A catalyst for producing synthesis gas by hydrogenation of carbon dioxide, and its preparation method and application

Abstract

The present invention discloses a carbon dioxide hydrogenation catalyst for producing synthesis gas, its preparation method, and application. The catalyst uses indium oxide rich in oxygen vacancies as a carrier, and metal Ni is loaded on the surface or surface layer of the carrier. The metal is highly dispersed by nitrogen-doped carbon to form a composite material. Since the reducing substances produced by 1,10-phenanthroline during the calcination process to form nitrogen-doped carbon partially reduce the indium oxide, enriching it with oxygen vacancies, and supplemented by alkali metals as electron donors, the catalyst has good carbon dioxide adsorption performance. The loaded Ni has good hydrogen dissociation performance, giving the catalyst excellent CO2 hydrogenation performance. At 360°C, the CO2 conversion rate can reach 31%, and the CO selectivity can reach 99%.

Description

Technical field:

[0001] The present invention relates to the technical field of carbon dioxide hydrogenation to synthesis gas, and in particular to a carbon dioxide hydrogenation to synthesis gas catalyst, a preparation method and an application thereof. Background technology:

[0002] The conversion of carbon dioxide (CO2) into carbon monoxide (CO) is of great significance and has many application values, including: 1. Chemical production: Carbon monoxide (CO) is an important intermediate in the synthesis of many chemicals. It can be used to produce chemicals such as methanol, dimethyl ether, and methane, and has a wide range of applications. 2. Fuel synthesis: Carbon monoxide (CO) can be reacted with hydrogen (H2) through the Fischer-Tropsch synthesis reaction to produce light olefins, fuels, lubricants and other products. 3. Energy storage: The conversion of carbon dioxide into carbon monoxide can use carbon dioxide as a form of storage for renewable energy, achieving efficient utilization and storage of energy. 4. Environmental protection: By converting carbon dioxide into useful chemicals and fuels, carbon dioxide emissions can be reduced, which helps to mitigate climate change and reduce the impact of carbon emissions on the environment. Therefore, the conversion of carbon dioxide into carbon monoxide is an important way to utilize CO2.

[0003] Traditional catalysts have some problems in the process of converting carbon dioxide (CO2) to carbon monoxide (CO), including: 1. Low selectivity: Some traditional catalysts produce byproducts during the reaction, which reduces the selectivity of CO and affects the purity and yield of the product. 2. Poor stability: Some catalysts are easily deactivated or lose activity under high temperature and high pressure reaction conditions, resulting in a short catalyst life and the need for frequent replacement or regeneration. 3. Harsh operating conditions: Some catalysts require higher operating temperatures and pressures to achieve high conversion rates, increasing energy consumption and production costs. 4. Complex synthesis: The synthesis process of some catalysts is complex, requiring expensive precursor materials and multi-step reactions, making it difficult to produce on a large scale and apply them industrially. 5. Poor environmental friendliness: Some traditional catalysts may contain precious metals or other environmentally harmful components, which is not conducive to sustainable development and environmental protection requirements. Therefore, previous catalysts have problems in selectivity, stability, operating conditions, synthesis complexity and environmental friendliness, which limit the efficiency and sustainability of carbon dioxide to carbon monoxide conversion. Summary of the invention:

[0004] The purpose of the present invention is to provide a catalyst for producing synthesis gas by hydrogenating carbon dioxide, and a preparation method and application thereof.

[0005] The present invention is achieved through the following technical solutions:

[0006] A carbon dioxide hydrogenation catalyst for producing synthesis gas consists of indium oxide, nitrogen-doped carbon and nickel. Indium oxide rich in oxygen vacancies is used as a carrier and nickel is loaded. The nickel loading amount is 0.5wt% to 20wt%, and most preferably 10wt%.

[0007] Nickel is highly dispersed by nitrogen-doped carbon to form a composite material.

