High-efficiency supported catalyst for hydrogenation of co2 to ch3oh and preparation method and application thereof

Abstract

The application discloses a kind of high-efficiency supported catalyst for CO2 hydrogenation to CH3OH and its preparation method and application.The catalyst of the application has high specific surface area, active component is highly dispersed Ni and In2O3, carrier is SBA-15.The catalyst of the application is obtained by three-step method: first, SBA-15 is synthesized, then In2O3-SBA-15 is obtained by using oleic acid assisted impregnation method, finally, Ni 2+ Is reduced to Ni 0 In solution using strong reducing agent NaBH4And directly combined with In2O3-SBA-15.Highly dispersed Ni and In2O3 can promote the adsorption and activation of CO2 and H2 respectively, SBA-15 provides large specific surface area, NaBH4Instead of high-temperature H2 reduction avoids the deactivation of In2O3.So the application can efficiently promote the activation of CO2 and H2, while having high stability, very conducive to the conversion of CO2 and the generation of CH3OH.

Description

Technical Field

[0001] The present invention relates to a high-efficiency supported catalyst for producing CH3OH by hydrogenating CO2, a preparation method thereof and an application thereof, and belongs to the fields of catalyst technology and industrial catalysis. Background Art

[0002] In recent years, with the rapid development of the economy and society, humanity's demand for energy has increased significantly. Excessive development and use of fossil fuels such as coal, oil, and natural gas have led to significant greenhouse gas emissions, particularly carbon dioxide. This has contributed to numerous serious environmental problems, including global warming, rising sea levels, ocean acidification, and extreme weather. Therefore, measures must be taken to reduce carbon dioxide emissions. Reducing carbon dioxide to methanol not only reduces carbon dioxide emissions but also produces methanol, which has great industrial value. Carbon dioxide has very high bond energies and is very stable, necessitating the development of highly active catalysts to facilitate its catalytic conversion.

[0003] Currently, the catalysts used for CO2 hydrogenation to methanol primarily include copper-based catalysts, indium-based catalysts, and precious metal-based catalysts. Copper-based catalysts are prone to deactivation and are highly susceptible to the reverse water-gas reaction, which reduces methanol selectivity. Precious metal catalysts are also expensive. Indium-based catalysts have good catalytic activity for methanol synthesis, but are susceptible to deactivation during high-temperature reduction and are relatively expensive. Nickel has a good ability to dissociate hydrogen, but large Ni particles can easily lead to over-hydrogenation of CO2 to form methane.

[0004] Therefore, it is urgent to prepare a hydrogenation catalyst with high catalytic activity, good methanol selectivity, low price, easy availability and good stability. Summary of the Invention

[0005] Purpose of the invention: The present invention provides a high-efficiency supported catalyst for CO2 hydrogenation to CH3OH, its preparation method and application, to solve the problems of current catalysts such as poor catalytic activity and methanol selectivity, poor stability, and the high price of indium-based catalysts despite their good activity and easy deactivation by high-temperature reduction.

[0006] Technical solution: The present invention provides a method for preparing a high-efficiency supported catalyst for CO2 hydrogenation to CH3OH, comprising the following steps:

[0007] (1) Surfactant P123 was dissolved in HCl solution, and then tetraethyl silicate (TEOS) was added and completely hydrolyzed. The resulting material was then transferred to a reactor for aging, and finally centrifuged, washed, dried, and calcined to obtain SBA-15;

[0008] (2) dissolving indium nitrate in water, then adding SBA-15 and oleic acid, sonicating, stirring, drying, and calcining to obtain In2O3-SBA-15;

[0009] (3) Nickel nitrate, In2O3-SBA-15 and polydiallyldimethylammonium chloride (PDDA) were added to water and stirred evenly. Then, NaBH4 solution was added dropwise under stirring. After complete reduction, Ni / In2O3-SBA-15 was obtained by centrifugation, washing and vacuum drying.

[0010] The concentration of the HCl solution in step (1) is 2 mol / L, the aging temperature is 60-120° C., the aging time is 4 h, the standard for clean washing is that the washing liquid is neutral, the calcination conditions are 100° C. and 5 h, and the mass ratio of P123, HCl and TEOS is 2:5.1:4.4.

[0011] Wherein, the molar ratio of oleic acid to indium nitrate in step (2) is 1:2; and the loading amount of In2O3 on SBA-15 is 1-10 wt.%.

[0012] Wherein, the loading amount of In2O3 on SBA-15 in step (2) is 10 wt.%.

