Method for preparing CO catalyst from CO2 and biomass charcoal and application

Abstract

The invention discloses a method for preparing a catalyst for CO from CO2 and biomass charcoal and application of the catalyst, and belongs to the technical field of CO2 utilization. The catalyst for preparing CO from CO2 and biomass charcoal is composed of an active component and an auxiliary agent, the active component and the auxiliary agent are combined with biomass charcoal through an equivalent-volume impregnation method, and impregnated catalyst biomass charcoal for preparing CO is obtained; and adding the catalyst-impregnated biomass charcoal into a tubular furnace, introducing CO2, and carrying out a reduction reaction on the CO2 and the biomass charcoal to prepare CO. The process flow is simple, the operation cost is low, the catalyst has high catalytic activity and low price, the reaction temperature is 700-850 DEG C, the reaction time is 60 minutes, the highest CO2 conversion rate can reach 90%, and the CO selectivity can reach 98%.

Description

Technical Field

[0001] The invention relates to a method and application of a catalyst for preparing CO from CO2 and biochar, belonging to the technical field of CO2 utilization. Background Art

[0002] CO2 has always been the main gas causing global warming. As people's environmental awareness increases, it is imperative to develop reasonable utilization technology for CO2 as a carbon resource. The technology of using CO2 as a raw material to produce CO is a new type of CO2 utilization technology. This technology can continuously and large-scale utilize CO2 to achieve the purpose of carbon reduction in carbon emission industries. At the same time, the generated CO can be used as a chemical raw material to produce almost all basic chemicals, such as ammonia, phosgene, alcohols, acids, anhydrides, esters, aldehydes, ethers, amines, alkanes and olefins. At the same time, carbon monoxide can be used as a reducing agent for refining metals, as well as fuel and food preservation. Industrial CO adopts the pure oxygen (oxygen-enriched) coke method. Although the pure oxygen (oxygen-enriched) coke method has the ability to produce a large amount of CO, it has high operating costs due to large investments, many power equipment, and high coke prices.

[0003] Biochar is a common and inexpensive environmentally friendly material. It refers to a carbon-rich material obtained by placing biomass raw materials in an oxygen-free or oxygen-restricted environment through high-temperature pyrolysis or hydrothermal carbonization. Biochar materials have the advantages of being environmentally friendly, sustainable, diverse in structural composition, and rich in functional groups. As a rare carbon resource, the development and utilization of CO2 and biochar to prepare CO has become a highly-regarded carbon resource utilization route.

[0004] Usually in the conversion and utilization of CO2, the reverse water gas shift reaction (CO2+H2=CO+H2O) is widely studied. Precious metals, copper-based catalysts, nickel-based catalysts, etc. are usually used. At the same time, hydrogen needs to be consumed, and there is a methanation side reaction (CO+3H2=CH4+H2O), which is not conducive to improving the CO selectivity. Chinese patent CN117654565A discloses a supported precious metal catalyst for reverse water gas shift reaction and its preparation method and application, including a zirconium carbide carrier and an active component uniformly loaded on the carrier; the active component includes precious metal elements such as Pt, Rh, Au, Ru, Pd, Ir, etc., the preparation method is simple, the catalytic effect is significant, but the cost of precious metals is high, and the CO2 conversion rate (33% to 42%) is also low; Chinese patent CN117504895A discloses a reverse water gas shift catalyst and its preparation method, the Mo / Ce bimetallic oxide is prepared by the sol-gel method, the mass percentage of copper / manganese / molybdenum / cerium in the carrier material catalyst is 2.5:2.5:90.25:4.75, the preparation process is long, and the CO2 conversion rate is also low. Chinese patent CN116143119A discloses a method for preparing CO by reducing CO2 with biochar based on variable frequency microwaves, in which microwave-promoted reactions have the advantages of accelerated reactions, selective heating, energy efficiency and process control, but also have disadvantages such as insufficient understanding of the reaction mechanism, high equipment cost, limited applicability and potential safety hazards. Summary of the invention

[0005] The present invention aims to provide a method and application of a catalyst for preparing CO from CO2 and biochar. The process flow of the present invention is simple, the reaction conditions are relatively mild, the operating cost is low, the catalytic activity is high, the price is low, and it has industrial application prospects.