[0008] In particular, an alkali metal or its oxide is also loaded. Preferably, the molar ratio of the alkali metal or its oxide to nickel is 1-10:10, and most preferably 1:5.

[0009] Using indium oxide, which is rich in oxygen vacancies and has a high ability to catalyze CO2 hydrogenation reactions, as a carrier, nickel dispersed in nitrogen-doped carbon is loaded on this support to enhance hydrogen cracking. Alkaline metals can also be added to enhance carbon dioxide adsorption. This catalyst has the advantages of efficiently catalyzing CO2 hydrogenation to CO at relatively low temperatures while maintaining high stability. Its preparation method is simple and does not require the use of precious metals.

[0010] The catalyst preparation method is as follows: dissolving a stoichiometric nickel metal precursor and a nitrogen-containing organic matter in anhydrous ethanol, then adding indium oxide or indium hydroxide powder, heating and stirring for several hours, and then drying the solid. Inert gas is introduced into a tube furnace, or air is introduced first and then converted to inert gas, with air being used below 250°C and inert gas being used above 250°C. The catalyst precursor is calcined at 250-500°C to obtain the catalyst.

[0011] The molar ratio of the nickel metal precursor to the nitrogen-containing organic matter is 1:1-3.

[0012] Specifically, the calcination temperature was raised from room temperature to 250° C., maintained for 1 hour, and then raised to 500° C., maintained for 3 hours.

[0013] The inert gas is nitrogen or argon. If only nitrogen or argon is introduced into the tube furnace, the effect is slightly worse. It is better to introduce air first and then nitrogen or argon.

[0014] In particular, the catalyst is further loaded with an alkali metal or its oxide, and when the nickel metal precursor is nickel acetate and the nitrogen-containing organic matter is 1,10-phenanthroline, the method specifically includes the following steps: pouring an alkali metal salt, nickel acetate and 1,10-phenanthroline into anhydrous ethanol according to a certain molar ratio, magnetically stirring at room temperature for 30 minutes, then adding indium hydroxide or indium oxide, vigorously stirring at 80°C for 3 hours, pouring the resulting suspension into an evaporating dish, and drying at low pressure in a vacuum drying oven at 60°C; and grinding the dried solid and then placing it in a tubular furnace for roasting while continuously introducing gas.

[0015] The alkali metal salt is one or more of lithium acetate, lithium nitrate, cesium acetate, cesium nitrate, sodium acetate, sodium nitrate, potassium acetate, potassium nitrate, rubidium acetate, and rubidium nitrate;

[0016] The molar ratio of the alkali metal salt to the nickel acetate is 1-10:10, and the molar ratio of the total amount of metals composed of the alkali metal salt and the nickel acetate to 1,10-phenanthroline is 1:1-3.

[0017] The present invention also protects the application of the carbon dioxide hydrogenation synthesis gas catalyst in a carbon dioxide hydrogenation reaction. The application conditions are: the catalyst is placed in the middle section of a stainless steel tubular furnace, the catalyst is fixed by quartz wool and a quartz rod, a reaction mixed gas is introduced, the mixed gas components are argon, carbon dioxide and hydrogen in a molar ratio of 1:6:18, the mixed gas flow rate is 30 to 100 sccm, heating and pressurizing are applied to promote the reaction, the reaction temperature is 260 to 360°C, and the reaction pressure is 0.2 to 4 MPa.

[0018] The beneficial effects of the present invention are:

[0019] The catalyst of the present invention uses indium oxide rich in oxygen vacancies as a carrier, with metallic nickel loaded onto the surface or surface layer of the carrier. The metal is highly dispersed in nitrogen-doped carbon, forming a composite material. Reducing substances generated during the calcination of 1,10-phenanthroline to form nitrogen-doped carbon partially reduce the indium oxide, enriching it with oxygen vacancies. With the addition of alkali metals as electron donors, the catalyst exhibits excellent carbon dioxide adsorption properties. The loaded nickel exhibits excellent hydrogen dissociation properties, resulting in excellent CO2 hydrogenation performance. At 360°C, the CO2 conversion rate can reach 31%, and the CO selectivity can reach 99%. Description of the drawings:

[0020] Figure 1 This is a diagram showing the catalytic reaction effects of the catalysts obtained in Examples 1-7 in Example 8.

