A catalytic conversion process for the decomposition of carbon dioxide into carbon monoxide

Abstract

The application discloses a catalytic conversion method for decomposing carbon dioxide into carbon monoxide, and is characterized by comprising the following steps: in the first step, carbon dioxide molecules and added hydrogen molecules are adsorbed on the surface of a biomass activated carbon / Rh2O3 / NiO phase material to form an adsorption state structure, the hydrogen molecules are decomposed into adsorption state hydrogen atoms, and the carbon dioxide reacts with part of the hydrogen atoms to generate carboxyl groups; in the second step, the generated adsorption state carboxyl groups react with the remaining hydrogen atoms to release a water molecule, and adsorption state carbon monoxide molecules are formed, and the adsorption state carbon monoxide is desorbed into a free state to obtain carbon monoxide gas. The application can more efficiently and stably realize the treatment of decomposing and converting carbon dioxide into carbon monoxide, and is more beneficial to large-scale production and preparation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of contaminated gas decomposition treatment, in particular to a catalytic conversion method for decomposing carbon dioxide into carbon monoxide. BACKGROUND

[0002] Carbon dioxide is one of the main pollutants discharged in the processes of industrial production, building operation and human metabolism. In order to better achieve the goal of carbon peak and carbon neutralization, it is necessary to further develop purification methods for carbon dioxide by means of adsorption capture, underground storage and other means. In addition, carbon dioxide can also be catalytically converted into carbon monoxide gas with utilization value, realizing multiple recycling of carbon dioxide and producing the effect of turning waste into treasure.

[0003] CN117548144A has disclosed a metal-loaded mesoporous cerium-based MOFs and its preparation method and application; CN116083949A has disclosed a MXene-loaded Ag-ZnO electrocatalyst and its preparation method, application and testing method; CN116043258A has disclosed a preparation method and application of a self-supporting copper selenide nanosheet electrocatalyst; and CN114799197A has disclosed a preparation method of a copper-antimony single-atom alloy catalyst and a carbon dioxide reduction application. The above-mentioned patent solutions can all realize the preparation process of decomposing and converting carbon dioxide into carbon monoxide. However, these existing catalysts for catalytically converting carbon dioxide into methane by hydrogenation cannot prevent the liquid water generated during the reaction from isolating gaseous carbon dioxide from the surface of the solid catalyst, thereby seriously affecting the catalytic conversion efficiency of carbon dioxide and failing to meet the requirement of rapidly and large-scale generating carbon monoxide fuel. Therefore, the existing catalytic conversion decomposition materials still have the defects of poor overall rate and poor catalyst stability, and it is difficult to meet the needs of rapid conversion and utilization of carbon dioxide.

[0004] Therefore, how to provide a catalytic conversion method for decomposing carbon dioxide into carbon monoxide, which is different from the prior art and can more efficiently and stably realize the decomposition of carbon dioxide into carbon monoxide, has become a problem to be considered and solved by those skilled in the art. SUMMARY

[0005] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present application is: how to provide a catalytic conversion method for decomposing carbon dioxide into carbon monoxide, which can more efficiently and stably realize the decomposition and conversion treatment of carbon dioxide, so as to be more beneficial to large-scale production and preparation.

[0006] In order to solve the above-mentioned technical problems, the present application adopts the following technical solution:

[0007] A catalytic conversion method for decomposing carbon dioxide into carbon monoxide, characterized in that it comprises the following steps:

[0008] In the first step, carbon dioxide molecules and added hydrogen molecules are adsorbed on the surface of the biomass activated carbon / Rh2O3 / NiO phase material to form an adsorbed structure. The hydrogen molecules are decomposed into adsorbed hydrogen atoms, and carbon dioxide reacts with some hydrogen atoms to form carboxyl groups. The reaction process includes the following reaction formula:

[0009] CO2(free) + Rh2O3 / NiO@C → CO2(ad),

[0010] H2(free) + Rh2O3 / NiO@C → 2*H (ad),

[0011] CO2 (ad) + *H (ad) → COOH (ad);

[0012] In the second step, the generated adsorbed carboxyl group reacts with the remaining hydrogen atom to release a water molecule, forming an adsorbed carbon monoxide molecule. The adsorbed carbon monoxide desorbs to a free state at the high reaction temperature to obtain carbon monoxide gas. The reaction process includes the following reaction formula:

[0013] COOH (ad) + *H (ad) → CO (ad) + H2O,

[0014] CO(ad) + energy → CO(free).

