A CO 2 Hydrogenation aerogel catalyst and its preparation method and application

Abstract

The present invention provides a preparation method of a CO2 hydrogenation aerogel catalyst, which comprises the following steps: S1: SiO2 fibers prepared by electrospinning are dried, calcined, hydroxylated on the surface of the SiO2 fibers, and then impregnated in a metal salt precursor solution, and high-speed dispersion is carried out by a disperser; S2: The SiO2 fibers loaded with metal salts are freeze-dried and calcined in an N2 atmosphere to obtain a CO2 hydrogenation aerogel catalyst; wherein the metal salt precursor solution contains zirconium salts, zinc salts and copper salts; based on the total weight of the catalyst, the molar ratio of the feed of copper salts, zirconium salts, zinc salts and copper, zirconium, zinc and silicon in the SiO2 fibers is 31:12:5:100. The introduction of transition metal components into the CO2 hydrogenation aerogel catalyst prepared by the present invention can promote the activation of H2, thereby reducing the reaction temperature, avoiding a large amount of by-product carbon monoxide caused by the reverse water gas shift reaction, and thus improving the selectivity of methanol.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a CO 2 Hydrogenation aerogel catalyst, preparation method and application thereof. Background Art

[0002] In recent years, the problem of global warming has become increasingly prominent, mainly due to CO 2 At present, the solution to CO 2 The main emission methods include carbon capture, storage and chemical conversion. 2 Hydrogenation to synthesize methanol is the main means to solve its conversion and utilization. This method not only solves CO 2 The methanol produced is also an important chemical raw material for synthesizing olefins, gasoline, biodiesel, etc., which is of great significance to alleviating fuel shortages.

[0003] For CO 2 The research on hydrogenation to methanol is currently focused on the development of its catalysts. The most widely studied is the CuZnAl catalyst developed by ICI. The improvements to Cu-based catalysts are mainly in the areas of additives, carrier types, morphology control, etc. Patents CN102000578A and CN101386564A add MgO and SiO to the CuZnAl catalyst. 2 Or Mg, Mn, V and other additives to improve the activity and stability of CuZnAl catalyst. CN102716749A introduces additives Zr and Mg into the catalyst to improve CO and CO 2 The conversion rate and selectivity of synthesized methanol. CN104275185A adds additives such as MgO, BaO, La 2 O 3 、CeO 2 , Ga 2 O 3 and ZrO 2 In addition to the above-mentioned metal additives, non-metal additives can also be used for modification, such as [Applied Catalysis A: General, 2013, 468 (12): 442-452.] The CuZnAl catalyst derived from a hydrotalcite precursor was synthesized by coprecipitation. The introduction of modifiers Mn, La, Ce, Zr and Y is beneficial to the production of methanol. The Cu / Zn / Al catalyst modified by Y and Zr has a high CO conversion rate. 2 Conversion rate and CH 3 OH selectivity. However, the above methods cannot fully and effectively utilize the additives embedded in the catalyst.

[0004] Choose a better carrier, such as CN109806878A with anatase TiO 2 The Cu-CeO nanosheets were used as carriers and loaded with metal Cu and metal oxide CeOx by co-precipitation method. x -TiO 2 Nanosheet catalyst has a higher methanol yield. 2 Nanotubes are used as carriers, and one or more of highly dispersed Ir, Rh, Pd, Ru, and Cu are used as active components to construct catalysts. At high space velocity, the carbon dioxide conversion rate is close to the equilibrium conversion rate, and the methanol selectivity is close to 100%. However, under high temperature and pressure, the above catalysts will undergo surface reconstruction and particle growth, thereby reducing catalytic activity and selectivity.

[0005] CN111514938A uses graphene oxide with a high specific surface area as a carrier to form a complex with copper nitrate to enhance interaction, prevent excessive loss of active component copper, and obtain Cu nanoparticles using the confinement effect to further improve the stability and dispersibility of the catalyst, thereby increasing the methanol yield while ensuring high selectivity; since GO has good thermal stability, it can avoid high-temperature carbon deposition and deactivation of the catalyst. However, there are disadvantages such as easy loss of the catalyst and increased pressure drop in the reactor.

[0006] By improving the morphology to improve the catalytic performance, CN105170151A uses Cu as the core and mesoporous SiO 2 As the shell layer, the specific surface area of ​​the catalyst and the dispersion of copper are increased. CN109731578A uses CuIn alloy as the core and porous SiO 2 CuIn@SiO 2 Core-shell structure catalysts have more oxygen vacancies and interface sites. CN105562009A uses urea coprecipitation to prepare a copper-zinc-aluminum catalyst with a layered structure. The copper loss is small and the dispersion is high, which can improve the carbon dioxide conversion rate and methanol selectivity. The catalyst in CN107185543A is a mixture of Cu and filamentous or cylindrical ZnO. ZnO exists in a specific form, has more oxygen vacancies, and has a large surface area of ​​exposed Cu, showing higher methanol synthesis activity. Constructing a stable catalyst is currently CO 2 One of the hot topics in research on hydrogenation to methanol.

[0007] In use, the above-mentioned catalysts have the problem of fragile particles, fine pore structure resulting in poor heat transfer, and difficulty in catalyst regeneration, which reduces the catalyst life. Considering the conversion rate and economy of the catalytic process, SiO 2 The unique material properties of aerogel make it possible to be used as both a catalyst and a catalyst carrier, so the present invention focuses on aerogel catalysts.2 Aerogel is a porous solid material with a unique network structure, whose structural framework is composed of nano-scale solid particles, polymers or a combination of the two. This structure gives it an extremely high specific surface area (≥800m 2 / g,≤1200m 2 / g), extremely high porosity (≥80%).

[0008] In the field of catalysis, transition metals and other catalysts are easily fixed inside aerogels. This discovery has opened up a path for the synthesis of new aerogel catalysts. [Applied Catalysis A General. 2005, 278 (2): 233-238.] 2 The catalytic effect of the catalyst containing cobalt and ruthenium as the carrier of aerogel was evaluated by the Fisher-Trop test. The results showed that SiO 2 The extremely high porosity and specific surface area of ​​aerogels are conducive to H 2 The synthesis methods and performance characteristics of many oxide aerogel catalysts are summarized in [Applied Catalysis. 1991, 72(2): 217-266.], indicating that aerogel catalysts have the characteristics of high efficiency, high selectivity and long life.

[0009] [AcsCatalysis, 2012, 2(8): 1667–1676.] The effect of calcination temperature on the physical and chemical properties of the prepared catalyst was studied. The results showed that the size of the copper particles increased with the increase of calcination temperature, resulting in a decrease in catalytic performance. [AppliedCatalysisBEnvironmental, 2014, s152–153: 152–161.] By studying the effect of the metal / oxide surface ratio on the catalytic performance, it was proved that the high dispersion of copper can reduce the sintering tendency of the catalyst. Large copper specific surface area and copper dispersion can improve the activity of the catalyst; while the copper particle size affects the selectivity of the catalyst, and catalysts with small particle sizes have higher catalytic selectivity. By increasing the specific surface area of ​​the catalyst carrier and increasing the dispersion of the active component copper of the catalyst, the catalytic performance of the catalyst can be improved. Based on the above analysis and summary, high-porosity SiO 2 Nanofiber aerogel becomes a good catalyst carrier material in the present invention.

