ZnO-loaded composite material, preparation method thereof and application of ZnO-loaded composite material in preparation of methanol by hydrogenation of carbon dioxide
By loading Cu single atoms onto the surface of ZnO nanorods to form a ZnO-supported composite material, the problem of instability of existing catalysts was solved, and a highly selective and stable CO2 hydrogenation to methanol reaction was achieved.
Patent Information
- Application Number
- CN202511308085.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-15
- Publication Date
- 2025-12-12
AI Technical Summary
Existing Cu-ZnO-Al2O3 catalysts are unstable in the reaction of carbon dioxide hydrogenation to methanol, and are prone to sintering and deactivation or loss of activation, resulting in short service life and poor stability.
A Cu single-atom catalyst supported on ZnO nanorods was prepared by uniformly distributing Cu single atoms on the surface of ZnO nanorods to form a ZnO-supported composite material. The Cu single atoms adsorbed and activated CO2, while hydrogen was dissociated on the surface of the ZnO rods, which synergistically improved the catalytic performance.
It achieves good catalytic activity, high selectivity and strong stability in the CO2 hydrogenation to methanol reaction. Cu single atoms are well dispersed on ZnO support, the active components are uniformly distributed and the catalytic performance is excellent.
Smart Images
Figure CN121103366A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst technology, and in particular to a ZnO-supported composite material, its preparation method, and its application in the hydrogenation of carbon dioxide to methanol. Background Technology
[0002] Carbon dioxide hydrogenation to methanol technology is currently a research hotspot in the fields of green chemistry and carbon neutrality. It aims to convert the greenhouse gas CO2 into high-value-added fuels and chemical feedstocks (such as methanol), achieving the recycling of carbon resources. With the intensification of global climate change, reducing CO2 emissions has become an urgent task. This technology, by coupling CO2 capture with renewable energy-based hydrogen production, can not only reduce atmospheric CO2 concentrations but also produce methanol, a clean energy carrier (which can be used for fuel, energy storage, or chemical synthesis), thus possessing both environmental benefits and economic potential.
[0003] The commonly used catalyst for the hydrogenation of CO2 to methanol is Cu-ZnO-Al2O3, in which Cu and ZnO are the active phases and Al2O3 is a structural aid. However, this catalyst is unstable in use and is prone to sintering and deactivation or loss of activity, resulting in a short service life and poor stability. Summary of the Invention
[0004] The purpose of this invention is to provide a ZnO-supported composite material, its preparation method, and its application in the hydrogenation of carbon dioxide to methanol, so as to solve the problems mentioned in the background art.
[0005] The technical problem solved by the present invention is to provide a ZnO-supported composite material, which has the advantages of high selectivity, good catalytic activity and strong stability in the CO2 hydrogenation to methanol reaction.
[0006] In view of this, this application provides a ZnO-supported composite material, comprising ZnO nanorods and Cu single atoms supported on the surface of the ZnO nanorods, wherein the loading amount of Cu single atoms is 0.1~1.0wt% and the length of the ZnO nanorods is 200~300nm.
[0007] This application also provides a method for preparing the ZnO-supported composite material, comprising the following steps:
[0008] S1: Zinc nitrate hexahydrate and sodium hydroxide were dissolved in water, and ethanol and ethylenediamine were added. The mixture was stirred at room temperature, centrifuged, washed, dried and then calcined to obtain ZnO nanorods.
[0009] S2: ZnO nanorods and copper source are mixed in water, rotary evaporated, and calcined to obtain ZnO-supported composite material.
[0010] Preferably, in step S1, the ratio of zinc nitrate hexahydrate, sodium hydroxide, water, ethanol and ethylenediamine is (1.4~1.6) g : (5.5~6.5) g : (9.0~11.0) mL : (95~105) mL : (4.5~5.5) mL.
[0011] Preferably, in step S1, the stirring time at room temperature is 20-30 hours, the drying temperature is 50-80°C, and the drying time is 10-15 hours.