[0021] Figure 2 This is an AC-TEM image of the catalyst obtained in Example 6 of the present invention.

[0022] Figure 3 This is an EDX image of the catalyst obtained in Example 6 of the present invention.

[0023] Figure 4 This is a life test chart of the catalyst obtained in Example 6 in Example 9. Specific implementation method:

[0024] The following is a further description of the present invention, but not a limitation of the present invention.

[0025] Example 1: Preparation of 5Ni / IO-1,10(3:1)-250,1,air,500,3,Ar catalyst

[0026] (1) 10 g of indium hydroxide was placed in a quartz boat and calcined in a muffle furnace at 550 °C for 3 h to obtain indium oxide (IO).

[0027] (2) 1 g of nickel acetate and 2.1726 g of 1,10-phenanthroline were poured into 15 mL of anhydrous ethanol and magnetically stirred at room temperature for 30 min to form a deep red solution. 4.7171 g of indium oxide (IO) was then added and vigorously stirred in an oil bath at 80 °C for 3 h. The suspension was then poured into a glass Petri dish and placed in a vacuum drying oven at 60 °C. The temperature was evacuated to -0.1 MPa using a rotary vane vacuum pump and maintained at 60 °C for 2 h. The resulting pink powder was ground to obtain 5Ni / IO-1,10 (3:1).

[0028] (3) 5Ni / IO-1,10 (3:1) was placed in a quartz boat, then placed in a quartz tube. Air was introduced and the temperature was raised to 250°C at a rate of 10°C / min. After holding for 1 hour, the temperature was switched to argon and raised to 500°C at a rate of 10°C / min. The temperature was held for 3 hours. After cooling, the catalyst was removed to obtain a 5Ni / IO-1,10 (3:1)-250,1,air,500,3,Ar catalyst.

[0029] Example 2: Preparation of 5Ni / IHO-1,10(1:1)-250,1,500,3,Ar catalyst

[0030] (1) 1 g of nickel acetate and 0.7242 g of 1,10-phenanthroline were poured into 15 mL of anhydrous ethanol and magnetically stirred at room temperature for 30 min to form a deep red solution. 5.6354 g of indium hydroxide was then added and vigorously stirred in an 80°C oil bath for 3 h. The suspension was then poured into a glass Petri dish and placed in a vacuum drying oven at 60°C. The temperature was evacuated to -0.1 MPa using a rotary vane vacuum pump and maintained at 60°C for 2 h. The resulting pink powder was ground to obtain 5Ni / IHO-1,10 (1:1).

[0031] (2) 5Ni / IHO-1,10 (1:1) was placed in a quartz boat, then placed in a quartz tube. Argon was introduced and the temperature was raised to 250°C at a rate of 10°C / min and maintained for 1 hour. Then, the temperature was raised to 500°C at a rate of 10°C / min and maintained for 3 hours. After cooling, the catalyst was removed to obtain a 5Ni / IHO-1,10 (1:1)-250,1,air,500,3,Ar catalyst.

[0032] Example 3: Preparation of 5Na5Ni / IHO-1,10(1:1)-250,1,500,3,N2 catalyst

[0033] (1) 1 g of nickel acetate, 0.3415 g of sodium nitrate, and 0.8690 g of 1,10-phenanthroline were poured into 15 mL of anhydrous ethanol and magnetically stirred at room temperature for 30 min to form a deep red solution. 5.6354 g of indium hydroxide was then added and vigorously stirred in an 80°C oil bath for 3 h. The suspension was then poured into a glass Petri dish and placed in a vacuum drying oven at 60°C. The temperature was evacuated to -0.1 MPa using a rotary vane vacuum pump and maintained at 60°C for 2 h. The green powder formed was ground to obtain 5Na5Ni / IHO-1,10 (1:1).