[0015] As an optimization, the biomass activated carbon is rice husk-based biomass activated carbon. It is easy to prepare and has better porosity, with an average specific surface area of ​​>1500 m 2 / g.

[0016] Thus, the present invention uses biomass activated carbon embedded with Rh2O3 and NiO as a catalytic conversion decomposition material for carbon dioxide decomposition, and the above reaction process can quickly and efficiently achieve the decomposition of carbon dioxide. In this process, first, the biomass activated carbon has a large specific surface area (as mentioned above, the average specific surface area is >1500 m 2 / g), which can provide a large number of adsorption sites for the adsorption of carbon dioxide and hydrogen molecules; secondly, the functional components Rh2O3 and NiO embedded in the activated carbon can be used to catalyze the formation of carboxyl groups and catalyze the formation of water molecules, respectively. The synergistic cooperation of the two can greatly increase the efficiency of the catalytic conversion of carbon dioxide into carbon monoxide.

[0017] Therefore, further, in the present invention, a carbon dioxide catalytic decomposition material whose main effective components are biomass activated carbon / Rh2O3 / NiO phase is used to achieve catalytic decomposition treatment of carbon dioxide.

[0018] In the above-mentioned carbon dioxide catalytic decomposition materials, biomass activated carbon serves as a matrix for loading effective active ingredients Rh2O3 and NiO and capturing and adsorbing carbon dioxide and hydrogen molecules, and is the base bed for the catalytic reaction. The specific reaction process principle is as follows.

[0019] (a) The Role of Rh2O3. The carbon dioxide hydrogenation step to form a carboxyl group in the fundamental process of catalytic conversion of carbon dioxide to carbon monoxide requires the cleavage of one of the C=O double bonds, allowing the O atom to form a bond with an adsorbed H atom. Because the Rh atom in Rh2O3 has an active outer-shell electron, it can combine with an active outer-shell electron of the C atom in CO2 to form a bond, thereby promoting the cleavage of one of the single bonds in the C=O double bond. Furthermore, a more fundamental role is played by the presence of unpaired electrons in all four outer-shell orbitals of the Rh atom, which has a high probability and strength of attraction-bonding interaction with adsorbed H atoms, making it easier to form multiple Rh(Rh2O3)-O(CO2) bonds, further enhancing the partial cleavage of the C=O double bond. Furthermore, a supplementary facilitating effect is that some CO2 can directly adsorb onto the O atom in Rh2O3, allowing the C atom to directly bond with this O atom, thereby reducing a C=O double bond to a CO single bond, which is then available for subsequent bonding with the adsorbed H atom.

[0020] (b) The role of NiO. The carboxyl hydrogenation and dehydration formation step in the basic process of catalytic conversion of carbon dioxide to carbon monoxide requires the hydroxyl group to break off from the carboxyl group and combine with another adsorbed H atom. This process involves the cleavage of the CO bond. Because the outer layer of the Ni atom in NiO has five active valence electrons, it can migrate across the entire surface through the delocalized π bonds on the porous carbon surface. When it migrates to the carboxyl group, it can combine with the O atom in the -OH group to form a free radical form, thereby breaking the CO bond and quickly combining with another adsorbed H atom. At the same time, a more fundamental role is that the H atoms formed after the decomposition of hydrogen molecules are more easily adsorbed on the O atoms in NiO. This is because the Ni surface in NiO still has three valence electrons, which can form a Ni···H structure with the H atom. This can significantly fix the free H atoms, attracting and aggregating the H atoms originally dispersed at different sites on the porous activated carbon surface around the NiO group, further increasing the rate of the carboxyl hydrogenation and dehydration reaction. It should be noted that the Rh2O3 group also has the above-mentioned function of combining NiO with H atoms, but since Rh in Rh2O3 has only one outer active valence electron left, its ability to aggregate adsorbed H atoms is lower than that of NiO, and it does not serve as the main functional component of the carboxyl hydrogenation and dehydration step.

