Precious metal catalyst and preparation method thereof

Abstract

The invention provides a noble metal catalyst and a preparation method thereof, and belongs to the technical field of catalytic material preparation. According to the noble metal catalyst provided by the invention, cerium dioxide is used as a carrier, and the oxidation-reduction cycle between the noble metal active component and the carrier is enhanced by utilizing the unique oxygen storage and release capacity of cerium dioxide; by adding the auxiliary metal and utilizing the interaction between the auxiliary metal and the noble metal active component, the chemical state of the noble metal is adjusted, the strong adsorption effect of the noble metal on CO is promoted, and the selectivity and conversion efficiency of the catalyst are improved; the noble metal active component is directly anchored on the surface of the cerium dioxide carrier, so that the specific surface area of the catalyst can be increased, more active sites are exposed, and the low-temperature activity of the catalyst is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic material preparation, and in particular relates to a noble metal catalyst and a preparation method thereof. Background Art

[0002] In recent years, environmental and energy issues have become increasingly prominent. Hydrogen-fuel cell technology has been widely used because of its high energy conversion efficiency and pollution-free. The current hydrogen source of proton exchange membrane fuel cells (PEMFC) mainly comes from the reforming reaction of hydrocarbons. China is the world's largest methanol producer, and China's methanol production accounts for 60% of the world's methanol production. Methanol is abundant in source, low in cost, and is a liquid at room temperature and pressure, which is convenient for storage and transportation. Compared with other methods of industrial hydrogen production, methanol hydrogen production has lower energy consumption and cost. In addition to H2 and CO2, there are trace amounts of CO in the methanol reforming product, and CO can cause poisoning and inactivation of the Pt / C electrode in PEMFC. The national standard GB / T 37244-2018 requires that the CO content in H2 used for PEMFC should be less than 0.2×10 -6 .

[0003] How to reduce the CO content in methanol reforming reaction gas to 0.2×10 -6 The following are key issues in the practical application of hydrogen-fuel cell systems. At the same time, the operating temperature of the fuel cell is between 20 and 100°C. The lower CO removal temperature and wider CO complete conversion range can enable the hydrogen-fuel cell system to better cope with cold start and dynamic conditions.

[0004] The CO preferential oxidation (CO-PROX) process, which has the advantages of low cost, no significant consumption of H2, simple operation and easy implementation, has become the most feasible method for removing CO from hydrogen-rich gas. The performance of the catalyst in the CO-PROX reaction directly determines the efficiency and life of the hydrogen energy-fuel cell. Currently, the commonly used CO removal catalysts are mainly precious metals and non-precious metals. Non-precious metal catalysts have the advantage of low price, but their performance in reformed gas with a CO2 content of 25% is poor, deactivation is serious, and the reaction temperature is high, which cannot effectively solve the system cold start requirements. Precious metal catalysts have excellent performance, but to reduce the CO content in the reformed gas to below 0.2ppm, a higher precious metal loading is required, such as the Pt loading of 1.4wt% in PtFe / CeO2 prepared by Rodolfo M. Antoniassi et al. Summary of the invention

[0005] The object of the present invention is to provide a precious metal catalyst for removing carbon monoxide from methanol reforming gas and a preparation method thereof. The precious metal catalyst provided by the present invention can reduce the CO content in methanol reforming gas to below 0.2 ppm at a low precious metal loading.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a noble metal catalyst for removing carbon monoxide from methanol reforming gas, comprising a cerium dioxide carrier, a noble metal active component anchored and loaded on the surface of the cerium dioxide carrier, and an auxiliary metal doped in the noble metal active component, wherein the molar ratio of the noble metal active component, the auxiliary metal and the cerium dioxide carrier is (0.002-0.003):(0.008-0.056):1; the auxiliary metal comprises any one of copper, zinc, manganese, iron, cobalt and nickel.

[0007] Preferably, the noble metal in the noble metal active component includes any one of Au, Pt and Pd.

[0008] Preferably, the ceria carrier is rod-shaped ceria.

[0009] Preferably, the diameter of the rod-shaped cerium dioxide is 5-10 nm, and the length of the rod-shaped cerium dioxide is 50-200 nm.