[0010] The present invention provides a CO 2 A hydrogenation aerogel catalyst and a preparation method and application thereof are used to solve the problems of fragile particles, unsatisfactory mass transfer effect, poor catalyst stability and poor dispersibility existing in Cu-based particle catalysts. Summary of the invention

[0011] In view of the above technical deficiencies, the present invention aims to provide a CO 2 Hydrogenation aerogel catalyst and its preparation method and application, the present invention utilizes SiO 2 Aerogel has the characteristics of high porosity and controllable preparation. 2 Cu, Zn, and Zr nanoparticles are introduced into aerogels to prepare loaded catalysts, which are used to improve the disadvantage of easy agglomeration and inactivation of nanoparticles. 2 Nanofibers were used as building blocks to prepare Cu / Zn / Zr@SiO 2 Nanofiber aerogel catalyst, through the reconstruction of fiber skeleton and the bonding of high-temperature particle fibers, prepares composite nanofiber aerogel with uniform particle dispersion and flexibility, and applies it to catalyze CO 2 Hydrogenation to make it CO 2 The advantages of high conversion rate, high methanol selectivity and low reaction temperature are to improve the stability and dispersibility of the catalyst, while ensuring CO 2 On the basis of selectivity, the methanol yield is improved.

[0012] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0013] The first object of the present invention is to provide a CO 2 The preparation method of hydrogenation aerogel catalyst comprises the following steps: S1, preparing SiO 2 The fiber, after drying and calcination, 2 The fiber surface is hydroxylated, and then immersed in a metal salt precursor solution and dispersed at high speed using a disperser; S2, the SiO2 loaded with metal salt in the above S1 is 2 The fibers were freeze-dried and 2 Calcination treatment under atmosphere to obtain Cu / Zn / Zr@SiO 2 Nanofiber aerogel catalyst; wherein the metal salt precursor solution contains zirconium salt, zinc salt and copper salt; based on the total weight of the catalyst, the copper salt, zirconium salt, zinc salt and SiO 2 The molar ratio of copper, zirconium, zinc and silicon in the fiber is (35-20):(15-5):(10-3):100.

[0014] Preferably, the first object of the present invention is to provide a CO 2 The preparation method of hydrogenation aerogel catalyst comprises the following steps S1, preparing SiO 2 The fiber, after drying and calcination, 2 The fiber surface is hydroxylated, and then immersed in a metal salt precursor solution and dispersed at high speed using a disperser; S2, the SiO2 loaded with metal salt in the above S1 is2 The fibers were freeze-dried and 2 Calcination treatment under atmosphere to obtain Cu / Zn / Zr@SiO 2 Nanofiber aerogel catalyst; wherein the metal salt precursor solution contains zirconium salt, zinc salt and copper salt; based on the total weight of the catalyst, the copper salt, zirconium salt, zinc salt and SiO 2 The molar ratio of copper, zirconium, zinc and silicon in the fiber is 31:12:5:100.

[0015] Preferably, the SiO 2 The fiber is made of tetraethyl orthosilicate, anhydrous ethanol, and 5wt% dilute hydrochloric acid at a temperature of 60-90°C for a reaction time of 0.5-8h, and is hydrolyzed and condensed to form a spinning solution. Then, the electrospinning conditions are as follows: a voltage of 15-22kv, a spinning solution flow rate of 0.3-2.0mL / h, a receiving distance of 10-20cm, a humidity of 35-65%, and a temperature of 15-35°C to form SiO 2 The fiber is dried at 50-100°C for 1-12 hours, calcined at 350-550°C for 1-4 hours, and then added to a mixed solution of 98% concentrated sulfuric acid and 30% hydrogen peroxide for 8-24 hours to make SiO 2 The fiber surface is hydroxylated; wherein the volume ratio of ethyl orthosilicate, anhydrous ethanol, and 5wt% dilute hydrochloric acid is 1:(0.1-1):(0.01-0.1), and the volume ratio of 98% concentrated sulfuric acid (98%) and 30% hydrogen peroxide is 3:1 to 5:1.

[0016] Preferably, the surface hydroxylated SiO 2 The molar ratio of the fiber to the metal salt precursor solution is 1:0.1-0.7, and the immersion time is 1-24 hours.

[0017] Preferably, the zirconium salt, zinc salt and copper salt are one or more of nitrate, sulfate or chloride.

[0018] Preferably, the zirconium salt, zinc salt and copper salt are nitrates, wherein the copper salt is copper nitrate trihydrate Cu(NO 3 ) 2 ·3H 2 O, zinc salt is zinc nitrate Zn(NO 3 ) 2 6H 2 O, zirconium salt is zirconium nitrate pentahydrate Zr(NO 3 ) 4 ·5H 2 O.

[0019] Preferably, the metal salt-loaded SiO 2The fiber is washed 3-5 times with distilled water, transferred to a vial, and frozen with liquid nitrogen or a cold trap, and then freeze-dried using a freeze dryer; wherein the temperature of the liquid nitrogen is -196°C to -50°C, the freezing time is 10-45 minutes, or the temperature of the cold trap is -50°C to -20°C, the freezing time is 6-12 hours, and the working conditions of the freeze dryer are: temperature -50°C to -30°C, pressure 9-15Pa, and time is 36-72 hours.

[0020] Preferably, the N 2 The conditions for atmosphere calcination are: temperature 400-800°C, time 4-12h; the high-speed dispersion conditions are: disperser speed 2000-10000rpm, dispersion time 1-4h.

[0021] A second object of the present invention is to provide CO 2 Cu / Zn / Zr@SiO prepared by the preparation method of hydrogenation aerogel catalyst 2 Nanofiber aerogel catalyst.

[0022] The third object of the present invention is to provide a Cu / Zn / Zr@SiO 2 Nanofiber aerogel catalyst in CO 2 Application in catalytic hydrogenation to produce methanol.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. Cu / Zn / Zr@SiO prepared by the present invention 2 Nanofiber aerogel catalyst can promote H 2 The activation of CO reduces the reaction temperature and avoids the large amount of byproduct carbon monoxide caused by the reverse water gas shift reaction, thereby improving the selectivity of methanol. 2 The single-pass conversion rate can reach 10%, and the methanol selectivity can reach 90%, which is higher than that of commercial Cu / ZnO / Al 2 O 3 Catalytic performance of catalysts.

[0025] 2. Cu / Zn / Zr@SiO prepared by the present invention 2 Nanofiber aerogel catalysts have unique physical and chemical properties of high porosity and high specific surface area, so the reaction gas can enter the aerogel pores unimpeded, allowing the active components to fully contact the reaction gas; and the aerogel is composed of nanoscale skeleton particles, which can fully expose the active components in the skeleton and highly disperse them, which can effectively improve the adsorption efficiency of the active centers and improve the reaction activity.

[0026] 3. The present invention utilizes SiO prepared by electrospinning 2Nanofibers, Cu, Zn and Zr metals were loaded on SiO by sol-gel method. 2 The nanofibers are not easy to break, and after freeze-drying, they form a porous, sponge-like structure with certain compression rebound properties, which is conducive to mass transfer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The Cu / Zn / Zr@SiO prepared by the present invention 2 Optical photograph of nanofiber aerogel catalyst;

[0028] Figure 2 The Cu / Zn / Zr@SiO prepared by the present invention 2 Scanning electron microscopy image of nanofiber aerogel catalyst;

[0029] Figure 3 The Cu / Zn / Zr@SiO prepared by the present invention 2 EDS element distribution diagram of nanofiber aerogel catalyst, where (a) Cu, Zn and Zr elements are loaded on SiO 2 EDS element distribution diagram on nanofibers, (b) Cu element loaded on SiO 2 EDS element distribution diagram on nanofibers, (c) Zn element loaded on SiO 2 EDS element distribution diagram on nanofibers, (d) Zr element loaded on SiO 2 EDS element distribution map on nanofibers;

[0030] Figure 4 The Cu / Zn / Zr@SiO prepared by the present invention 2 BET isotherms of nanofiber aerogel catalyst, where (a) is the nitrogen adsorption / desorption isotherm and (b) is the BJH pore size distribution diagram. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments and drawings.