[0021] Therefore, the present invention can be used for the industrial production of carbon dioxide decomposition to convert carbon monoxide. Under the action of the catalyst, the passing carbon dioxide and hydrogen are rapidly catalytically decomposed into carbon monoxide and water, reducing the environmental harm of carbon dioxide emissions and turning waste into resources. It can also improve the efficiency of carbon dioxide catalytic decomposition. The applicant has verified that the present invention can increase the Faradaic efficiency of carbon monoxide generation from 80% to 95% or more, and achieve a Faradaic efficiency loss of less than 5% after 6 hours of carbon dioxide catalytic conversion.

[0022] Furthermore, the carbon dioxide catalytic decomposition material used in the present invention includes the following phase components in the following mass proportions: 0.01-0.15 parts of biomass activated carbon phase, 0.01-0.08 parts of Rh2O3 phase, 0.01-0.11 parts of NiO phase, and 0.66-0.097 parts of biomass activated carbon / Rh2O3 / NiO phase.

[0023] Further better mass ratios are: 0.02 parts of biomass activated carbon phase, 0.08 parts of Rh2O3 phase, 0.11 parts of NiO phase, and 0.79 parts of biomass activated carbon / Rh2O3 / NiO phase.

[0024] Among the above-mentioned carbon dioxide catalytic decomposition materials, the biomass activated carbon / Rh2O3 / NiO phase is the main site of the carbon dioxide catalytic decomposition reaction and therefore accounts for a large proportion. The biomass activated carbon phase, Rh2O3 phase and NiO phase are common reaction products and can also be used to provide reaction sites and assist in enhancing the carbon dioxide catalytic decomposition process. Moreover, the components of each phase can play a certain dynamic conversion and supplement effect, thereby better ensuring the durability of the treatment effect.

[0025] Furthermore, the carbon dioxide catalytic decomposition material is prepared by the following steps:

[0026] Step 1: First obtain biomass activated carbon as a substrate;

[0027] Step 2: Complete the generation and loading of rhodium trioxide and nickel oxide; pour 20 g of the above-mentioned biomass activated carbon into 500 ml of ultrapure water, and add 0.25 mol of dihydrated rhodium nitrate (Rh(NO3)3·2H2O) and 0.15 mol of hexahydrated nickel nitrate (Ni(NO3)2·6H2O) to form a mixed solution; then, stir the obtained mixed solution evenly, dry it and grind it into powder (as an optimization, the drying and grinding process is to place it in a magnetic stirrer at 200 r / min and 50 ° C for 2 h; then, place the mixed solution in an oven at 70 ℃ to evaporate all water to obtain agglomerates, and grind the agglomerates into 200 mesh powder; completing the loading first can better ensure the subsequent calcination reaction effect); then, the obtained powder is calcined to obtain a porous activated carbon-supported rhodium trioxide (Rh2O3) / nickel oxide (NiO) composite catalyst (as an optimization, the calcination process is: the above-mentioned 200 mesh powder is placed in a muffle furnace and continuously calcined at 850 ℃ for 5 h (the heating rate from room temperature to 500 ℃ is 50 ℃ / min), and then cooled to room temperature by natural ventilation to obtain a porous activated carbon-supported rhodium trioxide (Rh2O3) / nickel oxide (NiO) composite catalyst. This better ensures the reaction effect).

[0028] In the above steps, the proportion of each reaction component can be increased or decreased in equal proportion. During the preparation process, rhodium nitrate and nickel nitrate will decompose into rhodium trioxide and nickel oxide at high temperature, and the reaction equation is: Rh(NO3)2 → Rh2O3 +NO2 + O2, Ni(NO3)2 → NiO + NO2 + O2. At the same time, the Rh2O3 and NiO produced after decomposition will be embedded in the activated carbon at high temperature to form a composite catalyst of biomass activated carbon loaded with Rh2O3 / NiO, that is, the carbon dioxide catalytic decomposition material, and the reaction equation is: Rh2O3 + NiO + C n →···C···Rh2O3···C···NiO···C···.