[0010] The present invention also provides a method for preparing the noble metal catalyst described in the above technical solution, comprising the following steps: (1) immersing the cerium dioxide support in a mixed solution of a noble metal salt and an auxiliary metal salt to perform ion exchange to obtain a slurry; (2) mixing the slurry obtained in step (1) with an alkali solution for auxiliary impregnation and then filtering to obtain an intermediate; (3) calcining the intermediate obtained in step (2) to obtain a noble metal catalyst.

[0011] Preferably, the temperature of the ion exchange in step (1) is 60-80° C., and the time of the ion exchange is 1.5-2.5 h.

[0012] Preferably, the concentration of the alkali solution in step (2) is 0.5-1 mol / L.

[0013] Preferably, the auxiliary impregnation time in step (2) is 8 to 12 minutes.

[0014] Preferably, the calcination temperature in step (3) is 150-750° C., and the calcination time is 1-3 hours.

[0015] The present invention provides a noble metal catalyst for removing carbon monoxide from methanol reforming gas, comprising a ceria carrier, a noble metal active component loaded on the surface of the ceria carrier, and an auxiliary metal doped in the noble metal active component, wherein the molar ratio of the noble metal active component, the auxiliary metal and the ceria carrier is (0.002~0.003):(0.008~0.056):1; the auxiliary metal comprises any one of copper, zinc, manganese, iron, cobalt and nickel. The present invention uses ceria as a carrier, and utilizes its unique oxygen storage and release capacity to strengthen the redox cycle between the noble metal active component and the carrier; utilizes the interaction between the auxiliary metal and the noble metal active component to adjust the chemical state of the noble metal, promote the strong adsorption of the noble metal on CO, and improve the selectivity and conversion efficiency of the catalyst; the noble metal active component is directly anchored on the surface of the ceria carrier, which can increase the specific surface area of ​​the catalyst, expose more active sites, and improve the low-temperature activity of the catalyst. The results of the examples show that the noble metal catalyst provided by the present invention can reduce the carbon monoxide content in the methanol reforming gas to below 0.2 ppm at 90°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a TEM image of the noble metal catalyst prepared in Example 1 of the present invention, magnified 100,000 times; Figure 2 This is a TEM image of the noble metal catalyst prepared in Example 1 of the present invention magnified 1,000,000 times; Figure 3 The XPS graphs of the noble metal catalyst prepared in Example 1 of the present invention and the catalysts prepared in Comparative Examples 1 to 3 are shown. DETAILED DESCRIPTION

[0017] All raw materials of the present invention have no particular limitation on their sources and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0018] There is no particular limitation on the purity of all raw materials in the present invention. The present invention preferably uses analytically pure raw materials or raw materials with a purity commonly used in the field of catalyst preparation.

[0019] The present invention provides a noble metal catalyst for removing carbon monoxide from methanol reforming gas, comprising a cerium dioxide carrier, a noble metal active component anchored and loaded on the surface of the cerium dioxide carrier, and an auxiliary metal doped in the noble metal active component, wherein the molar ratio of the noble metal active component, the auxiliary metal and the cerium dioxide carrier is (0.002-0.003):(0.008-0.056):1; the auxiliary metal comprises any one of copper, zinc, manganese, iron, cobalt and nickel.

[0020] The noble metal catalyst provided by the present invention comprises a ceria carrier.

[0021] In the present invention, the ceria carrier is preferably rod-shaped ceria. The ceria carrier has a unique oxygen storage and release capacity, which can improve the redox cycle between the noble metal active component and the carrier; rod-shaped ceria is conducive to further improving the catalytic activity of the catalyst.

[0022] In the present invention, the diameter of the rod-shaped ceria is preferably 5-10 nm, more preferably 6-8 nm; as an embodiment of the present invention, the diameter of the rod-shaped ceria can be 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm. The diameter of the rod-shaped ceria is within the above range, which is conducive to further improving the catalytic activity of the catalyst.

[0023] In the present invention, the length of the rod-shaped ceria is preferably 50-200 nm, more preferably 100-150 nm; as an embodiment of the present invention, the length of the rod-shaped ceria can be 60 nm, 70 nm, 80 nm, 90 nm, 110 nm, 130 nm, 160 nm or 180 nm. The length of the rod-shaped ceria within the above range is conducive to further improving the catalytic activity of the catalyst.

