A core-shell bifunctional CO2 adsorption catalyst of Amine-SiO2@Pd / TiO2 and its preparation and application
By preparing a core-shell catalyst of Amine-SiO2@Pd/TiO2, the problems of CO2 adsorption and activation were solved, the efficiency and stability of photocatalytic CO2 reduction were improved, and efficient CO2 capture and in-situ photocatalytic conversion were realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA THREE GORGES UNIV
- Filing Date
- 2024-03-11
- Publication Date
- 2026-06-26
AI Technical Summary
In existing photocatalytic CO2 reduction technologies, the problems of CO2 adsorption and activation have not been effectively solved, which limits the catalytic activity and the adsorption and diffusion of CO2 at the catalytic site, thus affecting the photocatalytic activity.
A core-shell bifunctional CO2 adsorption catalyst of the Amine-SiO2@Pd/TiO2 type was used. Organic amines were grafted into the mesoporous SiO2 support as active sites for CO2 adsorption, and Pd/TiO2 was loaded into the SiO2 shell to construct a CO2-rich microenvironment, which promoted CO2 adsorption and activation.
It improves the photocatalytic activity of CO2, enhances the adsorption and activation capacity of CO2, improves the CO2 capture efficiency, and increases the stability of the reaction system.
Smart Images
Figure CN118287066B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of carbon dioxide capture, adsorption, and photocatalytic conversion, and particularly to an Amine-SiO2@Pd / TiO2 type core-shell bifunctional CO2 adsorption catalyst and its preparation and application. Background Technology
[0002] For over a century, the extraction and utilization of fossil fuels has driven the progress and development of human society. However, their excessive use, accompanied by massive emissions of greenhouse gases, primarily CO2, has exacerbated global warming and posed a serious threat and damage to natural ecosystems and the human living environment. Among numerous carbon reduction technologies, CO2 capture, utilization, and storage (CCUS) is one of the effective means to achieve carbon reduction. Therefore, developing efficient CO2 capture technologies and converting them into fuels and high-value-added chemicals is one of the effective ways to solve environmental and energy problems.
[0003] Among numerous solutions, photocatalytic CO2 reduction driven by solar energy, known as artificial photosynthesis, has attracted widespread attention from researchers. To improve the performance of photocatalytic CO2 reduction, a series of strategies have been adopted to increase the visible light excitation of wide-bandgap semiconductors for CO2 photoreduction, such as quantum dot sensitization, ion doping, surface plasmon enhancement, and the development of novel visible light-responsive semiconductors. Patent CN201811543732.X discloses a method for preparing an In2O3 / CeO2 / HATP composite photocatalyst for CO2 reduction. This patent improves CO2 photocatalytic activity by introducing another semiconductor, In2O3, to construct a heterojunction with CeO2 to reduce the recombination rate of electrons and holes; however, this composite photocatalyst has not effectively solved or promoted the CO2 adsorption and activation problems in the photocatalytic CO2 reduction process. Studies have shown that CO2 adsorption and activation are key to improving the photocatalytic CO2 reduction activity, and the CO2 concentration around the catalyst limits the adsorption and diffusion of CO2 at the catalytic site, further affecting the photocatalytic activity. Therefore, developing efficient bifunctional CO2 adsorption catalysts, constructing CO2-rich microenvironments at catalytic sites, promoting CO2 adsorption and activation, thereby improving photocatalytic CO2 reduction performance, and realizing CO2 capture and in-situ photocatalytic conversion to prepare high-value-added chemicals is of great practical significance. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing an Amine-SiO2@Pd / TiO2 type core-shell bifunctional CO2 adsorption catalyst and its application to solve the problems existing in the prior art.
[0005] To achieve the above objectives, the following technical solution is adopted:
[0006] A method for preparing an Amine-SiO2@Pd / TiO2 type core-shell bifunctional CO2 adsorption catalyst includes the following steps:
[0007] (1) Under stirring conditions, mesoporous SiO2 support was added to the organic amine aqueous solution and stirred evenly to obtain an emulsion;
[0008] (2) Add Pd / TiO2 to the emulsion, continue stirring for 2-4 hours, remove water by rotary evaporation, and then dry under vacuum to obtain Amine-SiO2@Pd / TiO2 type core-shell bifunctional CO2 adsorption catalyst.