[0012] Preferably, in step S2, the copper source is Cu(NO3)2‧3H2O, and the ratio of ZnO nanorods, copper source and water is (2~3)g:(0.01~0.10)g:(30~50)mL.
[0013] Preferably, in step S2, the mixing method is ultrasonication followed by stirring, the ultrasonication time is 10~15 min, the stirring time is 3~5 h, and the rotary evaporation temperature is 50~70℃.
[0014] Preferably, in steps S1 and S2, the calcination temperature is 300~500℃ and the time is 3~5h.
[0015] Preferably, the calcination temperature is 300~500℃ and the time is 3~5h.
[0016] This application also provides the application of ZnO-supported composite materials as catalysts for the hydrogenation of CO2 to methanol.
[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0018] This application provides a ZnO-supported composite material, which consists of ZnO nanorods and Cu single atoms supported on the surface of the ZnO nanorods. In the ZnO-supported composite material, Cu single atoms can adsorb and activate CO2, and the surface of ZnO rods can effectively dissociate hydrogen. Using Cu single atoms supported on a ZnO support as a catalyst, the atomic dispersion is good and the active components are evenly distributed. The effects of Cu and ZnO can be synergistically combined, so that it has the advantages of good catalytic activity, high selectivity and strong stability in the CO2 hydrogenation to methanol reaction. Attached Figure Description
[0019] Figure 1 Transmission electron microscope image of a Cu single-atom catalyst supported on ZnO;
[0020] Figure 2 (ad) is a high-resolution transmission electron microscope image of a Cu single-atom catalyst supported on ZnO and the elemental mapping spectra of Cu (orange), Zn (red) and O (green).
[0021] Figure 3 Powder X-ray diffraction pattern of Cu single-atom catalyst supported on ZnO;
[0022] Figure 4 The changes in CO2 conversion rate and product selectivity over time of the ZnO-supported Cu single-atom catalyst obtained in Example 1 of this invention during CO2 hydrogenation.
[0023] Figure 5 The changes in CO2 conversion rate and product selectivity over time for the ZnO-supported Cu single-atom catalyst obtained in Example 2 of this invention during CO2 hydrogenation.
[0024] Figure 6 The changes in CO2 conversion rate and product selectivity over time of the ZnO-supported Cu single-atom catalyst obtained in Example 3 of this invention during CO2 hydrogenation.
[0025] Figure 7 The changes in CO2 conversion rate and product selectivity over time for the ZnO-supported Cu single-atom catalyst obtained in Comparative Example 1 of this invention are shown. Detailed Implementation
[0026] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.
[0027] In view of the poor stability of catalysts for CO2 hydrogenation to methanol in the prior art, this application provides a ZnO-supported composite material, namely a ZnO-supported Cu single-atom catalyst, wherein the Cu single atoms are well dispersed in the support and the active components are uniformly distributed. Therefore, it has the advantages of high selectivity, good catalytic activity and stable catalytic performance in CO2 hydrogenation to methanol. Specifically, this invention discloses a ZnO-supported composite material, which is composed of ZnO nanorods and Cu single atoms supported on the surface of the ZnO nanorods.
[0028] In the ZnO-supported composite material, the loading of Cu single atoms is 0.1–1 wt%. The support is ZnO nanorods with a length of 200–300 nm.
[0029] This application also provides a method for preparing ZnO-supported composite materials, including the following steps:
[0030] Zinc nitrate hexahydrate and sodium hydroxide were dissolved in water, then ethanol and ethylenediamine were added, the mixture was stirred at room temperature, and then calcined to obtain ZnO nanorods.
[0031] The ZnO nanorods and copper source were mixed in water, rotary evaporated, and calcined to obtain a ZnO-supported composite material.