[0024] The present invention has no particular limitation on the preparation method of the cerium dioxide carrier, and the conventional preparation method of rod-shaped cerium dioxide in the art can be used. As an embodiment of the present invention, the rod-shaped cerium dioxide is prepared by a precipitation method, including: adding a cerium nitrate solution dropwise into a sodium hydroxide solution, and then performing a hydrothermal reaction to obtain an intermediate; and calcining the intermediate to obtain a rod-shaped cerium dioxide. As an embodiment of the present invention, the molar ratio of cerium nitrate in the cerium nitrate solution to sodium hydroxide in the sodium hydroxide solution can be 1:(100~140) or 1:(110~130); the concentration of the cerium nitrate solution can be 0.3~0.5 mol / L, and the concentration of the sodium hydroxide solution can be 6~7 mol / L; during the process of adding the cerium nitrate solution dropwise into the sodium hydroxide solution, the cerium nitrate solution can be continuously stirred; the reaction device for the hydrothermal reaction can be a polytetrafluoroethylene-lined autoclave; the temperature of the hydrothermal reaction can be 80~120°C, and the time of the hydrothermal reaction can be 12~36h; after the hydrothermal reaction is completed, the solid product can be dried, the drying temperature can be 60~80°C, the drying time can be 8~12h, and the drying device can be a blast drying oven; the roasting is carried out in an air atmosphere, the roasting temperature can be 300~500°C, the roasting time can be 180~300min, and the roasting can be carried out in a muffle furnace.

[0025] The noble metal catalyst provided by the present invention also includes a noble metal active component anchored and loaded on the surface of the ceria carrier.

[0026] In the present invention, the noble metal in the noble metal active component preferably includes any one of Au, Pt and Pd, and more preferably Pt. The noble metals of the above types have better catalytic activity, which is conducive to further improving the catalytic activity of the catalyst. In the present invention, the noble metal active component is preferably an oxide of a noble metal.

[0027] In the present invention, the noble metal active component is anchored and loaded on the surface of the ceria carrier, which can increase the specific surface area of ​​the catalyst, expose more active sites, and improve the catalytic activity of the catalyst.

[0028] The noble metal catalyst provided by the present invention further comprises a promoter metal doped in the noble metal active component.

[0029] In the present invention, the auxiliary metal includes any one of copper, zinc, manganese, iron, cobalt and nickel, preferably copper. In the present invention, during the use of the noble metal catalyst, the auxiliary metal can interact with the noble metal active component to adjust the chemical state of the noble metal, promote the strong adsorption of CO by the noble metal, and improve the selectivity and conversion efficiency of the catalyst.

[0030] In the present invention, the auxiliary metal is doped in the noble metal active component, so that the auxiliary metal and the noble metal active component can be more fully contacted, thereby improving the catalytic activity of the noble metal active component.

[0031] In the present invention, the ratio of the amount of the noble metal active component, the auxiliary metal and the ceria carrier is (0.002-0.003): (0.008-0.056): 1, preferably 0.0026: (0.008-0.056): 1, and more preferably 0.0026: (0.008-0.026): 1. As an embodiment of the present invention, the ratio of the amount of the noble metal active component, the auxiliary metal and the ceria carrier can be 0.0026: 0.008: 1, 0.0026: 0.013: 1, 0.0026: 0.024: 1, 0.0026: 0.0375: 1 or 0.0026: 0.0525: 1. When the ratio of the amount of the noble metal active component, the auxiliary metal and the ceria carrier is within the above range, the effect of each component can be fully exerted, so that the catalyst has excellent catalytic activity.

[0032] The present invention uses cerium dioxide as a carrier and utilizes its unique oxygen storage and release capacity to strengthen the redox cycle between the noble metal active component and the carrier; by adding an auxiliary metal and utilizing the interaction between the auxiliary metal and the noble metal active component, the chemical state of the noble metal is adjusted, the strong adsorption of CO by the noble metal is promoted, and the selectivity and conversion efficiency of the catalyst are improved; the noble metal active component is directly anchored on the surface of the cerium dioxide carrier, which can increase the specific surface area of ​​the catalyst, expose more active sites, and improve the low-temperature activity of the catalyst.

[0033] The present invention also provides a method for preparing the noble metal catalyst described in the above technical solution, comprising the following steps: (1) immersing the cerium dioxide support in a mixed solution of a noble metal salt and an auxiliary metal salt to perform ion exchange to obtain a slurry; (2) mixing the slurry obtained in step (1) with an alkali solution for auxiliary impregnation and then filtering to obtain an intermediate; (3) calcining the intermediate obtained in step (2) to obtain a noble metal catalyst.