[0009] The organic amine is selected from one or more of tetraethylenepentamine, pentaethylenehexamine, and polyethyleneimine; the porous SiO2 support has a pore size of 6-12 nm.
[0010] The mass ratio of the organic amine to mesoporous SiO2 is 1:9 to 1:1, preferably 1:9 to 3:7; the mass ratio of the mesoporous SiO2 to Pd / TiO2 is 4:1 to 1:2, preferably 4:1 to 1:1.
[0011] The Pd / TiO2 catalyst is obtained by adding TiO2 support to an aqueous H2PdCl2 solution, stirring until an emulsion is formed, and then removing water by rotary evaporation, drying, calcining, and reducing with hydrogen.
[0012] The mass ratio of Pd to TiO2 is 0.2% to 5%, preferably 0.5% to 3%; the particle size of TiO2 is 30 to 200 nm, preferably 50 to 200 nm.
[0013] The rotary evaporation temperature is 40~80℃, preferably 50~80℃; the calcination temperature is 350~450℃, preferably 350~400℃.
[0014] The hydrogen reduction temperature is 350~400℃, preferably 350~380℃; the hydrogen flow rate is 20~50mL / min, preferably 25~40mL / min.
[0015] The rotary evaporation temperature in step 2 is 60~80℃, preferably 65~75℃; the vacuum drying temperature is 80~100℃, preferably 85~100℃.
[0016] The preparation method described yields an Amine-SiO2@Pd / TiO2 core-shell bifunctional CO2 adsorption catalyst. In SiO2@Pd / TiO2, the @ symbol generally represents the core-shell structure.
[0017] An application of the aforementioned adsorption catalyst in the CO2 adsorption process, wherein it is used as a bifunctional CO2 adsorption catalyst in the CO2 capture and in-situ photocatalytic conversion reaction.
[0018] A CH4 production catalyst is prepared by using an Amine-SiO2@Pd / TiO2 core-shell bifunctional CO2 adsorption catalyst prepared by the method described above to capture CO2 and convert it in situ to CH4 via photocatalytic conversion.
[0019] Compared with existing technologies, this invention utilizes the "confinement effect" of the carrier pore size to graft smaller organic amines into the mesoporous SiO2 channels, serving as the "core layer" of active sites for CO2 adsorption. In contrast, larger Pd-Cu / TiO2 catalysts can only be loaded onto the "shell layer" of SiO2. This allows for the design and preparation of an Amine-SiO2@Pd-Cu / TiO2 bifunctional adsorption catalyst. This structure not only efficiently adsorbs and enriches CO2, providing a CO2-rich microenvironment for the catalytic sites, promoting CO2 adsorption and activation, and enhancing CO2 photocatalytic activity, but also effectively protects the organic amine from becoming a hydrogen donor sacrificial agent, improving the stability of the reaction system. It is a promising bifunctional composite material for CO2 capture and in-situ photocatalytic conversion. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the structure and catalytic reaction process of the Amine-SiO2@Pd / TiO2 core-shell bifunctional CO2 adsorption catalyst in Example 1.
[0021] Figure 2 The results show the CH4 yield in the photocatalytic CO2 reduction products of Examples 1-3 and Comparative Examples 1-2. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.
[0023] Preparation of Pd / TiO2 catalyst: 40 mL of deionized water was placed in a pear-shaped flask, and then an aqueous solution of H2PdCl2 (4.26 mL, 2.348 mg / mL) was added dropwise and stirred until homogeneous to obtain solution A. Then, 1 g of TiO2 support was gradually added to solution A, and stirring was continued for 6 h to obtain emulsion B. Water in emulsion B was removed using a rotary evaporator, and the sample was dried in an oven at 100 °C for 2 h. The dried sample was then calcined at 400 °C in air (air flow rate 30 mL / min) for 4 h. After cooling, the sample was reduced at 350 °C in a hydrogen atmosphere (flow rate 30 mL / min) for 4 h to obtain the Pd / TiO2 catalyst, which was used in the following examples.