[0029] Therefore, the above reaction process can quickly and efficiently produce a carbon dioxide catalytic decomposition material with the main active ingredients, biomass activated carbon / Rh2O3 / NiO, accounting for more than 50%, ensuring efficient catalytic decomposition of carbon dioxide after adsorption. At the same time, the other phase components generated are evenly mixed and doped together, which can help enhance the decomposition reaction and better ensure the durability of the carbon dioxide catalytic treatment effect.

[0030] Furthermore, the biomass carbon-based substrate was prepared by the following method: first, 50 g of rice husk-based biomass powder / lump was weighed, dissolved in 500 ml of ultrapure water and placed in a sealed reactor, and heated continuously at 150 °C for 24 h; then, the suspension after hydrothermal treatment was filtered through a 0.22 μm microporous filter membrane, and the resulting filter residue was rinsed with ultrapure water for three times, dried in a drying oven at 50 °C for 72 h to obtain agglomerates, and then ground into 200 mesh powder; then, the obtained biomass powder was placed in a muffle furnace and calcined at 500 °C for 3 h under argon (Ar) protection (the heating rate from room temperature to 500 °C was 25 °C / min), and then cooled to room temperature by natural ventilation; the calcined powder was placed in 50 ml of sodium hydroxide solution (50 wt.%) and immersed for 1 h to form a paste, and the paste was placed in a muffle furnace and calcined at 500 °C for 6 h under a conventional air atmosphere. h (the heating rate from room temperature to 500 °C is 20 °C / min), cooled to room temperature by natural ventilation, and then ground into 200 mesh to obtain a porous activated carbon substrate.

[0031] In this way, rice husk is used as the material for preparing biomass carbon. The powder is hydrothermally treated, then washed, filtered and evaporated to complete the initial removal of non-carbonized components. Then, it is carbonized through two grinding and calcination processes. This allows the prepared pure bamboo-based biomass activated carbon to have a higher adsorption efficiency. The rice husk-based biomass powder / lump is converted into porous activated carbon (average pore size 5 nm, average specific surface area >1500 m2) after hot water activation and high-temperature calcination. 2 / g), the reaction equation is: C (inactive) → C (porous activated carbon). Therefore, it has the characteristics of low cost and easy preparation, and the product has good porosity and large specific surface area.

[0032] Therefore, the present invention can achieve the treatment of decomposing carbon dioxide into carbon monoxide more efficiently and stably, making it more conducive to large-scale production and preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the principle process of the catalytic decomposition of carbon dioxide by the carbon dioxide catalytic decomposition material of the present invention.

[0034] Figure 2 Schematic diagram comparing the Faraday efficiency of the carbon dioxide catalytic decomposition material of the present invention and other types of carbon dioxide catalytic decomposition materials.

[0035] Figure 3 Schematic diagram comparing the Faraday efficiency loss of the carbon dioxide catalytic decomposition material of the present invention and other types of carbon dioxide catalytic decomposition materials. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below with reference to specific embodiments.

[0037] Implementation method: A catalytic conversion method for decomposing carbon dioxide into carbon monoxide, characterized in that it includes the following steps:

[0038] In the first step, carbon dioxide molecules and added hydrogen molecules are adsorbed on the surface of the biomass activated carbon / Rh2O3 / NiO phase material to form an adsorbed structure. The hydrogen molecules are decomposed into adsorbed hydrogen atoms, and carbon dioxide reacts with some hydrogen atoms to form carboxyl groups. The reaction process includes the following reaction formula:

[0039] CO2(free) + Rh2O3 / NiO@C → CO2(ad),

[0040] H2(free) + Rh2O3 / NiO@C → 2*H (ad),

[0041] CO2 (ad) + *H (ad) → COOH (ad);

[0042] In the second step, the generated adsorbed carboxyl group reacts with the remaining hydrogen atom to release a water molecule, forming an adsorbed carbon monoxide molecule. The adsorbed carbon monoxide desorbs to a free state at the high reaction temperature to obtain carbon monoxide gas. The reaction process includes the following reaction formula:

[0043] COOH (ad) + *H (ad) → CO (ad) + H2O,

[0044] CO(ad) + energy → CO(free).