[0032] In the preparation of ZnO-supported composite materials, zinc nitrate hexahydrate and sodium hydroxide were first dissolved in water, followed by the addition of ethanol and ethylenediamine. The mixture was stirred at room temperature and then calcined to obtain ZnO nanorods. During this process, the ratio of zinc nitrate hexahydrate, sodium hydroxide, water, ethanol, and ethylenediamine was (1.4~1.6) g : (5.5~6.5) g : (9.0~11.0) mL : (95~105) mL : (4.5~5.5) mL to ensure the acquisition of ZnO nanorods with a length of 200~300 nm. The stirring time at room temperature was 20~30 h. The process prior to calcination includes washing, separation, and drying; the drying temperature is 50-80℃ for 10-15 hours; the calcination temperature is 300-450℃ for 3-5 hours; more specifically, the drying temperature is 60-70℃ for 12 hours; and the calcination temperature is 350-400℃ for 4 hours. The washing process uses water and ethanol to remove inorganic ions and inorganic alkalis adsorbed on the surface of the ZnO nanorods, respectively.
[0033] This application then mixes the ZnO nanorods obtained above with a copper source in water and calcines them to obtain a ZnO-supported composite material. In this process, the ratio of the ZnO nanorods, the copper source, and the water is (2~3) g : (0.01~0.10) g : (30~50) mL; more specifically, the copper source is selected from copper nitrate trihydrate. The mixing specifically involves ultrasonication followed by stirring, with the ultrasonication time being 10~15 min, the stirring time being 3~5 h, and the rotary evaporation temperature being 50~70℃; the calcination temperature is 300~500℃, and the time is 3~5 h. The specific preparation process of the ZnO-supported composite material obtained in this application is as follows: ZnO nanorods and Cu(NO3)2‧3H2O are dispersed in deionized water, ultrasonicated for 12 minutes, stirred at room temperature for 4 hours, the resulting solution is rotary evaporated at 60℃, and the resulting solid is calcined in a muffle furnace at 400℃ for 4 hours.
[0034] This application also provides the application of ZnO-supported composite materials in the CO2 hydrogenation reaction to produce methanol.
[0035] The CO2 hydrogenation to methanol reaction is a conventional method in the art, specifically:
[0036] The CO2 hydrogenation experiment was conducted in a fixed-bed reactor (Quzhou Wode Instrument Co., Ltd.) at 220℃. The flow rate of the CO2 / H2 feed gas was 10 mL / min, and the composition was 96 vol% CO2 / H2 (CO2:H2=3:1) and 4 vol% Ar (as internal standard gas). 3.0 g of 20-40 mesh ZnO-loaded composite material was placed in the fixed-bed reactor, and the inner diameter of the quartz tube used was 9 mm. All products in the reactor were introduced into two gas chromatographs (Shimadzu GC2014) in gaseous state. H2, CO, CO2, and Ar were separated by a carbon molecular sieve column TDX- and analyzed by a thermal conductivity detector (TCD). Methanol was analyzed by a flame ionization detector (FID) through a PONA capillary column.
[0037] In the prior art, neither Cu nor ZnO alone has catalytic performance. The catalyst with Cu single atoms supported on ZnO support as described in this application has good atomic dispersion and uniform distribution of active components. It can synergize the effects of Cu and ZnO, so that it has the advantages of good catalytic activity, high selectivity and stable catalytic performance in the reaction of CO2 hydrogenation to methanol.
[0038] To further understand the present invention, the following detailed description, in conjunction with embodiments, provides the ZnO-supported composite material, its preparation method, and its application. The scope of protection of the present invention is not limited by the following embodiments.
[0039] Example 1
[0040] A ZnO-supported Cu single-atom catalyst, the catalyst comprising highly dispersed Cu single atoms and ZnO nanorods in the hexagonal wurtzite phase.
