Method for preparing carbon monoxide through reverse water-gas shift

Abstract

The invention relates to a method for preparing carbon monoxide by reverse water gas shift, which comprises the following steps: under the catalytic action of a supported catalyst, carrying out reverse water gas shift reaction, carrying out pressure swing adsorption treatment on mixed gas generated in the reaction process, and desorbing to obtain carbon monoxide. By coupling the reverse water gas shift reaction and the pressure swing adsorption process and exerting the synergistic effect of the reverse water gas shift reaction and the pressure swing adsorption process, efficient and rapid separation of carbon monoxide is realized, the reverse water gas shift reaction is promoted to be carried out in the forward direction, the reaction requirement of reverse water gas shift is reduced, the reverse water gas shift reaction is carried out under relatively mild conditions, and the reaction efficiency is improved. The long-period efficient conversion of carbon dioxide is realized, and the conversion rate of carbon dioxide and the selectivity of carbon monoxide are further improved.

Description

Technical Field

[0001] This invention relates to the field of reverse water gas shift reaction technology, to a reverse water gas shift reaction, and more particularly to a method for preparing carbon monoxide by reverse water gas shift reaction. Background Technology

[0002] Currently, the combustion of fossil fuels leads to massive CO2 emissions, causing severe greenhouse effects and global warming. Statistics show that if current trends continue, global CO2 emissions are projected to rise from 35.3 billion tons in 2018 to 43.08 billion tons in 2050, far exceeding the environment's carrying capacity. Therefore, it is necessary to reduce CO2 emissions or recycle and reuse CO2 to mitigate its environmental impact. Carbon capture and storage (CCU) technology has proven to be an effective way to alleviate these problems. This involves using H2 to convert CO2 into high-value-added products such as methanol, ethanol, or liquid fuels. However, from a thermodynamic perspective, directly hydrogenating CO2 to produce methanol, ethanol, or olefins is quite difficult.

[0003] In existing technologies, producing CO via the reverse water-gas shift (RWGS) reaction is a relatively simple and effective conversion method. However, the RWGS reaction (CO2 + H2 → CO + H2O, ΔH) has a high ΔH... 298K The reaction with a heat output of 42.1 kJ / mol is a typical endothermic reaction, requiring a high reaction temperature. From a thermodynamic perspective, high temperatures are beneficial for the reverse water-gas shift reaction and can effectively suppress side reactions. At the same time, high temperatures can increase the reaction rate, but excessively high temperatures will reduce the activity of the catalyst.

[0004] Currently, the catalysts for reverse water-gas shift reactions are mostly Pt, Ni, or Cu-based catalysts. These catalysts can improve the selectivity of the products, increasing the CO selectivity to 90%-100%, but the CO2 conversion rate is low, only 50%-70%, and still needs improvement. Due to the equilibrium limitation in reverse water-gas shift reactions, although high temperatures are beneficial, they significantly reduce catalyst lifetime. CN116600885A discloses a method for producing syngas using catalytic reverse water-gas shift, which achieves a two-stage reverse water-gas shift reaction by using a heat exchanger and two reverse water-gas shift reactors, further improving the CO2 conversion rate, but the improvement is limited.

[0005] Pressure swing adsorption (PSA) technology utilizes the characteristic that the adsorption capacity of an adsorbent for different components varies with pressure. By selecting a suitable adsorbent, specific components in the feed gas are adsorbed under pressure, while weakly adsorbed components pass through the bed and are discharged from the adsorber, thus achieving effective gas separation. Simultaneously, the adsorbed components are removed during depressurization, enabling the adsorbent to be recycled. PSA is a common gas separation technology with significant advantages such as low energy consumption, simple process flow, high degree of automation, convenient operation, and continuous operation at room temperature.