[0045] During implementation, the biomass activated carbon is rice husk-based biomass activated carbon. It is easy to prepare and has better porosity, with an average specific surface area of ​​>1500 m 2 / g.

[0046] Thus, the present invention uses biomass activated carbon embedded with Rh2O3 and NiO as a catalytic conversion decomposition material for carbon dioxide decomposition, and the above reaction process can quickly and efficiently achieve the decomposition of carbon dioxide. In this process, first, the biomass activated carbon has a large specific surface area (as mentioned above, the average specific surface area is >1500 m 2 / g), which can provide a large number of adsorption sites for the adsorption of carbon dioxide and hydrogen molecules; secondly, the functional components Rh2O3 and NiO embedded in the activated carbon can be used to catalyze the formation of carboxyl groups and catalyze the formation of water molecules, respectively. The synergistic cooperation of the two can greatly increase the efficiency of the catalytic conversion of carbon dioxide into carbon monoxide.

[0047] In the embodiment, a carbon dioxide catalytic decomposition material mainly containing biomass activated carbon / Rh2O3 / NiO phase is used to realize the catalytic decomposition of carbon dioxide.

[0048] In the carbon dioxide catalytic decomposition material, the biomass activated carbon is used as a carrier of the effective components Rh2O3 and NiO and a substrate for capturing and adsorbing carbon dioxide and hydrogen molecules, and is used as a catalyst bed for the catalytic reaction. The specific reaction process is as follows.

[0049] (a) The role of Rh2O3. For the step of carbon dioxide hydrogenation to form a carboxyl group in the process of catalytic conversion of carbon dioxide to carbon monoxide, one bond in the C=O double bond needs to be broken, and then the O atom is bonded with the adsorbed H atom. Since the Rh atom in Rh2O3 has one active electron in the outer layer, it can combine with one active electron in the outer layer of CO2 to form a bond, thereby promoting the breaking of one single bond in the C=O double bond. Meanwhile, the more basic role is that the four orbitals of the Rh atom in the outer layer all have unpaired electrons, which have a high probability and strength of attraction-bonding with the adsorbed H atom, and can more easily form a multiple state Rh(Rh2O3)-O(CO2) valence bond, thereby further enhancing the partial breaking of the C=O double bond. In addition, the supplementary promotion is that part of CO2 can be directly adsorbed on the O atom in Rh2O3, and then the C atom can be directly bonded with the O atom, thereby reducing one C=O double bond to a C-O single bond for subsequent bonding with the adsorbed H atom.

[0050] (b) The role of NiO. For the step of carboxyl hydrogenation and dehydration in the process of catalytic conversion of carbon dioxide to carbon monoxide, the hydroxyl group needs to be broken from the carboxyl group and combined with another adsorbed H atom, which involves the breaking of the C-O bond. Since the Ni atom in NiO has five active valence electrons in the outer layer, it can migrate on the whole surface through the delocalized π bond of the porous carbon surface, and when it migrates to the carboxyl group, it can combine with the O atom in the -OH to form a free radical form, thereby destroying the C-O bond and quickly combining with another adsorbed H atom. Meanwhile, the more basic role is that the H atoms formed after the decomposition of hydrogen molecules are more easily adsorbed on the O atoms in NiO, because the Ni surface in NiO still has three valence electrons, which can form a Ni···H structure with the H atom, which can significantly fix the free H atoms, attract and gather the H atoms originally dispersed on different sites of the porous activated carbon surface to the surrounding of the NiO group, thereby further increasing the reaction rate of the carboxyl hydrogenation and dehydration. It should be noted that the Rh2O3 group also has the function of combining with H atoms as described above for NiO, but since Rh in Rh2O3 only has one active valence electron in the outer layer, its ability to gather adsorbed H atoms is lower than that of NiO, and it is not the main functional component for the step of carboxyl hydrogenation and dehydration.