[0024] Example 1
[0025] 4 mL of deionized water was added to a 50 mL round-bottom flask, and 0.3 g of tetraethylenepentamine (TEPA) solution was added and stirred to obtain solution C. Then, 0.7 g of mesoporous SiO2 support was added to solution C, and stirring was continued for 4 h to obtain emulsion D. 0.5 g of Pd / TiO2 (i.e., the mass ratio of organic amine to mesoporous SiO2 is 3:7; the mass ratio of mesoporous SiO2 to Pd / TiO2 is 1.4) was added to emulsion D, and stirring was continued for 4 h. Then, the aqueous solution was removed using a rotary evaporator at 60 °C. The obtained sample was placed in a vacuum drying oven and vacuum dried at 80 °C for 6 h. After drying, it was cooled to room temperature to obtain a TEPA-SiO2@Pd / TiO2 core-shell bifunctional CO2 adsorption catalyst. Figure 1 This is a schematic diagram of the TEPA-SiO2@Pd / TiO2 core-shell bifunctional CO2 adsorption catalyst. As shown in the figure, the "confinement effect" of the support pore size impregnates the smaller TEPA particles into the mesoporous SiO2 channels, serving as the "core layer" of active sites for CO2 adsorption. The larger Pd / TiO2 catalyst, however, can only be loaded onto the "shell layer" of SiO2. Therefore, the prepared TEPA-SiO2@Pd / TiO2 bifunctional CO2 adsorption catalyst has a core-shell structure.
[0026] The CO2 photocatalytic reduction test procedure was as follows: 20 mg of TEPA-SiO2@Pd / TiO2 bifunctional adsorption catalyst was loaded into a 5 mL quartz photoreaction tube; then, the atmosphere in the photoreaction tube was replaced with Ar atmosphere using a glove box. 5 mL of H2 and 500 μL of CO2 reaction gas were injected into the photoreaction tube. Finally, the photoreaction tube was transferred to a photoreactor, and the reaction was carried out under 365 nm light illumination for 10 h, with the reactor temperature maintained at room temperature throughout the reaction. The reaction products were analyzed using a Shimadzu GC-2014 gas chromatograph; the test results showed that the CH4 yield in this example was 8.2 μmol / g. cat. ,like Figure 2 As shown, the CH4 yield was 1.9 μmol / g compared to Comparative Example 1. cat. The yield of CH4 increased by approximately 4.3 times. Because the prepared core-shell bifunctional adsorption catalyst can efficiently adsorb and enrich CO2, providing a CO2-rich microenvironment for the catalytic site, it promotes CO2 adsorption and activation, thereby enhancing the CO2 photocatalytic activity. Possible catalytic reaction processes include... Figure 1 As shown.
[0027] Example 2
[0028] The method and steps are the same as in Example 1, except that 0.7g of Pd / TiO2 (i.e., the mass ratio of organic amine to mesoporous SiO2 is 3:7; the mass ratio of mesoporous SiO2 to Pd / TiO2 is 1) is added to emulsion D to obtain a TEPA-SiO2@Pd / TiO2 type core-shell bifunctional CO2 adsorption catalyst.
[0029] The CO2 photocatalytic reduction test procedure was the same as in Example 1, and the reaction products were analyzed using a Shimadzu GC-2014 gas chromatograph. According to the test results, the CH4 yield in the product of this example was 9.2 μmol / g. cat. ,like Figure 2 As shown, the CH4 yield was 1.9 μmol / g compared to Comparative Example 1. cat. The yield of product CH4 increased by approximately 4.8 times.
[0030] Example 3
[0031] The method and steps are the same as in Example 2, except that the amount of tetraethylenepentamine (TEPA) added is 0.25 g (i.e., the mass ratio of organic amine to mesoporous SiO2 is 1:2.8; the mass ratio of mesoporous SiO2 to Pd / TiO2 is 1), thus obtaining a TEPA-SiO2@Pd / TiO2 type core-shell bifunctional CO2 adsorption catalyst.
[0032] The CO2 photocatalytic reduction test procedure was the same as in Example 1, and the reaction products were analyzed using a Shimadzu GC-2014 gas chromatograph. According to the test results, the CH4 yield in the product of this example was 8.9 μmol / g. cat. ,like Figure 2 As shown, the CH4 yield was 1.9 μmol / g compared to Comparative Example 1. cat. The yield of product CH4 increased by approximately 4.7 times.
