CN100429814C - A kind of carbon monoxide water vapor shift catalyst and its preparation method and application - Google Patents

Abstract

A CO water vapor shift catalyst used in the hydrogen source process of a fuel cell, its preparation method and application. The composition of the catalyst is noble metal/CeO ₂ -transition metal oxide, the loading range of the noble metal is 0.1-3% of the total weight of the catalyst, and the molar ratio of the transition metal oxide to CeO ₂ is in the range of 1:1-9. Its preparation method is to prepare the CeO ₂ -transition metal oxide solid solution as the auxiliary agent and carrier of the particle catalyst by co-precipitation method or quick decomposition method, and the solid solution can also be prepared into transparent sol by sol-gel method or wet ball milling method The emulsion slurry is prepared as an auxiliary agent and a transition layer and coated on the honeycomb ceramic monolithic catalyst, and then the noble metal component is impregnated and supported on the pre-prepared solid solution. The catalyst can also be prepared by pre-impregnating the noble metal component on the CeO ₂ -transition metal oxide solid solution, and coating it on the honeycomb ceramic carrier by one-step coating.

Description

A kind of carbon monoxide water vapor shift catalyst and its preparation method and application

technical field

The invention relates to a CO water vapor shift catalyst.

The present invention also relates to a method for preparing the above-mentioned catalyst.

The invention also relates to the use of the catalysts described above.

Background technique

Hydrogen source technology has become one of the technical bottlenecks in the commercialization of fuel cell electric vehicles. As an energy source for fuel cells, hydrogen can be provided in the form of hydrogen storage materials (tanks), or it can be moved from natural gas, methanol, gasoline and other hydrocarbons through reforming or produced on-site for fuel cell power generation. The latter hydrogen supply method has the characteristics of high energy density, high energy conversion efficiency, easy transportation, replenishment and storage of liquid fuel, and also has advantages in terms of economy and safety. At present, all countries in the world have carried out research and development work in this field, and have displayed a number of fuel cell vehicles with methanol reforming and gasoline reforming hydrogen sources. At the same time, many large companies in the world have carried out fuel reforming and fuel cell integration. Demonstration of a power plant.

The movement of hydrocarbons or alcohols through reforming and on-site hydrogen production generally include processes such as reforming, CO shift, and CO selective oxidation removal or pressure swing adsorption removal. The reforming process converts hydrocarbon or alcohol fuels into hydrogen-rich gas, which contains about 4-10% CO, especially higher in autothermal reforming, and CO has a poisoning effect on the Pt catalyst of the fuel cell electrode, making the catalyst rapidly Therefore, it is necessary to reduce the CO in the reformed gas to less than 50-100ppm. This requirement will be realized through CO shift process and CO selective oxidation process. The so-called CO water vapor shift process is:

CO+ _H2O → _CO2 + _H2

This process can reduce about 4-10% CO to 1.0-2.0%, and at the same time generate an equal volume of H ₂ , which not only reduces the burden of the subsequent CO selective oxidation purification process, but also increases the H ₂ content.

As a fuel cell hydrogen supply system, the hydrogen production process will be an unsteady process, so the catalyst used in this process must not only adapt to the temperature changes and redox atmosphere changes caused by different working conditions such as start-up, load change, and shutdown, but also There must be sufficient stability and longevity. Traditional CO shift catalysts are generally divided into low shift (represented by Cu-Zn-Al catalyst, operating temperature 180-280°C) and high shift (represented by Fe-Cr catalyst, operating temperature 350-450°C) catalysts, mainly It is used in a steady-state industrial process with strict control of operating conditions, and after reduction, it will spontaneously ignite when exposed to air, resulting in sintering and deactivation of the active components of the catalyst. Therefore, these two types of shift catalysts cannot be applied to fuel cell hydrogen source systems that operate in an unsteady state. Therefore, the development of CO-shift catalysts with high activity, good thermal stability, resistance to the impact of redox atmosphere and long life has become one of the keys to the hydrogen source technology of fuel cells. In the related research in this field, the noble metal (represented by Pt)/CeO ₂ system has attracted extensive attention of scientists. Argonne National Laboratory (Pt/Mixed Oxides), NexTech (Pt/Ceria), Engelhard (Pt/CuO/Ceria/Al ₂ O ₃ ), Degussa (Pt-Pd-Fe/Ceria/Al ₂ O ₃ ) and the University of Pennsylvania (Pt, Pd, Rh, Co, Fe, Ni/Ceria) have carried out research on this system and published reports, articles and patents.