[0051] Therefore, the present invention can be used for the industrial production of carbon dioxide decomposition to convert carbon monoxide. Under the action of the catalyst, the passing carbon dioxide and hydrogen are rapidly catalytically decomposed into carbon monoxide and water, reducing the environmental harm of carbon dioxide emissions and turning waste into resources. It can also improve the efficiency of carbon dioxide catalytic decomposition. The applicant has verified that the present invention can increase the Faradaic efficiency of carbon monoxide generation from 80% to 95% or more, and achieve a Faradaic efficiency loss of less than 5% after 6 hours of carbon dioxide catalytic conversion.

[0052] Among them, the carbon dioxide catalytic decomposition material used in the present invention includes the following phase components in the following mass proportions: 0.01-0.15 parts of biomass activated carbon phase, 0.01-0.08 parts of Rh2O3 phase, 0.01-0.11 parts of NiO phase, and 0.66-0.097 parts of biomass activated carbon / Rh2O3 / NiO phase.

[0053] The better mass ratio is: 0.02 parts of biomass activated carbon phase, 0.08 parts of Rh2O3 phase, 0.11 parts of NiO phase, and 0.79 parts of biomass activated carbon / Rh2O3 / NiO phase.

[0054] Among the above-mentioned carbon dioxide catalytic decomposition materials, the biomass activated carbon / Rh2O3 / NiO phase is the main site of the carbon dioxide catalytic decomposition reaction and therefore accounts for a large proportion. The biomass activated carbon phase, Rh2O3 phase and NiO phase are common reaction products and can also be used to provide reaction sites and assist in enhancing the carbon dioxide catalytic decomposition process. Moreover, the components of each phase can play a certain dynamic conversion and supplement effect, thereby better ensuring the durability of the treatment effect.

[0055] During implementation, the carbon dioxide catalytic decomposition material is prepared by the following steps:

[0056] Step 1: First obtain biomass activated carbon as a substrate;

[0057] Step 2: Complete the generation and loading of rhodium trioxide and nickel oxide; pour 20 g of the above-mentioned biomass activated carbon into 500 ml of ultrapure water, and add 0.25 mol of dihydrated rhodium nitrate (Rh(NO3)3·2H2O) and 0.15 mol of hexahydrated nickel nitrate (Ni(NO3)2·6H2O) to form a mixed solution; then, place the obtained mixed solution in a magnetic stirrer and stir continuously at 200 r / min and 50 ° C for 2 h; then, place the mixed solution in an oven and evaporate all water at 70 ° C to obtain agglomerates, and grind the agglomerates into 200 mesh powder; then, place the above-mentioned 200 mesh powder in a muffle furnace and calcine continuously at 850 ° C for 5 h (the heating rate from room temperature to 500 ° C is 50 ℃ / min), and then cooled to room temperature with natural ventilation to obtain a porous activated carbon-supported rhodium trioxide (Rh2O3) / nickel oxide (NiO) composite catalyst (i.e., "Rh2O3 / NiO@C").

[0058] In the above steps, the proportion of each reaction component can be increased or decreased in equal proportion. During the preparation process, rhodium nitrate and nickel nitrate will decompose into rhodium trioxide and nickel oxide at high temperature, and the reaction equation is: Rh(NO3)2 → Rh2O3 +NO2 + O2, Ni(NO3)2 → NiO + NO2 + O2. At the same time, the Rh2O3 and NiO produced after decomposition will be embedded in the activated carbon at high temperature to form a composite catalyst of biomass activated carbon loaded with Rh2O3 / NiO, that is, the carbon dioxide catalytic decomposition material, and the reaction equation is: Rh2O3 + NiO + C n →···C···Rh2O3···C···NiO···C···.