[0032] In the description of the present invention, unless otherwise specified, all reagents used are commercially available and all methods used are conventional techniques in the art.

[0033] The following is a detailed description of the preferred embodiments of the present invention.

[0034] Example 1

[0035] A CO 2 The preparation method of the hydrogenation aerogel catalyst comprises the following steps:

[0036] (1) Preparation of SiO by electrospinning 2 Fiber, drying, calcination, SiO 2 The fiber surface is hydroxylated, then dispersed at high speed and immersed in a metal salt precursor solution, wherein SiO 2 The fiber was prepared by adding tetraethyl orthosilicate (TEOS), anhydrous ethanol (EtOH) and 5wt% dilute hydrochloric acid in a volume ratio of 20.0:10.3:1.3 into a 150mL round-bottom flask, mixing evenly under magnetic stirring, heating to 80°C, stirring and refluxing for 5h, and cooling to room temperature to obtain a silica sol spinning solution. The spinning solution was transferred to a 10mL syringe for electrospinning to make SiO 2 The electrospinning parameters are as follows: voltage 20±3KV, receiving distance 18cm, ambient temperature 25±3℃, humidity 50±15%, spinning solution flow rate 1.5mL / h, spinning time 5h, and then the prepared SiO 2 The fiber was removed from the aluminum foil and placed in a 90°C oven for 4 h to remove the solvent. 2 The fiber was placed in a muffle furnace and heated to 500°C at a heating rate of 5°C / min, kept at this temperature for 2 h, and then cooled in the furnace. 2 The fibers were cut into 5x5 cm sizes and soaked in piranha solution (the piranha solution consisted of 98% concentrated sulfuric acid and 30% H 2 O 2 The mixture was prepared with a volume ratio of 3:1, soaked for 12 hours, then taken out, washed with distilled water for 3-5 times, and dried in a vacuum oven at 60°C for 24 hours to obtain surface hydroxylated SiO 2 fiber;

[0037] Then weigh 0.6 g of surface hydroxylated SiO 2 The fiber was placed in a 200 mL conical flask, and 100 mL of metal salt precursor solution was added. 2 The molar ratio of the fiber to the metal salt precursor solution is 1:0.48, so the metal precursor includes copper nitrate trihydrate (Cu(NO 3 ) 2 ·3H 2 O) 0.76 g, zirconium nitrate pentahydrate (Zr(NO 3 ) 4 ·5H 2 O) 0.52 g, zinc nitrate (Zn(NO 3 ) 2 6H 2 O) 0.15g, (wherein the molar ratio of copper, zirconium, zinc and silicon is 31:12:5:100), let it stand for 4 hours, and then disperse it with a disperser at 5000rpm for 2 hours.

[0038] (2) SiO2 loaded with metal salt 2 The fibers were freeze-dried and 2 Calcination treatment under atmosphere to obtain CO 2 Hydrogenation aerogel catalyst; wherein the metal salt precursor solution contains zirconium salt, zinc salt and copper salt; based on the total weight of the catalyst, the copper salt, zirconium salt, zinc salt and SiO 2 The molar ratio of copper, zirconium, zinc and silicon in the fiber is 31:12:5:100. 2 The fiber dispersion was transferred to a mold and frozen with liquid nitrogen at a temperature of -80°C for 25 min, and then dried in a vacuum freeze dryer at a temperature of -50°C and a pressure of 9 Pa for 48 h. 2 The Cu / Zn / Zr@SiO 2 Nanofiber aerogel catalysts, such as Figure 1 As shown in the photo, it can be seen that the prepared catalyst has a loose sponge-like structure, which is beneficial to gas mass transfer in the catalytic reaction. Figure 2 As shown in the figure, the prepared Cu / Zn / Zr@SiO 2 The nanofiber aerogel catalyst was tested by scanning electron microscopy (SEM). It can be seen from the figure that Cu, Zn, and Zr are 2 The appearance and distribution of particles on the fiber. From the SEM image, it can be concluded that the metal salt precursor is impregnated and calcined on SiO 2 The successful loading and dispersion on the fiber indicates that Cu / Zn / Zr@SiO 2 Nanofiber aerogel catalyst was successfully prepared; in addition, Figure 3 As shown, the prepared Cu / Zn / Zr@SiO 2 The EDS element distribution analysis of the nanofiber aerogel catalyst was carried out to obtain the Cu / Zn / Zr elements and the Cu, Zn, and Zr elements in the SiO 2 The dispersion and loading of Cu, Zn and Zr on the fiber. From Figure (a), we can see that Cu, Zn and Zr are dispersed in SiO 2 Distribution of Cu, Zn and Zr in the fiber aerogel. Figures (b), (c) and (d) are the distribution of Cu, Zn and Zr in SiO 2 The distribution of Cu, Zn and Zr in the fiber aerogel is shown in green, yellow and red respectively. The number of color points indirectly reflects the amount of each metal loading. Figure (a) shows the distribution of SiO 2 Green, yellow, and red are distributed simultaneously in the fiber aerogel, indicating that Cu / Zn / Zr@SiO 2 Nanofiber aerogel catalyst; e.g. Figure 4 As shown, the prepared Cu / Zn / Zr@SiO 2 The nanofiber aerogel catalyst was analyzed for nitrogen adsorption / desorption isotherms and BJH pore size distribution. (a) is a type II isotherm adsorption curve, reflecting that the catalyst has sub-nanopores. The figure shows that the adsorption amount increases rapidly at a lower pressure, indicating that there is a strong interaction between the adsorbate and the surface, which is beneficial to the adsorption of the reaction gas on the catalyst surface in catalysis; (b) shows that the pore types are mainly micropores and mesopores, with pore sizes of 3-4nm. In the catalytic reaction, the pore size of 2-5nm is beneficial to the diffusion, adsorption and desorption of small molecular gases. The measured BET specific surface area is 71.656m 2 / g, indicating that the catalyst has a large specific surface area, which is conducive to the contact between the active components and the gas. The above characteristics show that the prepared catalyst has a good structure.

[0039] Example 2

[0040] Compared with Example 1, only the surface hydroxylated SiO 2 The molar amount of silicon copper in the metal salt precursor solution in which the fiber is impregnated is different from that in Example 1. The other experimental steps of the preparation method are the same as those in Example 1. Among them, 0.6 g of surface hydroxylated SiO 2 The fiber was placed in a 200 mL conical flask, and 100 mL of metal salt precursor solution was added. 2 The molar ratio of fiber to metal salt precursor solution is 1:0.25, and the zirconium nitrate pentahydrate (Zr(NO 3 ) 4 ·5H 2 O) 0.52 g, zinc nitrate (Zn(NO 3 ) 2 6H 2 O) 0.15 g, copper nitrate trihydrate (Cu(NO 3 ) 2 ·3H 2 O) 0.19g, based on the total weight of the catalyst, the molar ratio of silicon to zirconium is 25:3, and the molar ratio of silicon to zinc is 20:1; and SiO 2 Fiber and copper nitrate trihydrate (Cu(NO 3 ) 2 ·3H 2 The molar ratio of silicon to copper in the reactor is 13:1.

[0041] Example 3

[0042] Compared with Example 1, only the surface hydroxylated SiO 2The molar amount of silicon copper in the metal salt precursor solution in which the fiber is impregnated is different from that in Example 1. The other experimental steps of the preparation method are the same as those in Example 1. Among them, 0.6 g of surface hydroxylated SiO 2 The fiber was placed in a 200 mL conical flask, and 100 mL of metal salt precursor solution was added. 2 The molar ratio of fiber to metal salt precursor solution is 1:0.32, and the zirconium nitrate pentahydrate (Zr(NO 3 ) 4 ·5H 2 O) 0.52 g, zinc nitrate (Zn(NO 3 ) 2 6H 2 O) 0.15 g, copper nitrate trihydrate (Cu(NO 3 ) 2 ·3H 2 O) 0.37g, based on the total weight of the catalyst, the molar ratio of silicon to zirconium is 25:3, and the molar ratio of silicon to zinc is 20:1; and SiO 2 Fiber and copper nitrate trihydrate (Cu(NO 3 ) 2 ·3H 2 The molar ratio of silicon to copper in the reactor is 13:2.