[0006] The present invention uses CO2 and biochar as raw materials, develops a technology for preparing CO from CO2 and biochar, and performs a thermal reduction reaction in a tubular furnace to prepare CO. A catalyst is used in the reaction process. The catalyst is composed of an active component and an auxiliary agent. The active component includes an alkali metal or alkaline earth metal catalyst (such as K salt, Na salt, etc.).

[0007] The invention provides a catalyst for preparing CO from CO2 and biochar. The catalyst consists of an active component and an auxiliary agent. The active component and the auxiliary agent are combined with the biochar by an equal volume impregnation method to obtain the catalyst for preparing CO.

[0008] The above-mentioned active components are alkali metal and alkaline earth metal salt compounds, and the alkali metal and alkaline earth metal salt compounds are any one of NaOH, NaNO3, Na2CO3, KOH, KNO3, K2CO3, Mg(NO3)2, Ca(NO3)2, Ca(OH)2, LiNO3, Li2CO3, Ba(NO3)2; the auxiliary agent is a soluble nitrate of any one of the metals Mn, Ce, Fe, La, Zr, and Zn.

[0009] In the catalyst for preparing CO obtained above, based on biomass carbon, the mass percentage of active component metal is 1wt%-30wt%, and the mass percentage of auxiliary metal is 0.1wt%-10wt%.

[0010] The present invention provides a method for preparing a catalyst for CO from the above-mentioned CO2 and biochar, comprising preparing an alkali metal or an alkaline earth metal into a solution, adding an auxiliary agent to form a mixed solution, immersing the biochar in the mixed solution, standing at room temperature for 2-6 hours, filtering out, drying at room temperature, drying at 90-120°C for 2-6 hours, and waiting for the temperature to drop to room temperature to obtain biochar impregnated with the catalyst; that is, the catalyst preparation is completed.

[0011] The biomass charcoal is a solid carbonaceous material made by high-temperature pyrolysis of biomass materials. The types of biomass charcoal used in the present invention include charcoal and bamboo charcoal. The biomass charcoal is prepared into particles of 5-10 mm. The present invention provides an application of the catalyst for preparing CO from CO2 and biochar, that is, the catalyst is used to prepare CO, and the operation steps are as follows: Add the catalyst-impregnated biochar into a tubular furnace, introduce CO2 at a flow rate of 80-120 ml / min, raise the temperature in the tubular furnace to 700-850°C, and allow CO2 to react with the biochar for a reduction reaction. After 60-120 minutes of reaction, the CO and unreacted CO2 in the gas are analyzed by a flue gas analyzer.

[0012] Beneficial effects of the present invention: The present invention is a CO2 utilization technology for preparing CO from CO2 and biochar, which has a simple process flow, low operating cost, high catalytic activity of the catalyst, low price, reaction temperature of 700-850°C, reaction time of 60-120 minutes, CO2 maximum conversion rate of up to 90%, and CO selectivity of up to 98%. DETAILED DESCRIPTION

[0013] The present invention is further illustrated by the following examples, but is not limited to the following examples.

[0014] Comparative Example: Method for preparing CO from CO2 and charcoal (without catalyst) 50g of charcoal was added into the tube furnace, CO2 was introduced, and the temperature in the tube furnace was raised to 750℃ for reduction reaction with biochar. The reaction time was 60 minutes, and the CO and unreacted CO2 in the gas were analyzed by a flue gas analyzer. The CO2 conversion rate was 60%, the CO selectivity was 90%, and the rest was hydrogen H2 and CH4.

[0015] The following specific examples illustrate the application of the present invention in preparing CO with a catalyst by using CO2 and charcoal. Example 1

[0016] Preparation of catalyst for CO production from CO2 and charcoal Prepare Mg(NO3)2 into a solution, add Mn(NO3)2 solution, and use equal volume impregnation method to impregnate 50g of charcoal in the mixed solution. In the mixed solution, the mass concentration of Mg(NO3)2 is 1% and the mass concentration of Mn(NO3)2 is 1% based on biomass charcoal. Let it stand at room temperature for 2 hours, dry it at room temperature, and then put it into an electric hot air drying oven and dry it at 90℃ for 6 hours. Obtain impregnated catalyst charcoal.