[0041] The preparation method of the above-mentioned ZnO-supported Cu single-atom catalyst includes:
[0042] First, 1.4 g of zinc nitrate hexahydrate and 5.5 g of sodium hydroxide were dissolved in 9 mL of deionized water. The resulting solution was stirred for 10 minutes to obtain a clear solution. Next, 95 mL of ethanol and 4.5 mL of ethylenediamine were added to the resulting solution, and the mixture was stirred at room temperature for 24 hours. After centrifugation, the product was washed twice with deionized water and twice with ethanol. The washed sample was dried in a vacuum drying oven at 60 °C for 12 hours, and finally calcined in a muffle furnace at 400 °C for 4 hours to obtain a ZnO support. 2.0 g of ZnO support and 0.01 g of Cu(NO3)2‧3H2O were added to 40 mL of deionized water to obtain a suspension. After sonication for 12 minutes, the resulting mixture was stirred at room temperature for 4 hours to obtain a homogeneous solution. Subsequently, the solution was rotary evaporated at 60 °C, and the resulting solid was calcined in a muffle furnace at 400 °C for 4 hours to obtain a Cu single-atom catalyst with a loading of 0.25 wt% ZnO.
[0043] The catalytic performance of the ZnO-supported Cu single-atom catalyst prepared in Example 1 was tested for the CO2 hydrogenation reaction.
[0044] The CO2 hydrogenation experiment was conducted in a fixed-bed reactor (Quzhou Wode Instrument Co., Ltd.) at 220℃, with a reaction pressure of 5MPa. The flow rate of the CO2 / H2 feed gas was 10mL / min, and the composition was 96 vol% CO2 / H2 (CO2:H2=3:1) and 4 vol% Ar (as internal standard gas). 3.0 g of 20-40 mesh ZnO-supported Cu single-atom catalyst was placed in the fixed-bed reactor. The quartz tube used had an inner diameter of 9 mm. All products in the reactor were introduced into two gas chromatographs (Shimadzu GC2014) in gaseous state. H2, CO, CO2, and Ar were separated by a carbon molecular sieve column TDX- and analyzed by a thermal conductivity detector (TCD). Methanol was analyzed by a flame ionization detector (FID) through a PONA capillary column.
[0045] In the CO2 hydrogenation reaction catalyzed by the ZnO-supported Cu single-atom catalyst of Example 1, the transmission electron microscope image, EDS spectrum, and XRD characterization of the ZnO-supported Cu single-atom catalyst before catalysis are shown in the attached figures. Figure 1 The image in the middle is a transmission electron microscope image of a Cu single-atom catalyst supported on ZnO. Figure 2 (ad) is a high-resolution transmission electron microscope image of a Cu single-atom catalyst supported on ZnO and the elemental mapping spectra of Cu (orange), Zn (red) and O (green). Figure 3 Powder X-ray diffraction pattern of Cu single-atom catalyst supported on ZnO. Figure 4This describes the changes in CO2 conversion and product selectivity over time using the ZnO-supported Cu single-atom catalyst obtained in Example 1 of this invention during CO2 hydrogenation. Figure 4 Based on the selectivity distribution and stability test results, the ZnO-supported Cu single-atom catalyst obtained in this invention exhibits excellent selectivity for methanol in the CO2 hydrogenation reaction, with a selectivity of 73% for methanol at a CO2 conversion rate of 3.3%. During a continuous reaction of 15 hours, the product yield and selectivity remained relatively stable, demonstrating excellent stability.
[0046] Example 2
[0047] A ZnO-supported Cu single-atom catalyst, the catalyst comprising highly dispersed Cu single atoms and ZnO nanorods in the hexagonal wurtzite phase.
[0048] The preparation method of the above-mentioned ZnO-supported Cu single-atom catalyst includes:
[0049] First, 1.6 g of zinc nitrate hexahydrate and 6.5 g of sodium hydroxide were dissolved in 11 mL of deionized water. The resulting solution was stirred for 10 minutes to obtain a clear solution. Next, 105 mL of ethanol and 5.5 mL of ethylenediamine were added to the resulting solution, and the mixture was stirred at room temperature for 24 hours. After centrifugation, the product was washed twice with deionized water and twice with ethanol. The washed sample was dried in a vacuum drying oven at 60 °C for 12 hours, and finally calcined in a muffle furnace at 400 °C for 4 hours to obtain a ZnO support. 2.0 g of ZnO support and 0.1 g of Cu(NO3)2‧3H2O were added to 40 mL of deionized water to obtain a suspension. After sonication for 12 minutes, the resulting mixture was stirred at room temperature for 4 hours to obtain a homogeneous solution. Subsequently, the solution was rotary evaporated at 60 °C, and the resulting solid was calcined in a muffle furnace at 400 °C for 4 hours to obtain a Cu single-atom catalyst with a loading of 1.0 wt% ZnO.