[0034] (2) 5Na5Ni / IHO-1,10 (1:1) was placed in a quartz boat, then placed in a quartz tube. Nitrogen was introduced and the temperature was raised to 250°C at a rate of 10°C / min and maintained for 1 hour. Then, the temperature was raised to 500°C at a rate of 10°C / min and maintained for 3 hours. After cooling, the mixture was taken out to obtain the 5Na5Ni / IHO-1,10 (1:1)-250,1,500,3,N2 catalyst.

[0035] Example 4: Preparation of 5Cs5Ni / IHO-1,10(1:1)-250,1,500,3,N2 Catalyst

[0036] (1) 1 g of nickel acetate, 0.7714 g of cesium acetate, and 0.8690 g of 1,10-phenanthroline were poured into 15 mL of anhydrous ethanol and magnetically stirred at room temperature for 30 min to form a deep red solution. 5.6354 g of indium hydroxide was then added and vigorously stirred in an 80°C oil bath for 3 h. The suspension was then poured into a glass Petri dish and placed in a vacuum drying oven at 60°C. The temperature was evacuated to -0.1 MPa using a rotary vane vacuum pump and maintained at 60°C for 2 h. The green powder formed was ground to obtain 5Cs5Ni / IHO-1,10 (1:1).

[0037] (2) 5Cs5Ni / IHO-1,10 (1:1) was placed in a quartz boat, then placed in a quartz tube. Nitrogen was introduced and the temperature was raised to 250°C at a rate of 10°C / min and maintained for 1 hour. Then, the temperature was raised to 500°C at a rate of 10°C / min and maintained for 3 hours. After cooling, the mixture was taken out to obtain a 5Cs5Ni / IHO-1,10 (1:1)-250,1,500,3,N2 catalyst.

[0038] Example 5: Preparation of 5Cs5Ni / IHO-1,10(1:1)-250,1,air,500,3,Ar catalyst

[0039] (1) 1 g of nickel acetate, 0.7714 g of cesium acetate, and 0.8690 g of 1,10-phenanthroline were poured into 15 mL of anhydrous ethanol and magnetically stirred at room temperature for 30 min to form a deep red solution. 5.6354 g of indium hydroxide was then added and vigorously stirred in an 80°C oil bath for 3 h. The suspension was then poured into a glass Petri dish and placed in a vacuum drying oven at 60°C. The temperature was evacuated to -0.1 MPa using a rotary vane vacuum pump and maintained at 60°C for 2 h. The green powder formed was ground to obtain 5Cs5Ni / IHO-1,10 (1:1).

[0040] (2) 5Cs5Ni / IHO-1,10 (1:1) was placed in a quartz boat, then placed in a quartz tube. Air was introduced and the temperature was raised to 250°C at a rate of 10°C / min. After holding for 1 hour, the gas was switched to argon and the temperature was raised to 500°C at a rate of 10°C / min. The temperature was held for 3 hours. After cooling, the catalyst was taken out to obtain 5Cs5Ni / IHO-1,10 (1:1)-250,1,air,500,3,Ar catalyst.

[0041] Example 6: Preparation of 2Cs10Ni / IHO-1,10(1:1)-250,1,500,3,N2 Catalyst

[0042] (1) 2 g of nickel acetate, 0.3086 g of cesium acetate, and 1.7384 g of 1,10-phenanthroline were poured into 15 mL of anhydrous ethanol and magnetically stirred at room temperature for 30 min to form a deep red solution. 5.6354 g of indium hydroxide was then added and vigorously stirred in an 80°C oil bath for 3 h. The suspension was then poured into a glass Petri dish and placed in a vacuum drying oven at 60°C. The temperature was evacuated to -0.1 MPa using a rotary vane vacuum pump and maintained at 60°C for 2 h. The green powder formed was ground to obtain 2Cs10Ni / IHO-1,10 (1:1).