[0013] Wherein, the stirring time in step (2) is 6-10 hours; the calcination temperature is 400-600° C., and the calcination time is 2-4 hours.

[0014] Wherein, in step (2), the stirring time is 8 hours, the calcination temperature is 400° C., and the calcination time is 4 hours.

[0015] In step (3), the mass ratio of Ni to In2O3 is 0.1-0.5:1, preferably 0.2:1; the mass ratio of polydiallyldimethylammonium chloride to Ni is 1-10:1, preferably 5:1; the molar ratio of NaBH4 to Ni is 5:1; the reduction time is 4h; and the vacuum drying temperature and time are 80°C and 12h, respectively.

[0016] The present invention also includes a high-efficiency supported catalyst for CO2 hydrogenation prepared by the preparation method.

[0017] The active components of the catalyst of the present invention are highly dispersed Ni and In2O3, and the carrier is SBA-15. The catalyst is obtained by a three-step process: first, synthesizing SBA-15, then obtaining In2O3-SBA-15 by impregnation, and finally Ni 0 Combined with In2O3-SBA-15. In the first step, oleic acid is used to assist dispersion, and in the second step, NaBH4 is used to reduce Ni in the solution. 2+ , PDDA is needed to assist dispersion.

[0018] The present invention also includes the application of the high-efficiency supported catalyst for CO2 hydrogenation mainly in the thermal catalytic carbon dioxide hydrogenation to methanol reaction.

[0019] The reaction pressure is 1-5 MPa, preferably 3 MPa; the temperature is between 220-280°C, preferably 240°C; the space velocity is between 7500-30000 mL·g cat -1 ·h -1 between 15000 mL·g cat -1 ·h -1 .

[0020] Beneficial effects: Compared with the prior art, the advantages of the present invention are:

[0021] 1. This invention loads In2O3 onto SBA-15 with a large specific surface area and uses oleic acid as a dispersant to promote the dispersion of In2O3. Because the catalytic reaction occurs on the catalyst surface, this not only reduces the amount of indium used and saves costs, but also maximizes the utilization of indium and effectively promotes the activation of CO2.

[0022] 2. The present invention uses PDDA to disperse Ni nanoparticles, resulting in very small and highly dispersed Ni particles. Small Ni particles can greatly promote hydrogen activation without over-hydrogenation to form byproducts such as methane.

[0023] 3. The present invention uses SBA-15 as a carrier. SBA-15 has the characteristics of large specific surface area and high stability, which provides more active sites for the reaction while improving the stability of the catalyst.

[0024] 4. The present invention uses NaBH4 as a reducing agent instead of H2 for high-temperature reduction, which avoids the occurrence of deactivation caused by high-temperature reduction of In2O3. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a working principle diagram of the high-efficiency supported catalyst for producing CH3OH by hydrogenation of CO2 according to the present invention;

[0026] Figure 2 The catalysts of the present invention with different Ni and In2O3 contents were subjected to the conditions of 240℃, 3MPa and 15000mL·g cat -1 ·h -1 Catalytic activity diagram under different conditions.

[0027] Specific implementation method:

[0028] The present invention will be further described below with reference to specific embodiments.

[0029] Example 1

[0030] 2 g of P123 (Simga Aldrich, average Mw ~ 7100, average Mn ~ 5500) was added to 70 mL of 2 mol / L HCl and stirred until dissolved. Then 4.7 mL of TEOS was added dropwise and stirred for 24 h. Next, the solution was transferred to a reactor and aged at 100 ° C for 24 h. Finally, the product was centrifuged and washed to neutrality and calcined in a muffle furnace at 550 ° C for 4 h to obtain SBA-15; 1 g of SBA-15, 0.22 g of indium nitrate and 0.1 g of oleic acid were added to 5 mL of deionized water, ultrasonicated for 30 min, stirred for 8 h, and then dried at 80 ° C overnight. Finally, it was calcined at 450 ° C in a muffle furnace for 4 h to obtain In2O3-SBA-15. 0.2 g of the catalyst (20-40 mesh) and 0.5 g of quartz sand of the same mesh were mixed and added into a fixed bed reactor. cat -1 ·h -1 Catalytic experiments were carried out under the following conditions:

[0031] Experimental results: The conversion rate of carbon dioxide is 3.72%, the selectivity of methanol is 93.7%, and the space-time yield of methanol is 4.7mmol CH3OH ·g cat -1 ·h -1 Without the addition of Ni, although the methanol selectivity is high, the carbon dioxide conversion rate is very low, so the space-time yield of methanol is also low.