[0034] The invention immerses the cerium dioxide carrier into a mixed solution of a noble metal salt and an auxiliary metal salt to perform ion exchange to obtain a slurry.

[0035] The present invention has no particular requirements on the specific type of the noble metal salt, and the conventional noble metal salts in the art can be used. As an embodiment of the present invention, the noble metal salt can be chloroplatinic acid, sodium chloropalladate or chloroauric acid.

[0036] The present invention has no particular requirements on the specific type of the auxiliary metal salt, and conventional auxiliary metal salts in the art can be used. As an embodiment of the present invention, the auxiliary metal salt can be manganese nitrate, iron nitrate, cobalt nitrate, nickel nitrate, copper nitrate or zinc nitrate.

[0037] As an embodiment of the present invention, the concentration of the noble metal salt in the mixed solution may be 1-6 g / L, and the concentration of the auxiliary metal salt may be 1-24 g / L. In an embodiment of the present invention, the molar ratio of the noble metal salt to the auxiliary metal salt in the mixed solution is 1:3, 1:5, 1:9, 1:15 or 1:21.

[0038] As an embodiment of the present invention, a noble metal salt solution and an auxiliary metal salt solution may be mixed to obtain a mixed solution of the noble metal salt and the auxiliary metal salt.

[0039] The present invention does not particularly limit the specific method of immersing the ceria carrier in the mixed solution of the noble metal salt and the auxiliary metal salt, and the operation method familiar to those skilled in the art can be adopted. As an embodiment of the present invention, the ceria carrier is first immersed in deionized water, stirred evenly and then ultrasonicated for 5 minutes to obtain a ceria slurry, and then the mixed solution of the noble metal salt and the auxiliary metal salt is added dropwise to the ceria slurry.

[0040] In the present invention, the ion exchange temperature is preferably 60-80° C., more preferably 65-75° C.; as an embodiment of the present invention, the ion exchange temperature may be 62° C., 64° C., 68° C., 70° C., 72° C., 76° C. or 78° C. The ion exchange temperature within the above range is conducive to uniform loading of the noble metal active components and the auxiliary metal on the surface of the ceria carrier.

[0041] In the present invention, the ion exchange time is preferably 1.5 to 2.5 hours, more preferably 1.8 to 2.2 hours; as an embodiment of the present invention, the ion exchange time can be 1.6 hours, 1.7 hours, 1.9 hours, 2 hours, 2.1 hours, 2.3 hours or 2.4 hours. The ion exchange time within the above range is conducive to increasing the sufficient loading of the noble metal active components and the auxiliary metal on the surface of the ceria carrier.

[0042] In the present invention, the ion exchange is preferably carried out under stirring conditions. The present invention has no particular limitation on the specific parameters of the stirring, as long as the materials can be fully mixed. In an embodiment of the present invention, the stirring speed is 350 r / min.

[0043] After obtaining the slurry, the present invention mixes the slurry with an alkali solution for auxiliary impregnation and then filters to obtain an intermediate.

[0044] In the present invention, the alkali solution is preferably an aqueous solution of sodium hydroxide, ammonia or sodium carbonate. The use of the above alkali solution is conducive to the formation of hydroxides of the noble metal active components on the surface of the ceria support, thereby more effectively loading, and is also conducive to removing chloride ions introduced by the raw materials to avoid the catalyst active components being coated by chloride ions.

[0045] In the present invention, the concentration of the alkali solution is preferably 0.5-1 mol / L, more preferably 0.7-0.8 mol / L; as an embodiment of the present invention, the concentration of the alkali solution can be 0.55 mol / L, 0.65 mol / L, 0.75 mol / L, 0.85 mol / L or 0.95 mol / L. The concentration of the alkali solution within the above range is conducive to improving the effect of auxiliary impregnation and improving the structural stability of the catalyst.

[0046] In the present invention, the auxiliary impregnation time is preferably 8 to 12 minutes; as an embodiment of the present invention, the auxiliary impregnation time can be 8 minutes, 9 minutes, 10 minutes, 11 minutes or 12 minutes. The auxiliary impregnation time within the above range is conducive to adjusting the chemical state of each metal element, enhancing the interaction between the components, and further improving the catalytic activity of the catalyst.

[0047] The present invention has no particular limitation on the specific method of the filtration, and any conventional method in the art may be used. In an embodiment of the present invention, the filtration method is suction filtration.