Rare earth metal oxide _CeO2 has been successfully applied as an important additive in automobile exhaust purification catalysts. It is applied to the CO conversion process, and its function of storing and releasing oxygen (change in price) is used to change the CO conversion reaction process and improve the performance of noble metal catalysts. The activity; at the same time, the introduction of CeO ₂ helps to improve the thermal and structural stability of the catalyst, so that the shift reaction has a higher conversion rate in a wide temperature range of 270-400 °C.

Contents of the invention

The object of the present invention is to provide a CO water vapor shift catalyst used in a fuel cell hydrogen source system.

Another object of the present invention is to provide a method for preparing the above catalyst.

The composition of the catalyst provided by the invention is noble metal/CeO ₂ -transition metal oxide. In the catalyst of the present invention, the precious metal is selected from one or more of platinum (Pt), palladium (Pd), rhodium (Rh) and ruthenium (Ru), preferably platinum (Pt) and rhodium (Rh); The amount is in the range of 0.1-3%, preferably 0.2-1.5%, of the total weight of the catalyst. The transition metal oxide is selected from one or more of oxides such as titanium (Ti), chromium (Cr), zirconium (Zr), vanadium (V), manganese (Mn), iron (Fe), nickel (Ni), Zirconium (Zr), titanium (Ti), and iron (Fe) are preferred. The ratio of transition metal oxide to CeO ₂ in the CeO ₂ -transition metal oxide solid solution is particularly important, and the molar ratio range of transition metal oxide to CeO ₂ should be controlled between 1:1-9, preferably 1:3-4.

The present invention introduces transition metal oxides into noble metal/CeO ₂ , and the transition metal oxides enter into the CeO ₂ lattice to form a solid solution with it, thereby increasing the oxygen storage capacity of CeO ₂ and improving the mobility of lattice oxygen, thereby further improving the The activity of the Pt/Ceria system catalyst is improved; at the same time, the addition of transition metal oxides also improves the thermal stability and strength of the catalyst, thereby prolonging the service life of the catalyst.

In the method for preparing the above-mentioned catalyst provided by the present invention, the CeO ₂ -transition metal oxide solid solution is prepared as the auxiliary agent and carrier of the granular catalyst by coprecipitation method or quick decomposition method, and the CeO ₂ - The transition metal oxide solid solution is prepared as a transparent sol or as an emulsion slurry by wet ball milling method and coated on the honeycomb ceramic monolithic catalyst as an auxiliary agent and a transition layer. Then the precious metal component is impregnated and supported on the pre-prepared CeO ₂ -transition metal oxide solid solution. The impregnation method can be equal impregnation or excessive impregnation, preferably equal impregnation. A variety of complexes can be selected as the precursor of the noble metal component. Taking platinum (Pt) as an example, you can choose chloroplatinic acid (H ₂ PtCl ₆ ), amoplatinum (Pt(NH ₃ ) ₄ (OH) ₂ ), Ammonium nitrate (Pt(NH ₃ ) ₄ (NO ₃ ) ₂ ) and cisplatin (Pt(NH ₃ ) ₄ Cl ₂ ), etc., preferably amoplatinum (Pt(NH ₃ ) ₄ (OH) ₂ ) or nitric acid Ammonium platinum (Pt(NH ₃ ) ₄ (NO ₃ ) ₂ ); the impregnated catalyst is dried and calcined to obtain the finished catalyst. The selected drying temperature is 80-120°C for 2-8 hours, preferably 110°C for 4 hours; the calcination temperature is 400-800°C for 1-6 hours, preferably 500°C for 2 hours.