[0017] Application of catalysts for the preparation of CO from CO2 and charcoal The impregnated catalyst charcoal was added into the reactor, CO2 was introduced at a flow rate of 80 ml / min, and the temperature in the tube furnace was raised to 750°C to carry out reduction reaction with biochar. The reaction time was 60 minutes, and the CO and unreacted CO2 in the gas were analyzed by a flue gas analyzer. The CO2 conversion rate was 73% and the CO selectivity was 92%. Example 2

[0018] Preparation of catalyst for CO production from CO2 and bamboo charcoal Ba(NO3)2 was prepared into a solution, CeNO3 was added, and 50g of bamboo charcoal was impregnated in the mixed solution by equal volume impregnation method. In the mixed solution, the mass concentration of Ba(NO3)2 was 5% and the mass concentration of CeNO3 was 5% based on biomass charcoal. The mixture was left to stand at room temperature for 3 hours, dried at room temperature, and then placed in an electric heating blast drying oven and dried at 100°C for 3 hours to obtain impregnated catalyst bamboo charcoal.

[0019] Application of catalysts for preparing CO from CO2 and bamboo charcoal The impregnated catalyst bamboo charcoal was added into the tubular furnace, CO2 was introduced at a flow rate of 100 ml / min, and the temperature in the tubular furnace was raised to 750°C to carry out reduction reaction with biomass charcoal. The reaction time was 100 minutes, and the CO and unreacted CO2 in the gas were analyzed by a flue gas analyzer. The CO2 conversion rate was 78% and the CO selectivity was 93%. Example 3

[0020] Preparation of catalyst for CO production from CO2 and charcoal Prepare Ca(NO3)2 into a solution, add Fe(NO3)3, and use the equal volume impregnation method to impregnate 50g of charcoal in the mixed solution. In the mixed solution, the mass concentration of Ca(NO3)2 is 10% and the mass concentration of Fe(NO3)3 is 10% based on biomass charcoal. Let it stand at room temperature for 4 hours, dry it at room temperature, and then put it into an electric heating blast drying oven and dry it at 110℃ for 4 hours. Obtain impregnated catalyst charcoal.

[0021] Application of catalysts for the preparation of CO from CO2 and charcoal The impregnated catalyst charcoal was added into the tubular furnace, CO2 was introduced at a flow rate of 120 ml / min, the temperature in the tubular furnace was raised to 800°C, and the biomass charcoal was reduced for 120 minutes. The CO and unreacted CO2 in the gas were analyzed by a flue gas analyzer. The CO2 conversion rate was 82% and the CO selectivity was 94%. Example 4

[0022] Preparation of catalyst for CO production from CO2 and bamboo charcoal Prepare NaOH into a solution, add La(NO3)3, and use an equal volume impregnation method to impregnate 50g of bamboo charcoal in the mixed solution. In the mixed solution, the mass concentration of NaOH is 20% and the mass concentration of La(NO3)3 is 6% based on biomass charcoal. Let it stand at room temperature for 5 hours, dry it at room temperature, and then put it into an electric heating blast drying oven and dry it at 90°C for 6 hours to obtain impregnated catalyst bamboo charcoal.

[0023] Application of catalysts for preparing CO from CO2 and bamboo charcoal The impregnated catalyst bamboo charcoal was added into the tubular furnace, CO2 was introduced at a flow rate of 80 ml / min, and the temperature in the tubular furnace was raised to 700°C for reduction reaction with biomass charcoal. The reaction time was 60 minutes, and the CO and unreacted CO2 in the gas were analyzed by a flue gas analyzer. The CO2 conversion rate was 62% and the CO selectivity was 95%. Example 5

[0024] Preparation of catalyst for CO production from CO2 and charcoal Prepare Na2CO3 into a solution, add Zr(NO3)4, and use the equal volume impregnation method to impregnate 50g of charcoal in the mixed solution. In the mixed solution, the mass concentration of Na2CO3 is 25% and the mass concentration of Zr(NO3)4 is 1% based on biomass charcoal. Let it stand at room temperature for 6 hours, dry it at room temperature, and then put it into an electric heating blast drying oven and dry it at 120℃ for 5 hours. Obtain impregnated catalyst charcoal.