[0006] In summary, due to thermodynamic and kinetic limitations, achieving efficient conversion of carbon dioxide to carbon monoxide through reverse water-gas shift reaction under relatively mild conditions simply by optimizing the catalyst is extremely difficult. Therefore, how to achieve efficient conversion of carbon dioxide to carbon monoxide through reverse water-gas shift reaction under mild conditions has become an urgent problem to be solved. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method for preparing carbon monoxide via reverse water-gas shift reaction. This invention leverages the synergistic effect of coupled supported catalysts and pressure swing adsorption (PSA) technology to achieve efficient and rapid separation of carbon monoxide. This promotes the forward direction of the reverse water-gas shift reaction, reduces the reaction requirements of the reverse water-gas shift reaction, and allows the reaction to proceed under relatively mild conditions. This enables long-term, efficient conversion of carbon dioxide, further improving the conversion rate of carbon dioxide and the selectivity of carbon monoxide.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing carbon monoxide through reverse water-gas shift reaction, the method comprising the following steps:

[0010] Under the catalysis of a supported catalyst, a reverse water-gas shift reaction is carried out, and the mixed gas generated during the reaction is treated by pressure swing adsorption and desorbed to obtain carbon monoxide.

[0011] This invention achieves efficient and rapid separation of carbon monoxide by coupling a supported catalyst and a pressure swing adsorption process, leveraging their synergistic effect. This promotes the forward reaction of the reverse water-gas shift reaction, reduces the reaction requirements of the reverse water-gas shift reaction, and allows the reaction to proceed under milder conditions. This enables long-term, efficient conversion of carbon dioxide, further improving the conversion rate of carbon dioxide and the selectivity of carbon monoxide.

[0012] Preferably, the supported catalyst comprises a metal active component.

[0013] Preferably, the active metal component includes any one or a combination of at least two of Fe, Ni, Mo, Cu or Co. Typical but non-limiting combinations include combinations of Fe and Ni, combinations of Mo and Cu, or combinations of Mo, Cu and Co.

[0014] Preferably, the loading of the metal active component is 0.5wt%-12wt%, for example, it can be 0.5wt%, 1wt%, 5wt%, 10wt% or 12wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0015] Preferably, the supported catalyst includes any one or a combination of at least two of the following: nickel-supported cerium oxide (Ni / CeO2) catalyst, copper-supported zinc oxide (Cu / ZnO) catalyst, molybdenum carbide-supported silica (Mo2C / SiO2) catalyst, iron-supported alumina (Fe / Al2O3) catalyst, or cobalt-supported zirconium oxide (Co / ZrO2) catalyst. Typical but non-limiting combinations include the combination of nickel-supported cerium oxide (Ni / CeO2) catalyst and copper-supported zinc oxide (Cu / ZnO) catalyst, the combination of molybdenum carbide-supported silica (Mo2C / SiO2) catalyst and iron-supported alumina (Fe / Al2O3) catalyst, or the combination of molybdenum carbide-supported silica (Mo2C / SiO2) catalyst, iron-supported alumina (Fe / Al2O3) catalyst, and cobalt-supported zirconium oxide (Co / ZrO2) catalyst.

[0016] Preferably, an exemplary preparation method of the supported catalyst includes the following steps:

[0017] (1) The metal active components are washed and dried sequentially to obtain the pretreated metal active components;

[0018] (2) The pretreated metal active component is loaded onto the catalyst support by impregnation method to obtain the supported catalyst.

[0019] The supported catalyst of this invention can increase the reaction rate of the reverse water-gas shift reaction, drive the equilibrium reaction toward the forward direction, reduce the reaction requirements of the reverse water-gas shift reaction, and further improve the conversion rate of carbon dioxide and the selectivity of carbon monoxide.

[0020] Preferably, the reaction temperature of the reverse water-gas conversion reaction is 300℃-600℃, for example, it can be 300℃, 400℃, 500℃, 550℃ or 600℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] Preferably, the absolute pressure of the reverse water-gas conversion reaction is 95kPa-105kPa, for example, it can be 95kPa, 97kPa, 99kPa, 100kPa, 102kPa or 105kPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] Preferably, before pressure swing adsorption, the mixed gas after the reaction is pressurized and cooled sequentially.