The above-mentioned CeO ₂ -transition metal oxide solid solution not only participates in the shift reaction as a catalytic assistant, but also has sufficient strength as a catalyst support. The CeO ₂ -transition metal oxide solid solution is prepared by co-precipitation or thermal decomposition, preferably co-precipitation. The basic technique of catalyst preparation by co-precipitation is well known to researchers in the field. Taking the preparation of CeO ₂ -ZrO ₂ co-precipitation as an example, the precursor for preparing CeO ₂ -ZrO ₂ co-precipitation can be selected from nitrate, oxalate or chloride of Ce and Zr, preferably nitrate. The precipitant can be selected from NaOH, KOH, Na ₂ CO ₃ , NH ₄ OH, etc., preferably NH ₄ OH. The prepared coprecipitate is dried and calcined to obtain CeO ₂ -ZrO ₂ solid solution powder. The selected drying temperature is 80-150°C for 2-8 hours, preferably 110°C for 4 hours; the calcination temperature is 400-800°C for 1-6 hours, preferably 500°C for 2 hours. Grinding the CeO ₂ -transition metal oxide solid solution powder prepared above to below 75 μm, adding 1-20% by weight (preferably 5-10%) of 10% dilute nitric acid, 1-10% (preferably 3-5% ) Pseudo-boehmite (Al ₂ O ₃ ·H ₂ O), 1-5% (preferably 3%) polyvinyl alcohol (PVA), adjusted into wet powder and extruded into φ2-3mm by extruder of cylindrical shape. The solid solution obtained after drying and roasting can be impregnated with precious metal active components. The selected drying temperature is 80-150°C for 2-8 hours, preferably 110°C for 4 hours; the calcination temperature is 400-800°C for 1-6 hours, preferably 500-600°C for 2 hours.

The preparation method of the present invention can also impregnate the noble metal component on the cordierite honeycomb ceramic substrate coated with a CeO ₂ -transition metal oxide solid solution transition layer (support) in advance. A variety of complexes can be selected as the precursor of the noble metal component. Taking platinum (Pt) as an example, you can choose chloroplatinic acid (H ₂ PtCl ₆ ), amoplatinum (Pt(NH ₃ ) ₄ (OH) ₂ ), Ammonium nitrate (Pt(NH ₃ ) ₄ (NO ₃ ) ₂ ) and cisplatin (Pt(NH ₃ ) ₄ Cl ₂ ), etc., preferably amoplatinum (Pt(NH ₃ ) ₄ (OH) ₂ ) or nitric acid Ammonium Platinum (Pt(NH ₃ ) ₄ (NO ₃ ) ₂ ). The impregnation method adopts the excessive impregnation method. The dipping time is 30-300 seconds, preferably 60-180 seconds. After impregnation, the finished catalyst can be obtained through compressed air purging, drying, roasting and other processes. The drying method can be selected from natural air drying, oven drying, microwave drying or freeze drying, preferably microwave drying or freeze drying. The calcination temperature is 400-800°C, and the time is 1-6 hours, preferably 500°C for 2 hours.

The CeO ₂ - transition metal oxide solid solution transition layer is coated on the pre-treated cordierite honeycomb ceramic carrier in the form of composite oxide sol. Usually, in order to provide sufficient specific surface area, a pre-coated layer can also be used on the cordierite carrier. Layer aluminum sol or aluminum wet ball mill glue. The weight of the coated aluminum glue accounts for 5-15% of the weight of the blank honeycomb ceramics, preferably 8-12%. The composite oxide sol of the transition layer, that is, the CeO ₂ -transition metal oxide sol, is prepared by a sol-gel method. The weight of the transition layer accounts for 15-80% of the weight of the whole honeycomb ceramic catalyst, preferably 30-50%. A conventional preparation method of the honeycomb ceramic catalyst coating is adopted, and this method is well known to researchers in the field. After the preparation is completed, the catalyst intermediate is obtained through compressed air purging, drying and roasting processes. The drying method can be selected from air spontaneous combustion drying, oven drying, microwave drying or freeze drying, preferably microwave drying or freeze drying. The calcination temperature is 400-800°C, and the time is 1-6 hours, preferably 500°C for 2 hours.

The CeO ₂ -transition metal oxide solid solution transition layer can also be prepared into an emulsion slurry by wet ball milling and coated on the pretreated cordierite honeycomb ceramic carrier, the weight of the coated CeO ₂ -transition metal oxide solid solution transition layer accounts for the entire 15-80% by weight of the honeycomb ceramic catalyst, preferably 30-50%. The selection of drying method, channel purging and roasting process are the same as above.