[0043] Example 4

[0044] Compared with Example 1, only the surface hydroxylated SiO 2 The molar amount of silicon copper in the metal salt precursor solution in which the fiber is impregnated is different from that in Example 1. The other experimental steps of the preparation method are the same as those in Example 1. Among them, 0.6 g of surface hydroxylated SiO 2 The fiber was placed in a 200 mL conical flask, and 100 mL of metal salt precursor solution was added. 2 The molar ratio of fiber to metal salt precursor solution is 1:0.40, and the zirconium nitrate pentahydrate (Zr(NO 3 ) 4 ·5H 2 O) 0.52 g, zinc nitrate (Zn(NO 3 ) 2 6H 2 O) 0.15 g, copper nitrate trihydrate (Cu(NO 3 ) 2 ·3H 2 O) 0.56g, based on the total weight of the catalyst, the molar ratio of silicon to zirconium is 25:3, and the molar ratio of silicon to zinc is 20:1; and SiO 2 Fiber and copper nitrate trihydrate (Cu(NO 3 )2 ·3H 2 The molar ratio of silicon to copper in the reactor is 43:10.

[0045] Example 5

[0046] Compared with Example 1, only the surface hydroxylated SiO 2 The molar amount of silicon copper in the metal salt precursor solution in which the fiber is impregnated is different from that in Example 1. The other experimental steps of the preparation method are the same as those in Example 1. Among them, 0.6 g of surface hydroxylated SiO 2 The fiber was placed in a 200 mL conical flask, and 100 mL of metal salt precursor solution was added. 2 The molar ratio of fiber to metal salt precursor solution is 1:0.55, and the zirconium nitrate pentahydrate (Zr(NO 3 ) 4 ·5H 2 O) 0.52 g, zinc nitrate (Zn(NO 3 ) 2 6H 2 O) 0.15 g, copper nitrate trihydrate (Cu(NO 3 ) 2 ·3H 2 O) 0.93g, based on the total weight of the catalyst, the molar ratio of silicon to zirconium is 25:3, and the molar ratio of silicon to zinc is 20:1; and SiO 2 Fiber and copper nitrate trihydrate (Cu(NO 3 ) 2 ·3H 2 The molar ratio of silicon to copper in the reactor is 13:5.

[0047] The Cu / Zn / Zr@SiO prepared in Examples 1 to 5 above 2 Catalytic performance evaluation of nanofiber aerogel catalyst in a fixed bed reactor (length: 300 mm, inner diameter: 10 mm). A quartz plate was placed at the bottom of the reactor and Cu / Zn / Zr@SiO 2 800 mg of nanofiber aerogel catalyst, with appropriate amount of quartz sand on the top. Before the reaction, at 500 ° C, 3 min -1 Flow rate and 1.5℃ min -1 The catalyst was in situ reduced with a nitrogen-diluted hydrogen flow (10 vol%) at a heating rate of 1.5 % and then heated to 40 ℃ under pure N 2 The mixture was cooled to room temperature in an atmosphere and then H2O2 with a feed ratio of 3:1 was introduced. 2 , CO 2 , H 2 and CO 2The gas phase feed rate was 100 mL / min, the reaction temperature was 220° C., and the pressure was 5.0 MPa. The reaction product was detected by gas chromatography, and the results are shown in Table 1.

[0048] Table 1 shows the Cu / Zn / Zr@SiO prepared with different silicon-copper feed molar ratios. 2 Nanofiber aerogel catalyst for CO 2 The effect of hydrogenation reaction.

[0049]

[0050] It can be seen from Table 1 that Cu / Zn / Zr@SiO 2 The nanofiber aerogel catalyst has a stronger effect on CO with the decrease of silicon-copper feed molar ratio, that is, the increase of copper content. 2 The conversion rate and methanol selectivity of the hydrogenation reaction first increased and then decreased. When the molar ratio of silicon to copper was 100:31, CO 2 The conversion rate and methanol selectivity are maximized, so the highly dispersed Cu / Zn / Zr@SiO2 with a molar ratio of 100:31 is preferred. 2 Nanofiber aerogel catalyst.

[0051] Example 6

[0052] Compared with Example 1, only the surface hydroxylated SiO 2 The molar amount of silicon and zinc in the metal salt precursor solution in which the fiber is impregnated is different from that in Example 1. The other experimental steps of the preparation method are the same as those in Example 1. Among them, 0.6 g of surface hydroxylated SiO 2 The fiber was placed in a 200 mL conical flask, and 100 mL of metal salt precursor solution was added. 2 The molar ratio of fiber to metal salt precursor solution is 1:0.44, and the zirconium nitrate pentahydrate Zr(NO 3 ) 4 ·5H 2 O was used in an amount of 0.52 g, copper nitrate trihydrate Cu(NO 3 ) 2 ·3H 2 O was used in an amount of 0.76 g, zinc nitrate (Zn(NO 3 ) 2 6H 2 O) 0.037g, based on the total weight of the catalyst, the molar ratio of silicon to zirconium is 25:3, and the molar ratio of silicon to copper is 100:31; and SiO 2 Fiber and zinc nitrate (Zn(NO 3 ) 2 6H 2 The molar ratio of silicon to zinc in the reaction mixture is 80:1.

[0053] Example 7

[0054] Compared with Example 1, only the surface hydroxylated SiO 2 The molar amount of silicon and zinc in the metal salt precursor solution in which the fiber is impregnated is different from that in Example 1. The other experimental steps of the preparation method are the same as those in Example 1. Among them, 0.6 g of surface hydroxylated SiO 2 The fiber was placed in a 200 mL conical flask, and 100 mL of metal salt precursor solution was added. 2 The molar ratio of fiber to metal salt precursor solution is 1:0.46. The zirconium nitrate pentahydrate Zr(NO 3 ) 4 ·5H 2 O was used in an amount of 0.52 g, copper nitrate trihydrate Cu(NO 3 ) 2 ·3H 2 O was used in an amount of 0.76 g, zinc nitrate (Zn(NO 3 ) 2 6H 2 O) 0.074g, based on the total weight of the catalyst, the molar ratio of silicon to zirconium is 25:3, and the molar ratio of silicon to copper is 100:31; and SiO 2 Fiber and zinc nitrate (Zn(NO 3 ) 2 6H 2 The molar ratio of silicon to zinc in the reaction mixture is 40:1.

[0055] Example 8

[0056] Compared with Example 1, only the surface hydroxylated SiO 2 The molar amount of silicon and zinc in the metal salt precursor solution in which the fiber is impregnated is different from that in Example 1. The other experimental steps of the preparation method are the same as those in Example 1. Among them, 0.6 g of surface hydroxylated SiO 2 The fiber was placed in a 200 mL conical flask, and 100 mL of metal salt precursor solution was added. 2 The molar ratio of fiber to metal salt precursor solution is 1:0.47. The zirconium nitrate pentahydrate Zr(NO 3 ) 4 ·5H 2 O was used in an amount of 0.52 g, copper nitrate trihydrate Cu(NO 3 ) 2 ·3H 2 O was used in an amount of 0.76 g, zinc nitrate (Zn(NO 3 ) 2 6H2 O) 0.11g, based on the total weight of the catalyst, the molar ratio of silicon to zirconium is 25:3, and the molar ratio of silicon to copper is 100:31; and SiO 2 Fiber and zinc nitrate (Zn(NO 3 ) 2 6H 2 The molar ratio of silicon to zinc in the reaction mixture is 80:3.