[0023] Preferably, the pressure applied is 2MPa-3MPa, for example, it can be 2MPa, 2.2MPa, 2.4MPa, 2.6MPa, 2.8MPa or 3MPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the adsorbent for pressure swing adsorption includes a support and a matrix material.

[0025] Preferably, an exemplary method for preparing the adsorbent includes the following steps:

[0026] (1) Grind and mix the carrier and matrix materials to obtain a mixture;

[0027] (2) The mixture is calcined under a reducing atmosphere to obtain the adsorbent.

[0028] This invention uses an adsorbent to adsorb carbon monoxide in a gas mixture, achieving the adsorption and separation of carbon monoxide and carbon dioxide, thus reversing the reverse water-gas shift reaction and further improving the conversion rate of carbon dioxide and the selectivity of carbon monoxide.

[0029] Preferably, the support comprises any one or a combination of at least two of Cu, Fe, ZnO or MgO. Typical but non-limiting combinations include a combination of Cu and Fe, a combination of ZnO and MgO, or a combination of Fe, ZnO and MgO.

[0030] Preferably, the matrix material includes any one or a combination of at least two of activated carbon, molecular sieves, or metal-organic framework materials. Typical but not limited combinations include a combination of activated carbon and molecular sieves, or a combination of activated carbon, molecular sieves, and metal-organic framework materials.

[0031] Preferably, the adsorbent for pressure swing adsorption includes Cu-supported activated carbon, Fe-supported activated carbon, ZnO-supported molecular sieve, or MgO-supported metal-organic framework material.

[0032] Preferably, the pressure of the pressure swing adsorption is 2MPa-3MPa, for example, it can be 2MPa, 2.2MPa, 2.4MPa, 2.6MPa, 2.8MPa or 3MPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] This invention improves the adsorption rate and amount of carbon monoxide by further regulating the adsorption pressure of pressure swing adsorption, thereby promoting the reverse water gas shift reaction to proceed in the forward direction, reducing the reaction requirements of reverse water gas shift reaction, and further improving the conversion rate of carbon dioxide and the selectivity of carbon monoxide.

[0034] Preferably, the desorption pressure is 0.5MPa-1MPa, for example, it can be 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa or 1MPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] This invention achieves selective desorption of carbon monoxide by limiting the desorption pressure within a preferred range, resulting in carbon monoxide with fewer impurities and higher purity.

[0036] As a preferred technical solution of the present invention, the method includes the following steps:

[0037] (1) The supported catalyst is placed in a fixed bed reactor and the reverse water-gas shift reaction is carried out at 300℃-600℃ and 95kPa-105kPa absolute pressure.

[0038] (2) The mixed gas obtained during the reaction is pressurized to 2MPa-3MPa by an air compressor, then cooled and water vapor is removed in a filter to obtain a mixed gas with water vapor removed.

[0039] (3) The mixed gas after removing water vapor is introduced into the adsorption tower for pressure swing adsorption. Under the action of the adsorbent, selective pressure swing adsorption of CO is achieved, and the unadsorbed CO2 and H2 are recycled into the fixed bed reactor. The pressure of the pressure swing adsorption is 2MPa-3MPa.

[0040] (4) Desorb CO in the adsorption tower and store it to obtain CO gas; the desorption pressure is 0.5MPa-1MPa.

[0041] Compared with the prior art, the present invention has at least the following beneficial effects:

[0042] (1) This invention achieves efficient and rapid separation of carbon monoxide by coupling supported catalyst and pressure swing adsorption process, thereby promoting the reverse water gas conversion reaction to proceed in the forward direction, reducing the reaction requirements of reverse water gas conversion, and enabling the reverse water gas conversion reaction to proceed under relatively mild conditions.