[0050] In the CO2 hydrogenation reaction catalyzed by the ZnO-supported Cu single-atom catalyst of Example 2, the test conditions were as follows:
[0051] The CO2 hydrogenation experiment was conducted in a fixed-bed reactor (Quzhou Wode Instrument Co., Ltd.) at 180℃, with a reaction pressure of 5MPa. The flow rate of the CO2 / H2 feed gas was 10mL / min, and the composition was 96 vol% CO2 / H2 (CO2:H2=3:1) and 4 vol% Ar (as internal standard gas). 2.0 g of 20-40 mesh ZnO-supported Cu single-atom catalyst was placed in the fixed-bed reactor. The quartz tube used had an inner diameter of 9 mm. All products in the reactor were introduced into two gas chromatographs (Shimadzu GC2014) in gaseous state. H2, CO, CO2, and Ar were separated by a carbon molecular sieve column TDX- and analyzed by a thermal conductivity detector (TCD). Methanol was analyzed by a flame ionization detector (FID) through a PONA capillary column.
[0052] Test results showed that when the CO2 conversion rate was 1.5%, the selectivity for methanol was 95%. During the 10-hour continuous reaction, the product yield and selectivity were relatively stable, demonstrating excellent stability.
[0053] Example 3
[0054] A ZnO-supported Cu single-atom catalyst, the catalyst comprising highly dispersed Cu single atoms and ZnO nanorods in the hexagonal wurtzite phase.
[0055] The preparation method of the above-mentioned ZnO-supported Cu single-atom catalyst includes:
[0056] First, 1.5 g of zinc nitrate hexahydrate and 6.0 g of sodium hydroxide were dissolved in 10 mL of deionized water. The resulting solution was stirred for 10 minutes to obtain a clear solution. Next, 100 mL of ethanol and 5.0 mL of ethylenediamine were added to the resulting solution, and the mixture was stirred at room temperature for 24 hours. After centrifugation, the product was washed twice with deionized water and twice with ethanol. The washed sample was dried in a vacuum drying oven at 60 °C for 12 hours, and finally calcined in a muffle furnace at 400 °C for 4 hours to obtain a ZnO support. 2.0 g of ZnO support and 0.01 g of Cu(NO3)2‧3H2O were added to 40 mL of deionized water to obtain a suspension. After sonication for 12 minutes, the resulting mixture was stirred at room temperature for 4 hours to obtain a homogeneous solution. Subsequently, the solution was rotary evaporated at 60 °C, and the resulting solid was calcined in a muffle furnace at 400 °C for 4 hours to obtain a Cu single-atom catalyst with a loading of 0.25 wt% ZnO.
[0057] In the CO2 hydrogenation reaction catalyzed by the ZnO-supported Cu single-atom catalyst of Example 3, the test conditions were as follows:
[0058] The CO2 hydrogenation experiment was conducted in a fixed-bed reactor (Quzhou Wode Instrument Co., Ltd.) at 180℃, with a reaction pressure of 5 MPa. The flow rate of the CO2 / H2 feed gas was 10 mL / min, and the composition was 96 vol% CO2 / H2 (CO2:H2=3:1) and 4 vol% Ar (as internal standard gas). 3.0 g of 20-40 mesh ZnO-supported Cu single-atom catalyst was placed in the fixed-bed reactor. The quartz tube used had an inner diameter of 9 mm. All products in the reactor were introduced into two gas chromatographs (Shimadzu GC2014) in gaseous state. H2, CO, CO2, and Ar were separated by a carbon molecular sieve column TDX- and analyzed by a thermal conductivity detector (TCD). Methanol was analyzed by a flame ionization detector (FID) through a PONA capillary column.