[0057] Example 9

[0058] Compared with Example 1, only the surface hydroxylated SiO 2 The molar amount of silicon and zinc in the metal salt precursor solution in which the fiber is impregnated is different from that in Example 1. The other experimental steps of the preparation method are the same as those in Example 1. Among them, 0.6 g of surface hydroxylated SiO 2 The fiber was placed in a 200 mL conical flask, and 100 mL of metal salt precursor solution was added. 2 The molar ratio of fiber to metal salt precursor solution is 1:0.49, and the zirconium nitrate pentahydrate Zr(NO 3 )4·5H 2 O was used in an amount of 0.52 g, copper nitrate trihydrate Cu(NO 3 ) 2 ·3H 2 O was used in an amount of 0.76 g, zinc nitrate (Zn(NO 3 ) 2 6H 2 O) 0.186g, based on the total weight of the catalyst, the molar ratio of silicon to zirconium is 25:3, and the molar ratio of silicon to copper is 100:31; and SiO 2 Fiber and zinc nitrate Zn(NO 3 ) 2 6H 2 The molar ratio of silicon to zinc in O is 16:1.

[0059] The Cu / Zn / Zr@SiO prepared in Examples 1 and 6-9 above 2 The catalytic performance of the nanofiber aerogel catalyst was evaluated in a fixed bed reactor (length: 300 mm, inner diameter: 10 mm). A quartz plate was placed at the bottom of the reactor and Cu / Zn / Zr@SiO 2 800 mg of nanofiber aerogel catalyst, with appropriate amount of quartz sand on the top. Before the reaction, 3 min -1 Flow rate and 1.5℃ min -1 The catalyst was in situ reduced with a nitrogen-diluted hydrogen stream (10 vol%) at a heating rate of 1.02 The mixture was cooled to room temperature in an atmosphere and then H2O2 with a feed ratio of 3:1 was introduced. 2 , CO 2 , H 2 and CO 2 The gas phase feed rate was 100 mL / min, the reaction temperature was 220° C., and the pressure was 5.0 MPa. The reaction product was detected by gas chromatography, and the results are shown in Table 2.

[0060] Table 2 Cu / Zn / Zr@SiO prepared with different molar ratios of silicon and zinc 2 Nanofiber aerogel catalyst for CO 2 The effect of hydrogenation reaction.

[0061]

[0062]

[0063] It can be seen from Table 2 that Cu / Zn / Zr@SiO 2 The nanofiber aerogel catalyst has a stronger effect on CO with the decrease of the molar ratio of silicon to zinc, that is, the increase of zinc content. 2 The conversion rate and selectivity of the hydrogenation reaction first increased and then decreased. When the molar ratio of silicon and zinc was 20:1, CO 2 The conversion rate and methanol selectivity are maximized, so the highly dispersed Cu / Zn / Zr@SiO with a molar ratio of 20:1 is preferred. 2 Nanofiber aerogel catalyst.

[0064] Example 10

[0065] Compared with Example 1, only the surface hydroxylated SiO 2 The molar amount of silicon and zinc in the metal salt precursor solution in which the fiber is impregnated is different from that in Example 1. The other experimental steps of the preparation method are the same as those in Example 1. Among them, 0.6 g of surface hydroxylated SiO 2 The fiber was placed in a 200 mL conical flask, and 100 mL of metal salt precursor solution was added. 2 The molar ratio of fiber to metal salt precursor solution is 1:0.4, and the zinc nitrate (Zn(NO 3 ) 2 6H 2 O) were used in an amount of 0.15 g, copper nitrate trihydrate Cu(NO 3 ) 2 ·3H 2 O was used in an amount of 0.76 g, zirconium nitrate pentahydrate Zr(NO 3 )4·5H 2The amount of O used was 0.17 g. Based on the total weight of the catalyst, the molar ratio of silicon-zinc was 20:1, and the molar ratio of silicon-copper was 100:31. 2 Fiber and zirconium nitrate pentahydrate Zr(NO 3 ) 4 ·5H 2 The molar ratio of silicon to zirconium in O is 25:1.

[0066] Embodiment 11

[0067] Compared with Example 1, only the surface hydroxylated SiO 2 The molar amount of silicon and zinc in the metal salt precursor solution in which the fiber is impregnated is different from that in Example 1. The other experimental steps of the preparation method are the same as those in Example 1. Among them, 0.6 g of surface hydroxylated SiO 2 The fiber was placed in a 200 mL conical flask, and 100 mL of metal salt precursor solution was added. 2 The molar ratio of fiber to metal salt precursor solution is 1:0.44, and the zinc nitrate (Zn(NO 3 ) 2 6H 2 O) were used in an amount of 0.15 g, copper nitrate trihydrate Cu(NO 3 ) 2 ·3H 2 O was used in an amount of 0.76 g, zirconium nitrate pentahydrate Zr(NO 3 )4·5H 2 The amount of O used was 0.34 g. Based on the total weight of the catalyst, the molar ratio of silicon-zinc was 20:1, and the molar ratio of silicon-copper was 100:31. 2 Fiber and zirconium nitrate pentahydrate Zr(NO 3 ) 4 ·5H 2 The molar ratio of silicon to zirconium in O is 25:2.

[0068] Example 12

[0069] Compared with Example 1, only the surface hydroxylated SiO 2 The molar amount of silicon and zinc in the metal salt precursor solution in which the fiber is impregnated is different from that in Example 1. The other experimental steps of the preparation method are the same as those in Example 1. Among them, 0.6 g of surface hydroxylated SiO 2 The fiber was placed in a 200 mL conical flask, and 100 mL of metal salt precursor solution was added. 2 The molar ratio of fiber to metal salt precursor solution is 1:0.52, and the zinc nitrate (Zn(NO 3 )2 6H 2 O) were used in an amount of 0.15 g, copper nitrate trihydrate Cu(NO 3 ) 2 ·3H 2 O was used in an amount of 0.76 g, zirconium nitrate pentahydrate Zr(NO 3 )4·5H 2 The amount of O used was 0.69 g. Based on the total weight of the catalyst, the molar ratio of silicon-zinc was 20:1, and the molar ratio of silicon-copper was 100:31. 2 Fiber and zirconium nitrate pentahydrate Zr(NO 3 ) 4 ·5H 2 The molar ratio of silicon to zirconium in O is 25:4.

[0070] Embodiment 13

[0071] Compared with Example 1, only the surface hydroxylated SiO 2 The molar amount of silicon and zinc in the metal salt precursor solution in which the fiber is impregnated is different from that in Example 1. The other experimental steps of the preparation method are the same as those in Example 1. Among them, 0.6 g of surface hydroxylated SiO 2 The fiber was placed in a 200 mL conical flask, and 100 mL of metal salt precursor solution was added. 2 The molar ratio of fiber to metal salt precursor solution is 1:0.56. The zinc nitrate (Zn(NO 3 ) 2 6H 2 O) were used in an amount of 0.15 g, copper nitrate trihydrate Cu(NO 3 ) 2 ·3H 2 O was used in an amount of 0.76 g, zirconium nitrate pentahydrate Zr(NO 3 )4·5H 2 The amount of O used was 0.88 g. Based on the total weight of the catalyst, the molar ratio of silicon-zinc was 20:1, and the molar ratio of silicon-copper was 100:31. 2 Fiber and zirconium nitrate pentahydrate Zr(NO 3 ) 4 ·5H 2 The molar ratio of silicon to zirconium in O is 25:5.