The catalyst of the present invention can also be prepared by one-step coating. Pre-impregnate the metered precious metal component on the CeO ₂ -transition metal oxide solid solution, then mix it with an appropriate proportion of aluminum glue and wet ball mill to obtain the catalytic component slurry, and coat it on the pre-treated cordierite honeycomb ceramic carrier . The selection of drying method, channel purging and roasting process are the same as above. The weight of oxides in the coated slurry accounts for 30-70%, preferably 50-60%, of the weight of the entire catalyst. The weight ratio of each component in the slurry is noble metal:solid solution:aluminum glue=1:15-30:5-15, preferably 1:18-20:5-10.

The catalyst of the present invention has high activity, good strength, no spontaneous combustion, can be reductively activated in the reformed gas, can withstand the cycle of oxidation-reduction atmosphere caused by start-up and shutdown, is not affected by condensate, and does not lose its power when it contacts condensate during shutdown. live, so it is suitable for application in fuel cell hydrogen source systems.

The present invention has following effect:

1. The catalyst of the present invention is used in methanol reforming hydrogen production fuel cell hydrogen source system, and can be reductively activated in a reformed gas atmosphere (H ₂ 50%, CO 4-10%, CO ₂ 20%, N ₂ balance), without Pre-reduction; at the same time, the catalyst does not spontaneously ignite, withstands the cycle of oxidation-reduction atmosphere caused by start-up and shutdown, is not affected by condensate, and is not deactivated by contact with condensate during shutdown, so it is suitable for application in fuel cell hydrogen source systems . See attached picture 1.

2. The catalyst of the present invention is used in the CO water-gas shift process, and the dry basis composition of the reformed gas is _H2 50%, CO 6%, _CO2 19%, _N2 balance, water vapor/dry basis gas (Steam/Gas ratio) is 0.29, and when GHSV=10,000hr ^-1 , the catalyst has operated stably for more than 200 hours, and the activity has not declined. See attached picture 2.

3. The catalyst of the present invention is used in the CO water-gas shift process, and the dry basis composition of the reformed gas is _H2 50%, CO 4.5%, _CO2 19%, _N2 balance, water vapor/dry basis gas (Steam/Gas ratio) is 0.24, GHSV=10,000hr ^-1 , the catalyst runs for 1000 hours, the activity decay is less than 4%, and the stability is higher than that of the Pt/ _CeO2 catalyst of NexTech Company of the United States, see Figure 3.

4. The present invention forms a solid solution with _CeO by introducing transition metal oxides represented by ZrO in the noble metal/ _CeO system (see accompanying drawing 4, 50% and 80% Zr content is relatively large, and _{ZrO tetragonal} phase has occurred structure, see the black dot in the figure), which improves the oxygen storage capacity of _CeO2 and the activity capacity of lattice oxygen, thereby improving the activity of the Pt/Ceria system catalyst (see accompanying drawing 7), and also improving the thermal conductivity of the catalyst Stability and the ability to resist the impact of redox atmosphere (see Figure 5).

5. The catalyst of the present invention is used in the CO-water vapor shift process of the 5kW methanol reforming hydrogen production fuel cell hydrogen source system. The dry basis composition of the reformed gas is _H2 50%, CO 4.5%, _CO2 19%, _N2 balance, water When the steam/dry gas (Steam/Gas ratio) is 0.22-0.25, the reaction temperature is 300-350°C, and the GHSV=10,000hr ^-1 , the catalyst activity is 50-55%, and the activity has not declined after more than 200 hours of stable operation.

The CO water vapor shift catalyst provided by the invention is suitable for a fuel cell system supplying hydrogen in the form of mobile and on-site hydrogen production, especially a proton exchange membrane fuel cell (PEMFC) system. The catalyst can be applied not only to the hydrogen production process of methanol reforming, but also to the reforming hydrogen production process of other hydrocarbons such as natural gas, gasoline, ethanol, coal, etc., wherein the granular catalyst of the present invention is suitable for on-site hydrogen production from fixed sources The fuel cell hydrogen source system, and the monolithic catalyst can be used in both stationary and mobile source fuel cell hydrogen source systems.