[0043] (2) This invention achieves long-term and efficient conversion of carbon dioxide, further improving the conversion rate of carbon dioxide and the selectivity of carbon monoxide. Under 500 hours of operation, the carbon dioxide conversion rate is higher than 74.2% and the carbon monoxide selectivity is higher than 92.9%. Attached Figure Description

[0044] Figure 1 This is a process flow diagram of the reverse water gas shift process for preparing carbon monoxide according to the present invention;

[0045] Among them, 1-fixed bed reactor; 2-air compressor; 3-filter; 4-buffer tank; 5-adsorption tower; 6-vacuum pump. Detailed Implementation

[0046] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0047] Example 1

[0048] This embodiment provides a method for preparing carbon monoxide via reverse water-gas shift conversion, the method comprising the following steps:

[0049] (1) One part by mass of the supported catalyst Ni / CeO2 was placed in a fixed bed reactor and a reverse water-gas shift reaction was carried out at 450℃ and 100kPa absolute pressure; wherein, the loading of the metal active component Ni was 8wt%.

[0050] (2) The mixed gas obtained during the reaction process is pressurized to 2.5MPa by an air compressor, then cooled and water vapor is removed in a filter to obtain a mixed gas with water vapor removed;

[0051] (3) The mixed gas after removing water vapor is introduced into the adsorption tower for pressure swing adsorption. Under the action of Cu-supported activated carbon adsorbent, CO is selectively adsorbed, and the unadsorbed CO2 and H2 are recycled into the fixed bed reactor; the pressure of the pressure swing adsorption is 2.5 MPa.

[0052] (4) Desorb CO in the adsorption tower and store it to obtain CO gas; the desorption pressure is 1 MPa.

[0053] Example 2

[0054] This embodiment provides a method for preparing carbon monoxide via reverse water-gas shift conversion, the method comprising the following steps:

[0055] (1) One part by mass of the supported catalyst Cu / ZnO was placed in a fixed bed reactor and subjected to a reverse water-gas shift reaction at 300℃ and 105kPa absolute pressure; wherein the loading of the metal active component Cu was 0.5wt%.

[0056] (2) The mixed gas obtained during the reaction process is pressurized to 3MPa by an air compressor, then cooled and water vapor is removed in a filter to obtain a mixed gas with water vapor removed.

[0057] (3) The mixed gas after removing water vapor is introduced into the adsorption tower for pressure swing adsorption. Under the action of the molecular sieve adsorbent supported by ZnO, selective pressure swing adsorption of CO is achieved, and the unadsorbed CO2 and H2 are recycled into the fixed bed reactor; the pressure of the pressure swing adsorption is 3 MPa.

[0058] (4) Desorb CO in the adsorption tower and store it to obtain CO gas; the desorption pressure is 1 MPa.

[0059] Example 3

[0060] This embodiment provides a method for preparing carbon monoxide via reverse water-gas shift conversion, the method comprising the following steps:

[0061] (1) One part by mass of the supported catalyst Mo2C / SiO2 was placed in a fixed bed reactor and subjected to a reverse water-gas shift reaction at 600℃ and 95kPa absolute pressure; wherein the loading of the metal active component Mo2C was 12wt%.

[0062] (2) The mixed gas obtained during the reaction process is pressurized to 2MPa by an air compressor, then cooled and water vapor is removed in a filter to obtain a mixed gas with water vapor removed.

[0063] (3) The mixed gas after removing water vapor is introduced into the adsorption tower for pressure swing adsorption. Under the action of Fe-supported activated carbon adsorbent, CO selective pressure swing adsorption is achieved, and the unadsorbed CO2 and H2 are recycled into the fixed bed reactor; the pressure of the pressure swing adsorption is 2 MPa.

[0064] (4) Desorb CO in the adsorption tower and store it to obtain CO gas; the desorption pressure is 0.5 MPa.

[0065] Example 4

[0066] The only difference between this embodiment and Example 1 is that, except that step (1) uses a supported catalyst Fe / Al2O3 and the loading of the metal active component Fe is 8wt%, everything else is the same as in Example 1.

[0067] Example 5

[0068] The only difference between this embodiment and Example 1 is that, except that step (1) uses a supported catalyst Co / ZrO2 and the loading of the metal active component Co is 8wt%, everything else is the same as in Example 1.