[0043] (2) 2Cs10Ni / IHO-1,10 (1:1) was placed in a quartz boat, then placed in a quartz tube. Nitrogen was introduced and the temperature was raised to 250°C at a rate of 10°C / min and held for 1 hour. Then, the temperature was raised to 500°C at a rate of 10°C / min and held for 3 hours. After cooling, the mixture was removed to obtain the 2Cs10Ni / IHO-1,10 (1:1)-250,1,500,3,N2 catalyst.

[0044] Example 7: Preparation of 2Cs10Ni / IHO-1,10(1:1)-250,1,air,500,3,Ar catalyst

[0045] (1) 2 g of nickel acetate, 0.3086 g of cesium acetate, and 1.7384 g of 1,10-phenanthroline were poured into 15 mL of anhydrous ethanol and magnetically stirred at room temperature for 30 min to form a deep red solution. 5.6354 g of indium hydroxide was then added and vigorously stirred in an 80°C oil bath for 3 h. The suspension was then poured into a glass Petri dish and placed in a vacuum drying oven at 60°C. The temperature was evacuated to -0.1 MPa using a rotary vane vacuum pump and maintained at 60°C for 2 h. The green powder formed was ground to obtain 2Cs10Ni / IHO-1,10 (1:1).

[0046] (2) 2Cs10Ni / IHO-1,10 (1:1) was placed in a quartz boat, then placed in a quartz tube. Air was introduced and the temperature was raised to 250°C at a rate of 10°C / min. After holding for 1 hour, the gas was switched to argon and the temperature was raised to 500°C at a rate of 10°C / min. The temperature was held for 3 hours. After cooling, the catalyst was taken out to obtain 2Cs10Ni / IHO-1,10 (1:1)-250,1,500,3,Ar catalyst.

[0047] Example 8: Application of Catalyst

[0048] 0.1 g of catalyst was placed in the middle section of a 316L stainless steel tube with a diameter of 10 mm. The catalyst was fixed by quartz wool and a quartz rod. An electric heating furnace was installed outside the tube. The reaction mixture (Ar:CO2:H2=1:6:18) was introduced into the tube. After blowing at a flow rate of 400 sccm for 2 minutes, the back pressure valve was increased to make the gas pressure in the tube reach 4 MPa, the flow rate was reduced to 30 sccm, and the electric heating furnace was controlled to raise it to 300°C at a rate of 10°C / min. At the same time, the product composition was detected online by gas chromatography, and samples were taken every 15 minutes.

[0049] The calculation formula is: CO2 conversion rate = (inlet CO2 concentration - outlet CO2 concentration * inlet Ar concentration / outlet Ar concentration) / inlet CO2 concentration

[0050] CO selectivity = outlet CO concentration / (outlet CO concentration + outlet CH4 concentration + outlet CH3OH concentration)

[0051] Figure 1 This is a catalyst performance diagram obtained by using the catalysts prepared in Example 1, Example 2, Example 3, Example 4, Example 5, Example 6 and Example 7 according to the application method of this example.

[0052] Example 9: Application of 2Cs10Ni / IHO-1,10(1r1)-250,1,500,3,N2

[0053] 0.1 g of catalyst was placed in the middle of a 10 mm diameter 316L stainless steel tube secured with quartz wool and a quartz rod. An electric furnace was installed outside the tube. A reaction mixture (Ar:CO₂:H₂ = 1:6:18) was introduced into the tube at a flow rate of 400 sccm for 2 minutes. The back pressure valve was then adjusted to a pressure of 4 MPa. The flow rate was reduced to 30 sccm. The electric furnace was controlled to raise the temperature to 360°C at a rate of 10°C / min. Simultaneously, product composition was monitored online by gas chromatography, with samples taken every 15 minutes. The calculation formula was the same as in Example 8.

[0054] Figure 4 This is a catalyst stability test chart obtained by using the catalyst prepared in Example 6 according to the application method of this example.