[0048] After the filtration is completed, the present invention preferably washes the filtered solid to neutrality, then dries and grinds it to obtain an intermediate. As an embodiment of the present invention, the washing includes sequentially washing with water and washing with ethanol; the drying can be dried at 60° C. for 8 hours. The present invention has no particular limitation on the specific operation of the grinding, as long as the intermediate can be ground into powder.

[0049] After obtaining the intermediate, the present invention calcines the intermediate to obtain a noble metal catalyst.

[0050] In the present invention, the calcination temperature is preferably 150-750° C., more preferably 400-700° C., and further preferably 500-600° C. As an embodiment of the present invention, the calcination temperature may be 200° C., 300° C., 350° C., 450° C., 550° C., 580° C., 650° C. or 700° C. The calcination temperature within the above range is conducive to further improving the selectivity and conversion rate of the catalyst for CO.

[0051] In the present invention, the calcination time is preferably 1-3 hours, more preferably 1.5-2.5 hours; as an embodiment of the present invention, the calcination time can be 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours or 2.8 hours. The calcination time within the above range is conducive to further improving the selectivity and conversion rate of the catalyst for CO.

[0052] The present invention has no particular limitation on the calcination device, and any conventional calcination device in the art may be used. In an embodiment of the present invention, the calcination is performed in a muffle furnace.

[0053] The present invention has no particular limitation on the cooling method after calcination, and conventional cooling methods in the art may be used. In the embodiments of the present invention, the calcination is followed by natural cooling to room temperature.

[0054] The ion exchange of the present invention exchanges the cations on the surface of the ceria carrier and replaces them with precious metal ions, thereby realizing the loading of the precious metal on the carrier surface; through the auxiliary impregnation of alkaline solution, the precious metal active components can be anchored on the surface of the ceria carrier before calcination, thereby achieving the effect of increasing the specific surface area of ​​the catalyst, exposing more active sites, and effectively improving the low-temperature activity of the catalyst; in addition, the auxiliary impregnation can also effectively remove the chloride ions brought by the precious metal chlorate, thereby avoiding the poisoning effect of the chloride ions on the precious metal active components.

[0055] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] Example 1 A noble metal catalyst for removing carbon monoxide from methanol reforming gas comprises a ceria carrier, platinum oxide anchored on the surface of the ceria carrier, and copper oxide doped in the platinum oxide, wherein the molar ratio of platinum, copper and ceria carrier is 0.0026:0.024:1.

[0057] The preparation method of the noble metal catalyst is as follows: (1) Preparation of cerium dioxide carrier: Dissolve hexahydrated cerium nitrate and sodium hydroxide in deionized water at a molar ratio of 1:120 to obtain a clear solution; add the obtained cerium nitrate solution dropwise into the sodium hydroxide solution under constant stirring, continue stirring at room temperature for 30 minutes, and then transfer to a polytetrafluoroethylene-lined autoclave, hydroheat at 100°C for 24 hours and then naturally cool to room temperature; filter the obtained slurry, and rinse it alternately with water and ethanol until the filtrate is neutral; dry it at 60°C for 8 hours, and then calcine it at 400°C for 240 minutes to obtain a rod-shaped cerium dioxide carrier.

[0058] (2) Mixing 0.5 mL of a prepared chloroplatinic acid solution containing 3 g / L of platinum with 0.5 mL of a copper nitrate solution containing 8.8 g / L of copper to obtain a clear solution, and ultrasonicating for 5 min to fully mix them; adding deionized water at a ratio of 1 g:10 mL to 0.5 g of the rod-shaped cerium dioxide powder prepared in step (1), stirring and ultrasonicating for 5 min to obtain a cerium dioxide slurry; adding the obtained clear solution dropwise to the cerium dioxide slurry; stirring at 70°C and 300 r / min for 2 h to perform ion exchange to obtain a slurry.

[0059] (3) Add 2 mL of 0.5 mol / L sodium hydroxide solution to the slurry obtained in step (2), stir and ultrasonicate for 10 min to fully react; after suction filtration, rinse the filter cake with deionized water and ethanol solution alternately until it is neutral, dry at 60° C. for 2 h, grind into powder, calcine at 550° C. for 2 h, and cool naturally to room temperature to obtain a precious metal catalyst.

[0060] The precious metal catalyst was observed using a transmission electron microscope, and the TEM image was obtained as follows: Figure 1 , Figure 2 As shown. Figure 1 , Figure 2 It can be seen that the noble metal catalyst is in the shape of a rod.

