol.

[0032] The methods of the presently disclosed subject matter provide advantages over certain existing technologies for producing syngas from carbon dioxide. Exemplary advantages include improved syngas composition for downstream processes, as well as increased catalyst stability and carbon dioxide conversion.

EXAMPLES

[0033] The following example provides methods for producing syngas from carbon dioxide in accordance with the disclosed subject matter. However, the following example is merely illustrative of the presently disclosed subject matter and should not be considered as a limitation in any way.

Example 1: Hydrogenation of CO? over a Catofin catalyst

[0034] In this Example, carbon dioxide (C0₂) was hydrogenated in the presence of hydrogen (H₂) to produce syngas. The hydrogenation of carbon dioxide (C0₂) was performed in a quartz reactor under adiabatic conditions. For the top of the reactor, the temperature distribution was: 829°C, 798°C, 753°C, 723°C, 702°C, and 66FC.

[0035] The reactor was loaded with an industrial Catofin catalyst. The catalyst loading was 426 mL. The flow rate of H₂ was 803 cc/min and the flow rate of C0₂ was 1200 cc/min. Table 1 displays the composition of the syngas after 80 and more days on stream, as well as the conversion of C0₂.

Table 1. Com osition of Exam le 1 s n as

[0036] The Catofin catalyst remained stable after 107 days on stream, and achieved C0₂ conversion greater than 36%. Additionally, the molar ratio of H₂ to CO (H₂/CO) was about 1.

* * *

[0037] In addition to the various embodiments depicted and claimed, the disclosed subject matter is also directed to other embodiments having other combinations of the features disclosed and claimed herein. As such, the particular features presented herein can be combined with each other in other manners within the scope of the disclosed subject matter such that the disclosed subject matter includes any suitable combination of the features disclosed herein. The foregoing description of specific embodiments of the disclosed subject matter has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosed subject matter to those embodiments disclosed.

[0038] It will be apparent to those skilled in the art that various modifications and variations can be made in the systems and methods of the disclosed subject matter without departing from the spirit or scope of the disclosed subject matter. Thus, it is intended that the disclosed subject matter include modifications and variations that are within the scope of the appended claims and their equivalents.

Claims

1. A method for producing syngas, the method comprising:

(a) heating a feed stream comprising H₂ and C0₂ to a temperature from about 800°C to about 900°C to generate a heated feed stream; and

(b) feeding the heated feed stream to an adiabatic reactor comprising a Catofin catalyst to generate a product stream comprising syngas.

2. The method of claim 1, wherein the feed stream comprises H₂ and C0₂ in a molar ratio (H₂/C0₂) of less than about 2.

3. The method of claim 1, wherein the feed stream comprises H₂ and C0₂ in a molar ratio (H₂/C0₂) of less than about 1.

4. The method of claim 1, wherein the feed stream comprises H₂ and C0₂ in a molar ratio (H₂/CO₂) of about 0.67.

5. The method of claim 1, wherein the feed stream is heated to a temperature of about 830°C.

6. The method of claim 1, wherein the Catofin catalyst comprises chromium supported on alumina.

7. The method of claim 1, wherein the syngas comprises H₂ and CO in a molar ratio

(H₂/CO) of less than about 2.

8. The method of claim 1, wherein the syngas comprises H₂ and CO in a molar ratio

(H₂/CO) of less than about 1.

9. The method of claim 1, wherein the product stream has a temperature from about 600°C to about 700°C.

10. The method of claim 1, wherein the product stream has a temperature of about 660°C.

11. The method of claim 1, wherein from about 35% to about 40% of the C0₂ in the feed stream is converted.

12. The method of claim 1, further comprising using the syngas to produce olefins.

13. The method of claim 1, further comprising using the syngas in an oxo-synthesis reaction.

14. The method of claim 1, further comprising using the syngas in a carbonylation reaction.

15. A method for producing syngas, comprising:

(a) heating a feed stream comprising H₂ and C0₂ to a temperature from about 800°C to about 900°C to generate a heated feed stream;

(b) feeding the heated feed stream to an adiabatic reactor comprising a Catofin

catalyst; and

(c) removing a product stream comprising syngas from the reactor, wherein

i. the product stream has a temperature from about 600°C to about 700°C; and

ii. the syngas comprises H₂ and CO in a molar ratio (H₂/CO) of about 1.