[0072] The Cu / Zn / Zr@SiO prepared in Examples 1 and 10 to 13 above were 2The catalytic performance of the nanofiber aerogel catalyst was evaluated in a fixed bed reactor (length: 300 mm, inner diameter: 10 mm). A quartz plate was placed at the bottom of the reactor and Cu / Zn / Zr@SiO 2 800 mg of nanofiber aerogel catalyst, with appropriate amount of quartz sand on the top. Before the reaction, 3 min -1 Flow rate and 1.5℃ min -1 The catalyst was in situ reduced with a nitrogen-diluted hydrogen stream (10 vol%) at a heating rate of 1.0 2 The mixture was cooled to room temperature in an atmosphere and then H2O2 with a feed ratio of 3:1 was introduced. 2 , CO 2 , H 2 and CO 2 The gas phase feed rate was 100 mL / min, the reaction temperature was 220° C., and the pressure was 5.0 MPa. The reaction product was detected by gas chromatography, and the results are shown in Table 3.

[0073] Table 3 Cu / Zn / Zr@SiO prepared with different Si / Zr feed molar ratios 2 Nanofiber aerogel catalyst for CO 2 The effect of hydrogenation reaction.

[0074]

[0075] It can be seen from Table 3 that Cu / Zn / Zr@SiO 2 The nanofiber aerogel catalyst has a stronger effect on CO with the decrease of the molar ratio of silicon to zirconium, that is, the increase of zirconium content. 2 The conversion rate and selectivity of the hydrogenation reaction first increased and then decreased. When the molar ratio of silicon to zirconium was 25:3, CO 2 The conversion rate and methanol selectivity are maximized, so the highly dispersed Cu / Zn / Zr@SiO with a silicon-zirconium feed molar ratio of 25:3 is preferred. 2 Nanofiber aerogel catalyst.

[0076] Embodiment 14

[0077] Compared with Example 1, Example 14 is different in that the Cu / Zn / Zr@SiO prepared in Example 1 is prepared according to the preparation method given in Example 1. 2 Nanofiber aerogel catalyst for CO 2 The reaction conditions for preparing methanol by catalytic hydrogenation are different. The prepared Cu / Zn / Zr@SiO 2 The catalytic performance of the nanofiber aerogel catalyst was evaluated in a fixed bed reactor (length: 300 mm, inner diameter: 10 mm). A quartz plate was placed at the bottom of the reactor and Cu / Zn / Zr@SiO2 800 mg of nanofiber aerogel catalyst, with appropriate amount of quartz sand on the top. Before the reaction, 3 min -1 flow rate and 1.5℃ min -1 The catalyst was in situ reduced with a nitrogen-diluted hydrogen stream (10 vol%) at a heating rate of 1.0 2 The mixture was cooled to room temperature in an atmosphere and then H2O2 with a feed ratio of 3:1 was introduced. 2 , CO 2 , H 2 and CO 2 The gas phase feed rate was 100 mL / min, the reaction temperature was 180° C., and the pressure was 5.0 MPa. The reaction product was detected by gas chromatography, and the results are shown in Table 4.

[0078] Embodiment 15

[0079] Compared with Example 1, Example 15 is different in that the Cu / Zn / Zr@SiO prepared in Example 14 according to the preparation method given in Example 1 is 2 Nanofiber aerogel catalyst for CO 2 The reaction conditions for preparing methanol by catalytic hydrogenation are different. The prepared Cu / Zn / Zr@SiO 2 The catalytic performance of the nanofiber aerogel catalyst was evaluated in a fixed bed reactor (length: 300 mm, inner diameter: 10 mm). A quartz plate was placed at the bottom of the reactor and Cu / Zn / Zr@SiO 2 800 mg of nanofiber aerogel catalyst, with appropriate amount of quartz sand on the top. Before the reaction, 3 min -1 flow rate and 1.5℃ min -1 The catalyst was in situ reduced with a nitrogen-diluted hydrogen stream (10 vol%) at a heating rate of 1.0 2 The mixture was cooled to room temperature in an atmosphere and then H2O2 with a feed ratio of 3:1 was introduced. 2 , CO 2 , H 2 and CO 2 The gas phase feed rate was 100 mL / min, the reaction temperature was 200° C., and the pressure was 5.0 MPa. The reaction product was detected by gas chromatography, and the results are shown in Table 4.

[0080] Example 16

[0081] Compared with Example 1, Example 16 is different in that the Cu / Zn / Zr@SiO prepared in Example 14 according to the preparation method given in Example 1 is 2 Nanofiber aerogel catalyst for CO2 The reaction conditions for preparing methanol by catalytic hydrogenation are different. The prepared Cu / Zn / Zr@SiO 2 The catalytic performance of the nanofiber aerogel catalyst was evaluated in a fixed bed reactor (length: 300 mm, inner diameter: 10 mm). A quartz plate was placed at the bottom of the reactor and Cu / Zn / Zr@SiO 2 800 mg of nanofiber aerogel catalyst, with appropriate amount of quartz sand on the top. Before the reaction, 3 min -1 Flow rate and 1.5℃ min -1 The catalyst was in situ reduced with a nitrogen-diluted hydrogen stream (10 vol%) at a heating rate of 1.0 2 The mixture was cooled to room temperature in an atmosphere and then H2O2 with a feed ratio of 3:1 was introduced. 2 , CO 2 , H 2 and CO 2 The gas phase feed rate was 100 mL / min, the reaction temperature was 240° C., and the pressure was 5.0 MPa. The reaction product was detected by gas chromatography, and the results are shown in Table 4.

[0082] Table 4 shows the effects of different reaction temperatures on Cu / Zn / Zr@SiO 2 Nanofiber aerogel catalyst in CO 2 Effect of hydrogenation performance.

[0083]

[0084] It can be seen from Table 4 that Cu / Zn / Zr@SiO 2 The nanofiber aerogel catalyst has a higher CO 2 The conversion rate and selectivity of the hydrogenation reaction first increased and then decreased. When the reaction temperature was 220℃, CO 2 The conversion rate and methanol selectivity reach the maximum, so the reaction is preferably carried out at a reaction temperature of 220°C.

[0085] Embodiment 17

[0086] Compared with Example 1, Example 17 is different in that the Cu / Zn / Zr@SiO prepared in Example 14 according to the preparation method given in Example 1 is 2 Nanofiber aerogel catalyst for CO 2 The reaction conditions for preparing methanol by catalytic hydrogenation are different. The prepared Cu / Zn / Zr@SiO 2The catalytic performance of the nanofiber aerogel catalyst was evaluated in a fixed bed reactor (length: 300 mm, inner diameter: 10 mm). A quartz plate was placed at the bottom of the reactor and Cu / Zn / Zr@SiO 2 800 mg of nanofiber aerogel catalyst, with appropriate amount of quartz sand on the top. Before the reaction, 3 min -1 Flow rate and 1.5℃ min -1 The catalyst was in situ reduced with a nitrogen-diluted hydrogen stream (10 vol%) at a heating rate of 1.0 2 The mixture was cooled to room temperature in an atmosphere and then H2O2 with a feed ratio of 3:1 was introduced. 2 , CO 2 , H 2 and CO 2 The gas phase feed rate was 100 mL / min, the reaction temperature was 220° C., and the pressure was 2.0 MPa. The reaction product was detected by gas chromatography, and the results are shown in Table 5.