[0061] Example 2 A noble metal catalyst for removing carbon monoxide from methanol reforming gas comprises a ceria carrier, platinum oxide anchored on the surface of the ceria carrier, and copper oxide doped in the platinum oxide, wherein the molar ratio of platinum, copper and ceria carrier is 0.0026:0.008:1.

[0062] The preparation method is the same as that of Example 1, except that the copper content of the copper nitrate solution is 3 g / L.

[0063] Example 3 A noble metal catalyst for removing carbon monoxide from methanol reforming gas comprises a ceria carrier, platinum oxide anchored on the surface of the ceria carrier, and copper oxide doped in the platinum oxide, wherein the molar ratio of platinum, copper and ceria carrier is 0.0026:0.013:1.

[0064] The preparation method is the same as that of Example 1, except that the copper content of the copper nitrate solution is 5 g / L.

[0065] Example 4 A noble metal catalyst for removing carbon monoxide from methanol reforming gas comprises a ceria carrier, platinum oxide anchored on the surface of the ceria carrier, and copper oxide doped in the platinum oxide, wherein the molar ratio of platinum, copper and ceria carrier is 0.0026:0.0375:1.

[0066] The preparation method is the same as that of Example 1, except that the copper content of the copper nitrate solution is 15 g / L.

[0067] Example 5 A noble metal catalyst for removing carbon monoxide from methanol reforming gas comprises a ceria carrier, platinum oxide anchored on the surface of the ceria carrier, and copper oxide doped in the platinum oxide, wherein the molar ratio of platinum, copper and ceria carrier is 0.0026:0.0525:1.

[0068] The preparation method is the same as that of Example 1, except that the copper content of the copper nitrate solution is 21 g / L.

[0069] Example 6 A precious metal catalyst for removing carbon monoxide from methanol reforming gas, the raw materials and preparation method are the same as those in Example 1, except that gold is used to replace the platinum in Example 1.

[0070] Example 7 A noble metal catalyst for removing carbon monoxide from methanol reforming gas, the raw materials and preparation method are the same as those in Example 1, except that the calcination temperature is 150°C.

[0071] Example 8 A noble metal catalyst for removing carbon monoxide from methanol reforming gas, the raw materials and preparation method are the same as those in Example 1, except that the calcination temperature is 750°C.

[0072] Comparative Example 1 A noble metal catalyst, the preparation method is the same as that of Example 1, except that no auxiliary metal copper is added.

[0073] Comparative Example 2 A noble metal catalyst is composed of a cerium dioxide carrier, platinum oxide physically supported on the surface of the cerium dioxide carrier, and copper oxide doped in the platinum oxide. The raw materials and preparation method are the same as those in Example 1, except that no alkali solution is used to assist impregnation.

[0074] Comparative Example 3 A non-noble metal catalyst consists of a cerium dioxide carrier and copper oxide supported on the surface of the cerium dioxide carrier.

[0075] The preparation method of the non-precious metal catalyst is: (1) Preparation of cerium dioxide carrier: Same as Example 1.

[0076] (2) preparing 0.5 mL of a copper nitrate solution having a copper content of 8.8 g / L for later use; adding deionized water at a ratio of 1 g:10 mL to 0.5 g of the rod-shaped cerium dioxide powder prepared in step (1), stirring and ultrasonicating for 5 min to obtain a cerium dioxide slurry; adding the copper nitrate solution dropwise to the cerium dioxide slurry; stirring at 70° C. and 300 r / min for 2 h to perform sufficient ion exchange to obtain a slurry.

[0077] (3) The slurry obtained in step (2) is filtered, and the filter cake is alternately rinsed with deionized water and ethanol solution until it is neutral, dried at 60° C. for 2 h, ground into powder, calcined at 550° C. for 2 h, and naturally cooled to room temperature to obtain a non-precious metal catalyst.

[0078] Application Examples 0.2 g of the catalysts prepared in Examples 1 to 8 and Comparative Examples 1 to 3 were mixed with 0.8 g of quartz sand (40-80 mesh) and placed in the middle of a reaction tube. The mixture was reduced at 300° C. under 50 vol.% H2 and 50 vol.% N2 (40 mL / min) for 2 h. The methanol reforming gas had a hydrogen concentration of 70 vol.%, a carbon dioxide concentration of 24 vol.%, a nitrogen concentration of 4 vol.%, an oxygen concentration of 1 vol.%, a carbon monoxide concentration of 1 vol.%, and a gas space velocity of 10000 mL·(gcat·h). -1 , the temperature is 90℃, after stable sampling, gas samples are collected at the reaction gas outlet, and the composition of the gas samples is analyzed by gas chromatograph.