[0059] Therefore, the above reaction process can quickly and efficiently produce a carbon dioxide catalytic decomposition material with the main active ingredients, biomass activated carbon / Rh2O3 / NiO, accounting for more than 50%, ensuring efficient catalytic decomposition of carbon dioxide after adsorption. At the same time, the other phase components generated are evenly mixed and doped together, which can help enhance the decomposition reaction and better ensure the durability of the carbon dioxide catalytic treatment effect.

[0060] During implementation, the biomass carbon-based substrate was prepared by the following method: first, 50 g of rice husk-based biomass powder / lump was weighed, dissolved in 500 ml of ultrapure water and placed in a sealed reactor, and heated continuously at 150 ° C for 24 h; then, the suspension after hydrothermal treatment was filtered through a 0.22 μm microporous filter membrane, and the resulting filter residue was rinsed with ultrapure water for 3 times, dried in a drying oven at 50 ° C for 72 h to obtain agglomerates, and then ground into 200 mesh powder; then, the obtained biomass powder was placed in a muffle furnace and calcined at 500 ° C for 3 h under argon (Ar) protection (the heating rate from room temperature to 500 ° C was 25 ° C / min), and then cooled to room temperature by natural ventilation; the calcined powder was placed in 50 ml of sodium hydroxide solution (50 wt.%) and immersed for 1 h to form a paste, and the paste was placed in a muffle furnace and calcined at 500 ° C for 6 h under conventional air atmosphere. h (the heating rate from room temperature to 500 °C is 20 °C / min), cooled to room temperature by natural ventilation, and then ground into 200 mesh to obtain a porous activated carbon substrate.

[0061] In this way, rice husk is used as the material for preparing biomass carbon. The powder is hydrothermally treated, then washed, filtered and evaporated to complete the initial removal of non-carbonized components. Then, it is carbonized through two grinding and calcination processes. This allows the prepared pure bamboo-based biomass activated carbon to have a higher adsorption efficiency. The rice husk-based biomass powder / lump is converted into porous activated carbon (average pore size 5 nm, average specific surface area >1500 m2) after hot water activation and high-temperature calcination. 2 / g), the reaction equation is: C (inactive) → C (porous activated carbon). Therefore, it has the characteristics of low cost and easy preparation, and the product has good porosity and large specific surface area.

[0062] In order to better verify the effect of the present invention, the applicant conducted a comparative test, using the carbon dioxide catalytic decomposition material obtained in the above specific embodiment as the experimental group, and using other carbon dioxide catalytic decomposition materials as the comparative group, and conducted a catalytic conversion efficiency comparison test and a conversion efficiency loss degree comparison. The test results are shown in Figure 2 and Figure 3 .

[0063] for Figure 2Under the environmental conditions of 300°C / 3.5 MPa / 0% relative humidity, experiments were conducted to compare the catalytic efficiency of carbon dioxide hydrogenation to carbon monoxide (CO) at a 19% molar concentration, using Pd-supported Ag, AuCu, AuCuB, and NiMn as control catalysts, with hydrogen (reactant gas) and nitrogen (carrier gas) molar contents of 76% and 5%, respectively. The experimental results show that the CO conversion efficiency of the control catalysts is lower than that of the rice husk-based activated carbon-supported Rh2O3 / NiO catalyst. In particular, the CO conversion efficiency of the rice husk-based activated carbon-supported Rh2O3 / NiO is much higher than that of AuCu, indicating that the coexistence of Rh2O3 and NiO can produce a synergistic effect on the CO conversion on the rice husk-based activated carbon surface, greatly enhancing the catalytic conversion ability of this composite catalyst.

[0064] for Figure 3 Under the environmental conditions of 300°C / 3.5 MPa / 0% relative humidity, experiments were conducted to compare the 6-hour conversion efficiency loss of carbon dioxide hydrogenation to carbon monoxide (CO) at a 19% molar concentration, using Pd-supported Ag and AuCu as control catalysts, respectively. The results show that the 6-hour conversion efficiency loss of the Pd-supported Ag catalyst is higher than that of the rice husk-based activated carbon-supported Rh2O3 / NiO catalyst, indicating that the coexistence of Rh2O3 and NiO can create a synergistic effect on the catalytic conversion of CO on the rice husk-based activated carbon surface, significantly reducing the loss of catalytic conversion ability of this composite catalyst.