[0033] Example 4
[0034] 4 mL of deionized water was added to a 50 mL round-bottom flask, and 0.3 g of pentaethylene hexamine (PEHA) solution was added and stirred to obtain solution C. Then, 0.7 g of mesoporous SiO2 support was added to solution C, and stirring was continued for 4 h to obtain emulsion D. 0.7 g of Pd / TiO2 was added to emulsion D, and stirring was continued for 4 h. The aqueous solution was then removed using a rotary evaporator at 60 °C. The obtained sample was placed in a vacuum drying oven and vacuum dried at 80 °C for 6 h. After drying, it was cooled to room temperature to obtain a TEPA-SiO2@Pd / TiO2 core-shell bifunctional CO2 adsorption catalyst.
[0035] Example 5
[0036] Take 4 mL of deionized water into a 50 mL round-bottom flask, add 0.3 g of tetraethylenepentamine (TEPA) solution and stir to obtain solution C; then add 0.7 g of mesoporous SiO2 support to solution C and continue stirring for 6 h to obtain emulsion D; add 0.6 g of Pd / TiO2 (i.e., the mass ratio of organic amine to mesoporous SiO2 is 3:7; the mass ratio of mesoporous SiO2 to Pd / TiO2 is 7:6) to emulsion D and continue stirring for 4 h; then remove the aqueous solution using a rotary evaporator at 65 °C; place the obtained sample in a vacuum drying oven at 80 °C for 6 h, and cool to room temperature after drying to obtain a TEPA-SiO2@Pd / TiO2 core-shell bifunctional CO2 adsorption catalyst.
[0037] Comparative Example 1
[0038] 40 mL of deionized water was placed in a pear-shaped flask, and then an aqueous solution of H₂PdCl₂ (4.26 mL, 2.348 mg / mL) was added dropwise and stirred until homogeneous to obtain solution A. 1 g of TiO₂ support was then gradually added to solution A, and stirring was continued for 6 h to obtain emulsion B. Water was then removed from emulsion B using a rotary evaporator, and the sample was dried in an oven at 100 °C for 2 h. The dried sample was then calcined at 400 °C in air (air flow rate 30 mL / min) for 4 h. After cooling, the sample was reduced at 350 °C in a hydrogen atmosphere (flow rate 30 mL / min) for 4 h to obtain the Pd / TiO₂ catalyst.
[0039] The CO2 photocatalytic reduction test procedure was as follows: 20 mg of Pd / TiO2 catalyst was loaded into a 5 mL quartz photoreaction tube; then, the atmosphere in the photoreaction tube was replaced with Ar atmosphere using a glove box. 5 mL of H2 and 500 μL of CO2 reaction gas were injected into the photoreaction tube. Finally, the photoreaction tube was transferred to a photoreactor, and the reaction was carried out under 365 nm light illumination for 10 h, with the reactor temperature maintained at room temperature throughout the reaction. The reaction products were analyzed using a Shimadzu GC-2014 gas chromatograph; the test results showed that the yield of CH4 in the product was 1.9 μmol / g. cat. ,like Figure 2 As shown.
[0040] Comparative Example 2
[0041] 40 mL of deionized water was placed in a pear-shaped flask, and then an aqueous solution of H₂PdCl₂ (4.26 mL, 2.348 mg / mL) was added dropwise and stirred until homogeneous to obtain solution A. 1 g of TiO₂ support was then gradually added to solution A, and stirring was continued for 6 h to obtain emulsion B. Water was then removed from emulsion B using a rotary evaporator, and the sample was dried in an oven at 100 °C for 2 h. The dried sample was then calcined at 400 °C in air (air flow rate 30 mL / min) for 4 h. After cooling, the sample was reduced at 350 °C in a hydrogen atmosphere (flow rate 30 mL / min) for 4 h to obtain the Pd / TiO₂ catalyst.