[0025] Application of catalysts for the preparation of CO from CO2 and charcoal The impregnated catalyst charcoal was added into the tubular furnace, CO2 was introduced at a flow rate of 100 ml / min, and the temperature in the tubular furnace was raised to 850°C to carry out a reduction reaction with the biochar. The reaction time was 100 minutes, and the CO and unreacted CO2 in the gas were analyzed by a flue gas analyzer. The CO2 conversion rate was 86%, and the CO selectivity was 96%. Example 6

[0026] Preparation of catalyst for CO production from CO2 and bamboo charcoal K2CO3 was prepared into a solution, and Zn(NO3)2 was added. Using the equal volume impregnation method, 50 g of bamboo charcoal was impregnated in the mixed solution. In the mixed solution, the mass concentration of K2CO3 was 30% and the mass concentration of Zn(NO3)2 was 0.1% based on the biomass charcoal. The mixture was left to stand at room temperature for 6 h, dried at room temperature, and then placed in an electric blast drying oven and dried at 100°C for 6 h. The impregnated catalyst bamboo charcoal was obtained.

[0027] Application of catalysts for preparing CO from CO2 and bamboo charcoal The impregnated catalyst bamboo charcoal was added into the tubular furnace, CO2 was introduced at a flow rate of 120 ml / min, and the temperature in the tubular furnace was raised to 850°C to carry out reduction reaction with biomass charcoal. The reaction time was 120 minutes, and the CO and unreacted CO2 gas in the gas were analyzed by a flue gas analyzer. The CO2 conversion rate was 90%, and the CO selectivity was 98%.

Claims

1. A catalyst for preparing CO from CO2 and biochar, characterized in that: The invention is composed of active components and auxiliary agents. The active components and auxiliary agents are combined with biomass carbon through an equal volume impregnation method to obtain an impregnated catalyst biomass carbon for preparing CO.

2. The catalyst for preparing CO from CO2 and biochar according to claim 1, characterized in that: The active components are alkali metal and alkaline earth metal salt compounds, and the alkali metal and alkaline earth metal salt compounds are any one of NaOH, NaNO3, Na2CO3, KOH, KNO3, K2CO3, Mg(NO3)2, Ca(NO3)2, Ca(OH)2, LiNO3, Li2CO3, and Ba(NO3)2; the auxiliary agent is a soluble nitrate of any one of Mn, Ce, Fe, La, Zr, and Zn.

3. The catalyst for preparing CO from CO2 and biochar according to claim 1, characterized in that: Based on the biomass carbon, the mass percentage of the active component metal is 1wt%-30wt%, and the mass percentage of the auxiliary metal is 0.1wt%-10wt%.

4. A method for preparing CO from a catalyst using CO2 and biochar according to any one of claims 1 to 3, characterized in that: Alkali metal or alkaline earth metal is prepared into a solution, and an auxiliary agent is added to form a mixed solution. Biomass carbon is immersed in the mixed solution, and after standing at room temperature for 2-6 hours, it is filtered out, dried at room temperature, and dried at 90-120° C. for 2-6 hours. When the temperature drops to room temperature, the catalyst-impregnated biomass carbon is obtained; that is, the catalyst preparation is completed.

5. The method for preparing CO from a catalyst using CO2 and biochar according to claim 4, characterized in that: The biomass charcoal is a solid carbonaceous material produced by high-temperature pyrolysis of biomass materials, and the biomass charcoal includes one of wood charcoal and bamboo charcoal.

6. The method for preparing CO from a catalyst using CO2 and biochar according to claim 5, characterized in that: The biochar is in the form of particles of 5-10 mm.

7. A use of a catalyst for preparing CO from CO2 and biochar according to any one of claims 1 to 3, characterized in that The steps are as follows: Add the catalyst-impregnated biochar into a tubular furnace, introduce CO2 at a flow rate of 80-120 ml / min, raise the temperature in the tubular furnace to 700-850°C, and CO2 and biochar undergo a reduction reaction. The CO and unreacted CO2 in the gas are analyzed by a flue gas analyzer.

8. The use according to claim 7, characterized in that: After 60 to 120 minutes of reaction, the CO2 conversion rate can reach 90% and the CO selectivity can reach 98%.