[0032] Example 2

[0033] 2 g of P123 was added to 70 mL of 2 mol / L HCl and stirred until dissolved. Then 4.7 mL of TEOS was added dropwise and stirred for 24 h. The solution was then transferred to a reactor and aged at 100 ° C for 24 h. Finally, the product was centrifuged and washed to neutrality and calcined at 550 ° C in a muffle furnace for 4 h to obtain SBA-15. 1 g of SBA-15, 0.22 g of indium nitrate and 0.1 g of oleic acid were added to 5 mL of deionized water, ultrasonicated for 30 min, stirred for 8 h, and then dried at 80 ° C overnight. Finally, calcined at 450 ° C in a muffle furnace for 4 h to obtain In2O3-SBA-15. 1.1 g of In2O3-SBA-15, 0.05 g of nickel nitrate and 0.25 g of PDDA was added to 50 mL of water and stirred for 30 min. Then, 20 mL of 0.043 mol / L NaBH4 methanol solution was added dropwise under stirring. Finally, the mixture was centrifuged, washed, and vacuum-dried to obtain a 0.1 Ni / In2O3-SBA-15 catalyst (0.1 means the mass ratio of Ni to In2O3 is 0.1). 0.2 g of the catalyst (20-40 mesh) and 0.5 g of quartz sand of the same mesh were mixed and added to a fixed bed reactor. The mixture was heated at 240 ° C, 3 MPa, and 15000 mL g cat -1 ·h -1 Catalytic experiments were carried out under the following conditions:

[0034] Experimental results: The conversion rate of carbon dioxide was 7.5%, the selectivity of methanol was 85.2%, and the space-time yield of methanol was 8.4 mmol. CH3OH ·g cat -1 ·h -1 The addition of Ni promoted the conversion of carbon dioxide, but the selectivity of methanol decreased.

[0035] Example 3

[0036] 2g of P123 was added to 70mL of 2mol / L HCl and stirred until dissolved, then 4.7mL of TEOS was added dropwise and stirred for 24h. Next, the solution was transferred to a reactor and aged at 100℃ for 24h. Finally, the product was centrifuged and washed to neutrality and calcined at 550℃ in a muffle furnace for 4h to obtain SBA-15; 1g of SBA-15, 0.22g of indium nitrate and 0.1g of oleic acid were added to 5mL of deionized water, ultrasonicated for 30min and stirred for 8h, then dried at 80℃ overnight, and finally calcined at 450℃ in a muffle furnace for 4h to obtain In2O3-SBA-15; 1.1g of In2O3-SBA-15, 0.1g of nickel nitrate and 0.5g of PDDA was added to 50 mL of water and stirred for 30 min. Then, 20 mL of 0.086 mol / L NaBH4 methanol solution was added dropwise under stirring. Finally, the catalyst was centrifuged, washed, and dried under vacuum to obtain a 0.2 Ni / In2O3-SBA-15 catalyst (0.2 means the mass ratio of Ni to In2O3 is 0.2). 0.2 g of the catalyst (20-40 mesh) and 0.5 g of quartz sand of the same mesh were mixed and added to a fixed bed reactor. The mixture was heated at 240 ° C, 3 MPa, and 15000 mL g cat -1 ·h -1 Catalytic experiments were carried out under the following conditions:

[0037] Experimental results: The conversion rate of carbon dioxide is 11.3%, the selectivity of methanol is 80.2%, and the space-time yield of methanol is 12.2 mmol CH3OH ·g cat -1 ·h -1 This Ni loading is the most suitable because the carbon dioxide conversion rate is the highest, the methanol selectivity is above 80%, and the methanol space-time yield is the highest.

[0038] Example 4

[0039] 2g of P123 was added to 70mL of 2mol / L HCl and stirred until dissolved, then 4.7mL of TEOS was added dropwise and stirred for 24h. Next, the solution was transferred to a reactor and aged at 100℃ for 24h. Finally, the product was centrifuged and washed to neutrality and calcined at 550℃ in a muffle furnace for 4h to obtain SBA-15; 1g of SBA-15, 0.22g of indium nitrate and 0.1g of oleic acid were added to 5mL of deionized water, ultrasonicated for 30min, stirred for 8h, then dried at 80℃ overnight, and finally calcined at 450℃ in a muffle furnace for 4h to obtain In2O3-SBA-15; 1.1g of In2O3-SBA-15, 0.25g nickel nitrate and 1.25g PDDA were added to 50mL water and stirred for 30min. Then, 20ml of 0.21mol / L NaBH4 methanol solution was added dropwise under stirring. Finally, the mixture was centrifuged, washed and vacuum dried to obtain a 0.5Ni / In2O3-SBA-15 catalyst (0.5 means the mass ratio of Ni to In2O3 is 0.5). 0.2g of the catalyst (20-40 mesh) and 0.5g of quartz sand of the same mesh were mixed and added to a fixed bed reactor. The mixture was heated at 240℃, 3MPa and 15000mL·g cat -1 ·h -1 Catalytic experiments were carried out under the following conditions:

[0040] Experimental results: The conversion rate of carbon dioxide is 12.5%, the selectivity of methanol is 63.6%, and the space-time yield of methanol is 10.6g CH3OH ·g cat -1 ·h -1 The Ni loading was a bit too much, and methane was produced during the reaction, which reduced the selectivity of methanol and the space-time yield.

Claims

1. A method for preparing a high-efficiency supported catalyst for producing CH3OH by hydrogenation of CO2, characterized in that: The following steps are involved: (1) The surfactant P123 was dissolved in HCl solution, and then tetraethyl silicate was added and completely hydrolyzed. The resulting material was then transferred to a reactor for aging, and finally centrifuged, washed, dried, and calcined to obtain SBA-15. (2) Indium nitrate was dissolved in water, and then SBA-15 and oleic acid were added, followed by ultrasonication, stirring, drying, and calcination to obtain In2O3-SBA-15; (3) Nickel nitrate, In2O3-SBA-15 and polydiallyldimethylammonium chloride were added to water and stirred evenly. Then, NaBH4 solution was added dropwise under stirring. After complete reduction, Ni / In2O3-SBA-15 was obtained by centrifugation, washing and vacuum drying.

2. The method for preparing a high-efficiency supported catalyst for producing CH3OH by hydrogenation of CO2 according to claim 1, wherein In step (1), the concentration of the HCl solution is 2 mol / L, the aging temperature is 60-100°C, the aging time is 24 h, the standard for clean washing is that the washing liquid is neutral, the calcination conditions are 550°C and 5 h, and the mass ratio of P123, HCl and TEOS is 2:5.1:4.

4.

3. The method for preparing a high-efficiency supported catalyst for producing CH3OH by hydrogenation of CO2 according to claim 1, wherein In step (2), the molar ratio of oleic acid to indium nitrate is 1:2; and the loading amount of In2O3 on SBA-15 is 1-10 wt.%.

4. The method for preparing a high-efficiency supported catalyst for producing CH3OH by hydrogenation of CO2 according to claim 1, wherein The loading amount of In2O3 on SBA-15 in step (2) is 10 wt.%.

5. The method for preparing a high-efficiency supported catalyst for producing CH3OH by hydrogenation of CO2 according to claim 1, wherein: In step (2), the stirring time is 6-10 h; the calcination temperature is 400-600 °C, and the calcination time is 2-4 h.

6. The method for preparing a high-efficiency supported catalyst for producing CH3OH by hydrogenation of CO2 according to claim 1, wherein: In step (2), the stirring time is 8 h, the calcination temperature is 400 °C, and the calcination time is 4 h.

7. The method for preparing a high-efficiency supported catalyst for producing CH3OH by hydrogenation of CO2 according to claim 1, wherein: In step (3), the mass ratio of Ni to In2O3 is 0.1-0.5:1; the mass ratio of polydiallyldimethylammonium chloride to Ni is 1-10:1; the molar ratio of NaBH4 to Ni is 5:1; the reduction time is 4 h; and the vacuum drying temperature and time are 80 °C and 12 h, respectively.

8. The method for preparing a high-efficiency supported catalyst for producing CH3OH by hydrogenation of CO2 according to claim 7, wherein: In step (3), the mass ratio of Ni to In2O3 is 0.2:1; the mass ratio of polydiallyldimethylammonium chloride to Ni is 5:

1.

9. A highly efficient supported catalyst for producing CH3OH from CO2 hydrogenation prepared by the preparation method according to claim 1.

10. Use of the high-efficiency supported catalyst for CO2 hydrogenation according to claim 9 in the thermal catalytic carbon dioxide hydrogenation reaction to produce methanol.

11. The use according to claim 10, characterized in that The reaction pressure is 1-5 MPa; the temperature is 220-280°C; the space velocity is 7500-30000 mL·g cat -1 ·h -1 .

12. The use according to claim 11, characterized in that The reaction pressure is 3 MPa; the temperature is 240°C; the space velocity is 15000 mL·g cat -1 ·h -1 .

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