[0087] Embodiment 18

[0088] Compared with Example 1, Example 18 is different in that the Cu / Zn / Zr@SiO prepared in Example 14 according to the preparation method given in Example 1 is 2 Nanofiber aerogel catalyst for CO 2 The reaction conditions for preparing methanol by catalytic hydrogenation are different. The prepared Cu / Zn / Zr@SiO 2 The catalytic performance of the nanofiber aerogel catalyst was evaluated in a fixed bed reactor (length: 300 mm, inner diameter: 10 mm). A quartz plate was placed at the bottom of the reactor and Cu / Zn / Zr@SiO 2 800 mg of nanofiber aerogel catalyst, with appropriate amount of quartz sand on the top. Before the reaction, 3 min -1 Flow rate and 1.5℃ min -1 The catalyst was in situ reduced with a nitrogen-diluted hydrogen stream (10 vol%) at a heating rate of 1.0 2 The mixture was cooled to room temperature in an atmosphere and then H2O2 with a feed ratio of 3:1 was introduced. 2 , CO 2 , H 2 and CO 2 The gas phase feed rate was 100 mL / min, the reaction temperature was 220°C, and the pressure was 3.0 MPa. The reaction product was detected by gas chromatography, and the results are shown in Table 4.

[0089] Embodiment 19

[0090] Compared with Example 1, Example 19 is different in that the Cu / Zn / Zr@SiO prepared in Example 14 according to the preparation method given in Example 1 is 2 Nanofiber aerogel catalyst for CO 2 The reaction conditions for preparing methanol by catalytic hydrogenation are different. The prepared Cu / Zn / Zr@SiO 2 The catalytic performance of the nanofiber aerogel catalyst was evaluated in a fixed bed reactor (length: 300 mm, inner diameter: 10 mm). A quartz plate was placed at the bottom of the reactor and Cu / Zn / Zr@SiO 2 800 mg of nanofiber aerogel catalyst, with appropriate amount of quartz sand on the top. Before the reaction, 3 min -1 Flow rate and 1.5℃ min -1 The catalyst was in situ reduced with a nitrogen-diluted hydrogen stream (10 vol%) at a heating rate of 1.0 2 The mixture was cooled to room temperature in an atmosphere and then H2O2 with a feed ratio of 3:1 was introduced. 2 , CO 2 , H 2 and CO 2 The gas phase feed rate was 100 mL / min, the reaction temperature was 220° C., and the pressure was 4.0 MPa. The reaction product was detected by gas chromatography, and the results are shown in Table 5.

[0091] Embodiment 20

[0092] Compared with Example 1, Example 20 is different in that the Cu / Zn / Zr@SiO prepared in Example 14 according to the preparation method given in Example 1 is 2 Nanofiber aerogel catalyst for CO 2 The reaction conditions for preparing methanol by catalytic hydrogenation are different. The prepared Cu / Zn / Zr@SiO 2 The catalytic performance of the nanofiber aerogel catalyst was evaluated in a fixed bed reactor (length: 300 mm, inner diameter: 10 mm). A quartz plate was placed at the bottom of the reactor and Cu / Zn / Zr@SiO 2 800 mg of nanofiber aerogel catalyst, with appropriate amount of quartz sand on the top. Before the reaction, 3 min -1 Flow rate and 1.5℃ min -1 The catalyst was in situ reduced with a nitrogen-diluted hydrogen stream (10 vol%) at a heating rate of 1.0 2 The mixture was cooled to room temperature in an atmosphere and then H2O2 with a feed ratio of 3:1 was introduced. 2 , CO 2 , H 2and CO 2 The gas phase feed rate was 100 mL / min, the reaction temperature was 220° C., and the pressure was 5.5 MPa. The reaction product was detected by gas chromatography, and the results are shown in Table 5.

[0093] Table 5 shows the effects of different reaction pressures on Cu / Zn / Zr@SiO 2 Nanofiber aerogel catalyst in CO 2 Effect of hydrogenation performance.

[0094]

[0095] It can be seen from Table 5 that Cu / Zn / Zr@SiO 2 The nanofiber aerogel catalyst has a stronger effect on CO with increasing reaction pressure. 2 The conversion rate of the hydrogenation reaction increased, while the selectivity for methanol first increased and then decreased. At a pressure of 5 MPa, CO 2 The conversion rate and methanol selectivity reach the maximum, so the reaction is preferably carried out at a reaction pressure of 5 MPa.

[0096] Embodiment 21

[0097] Compared with Example 1, Example 21 is different in that the Cu / Zn / Zr@SiO prepared in Example 14 according to the preparation method given in Example 1 is 2 Nanofiber aerogel catalyst for CO 2 The reaction conditions for preparing methanol by catalytic hydrogenation are different. The prepared Cu / Zn / Zr@SiO 2 The catalytic performance of the nanofiber aerogel catalyst was evaluated in a fixed bed reactor (length: 300 mm, inner diameter: 10 mm). A quartz plate was placed at the bottom of the reactor and Cu / Zn / Zr@SiO 2 800 mg of nanofiber aerogel catalyst, with appropriate amount of quartz sand on the top. Before the reaction, 3 min -1 flow rate and 1.5℃ min -1 The catalyst was in situ reduced with a nitrogen-diluted hydrogen stream (10 vol%) at a heating rate of 1.0 2 The mixture was cooled to room temperature in an atmosphere and then H2O2 with a feed ratio of 1:1 was introduced. 2 , CO 2 , H 2 and CO 2 The gas phase feed rate was 100 mL / min, the reaction temperature was 220° C., and the pressure was 5.0 MPa. The reaction product was detected by gas chromatography, and the results are shown in Table 6.

[0098] Embodiment 22

[0099] Compared with Example 1, Example 22 is different in that the Cu / Zn / Zr@SiO prepared in Example 14 according to the preparation method given in Example 1 is 2 Nanofiber aerogel catalyst for CO 2 The reaction conditions for preparing methanol by catalytic hydrogenation are different. The prepared Cu / Zn / Zr@SiO 2 The catalytic performance of the nanofiber aerogel catalyst was evaluated in a fixed bed reactor (length: 300 mm, inner diameter: 10 mm). A quartz plate was placed at the bottom of the reactor and Cu / Zn / Zr@SiO 2 800 mg of nanofiber aerogel catalyst, with appropriate amount of quartz sand on the top. Before the reaction, 3 min -1 Flow rate and 1.5℃ min -1 The catalyst was in situ reduced with a nitrogen-diluted hydrogen stream (10 vol%) at a heating rate of 1.0 2 The mixture was cooled to room temperature in an atmosphere and then H2O2 with a feed ratio of 2:1 was introduced. 2 , CO 2 , H 2 and CO 2 The gas phase feed rate was 100 mL / min, the reaction temperature was 220° C., and the pressure was 5.5 MPa. The reaction product was detected by gas chromatography, and the results are shown in Table 6.

[0100] Embodiment 23

[0101] Compared with Example 1, Example 23 is different in that the Cu / Zn / Zr@SiO prepared in Example 14 according to the preparation method given in Example 1 is 2 Nanofiber aerogel catalyst for CO 2 The reaction conditions for preparing methanol by catalytic hydrogenation are different. The prepared Cu / Zn / Zr@SiO 2 The catalytic performance of the nanofiber aerogel catalyst was evaluated in a fixed bed reactor (length: 300 mm, inner diameter: 10 mm). A quartz plate was placed at the bottom of the reactor and Cu / Zn / Zr@SiO 2 800 mg of nanofiber aerogel catalyst, with appropriate amount of quartz sand on the top. Before the reaction, 3 min -1 Flow rate and 1.5℃ min -1 The catalyst was in situ reduced with a nitrogen-diluted hydrogen stream (10 vol%) at a heating rate of 1.0 2 The mixture was cooled to room temperature in an atmosphere and then H2O2 with a feed ratio of 4:1 was introduced. 2 , CO 2 , H2 and CO 2 The gas phase feed rate was 100 mL / min, the reaction temperature was 220° C., and the pressure was 5.5 MPa. The reaction product was detected by gas chromatography, and the results are shown in Table 6.