[0069] Example 6

[0070] The only difference between this embodiment and embodiment 1 is that, except that the temperature of the reverse water gas reaction in step (1) is 250°C, everything else is the same as in embodiment 1.

[0071] Example 7

[0072] The only difference between this embodiment and embodiment 1 is that, except that the temperature of the reverse water gas reaction in step (1) is 650°C, everything else is the same as in embodiment 1.

[0073] Example 8

[0074] The only difference between this embodiment and embodiment 1 is that, except that the pressure of pressure swing adsorption in step (3) is 1.5 MPa, everything else is the same as in embodiment 1.

[0075] Example 9

[0076] The only difference between this embodiment and Embodiment 1 is that, except that the pressure of pressure swing adsorption in step (3) is 3.5 MPa, everything else is the same as in Embodiment 1.

[0077] Example 10

[0078] The only difference between this embodiment and Example 1 is that, except that the adsorbent in step (3) is activated carbon, everything else is the same as in Example 1.

[0079] Comparative Example 1

[0080] This comparative example provides a method for preparing a mixed gas by reverse water-gas shift conversion, the method comprising the following steps:

[0081] One part of the supported catalyst Ni / CeO2 was placed in a fixed-bed reactor, wherein the loading of the metal active component Ni was 8 wt%, and a reverse water-gas shift reaction was carried out at 450℃ and 100 kPa absolute pressure to obtain a mixed gas after the reaction.

[0082] Comparative Example 2

[0083] The only difference between this comparative example and Example 1 is that, except that a supported catalyst is not added in step (1), everything else is the same as in Example 1.

[0084] Comparative Example 3

[0085] This comparative example provides a method for preparing a mixed gas by reverse water-gas shift conversion, the method comprising the following steps:

[0086] (1) One part of the supported catalyst Ni / CeO2 was placed in the first fixed bed reactor and the first reverse water-gas shift reaction was carried out at 450℃ and 100kPa absolute temperature; wherein the loading of the metal active component Ni was 8wt%.

[0087] (2) Cool the mixture obtained from the first reaction and remove water vapor in a filter to obtain the first mixture with water vapor removed;

[0088] (3) After heating the first mixed gas after removing water vapor, the second countercurrent water gas reaction is carried out in the second fixed bed reactor.

[0089] (4) Cool the mixture obtained from the second reaction and remove water vapor in a filter to obtain a second mixture with water vapor removed.

[0090] Test methods

[0091] The gaseous products obtained in Examples 1-10 and Comparative Examples 1-3 were analyzed using a Haixin GC-950 gas chromatograph. The detector type was a TCD detector, and the detection conditions were: column oven temperature 70℃, detector temperature 100℃, TCD current 60mA, and Ar gas was used as the carrier gas. The analysis results are recorded in Table 1.

[0092] Table 1

[0093]

[0094]

[0095] The test results show that:

[0096] (1) As can be seen from Examples 1-10 and Comparative Examples 1-3, the present invention achieves efficient and rapid separation of carbon monoxide by coupling supported catalyst and pressure swing adsorption process, thereby promoting the reverse water gas shift reaction to proceed in the forward direction, reducing the reaction requirements of reverse water gas shift reaction, and enabling the reverse water gas shift reaction to achieve long-term efficient conversion of carbon dioxide under relatively mild conditions, thereby further improving the conversion rate of carbon dioxide and the selectivity of carbon monoxide.

[0097] (2) As can be seen from Examples 1 and 4-5, the present invention selects a metal active component supported catalyst, which has strong thermal stability and reusability, which is conducive to further improving the reaction efficiency of the reverse water gas reaction, promoting the reverse water gas conversion reaction to proceed in the forward direction, reducing the reaction requirements of the reverse water gas conversion, and further improving the conversion rate of carbon dioxide and the selectivity of carbon monoxide.