As the best solution and new technology platform for hydrogen energy utilization, fuel cell technology will play a dominant role in energy utilization in the 21st century due to its high efficiency (2-3 times that of internal combustion engines) and no pollution. R&D hotspots in the field of transportation. Considering factors such as cost, performance, and national conditions, on-site hydrogen production from natural gas, methanol, gasoline and other hydrocarbons for fuel cell power generation will be the preferred solution for fuel cell hydrogen source technology in my country in the next 10-20 years. Therefore, the developed Advanced fossil fuel reforming hydrogen production technology and related catalysts have important practical significance and broad development prospects. The catalyst of the present invention has high activity, good strength, no spontaneous combustion, adapts to temperature impact changes and redox atmosphere changes caused by different working conditions such as fuel cell start-up, load change, and shutdown, and has sufficient stability and life, so it is suitable for It is suitable for application in the fuel cell hydrogen source system, filling the gaps in the domestic related research fields.

The novelty and inventiveness of the present invention are,

(1) The catalyst has high activity, good strength, no spontaneous combustion, no need for pre-reduction, adapts to temperature shock changes and redox atmosphere changes caused by different working conditions such as fuel cell start-up, load change, and shutdown, and has good stability and long life. It overcomes many limitations of the unsteady operation of traditional shift catalysts, and is suitable for application in fuel cell hydrogen source systems.

(2) In the invention point (1), a noble metal/ _CeO2 -transition metal oxide catalyst system is proposed, and the transition metal oxide enters the _CeO2 crystal lattice to form a solid solution with it, which improves the oxygen storage capacity of _CeO2 and enhances the The activity of lattice oxygen is improved, thereby improving the activity of Pt/Ceria system catalyst.

(3) In the invention point (1), introducing transition metal oxide and _CeO into the noble metal/ _CeO2 system forms a solid solution, which improves the thermal stability and strength of the catalyst, and withstands the oxidation-reduction atmosphere caused by starting and shutting down Cycling, temperature shock resistance, and contact with condensate will not deactivate, thus improving the stability and life of the catalyst.

Description of drawings

Fig. 1 shows the comparison test of the anti-oxidative impact ability of the catalyst of the present invention.

Figure 2 shows the performance of the particulate catalyst of the present invention.

Figure 3 shows the life of the catalyst of the present invention.

Figure 4 shows the X-ray diffraction spectrum of the catalyst of the present invention.

Figure 5 shows the comparison of the oxidation shock resistance of the catalysts of the present invention.

Figure 6-1 shows the performance of the granular catalyst of the present invention.

Figure 6-2 shows the performance of the honeycomb ceramic monolithic catalyst of the present invention.

Figure 7-1 shows the performance comparison of the granular catalysts of the present invention.

Figure 7-2 shows the performance comparison of the honeycomb ceramic monolithic catalysts of the present invention.

Detailed ways

Example 1: Granular Catalyst Preparation

左右的圆柱体。将圆柱体放入烘箱110℃烘干4小时左右，然后放入马弗炉500℃焙烧2小时，得CeO₂-ZrO₂固溶体供制备催化剂用。a) Weigh 630g of industrial grade Ce(NO ₃ ) ₃ 6H ₂ O and 57.8g of industrial grade Zr(OH) ₄ . Stir and dissolve the weighed Ce(NO ₃ ) ₃ 6H ₂ O with deionized water, put the weighed Zr(OH) ₄ into a beaker, add 110±2ml of 65-68% concentrated nitric acid, and heat until no visible Particles and solutions are transparent. Add 200±10ml deionized water, then the solution is clear. Pour the dissolved Zr(NO ₃ ) ₄ solution into the Ce(NO ₃ ) ₃ solution, filter, stir and mix evenly. Under the condition of constant stirring, drop 430±50ml of 25-28% ammonia water into the above mixed solution with a separatory funnel, the amount of ammonia water is controlled according to the pH value until the pH value reaches 8-9. The co-precipitation of Ce-Zr was fully stirred, vacuum filtered and washed, then put into an oven to dry at 110°C for 15 hours, and then put into a muffle furnace to bake at 500°C for 2 hours. Grind the roasted product to below 200 mesh, add 15g of pseudo-boehmite and 30ml of 10% dilute nitric acid, mix well, extrude with extruder, and cut it into

left and right cylinders. The cylinder was dried in an oven at 110°C for about 4 hours, and then baked in a muffle furnace at 500°C for 2 hours to obtain a CeO ₂ -ZrO ₂ solid solution for catalyst preparation.

b) Take the above-mentioned CeO ₂ -ZrO ₂ solid solution and crush it, take 11.5 g of a 30-60 mesh sample, take 4.2 ml of H ₂ PtCl ₆ solution with a Pt content of 14 mg/ml, and impregnate the CeO ₂ -ZrO ₂ solid solution in equal volume. The sample was dried in an oven at 110°C for about 4 hours, and then baked in a muffle furnace at 500°C for 2 hours to obtain a Pt/CeO ₂ -ZrO ₂ supported catalyst (A).