Claims

1. A catalytic conversion method for decomposing carbon dioxide into carbon monoxide, characterized in that: The following steps are involved: In the first step, carbon dioxide molecules and added hydrogen molecules are adsorbed on the surface of the biomass activated carbon / Rh2O3 / NiO phase material to form an adsorbed structure. The hydrogen molecules are decomposed into adsorbed hydrogen atoms, and carbon dioxide reacts with some hydrogen atoms to generate carboxyl groups. The reaction process includes the following reaction formula: CO2(free) + Rh2O3 / NiO@C → CO2(ad), H2(free) + Rh2O3 / NiO@C → 2*H (ad), CO2 (ad) + *H (ad) → COOH (ad); In the second step, the generated adsorbed carboxyl group reacts with the remaining hydrogen atom to release a water molecule, forming an adsorbed carbon monoxide molecule. The adsorbed carbon monoxide desorbs to a free state at the high reaction temperature to obtain carbon monoxide gas. The reaction process includes the following reaction formula: COOH (ad) + *H (ad) → CO (ad) + H2O, CO(ad) + energy → CO(free); The catalytic conversion method is achieved by using a carbon dioxide catalytic decomposition material; The carbon dioxide catalytic decomposition material is prepared by the following steps: Step 1: First obtain biomass activated carbon as a substrate; Step 2: completing the generation and loading of rhodium trioxide and nickel oxide; pouring 20 g of the above-mentioned biomass activated carbon into 500 ml of ultrapure water, and adding 0.25 mol of rhodium nitrate dihydrate and 0.15 mol of nickel nitrate hexahydrate to form a mixed solution; then, stirring the obtained mixed solution evenly, drying it and grinding it into a powder; then, calcining the obtained powder to obtain a porous activated carbon-supported rhodium trioxide / nickel oxide composite catalyst; In step 1, the biomass carbon substrate is prepared by the following method: first, 50 g of rice husk-based biomass powder / lump is weighed, dissolved in 500 ml of ultrapure water and placed in a sealed reactor, and continuously heated at 150 ° C for 24 h; then, the suspension after hydrothermal treatment is filtered through a 0.22 μm microporous filter membrane, and the resulting filter residue is continuously rinsed with ultrapure water for 3 times, and continuously dried in a drying oven at 50 ° C for 72 h to obtain agglomerates, which are then ground into 200 mesh powder; then, the obtained biomass powder is placed in a muffle furnace and calcined at 500 ° C for 3 h under argon protection. The heating rate from room temperature to 500 ° C before calcination is 25 ° C / min, and then cooled to room temperature by natural ventilation; the calcined powder is placed in 50 ml of sodium hydroxide solution and immersed for 1 h to form a paste, and the paste is placed in a muffle furnace and calcined at 500 ° C for 6 h under a conventional air atmosphere. h, the heating rate from room temperature to 500 °C before calcination was 20 °C / min, and the porous activated carbon substrate was obtained after cooling to room temperature under natural ventilation and grinding to 200 mesh.

2. The catalytic conversion method for decomposing carbon dioxide into carbon monoxide according to claim 1, characterized in that: In step 2, the drying and grinding process is to place the mixture in a magnetic stirrer and stir it continuously at 200 r / min and 50°C for 2 h; then, place the mixed solution in an oven and evaporate all water at 70°C to obtain agglomerates, and grind the agglomerates into 200 mesh powder.

3. The catalytic conversion method for decomposing carbon dioxide into carbon monoxide according to claim 1, characterized in that: In step 2, the calcination process is as follows: placing the 200-mesh powder in a muffle furnace and continuously calcining at 850 °C for 5 h, with a heating rate of 50 °C / min from room temperature to 500 °C before calcination, and then cooling to room temperature by natural ventilation to obtain a porous activated carbon-supported rhodium trioxide / nickel oxide composite catalyst.

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