[0059] Test results showed that when the CO2 conversion rate was 1.0%, the selectivity for methanol was 92%. During the 10-hour continuous reaction, the product yield and selectivity were relatively stable, demonstrating excellent stability.
[0060] Comparative Example 1
[0061] In contrast, commercial ZnO nanoparticles (Shanghai Aladdin Biochemical Technology Co., Ltd.) were used as a support to load Cu single atoms, and catalytic tests were conducted.
[0062] A ZnO-supported Cu single-atom catalyst, the catalyst comprising highly dispersed Cu single atoms and commercially available ZnO nanoparticles in the hexagonal wurtzite phase.
[0063] The preparation method of the above-mentioned ZnO-supported Cu single-atom catalyst includes:
[0064] 2.0 g of commercial ZnO support and 0.01 g of Cu(NO3)2‧3H2O were added to 40 mL of deionized water to obtain a suspension. After sonication for 12 minutes, the resulting mixture was stirred at room temperature for 4 hours to obtain a homogeneous solution. Subsequently, the solution was rotary evaporated at 60 °C, and the resulting solid was calcined in a muffle furnace at 400 °C for 4 hours to obtain a Cu single-atom catalyst supported on 0.25 wt% commercial ZnO.
[0065] In the CO2 hydrogenation reaction catalyzed by the commercial ZnO-supported Cu single-atom catalyst of Comparative Example 1, the test conditions were as described in Example 1. The test results showed that when the CO2 conversion rate was 0.9%, the selectivity for methanol was 76.4%. In the continuous reaction, the product yield and selectivity were relatively stable. However, under the same loading conditions, the activity of the commercial ZnO particle-supported Cu single-atom catalyst was far inferior to that of the ZnO-supported Cu single-atom catalyst in Example 1.
[0066] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
[0067] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A ZnO-supported composite material, characterized in that: It includes ZnO nanorods and Cu single atoms loaded on the surface of ZnO nanorods, with the loading amount of Cu single atoms being 0.1~1.0wt%, and the length of ZnO nanorods being 200~300 nm.
2. A method for preparing the ZnO-supported composite material as described in claim 1, characterized in that: Includes the following steps: S1: Zinc nitrate hexahydrate and sodium hydroxide were dissolved in water, ethanol and ethylenediamine were added, the mixture was stirred at room temperature, centrifuged, washed, dried and then calcined to obtain ZnO nanorods; S2: ZnO nanorods and copper source are mixed in water, rotary evaporated, and calcined to obtain ZnO-supported composite material.
3. The method for preparing the ZnO-supported composite material according to claim 2, characterized in that: In step S1, the ratio of zinc nitrate hexahydrate, sodium hydroxide, water, ethanol and ethylenediamine is (1.4~1.6) g : (5.5~6.5) g : (9.0~11.0) mL : (95~105) mL : (4.5~5.5) mL.
4. The method for preparing the ZnO-supported composite material according to claim 2, characterized in that: In step S1, the stirring time at room temperature is 20-30 hours, the drying temperature is 50-80℃, and the drying time is 10-15 hours. During washing, deionized water and ethanol are used to wash twice each.
5. The method for preparing the ZnO-supported composite material according to claim 2, characterized in that: In step S2, the copper source is Cu(NO3)2‧3H2O, and the ratio of ZnO nanorods, copper source and water is (2~3)g:(0.01~0.10)g:(30~50)mL.
6. The method for preparing the ZnO-supported composite material according to claim 2, characterized in that: In step S2, the mixing method is ultrasonication followed by stirring. The ultrasonication time is 10-15 minutes, the stirring time is 3-5 hours, and the rotary evaporation temperature is 50-70℃.
7. The method for preparing the ZnO-supported composite material according to claim 2, characterized in that: In steps S1 and S2, the calcination temperature is 300~500℃ and the time is 3~5h.
8. The application of the ZnO-supported composite material as described in claim 1, characterized in that: ZnO-supported composite materials were used as catalysts for the hydrogenation of CO2 to produce methanol.