[0098] (3) As can be seen from Examples 1 and 6-7, the present invention further improves the conversion rate of carbon dioxide and the selectivity of carbon monoxide by further controlling the reaction temperature of the reverse water gas conversion reaction and promoting the reverse water gas conversion reaction to proceed in the forward direction.

[0099] (4) As can be seen from Examples 1 and 8-10, the present invention improves the adsorption rate and adsorption amount of carbon monoxide by further controlling the pressure of pressure swing adsorption and selecting a suitable pressure swing adsorbent, thereby promoting the equilibrium reaction to proceed in the forward direction and achieving selective adsorption of carbon monoxide, so as to make the reverse water gas shift reaction proceed in the forward direction, thereby further improving the conversion rate of carbon dioxide and the selectivity of carbon monoxide.

[0100] (5) As can be seen from Example 1 and Comparative Examples 1-3, the present invention significantly improves the conversion rate of carbon dioxide by leveraging the synergistic effect of supported catalyst and pressure swing adsorption process, while simplifying the process flow.

[0101] In summary, this invention achieves efficient and rapid separation of carbon monoxide by coupling a supported catalyst and a pressure swing adsorption (PSA) process, leveraging their synergistic effect. This promotes the forward reaction of the reverse water-gas shift reaction, reduces the reaction requirements of the reverse water-gas shift reaction, and allows the reaction to proceed under relatively mild conditions. This enables long-term, efficient conversion of carbon dioxide, further improving the conversion rate of carbon dioxide and the selectivity of carbon monoxide.

[0102] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing carbon monoxide through reverse water-gas shift reaction, characterized in that, The method includes the following steps: Under the catalysis of a supported catalyst, a reverse water-gas shift reaction is carried out, and the mixed gas generated during the reaction is treated by pressure swing adsorption and desorbed to obtain carbon monoxide.

2. The method according to claim 1, characterized in that, The supported catalyst includes a metal active component; Preferably, the active metal component includes any one or a combination of at least two of Fe, Ni, Mo, Cu, or Co.

3. The method according to claim 2, characterized in that, The loading of the metal active component is 0.5wt%-12wt%.

4. The method according to any one of claims 1-3, characterized in that, The reaction temperature of the reverse water-gas shift reaction is 300℃-600℃.

5. The method according to any one of claims 1-4, characterized in that, The absolute pressure of the reverse water-gas shift reaction is 95 kPa-105 kPa.

6. The method according to any one of claims 1-5, characterized in that, Before the pressure swing adsorption, the mixed gas after the reaction is pressurized and cooled sequentially. Preferably, the pressurized pressure is 2MPa-3MPa.

7. The method according to any one of claims 1-5, characterized in that, The adsorbent for pressure swing adsorption includes a support and a matrix material; Preferably, the support comprises any one or a combination of at least two of Cu, Fe, ZnO or MgO; Preferably, the matrix material includes any one or a combination of at least two of activated carbon, molecular sieves, or metal-organic framework materials.

8. The method according to any one of claims 1-7, characterized in that, The pressure swing adsorption is 2MPa-3MPa.

9. The method according to any one of claims 1-8, characterized in that, The desorption pressure is 0.5 MPa-1 MPa.

10. The method according to claim 1, characterized in that, The method includes the following steps: (1) The supported catalyst was placed in a fixed-bed reactor and the reverse water-gas shift reaction was carried out at 300℃-600℃ and 95kPa-105kPa absolute pressure. (2) The mixed gas obtained during the reaction is pressurized to 2MPa-3MPa by an air compressor, then cooled and water vapor is removed in a filter to obtain a mixed gas with water vapor removed. (3) The mixed gas after removing water vapor is introduced into the adsorption tower for pressure swing adsorption. Under the action of the adsorbent, selective pressure swing adsorption of CO is achieved, and the unadsorbed CO2 and H2 are recycled into the fixed bed reactor. The pressure of the pressure swing adsorption is 2MPa-3MPa. (4) Desorb CO in the adsorption tower and store it to obtain CO gas; the desorption pressure is 0.5MPa-1MPa.

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