[0055] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. Persons skilled in the art will appreciate that improvements and modifications may be made without departing from the spirit and scope of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A catalyst for producing synthesis gas by hydrogenation of carbon dioxide, characterized in that: The catalyst is composed of indium oxide, nitrogen-doped carbon and nickel, with indium oxide rich in oxygen vacancies as a carrier and nickel loaded. The nickel loading amount is 0.5wt% to 20wt%, and the nickel is highly dispersed in the nitrogen-doped carbon to form a composite material. The preparation method of the catalyst comprises the following steps: dissolving a stoichiometric nickel metal precursor and a nitrogen-containing organic matter in anhydrous ethanol, then adding indium oxide or indium hydroxide powder, heating and stirring for several hours, drying the solid, and calcining the catalyst precursor in a tube furnace by introducing an inert gas or first introducing air and then switching to an inert gas to obtain the catalyst.

2. The catalyst according to claim 1, characterized in that An alkali metal or its oxide is also supported.

3. The catalyst according to claim 2, characterized in that The molar ratio of the alkali metal or its oxide to nickel is 1-10:

10.

4. The method for preparing the catalyst according to claim 1, characterized in that: The steps are as follows: dissolving a stoichiometric nickel metal precursor and a nitrogen-containing organic compound in anhydrous ethanol, then adding indium oxide or indium hydroxide powder, heating and stirring for several hours and then drying the solid, and calcining the catalyst precursor at 250-500°C in a tube furnace by introducing an inert gas or first introducing air and then switching to an inert gas to obtain a catalyst.

5. The method for preparing the catalyst according to claim 4, wherein: The molar ratio of the nickel metal precursor to the nitrogen-containing organic matter is 1:1~3.

6. The method for preparing the catalyst according to claim 4, wherein: The calcination temperature was raised from room temperature to 250°C, maintained for 1 hour, and then raised to 500°C and maintained for 3 hours.

7. The method for preparing the catalyst according to claim 4, characterized in that: The air is first introduced and then converted into inert gas: when the temperature is below 250°C, it is air, and when the temperature is above 250°C, it is inert gas; the inert gas is nitrogen or argon.

8. The method for preparing the catalyst according to claim 4, wherein: The catalyst is also loaded with an alkali metal or its oxide. When the nickel metal precursor is nickel acetate and the nitrogen-containing organic matter is 1,10-phenanthroline, the method specifically includes the following steps: adding an alkali metal salt, nickel acetate and 1,10-phenanthroline in a certain molar ratio to anhydrous ethanol, magnetically stirring at room temperature for 30 minutes, adding indium hydroxide or indium oxide, vigorously stirring at 80° C. for 3 hours, pouring the resulting suspension into an evaporating dish, and drying under low pressure in a vacuum drying oven at 60° C.; and grinding the dried solid and then calcining it in a tube furnace while continuously introducing gas.

9. The method for preparing the catalyst according to claim 8, characterized in that: The alkali metal salt is one or more of lithium acetate, lithium nitrate, cesium acetate, cesium nitrate, sodium acetate, sodium nitrate, potassium acetate, potassium nitrate, rubidium acetate, and rubidium nitrate; the molar ratio of the alkali metal salt to nickel acetate is 1-10:10, and the molar ratio of the total amount of metal composed of the alkali metal salt and nickel acetate to 1,10-phenanthroline is 1:1-3.

10. Use of the catalyst according to claim 1 in carbon dioxide hydrogenation reaction, characterized in that: The application conditions are as follows: the catalyst is placed in the middle section of a stainless steel tube furnace, the catalyst is fixed by quartz wool and quartz rods, a reaction mixed gas is introduced, the mixed gas composition is argon, carbon dioxide and hydrogen in a molar ratio of 1:6:18, the mixed gas flow rate is 30~100 sccm, heating and pressurization are applied to promote the reaction, the reaction temperature is 260~360℃, and the reaction pressure is 0.2~4MPa.

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