[0102] Table 6 shows the different H 2 , CO 2 Feed ratio Cu / Zn / Zr@SiO 2 Nanofiber aerogel catalyst in CO 2 Effect of hydrogenation performance.

[0103]

[0104] It can be seen from Table 6 that Cu / Zn / Zr@SiO 2 Nanofiber aerogel catalyst with H 2 , CO 2 The increase of feed ratio has a significant effect on CO 2 The conversion rate of the hydrogenation reaction increases, while the selectivity of methanol increases first and then decreases. 2 , CO 2 When the feed ratio is 3:1, CO 2 The conversion rate and methanol selectivity are maximized, so H 2 , CO 2 The reaction was carried out at a feed ratio of 3:1.

[0105] Comparative Example 1

[0106] The existing technology uses Cu / ZnO / Al 2 O 3 Catalyst, measured in CO 2 Application of catalytic hydrogenation to produce methanol 2 Effect of hydrogenation performance.

[0107] The catalyst preparation method is as follows: Gao, P. et al. Yttrium oxide modified Cu / ZnO / Al2O3catalysts via hydrotalcite-like precursors for CO 2 Hydrogenation of tomethanol. Catal. Sci. Technol. 5, 4365-4377 (2015).

[0108] The catalysts prepared in Comparative Example 1 and Example 1 were added to a fixed bed reactor (length: 300 mm, inner diameter: 10 mm) to evaluate their catalytic performance. A quartz plate was placed at the bottom of the reactor, and 800 mg of Cu / Zn / Zr@SiO 2 Nanofiber aerogel catalyst or Cu / ZnO / Al 2 O 3 Catalyst, with appropriate amount of quartz sand on the top. Before the reaction, at 500℃, 3 min -1 Flow rate and 1.5℃ min -1 The catalyst was in situ reduced with a nitrogen-diluted hydrogen flow (10 vol%) at a heating rate of 1.5 % and then heated to 40 ℃ under pure N 2 The mixture was cooled to room temperature in an atmosphere and then H2O2 with a feed ratio of 3:1 was introduced. 2 , CO 2 , H 2 and CO 2 The gas phase feed rate was 100 mL / min, the reaction temperature was 220°C, and the pressure was 5.0 MPa. The reaction products were detected by gas chromatography, the detectors were hydrogen flame ionization detector (FID) and thermal conductivity detector (TCD), the chromatographic columns used were KB-Wax (30 m) and TDX-01 (1 m), respectively, and the results are shown in Table 7.

[0109] Table 7 shows the different catalysts under the same CO 2 Application of catalytic hydrogenation to produce methanol 2 Effect of hydrogenation performance.

[0110]

[0111]

[0112] It can be seen from Table 7 that the Cu / Zn / Zr@SiO prepared by the present invention 2 Nanofiber aerogel catalyst and Cu / ZnO / Al given in Comparative Example 1 2 O 3 Compared with the catalyst, Cu / Zn / Zr@SiO 2 Nanofiber aerogel catalyst can promote H 2 The activation of the reaction temperature is reduced, and a large amount of byproduct CO caused by the reverse water gas shift reaction is avoided. The yield and selectivity of CO in Example 1 are lower than those of CO in Comparative Example 1, thereby improving the selectivity and yield of methanol. That is, the yield of methanol in Example 1 is 8.9%, which is greater than the yield of methanol in Comparative Example 1 of 7.79%. The selectivity of methanol in Example 1 is 89%, which is much higher than the selectivity of methanol in Comparative Example 1 of 58.1%. And the CO in Example 1 is2 The single-pass conversion rate can reach 10%, and the methanol selectivity of Example 1 can reach 90%, which is higher than that of commercial Cu / ZnO / Al 2 O 3 Catalytic performance of catalysts.

[0113] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A CO 2 Preparation method of hydrogenation aerogel catalyst, It is characterized in that The steps include: S1. SiO prepared by electrospinning 2 The fiber, after drying and calcination, 2 The fiber surface is hydroxylated, then immersed in a metal salt precursor solution, and dispersed at high speed using a disperser; S2, then the SiO2 loaded with metal salt in S1 2 The fibers were freeze-dried and 2 Calcination treatment under atmosphere to obtain Cu / Zn / Zr@SiO 2 Nanofiber aerogel catalyst; The metal salt precursor solution contains zirconium salt, zinc salt and copper salt; based on the total weight of the catalyst, the copper salt, zirconium salt, zinc salt and SiO 2 The molar ratio of copper, zirconium, zinc and silicon in the fiber is 35-20:15-5:10-3:100; The SiO 2 The fiber is made of tetraethyl orthosilicate, anhydrous ethanol, and 5wt% dilute hydrochloric acid at a temperature of 60-90°C for a reaction time of 0.5-8h, and then subjected to electrospinning conditions of voltage 15-22kv, spinning solution flow rate 0.3-2.0mL / h, receiving distance 10-20cm, humidity 35-65%, temperature 15-35°C to make SiO 2 The fiber is dried at 50-100°C for 1-12 hours, calcined at 350-550°C for 1-4 hours, and then added to a mixed solution of 98% concentrated sulfuric acid and 30% hydrogen peroxide for 8-24 hours to make SiO 2 Fiber surface hydroxylation; The volume ratio of ethyl orthosilicate, anhydrous ethanol and 5wt% dilute hydrochloric acid is 1:0.1-1:0.01-0.1, and the volume ratio of 98% concentrated sulfuric acid and 30% hydrogen peroxide is 3-5:

1.

2. A CO according to claim 1 2 Preparation method of hydrogenation aerogel catalyst, It is characterized in that The copper salt, zirconium salt, zinc salt and SiO 2 The molar ratio of copper, zirconium, zinc and silicon in the fiber is 31:12:5:

100.

3. A CO according to claim 1 2 Preparation method of hydrogenation aerogel catalyst, It is characterized in that The zirconium salt, zinc salt and copper salt are one or more of nitrate, sulfate or chloride.

4. A CO according to claim 3 2 Preparation method of hydrogenation aerogel catalyst, It is characterized in that The zirconium salt, zinc salt and copper salt are nitrates, wherein the copper salt is copper nitrate trihydrate Cu (NO 3 ) 2 ·3H 2 O, zinc salt is zinc nitrate Zn(NO 3 ) 2 6H 2 O, zirconium salt is zirconium nitrate pentahydrate Zr(NO 3 ) 4 ·5H 2 O.

5. A CO according to claim 4 2 Preparation method of hydrogenation aerogel catalyst, It is characterized in that Metal salt loaded SiO 2 The fiber is washed 3-5 times with distilled water, transferred to a vial, and frozen with liquid nitrogen or a cold trap, and then freeze-dried using a freeze dryer; wherein the temperature of the liquid nitrogen is -196°C to -50°C, the freezing time is 10-45 minutes, or the temperature of the cold trap is -50°C to -20°C, the freezing time is 6-12 hours, and the working conditions of the freeze dryer are: temperature -50°C to -30°C, pressure 9-15Pa, and time is 36-72 hours.

6. A CO according to claim 1 2 Preparation method of hydrogenation aerogel catalyst, It is characterized in that The N 2 The conditions for calcination under atmosphere are: temperature 400-800° C., time 4-12 h; the conditions for high-speed dispersion are: disperser speed 2000-10000 rpm, dispersion time 1-4 h.

7. The CO according to any one of claims 1 to 6 2 Cu / Zn / Zr@SiO prepared by the preparation method of hydrogenation aerogel catalyst 2 Nanofiber aerogel catalyst.

8. The Cu / Zn / Zr@SiO according to claim 7 2 Nanofiber aerogel catalyst in CO 2 Application in catalytic hydrogenation to produce methanol.

Images