[0042] 4 mL of deionized water was placed in a 50 mL round-bottom flask, and 0.7 g of mesoporous SiO2 support and 0.5 g of Pd / TiO2 were added sequentially and stirred for 4 h. The aqueous solution was then removed using a rotary evaporator at 60 °C. The resulting sample was placed in a vacuum drying oven and dried under vacuum at 80 °C for 6 h. After drying, the sample was cooled to room temperature. The resulting product was non-core-shell structure, and therefore named Pd / TiO2 / SiO2 catalyst.
[0043] The CO2 photocatalytic reduction test procedure was as follows: 20 mg of Pd / TiO2 / SiO2 catalyst was loaded into a 5 mL quartz photoreaction tube; then, the atmosphere in the photoreaction tube was replaced with Ar atmosphere using a glove box. 5 mL of H2 and 500 μL of CO2 reaction gas were injected into the photoreaction tube. Finally, the photoreaction tube was transferred to a photoreactor, and the reaction was carried out under 365 nm light for 10 h, with the reactor temperature maintained at room temperature throughout the reaction. The reaction products were analyzed using a Shimadzu GC-2014 gas chromatograph; the test results showed that the yield of CH4 in the product was 1.8 μmol / g. cat. ,like Figure 2 As shown.
[0044] The above description, with detailed implementation steps and experiments, provides a comprehensive overview of the invention. This is merely an illustration and cannot limit the scope of the invention. Therefore, any modifications or improvements made without departing from the spirit of the invention are within the scope of protection claimed by the invention.
Claims
1. A method for preparing an Amine-SiO2@Pd / TiO2 type core-shell bifunctional CO2 adsorption catalyst, characterized in that, Includes the following steps: (1) Under stirring conditions, mesoporous SiO2 support is added to the aqueous solution of organic amine and stirred evenly to obtain an emulsion. The mass ratio of organic amine to mesoporous SiO2 is 1:9 to 1:
1. (2) Add Pd / TiO2 to the emulsion, continue stirring for 2-4 hours, remove water by rotary evaporation, and dry under vacuum to obtain Amine-SiO2@Pd / TiO2 core-shell bifunctional CO2 adsorption catalyst. The Pd / TiO2 catalyst is obtained by adding TiO2 support to H2PdCl2 aqueous solution, stirring until an emulsion is formed, and then removing water by rotary evaporation, drying, calcining, and reducing with hydrogen. The mass ratio of mesoporous SiO2 to Pd / TiO2 is 4:1 to 1:
2.
2. The preparation method according to claim 1, characterized in that, The organic amine is selected from one or more of tetraethylenepentamine, pentaethylenehexamine, and polyethyleneimine; the porous SiO2 support has a pore size of 6-12 nm.
3. The preparation method according to claim 1, characterized in that, The mass ratio of the organic amine to mesoporous SiO2 is 1:9 to 3:7; the mass ratio of the mesoporous SiO2 to Pd / TiO2 is 4:1 to 1:
1.
4. The preparation method according to claim 1, characterized in that, The mass ratio of Pd to TiO2 is 0.2% to 5%, and the particle size of TiO2 is 30 to 200 nm.
5. The preparation method according to claim 4, characterized in that, The mass ratio of Pd to TiO2 is 0.5% to 3%; the particle size of TiO2 is 50 to 200 nm.
6. The preparation method according to claim 4, characterized in that, The rotary evaporation temperature is 40~80℃; the calcination temperature is 350~450℃; the hydrogen reduction temperature is 350~400℃; the hydrogen flow rate is 20~50mL / min; and the vacuum drying temperature is 80~100℃.
7. The preparation method according to claim 6, characterized in that, The rotary evaporation temperature in step 2 is 50~80℃; the calcination temperature is 350~400℃; the hydrogen reduction temperature is 350~380℃; the hydrogen flow rate is 25~40mL / min; and the vacuum drying temperature is 85~100℃.
8. The application of an Amine-SiO2@Pd / TiO2 core-shell bifunctional CO2 adsorption catalyst prepared by the preparation method according to any one of claims 1-7 in the CO2 adsorption process, characterized in that, It is used as a bifunctional CO2 adsorption catalyst in CO2 capture and in-situ photocatalytic conversion reactions.
9. The application of an Amine-SiO2@Pd / TiO2 core-shell bifunctional CO2 adsorption catalyst prepared by any one of claims 1-7 for CO2 capture and in-situ photocatalytic conversion to CH4.