Example 2: Granular Catalyst Preparation

a) Prepare CeO ₂ -ZrO ₂ solid solution by the method of Example 1 for future use.

b) Take the above-mentioned CeO ₂ -ZrO ₂ solid solution and crush it, take 11.5 g of a 30-60 mesh sample, take 4.2 ml of H ₂ PtCl ₆ solution with a Pt content of 40 mg/ml, and prepare Pt/CeO ₂ -ZrO ₂ by the method of Example 1 Supported Catalyst (B).

Example 3: Preparation of honeycomb ceramic monolithic catalyst

a) Take one piece of cordierite honeycomb ceramics with φ15×20mm 400cpsi (400 holes/square inch), pretreat with 3% HNO ₃ for 12 hours, dry at 120°C for 12 hours, and bake at 900°C for 2 hours for later use.

b) Weigh 9.5g of pseudoboehmite (Al ₂ O ₃ ·H ₂ O), 12.4g of gibbsite (Al(OH) ₃ ), and 14.3g of aluminum oxide (γ-Al ₂ O ₃ ) , aluminum nitrate Al(NO ₃ ) ₃ 9H ₂ O6.7g, after mixing, add 250ml deionized water, 5ml 65-68% nitric acid, and ball mill for 12 hours to obtain aluminum latex (slurryA) with an average particle size of 1 μm. The viscosity is 1300 centipoise (cp) and the pH is 3.60.

c) Weigh 630g of industrial grade Ce(NO ₃ ) ₃ 6H ₂ O and 57.8g of industrial grade Zr(OH) ₄ . It was prepared as a mixed solution of Ce(NO ₃ ) ₃ and Zr(NO ₃ ) ₄ by the method of Example 1. CeO ₂ -ZrO ₂ composite oxide sol was prepared by sol-gel method with 13% NH ₄ OH as gelling agent and 35% HNO ₃ as degelling agent. The measured pH of the sol was 1.16.

d) Weigh 1.0726 g of the above-mentioned honeycomb ceramic carrier, impregnate it with aluminum latex for 3 minutes, blow the channel with compressed air after taking it out, dry it in microwave for 3 minutes, and bake it in a muffle furnace at 500° C. for 2 hours. This process was repeated 3 times to obtain a catalyst intermediate weight of 1.2230 g.

e) Take the above catalyst intermediate, impregnate it with CeO ₂ -ZrO ₂ composite oxide sol for 3 minutes, blow the channel with compressed air after taking it out, dry it with microwave for 3 minutes, and bake it in a muffle furnace at 500°C for 2 hours. This process was repeated 3 times to obtain a catalyst intermediate weight of 1.5027 g.

f) Take the above catalyst intermediate, soak it in H ₂ PtCl ₆ solution with a Pt content of 37 mg/ml for 3 minutes, blow the channel with compressed air after taking it out, dry it in microwave for 3 minutes, and bake it in a muffle furnace at 500°C for 2 hours to obtain the finished product Catalyst (C), weighing 1.5178 g.

Example 4: Preparation of honeycomb ceramic monolithic catalyst

a) The pretreatment of cordierite honeycomb ceramic carrier and the preparation of aluminum latex (slurryA) are the same as in Example 3.

b) Take 10 g of CeO ₂ -ZrO ₂ solid solution powder below 200 mesh in Example 1, take 2.5 ml of H ₂ PtCl ₆ solution with a Pt content of 200 mg/ml, and impregnate the CeO ₂ -ZrO ₂ solid solution in equal volume. The sample was dried in an oven at 110°C for about 4 hours, and then baked in a muffle furnace at 500°C for 2 hours to obtain Pt/CeO ₂ -ZrO ₂ supported powder. 40ml of aluminum latex (slurryA) was added thereto, and ball milled for 12 hours to obtain slurryB. Impregnate the cordierite honeycomb ceramic carrier (0.8714 g) with slurry B for 3 minutes, blow the channel with compressed air after taking it out, microwave dry for 3 minutes, and bake in a muffle furnace at 500°C for 2 hours. This process was repeated 3 times to obtain the finished catalyst (D) with a weight of 1.5648g.