[0079] Table 1 Application results of the examples and comparative examples

[0080] The experimental results of Examples 1 to 5 show that when the molar ratio of the noble metal active component to the auxiliary metal is in the range of 1:(3-21), the noble metal catalysts all have good catalytic effects and meet the requirements for removing CO from methanol reforming gas.

[0081] It can be seen from the results of Example 1 and Example 6 that the precious metal catalyst provided by the present invention has good catalytic effects when using platinum and gold, among which platinum has a better catalytic effect.

[0082] The results of Examples 1, 7 and 8 show that the present invention can prepare precious metal catalysts with good catalytic effects when the calcination temperature is within the range of 150-750°C. When the calcination temperature is 550°C, the catalyst has the best catalytic effect.

[0083] It can be seen from the results of Comparative Examples 1-2 that without using auxiliary metals or without using alkaline solution to assist impregnation, the obtained precious metal catalysts cannot meet the requirements for removing CO from methanol reforming gas.

[0084] Test Case The precious metal catalyst prepared in Example 1 and the catalyst prepared in Comparative Examples 1 to 3 were analyzed using an X-ray photoelectron spectrometer to obtain XPS graphs, as shown in FIG. Figure 3 As shown. Figure 3 It can be observed that the catalyst of Example 1 has a peak of Cu3p orbital and a peak of Pt4f orbital. By comparing the XPS results of Example 1 and Comparative Example 1, it can be found that after copper doping, Pt 4+ The ion content increased significantly, which indicates that copper doping can effectively adjust the chemical state of Pt. 4+It has a stronger adsorption effect on carbon monoxide, can inhibit the adsorption of hydrogen on the surface, reduce the occurrence of side reactions, and thus improve the catalyst's selectivity and conversion rate for carbon monoxide.

[0085] From the above examples and comparative examples, it can be seen that the present invention can effectively improve the selectivity and catalytic efficiency of the precious metal catalyst for CO by adding a promoter metal to the precious metal catalyst, and reduce the CO content in the methanol reforming gas to 0.2 ppm while reducing the precious metal loading.

[0086] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A noble metal catalyst for removing carbon monoxide from methanol reforming gas, characterized in that: The invention comprises a cerium dioxide carrier, a noble metal active component anchored and loaded on the surface of the cerium dioxide carrier, and an auxiliary metal doped in the noble metal active component, wherein the amount ratio of the noble metal active component, the auxiliary metal and the cerium dioxide carrier is (0.002-0.003):(0.008-0.056):1; the auxiliary metal comprises any one of copper, zinc, manganese, iron, cobalt and nickel.

2. The noble metal catalyst according to claim 1, characterized in that The noble metal in the noble metal active component includes any one of Au, Pt and Pd.

3. The noble metal catalyst according to claim 1, characterized in that The ceria carrier is rod-shaped ceria.

4. The noble metal catalyst according to claim 3, characterized in that The diameter of the rod-shaped cerium dioxide is 5-10 nm, and the length of the rod-shaped cerium dioxide is 50-200 nm.

5. The method for preparing the noble metal catalyst according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) immersing the cerium dioxide support in a mixed solution of a noble metal salt and an auxiliary metal salt to perform ion exchange to obtain a slurry; (2) mixing the slurry obtained in step (1) with an alkali solution for auxiliary impregnation and then filtering to obtain an intermediate; (3) calcining the intermediate obtained in step (2) to obtain a noble metal catalyst.

6. The preparation method according to claim 5, characterized in that: The temperature of the ion exchange in step (1) is 60-80° C., and the time of the ion exchange is 1.5-2.5 h.

7. The preparation method according to claim 5, characterized in that: The concentration of the alkali solution in step (2) is 0.5-1 mol / L.

8. The preparation method according to claim 7, characterized in that: The auxiliary dipping time in step (2) is 8 to 12 minutes.

9. The preparation method according to claim 5, characterized in that: In the step (3), the calcination temperature is 150-750° C., and the calcination time is 1-3 hours.

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