Example 5: Preparation of honeycomb ceramic monolithic catalyst

a) The pretreatment of the cordierite honeycomb ceramic carrier is the same as in Example 3.

b) The weight of the above carrier is 1.177g, impregnated with the CeO ₂ -ZrO ₂ composite oxide sol of Example 3 for 3 minutes, blow the channel with compressed air after taking it out, freeze-dry for 20 hours, and bake in a muffle furnace at 500°C for 2 hours. This process was repeated 4 times to obtain a catalyst intermediate weight of 1.6827g.

c) Take the above catalyst intermediate, soak it in H ₂ PtCl ₆ solution with a Pt content of 37 mg/ml for 3 minutes, blow the channel with compressed air after taking it out, freeze-dry it for 20 hours, and roast it in a muffle furnace at 500°C for 2 hours to obtain the finished product Catalyst (E), weighing 1.6995 g.

Example 6: Catalyst Performance Evaluation

The catalyst (30-60 mesh) was loaded into a quartz tube microreactor with an inner diameter of 8mm, the pressure of the reaction system was normal pressure, and the conversion rate of CO was measured at 200-400°C. The reaction feed gas is a simulated reformed gas, and its composition is:

(1) 50% H ₂ , 6% CO, 19% CO ₂ , N ₂ balance (HTSG),

(2) 50% H ₂ , 4% CO, 19% CO ₂ , N ₂ balance (LTSG).

The performances of the above five catalyst samples are shown in Figure 6.

The comparative example relevant to the present invention:

Example 7: Granular Catalyst Preparation

a) Weigh 630g of industrial grade Ce(NO ₃ ) ₃ 6H ₂ O, add deionized water and stir to dissolve, use 25-28% ammonia water as precipitant, control the amount of ammonia water according to the pH value until the pH value reaches 8-9. _CeO2 particles were prepared by the precipitation method, and all the other steps were the same as in Example 1.

b) Take the above-mentioned CeO ₂ and crush it, take 11.5 g of a 30-60 mesh sample, take 3.7 ml of H ₂ PtCl ₆ solution with a Pt content of 16 mg/ml, and impregnate the CeO ₂ sample in equal volume. The sample was dried in an oven at 110°C for about 4 hours, and then baked in a muffle furnace at 500°C for 2 hours to obtain a Pt/CeO ₂ supported catalyst comparative example (F).

Example 8: Preparation of honeycomb ceramic monolithic catalyst

a) The pretreatment of cordierite honeycomb ceramic carrier and the preparation of aluminum latex (slurryA) are the same as in Example 3.

b) Weigh 630g of industrial grade Ce(NO ₃ ) ₃ 6H ₂ O, use 13% NH ₄ OH as gelling agent, and 35% HNO ₃ as degelling agent, prepare CeO ₂ sol by sol-gel method for future use .

c) Weigh 1.1103 g of the above-mentioned honeycomb ceramic carrier, impregnate it with aluminum latex for 3 minutes, blow out the channel with compressed air after taking it out, freeze-dry it for 20 hours, and bake it in a muffle furnace at 500°C for 2 hours. This process was repeated 3 times to obtain a catalyst intermediate weight of 1.2822 g.

d) Take the above catalyst intermediate, impregnate it with CeO ₂ sol for 3 minutes, blow the channel with compressed air after taking it out, freeze-dry it for 20 hours, and bake it in a muffle furnace at 500°C for 2 hours. This process was repeated 3 times to obtain a catalyst intermediate weight of 1.5452 g.

e) The above catalyst intermediate was taken and immersed in H ₂ PtCl ₆ solution with a Pt content of 37 mg/ml for 3 minutes. After taking it out, the channel was purged with compressed air, freeze-dried for 20 hours, and calcined in a muffle furnace at 500° C. for 2 hours. Obtain catalyst comparative example (G), weight 1.5606g.

Example 9: A commercial Cu/Zn/Al low-temperature shift catalyst (B206, purchased from Nanhua Group). Crushed to 30-60 mesh as catalyst comparative example (H).

The comparison between the catalyst comparative example and the present invention is shown in accompanying drawing 7.

Claims (5)

1. A method for preparing a carbon monoxide water vapor shift catalyst in the fuel cell hydrogen source process, the catalyst is composed of noble metal/CeO ₂ -transition metal oxide; wherein the noble metal loading is 0.1-3wt% of the total amount of the catalyst, The molar ratio of transition metal oxide and _CeO2 is 1:4; Transition metal oxide is titanium, chromium, zirconium, vanadium, manganese, iron or/and nickel oxide; Noble metal is platinum, palladium, rhodium or/and ruthenium, The main steps of preparation are: a) adjusting the pH value of the mixed solution of the cerium salt and the transition metal salt to 8-9 with a precipitating agent to form a precipitate; b) drying the precipitate at 80-150°C for 2-8 hours, and calcining at 400-800°C for 1-6 hours to obtain CeO ₂ -transition metal oxide solid solution powder; c) Grinding the CeO ₂ -transition metal oxide solid solution powder obtained in step b) to below 75 μm, adding 1-20% by weight of 10wt% dilute nitric acid, 1-10wt% of pseudo-boehmite and 1-5wt % of polyvinyl alcohol, mixed evenly and extruded into a cylindrical shape with an extruder; d) drying the product obtained in step c at 80-150°C for 2-8 hours, and calcining at 400-800°C for 1-6 hours to obtain a cylindrical CeO ₂ -transition metal oxide solid solution; e) The noble metal component is supported on the cylindrical CeO ₂ -transition metal oxide solid solution obtained in step d) by impregnation, dried at 80-120°C for 2-8 hours, and calcined at 400-800°C for 1-6 hours , to obtain granular noble metal/CeO ₂ -transition metal oxide catalyst. 2. the preparation method of catalyzer as claimed in claim 1 is characterized in that, after obtaining CeO ₂ -transition metal oxide precipitate solid solution powder, adopt following steps to prepare honeycomb ceramic monolithic catalyst: The CeO ₂ -transition metal oxide solid solution powder is made into an emulsified slurry by wet ball milling, and coated on the cordierite honeycomb ceramic carrier; the weight of the formed CeO ₂ -transition metal oxide solid solution transition layer accounts for 15% of the total weight of the honeycomb ceramic catalyst. -80%; on the ceramic honeycomb carrier coated with CeO ₂ -transition metal oxide solid solution transition layer by dipping method, impregnate the precious metal component, and the dipping time is 30-300 seconds; after purging the honeycomb ceramic channel and drying, in 400- Calcined at 800°C for 1-6 hours to obtain a honeycomb ceramic monolithic catalyst. 3. The preparation method according to claim 2, wherein the cordierite honeycomb ceramic carrier is pre-coated with one deck aluminum sol or aluminum wet ball mill glue, and the weight of the aluminum glue accounts for 5-15% of the blank honeycomb ceramic carrier weight . 4. preparation method as claimed in claim 2 is characterized in that, after obtaining CeO ₂ -transition metal oxide solid solution powder, adopt following steps to prepare honeycomb ceramic monolithic catalyst: Impregnate the metered precious metal component on the CeO ₂ -transition metal oxide solid solution powder, then mix it with aluminum glue and wet ball mill to prepare the catalytic component slurry, and coat it on the cordierite honeycomb ceramic carrier; purge and dry through the channel , baked at 400-800°C for 1-6 hours to obtain a honeycomb ceramic monolithic catalyst; the weight of the oxide in the coated slurry accounts for 30-70% of the weight of the entire catalyst; precious metal by weight: CeO ₂ -transition metal Oxide solid solution: aluminum glue = 1: 15-30: 5-15. 5. The preparation method according to any one of claims 1, 2 or 4, characterized in that, CeO ₂ - the precursor of the transition metal oxide solid solution is Ce nitrate, oxalate or chloride and transition metal Nitrate, oxalate or chloride; the precipitating agent is NaOH, KOH, Na ₂ CO ₃ or NH ₄ OH; the precursor of the noble metal component is chloroplatinic acid, amoplatinum, ammonium nitrate or cisplatinum.

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