CN1291784C - Copper base catalyst in use for preparing hydrogen by reforming vapor of methanol and preparation method - Google Patents

Abstract

The invention relates to a mesoporous silicon oxide modified copper-based catalyst for hydrogen production by steam reforming of methanol and a preparation method thereof. The catalyst is composed of CuO/ZnO/Al ₂ O ₃ active components and silicon oxide-based mesoporous materials, wherein the mesoporous silicon oxide accounts for 1-30Wt% of the total weight of the catalyst. In the active component, the content of CuO is 30-70% by molar ratio, the content of ZnO is 20-60% by molar ratio, and the content of Al ₂ O ₃ is 0-15% by molar ratio. The catalyst is prepared by the carbonate co-precipitation method, that is, under the condition of stirring and 30-80 ° C, the nitrate solution and the sodium carbonate solution are poured into the reactor preset with metered mesoporous silica at the same velocity and in parallel. Co-precipitation reaction is carried out in the medium to obtain a carbonate co-precipitate containing mesoporous silica, which is prepared by washing, drying, roasting and other steps. The catalyst has a unique large-surface porous structure, high low-temperature activity and good stability, and high selectivity to hydrogen. The hydrogen content in the reformed product can reach up to 75%, and the CO content is less than 0.1%.

Description

Copper-based catalyst for hydrogen production by steam reforming of methanol and preparation method thereof

technical field

The invention belongs to the technical field of chemical industry, and in particular relates to a novel copper-based catalyst for hydrogen production by steam reforming of methanol and a preparation method thereof.

technical background

As a liquid fuel, methanol has become the most promising high-energy-carrying fuel due to its advantages of high energy density, low carbon content, and transportation and storage. Through catalytic conversion, hydrogen can be generated instantly, which can effectively solve the problems existing in the utilization of hydrogen energy. To solve this technical problem, it becomes an ideal hydrogen carrier, and using it as a hydrogen source for fuel cells is a hot research topic at present. As a hydrogen source for fuel cells, there are relatively strict requirements on the hydrogen production rate of the methanol steam reforming hydrogen production reaction and the _H2 and CO content in the reformed gas, especially the stricter requirements on the CO content, because CO is easily Causes permanent poisoning of proton exchange membrane fuel cell (PEMFC) anode catalyst. Hydrogen production by catalytic methanol steam reforming with copper-based catalysts is a potential way to effectively meet the demand for hydrogen production such as on-board fuel cells. However, the low-temperature activity, hydrogen production selectivity and catalytic stability of traditional copper-based methanol synthesis catalysts are not ideal for this reaction. Therefore, a new methanol steam reforming hydrogen production catalyst with high activity, high hydrogen selectivity and stability has been developed. It has become an extremely important research topic facing the further practical application of vehicle-mounted hydrogen production systems such as fuel cells.

At present, the research on the application and development of new copper-based methanol steam reforming catalysts for hydrogen production has been extensive and in-depth. According to reports, preparation methods and conditions play a very important role in the structure and catalytic performance of copper-based catalysts [J.Mol.Catal.A: Chem., 1997,124 (1): 123; J.Power Sources, 1999, 84(2): 187; Appl. Catal. A, 1999, 179(1): 21.]. The preparation methods of copper-based catalysts reported in the literature include methods such as impregnation method, template method and co-precipitation [Catal.Today, 2002, 77 (1): 89; Int.J.Hydrogen Energy [J], 2000, 25 (2): 211; Appl. Catal. A [J], 2000, 194(1): 21.]. It is generally believed that the CuO/ZnO/Al ₂ O ₃ catalyst prepared by co-precipitation method has better hydrogen production activity and hydrogen selectivity in steam reforming of methanol. However, the CuO/ZnO/Al ₂ O ₃ catalyst prepared by this method can usually achieve a high methanol conversion rate at a temperature > 280°C, which obviously cannot meet the actual hydrogen production needs of vehicle-mounted fuel cells. Recently, it has been reported that oxides of transition metal elements such as Mn, Cr, and Zr were used as promoters to prepare oxide-modified CuO/ZnO/Al ₂ O ₃ catalysts, which can achieve 95 More than % methanol conversion, but the content of carbon monoxide in the reformed gas obtained by this type of catalyst is still relatively high. Therefore, the further search for catalysts with stable performance, high activity at low temperature and high hydrogen selectivity has become the focus of researchers [J.Mol.Catal.A, 2003, 194(1):99.]. New silica mesoporous molecular sieves such as SBA-15 and MCM-41 have attracted widespread attention as potential new catalytic materials due to their unique large pore volume, high specific surface area and good thermal stability [Nature, 1992 , 359: 710; Science 1998, 282: 2244.]. Using new silica-based mesoporous materials as structural aids, new copper-based catalysts with large specific surfaces and highly dispersed copper/zinc active components can be prepared, which is expected to achieve high activity and high selectivity for methanol at low temperatures around 230 °C Reforming to produce hydrogen.

Contents of the invention

The object of the present invention is to propose a novel copper-based catalyst with low-temperature catalytic activity, stable performance, and high hydrogen selectivity for producing hydrogen from steam reforming of methanol and a preparation method thereof. The content of hydrogen in the gas can be reduced, and the content of CO can be reduced, so as to meet the actual demand of on-board hydrogen production.

The copper-based catalyst for methanol steam reforming hydrogen production proposed by the present invention is composed of CuO/ZnO/Al ₂ O ₃ active components and silica mesoporous molecular sieve materials, wherein CuO/ZnO/Al ₂ O _3. The weight percentage of the active component is 70-99 wt%, and the remaining 1-30 wt% is silicon oxide mesoporous molecular sieve. The weight content of the mesoporous silicon oxide component is optimal between 3-12wt%.

The copper-based catalyst modified by the above-mentioned silica mesoporous molecular sieve, wherein the CuO content in the CuO/ZnO/Al ₂ O ₃ component is 30-70% molar ratio, preferably 45-60% molar ratio; ZnO content is 20% -60% molar ratio, preferably 30-45% molar ratio; Al ₂ O ₃ content is 0-15% molar ratio, preferably 5-12% molar ratio. The total amount of the three satisfies a 100% molar ratio.

The copper-based catalyst modified by the above mesoporous silica material, wherein the mesoporous silica material is mesoporous silica gel (specific surface area 400-500m ² /g), MCM-41 (specific surface area 800-1000m ² /g), SBA One or more of -15 (specific surface area 700-1000m ² /g), SiO ₂ airgel (specific surface area 100-1200m ² /g), etc.

The mesoporous silicon oxide-promoted copper-based catalyst proposed in the present invention can be prepared by a traditional carbonate co-current co-precipitation method. The specific steps are: according to the dosage ratio, add the aqueous solution of sodium carbonate and the aqueous solution of nitrate containing copper, zinc and aluminum to the medium pre-dispersed with a given amount of silicon oxide in a parallel flow under the condition of stirring and 30-80 ° C. In the aqueous solution of pore molecular sieves, carry out co-precipitation reaction and age to obtain carbonate co-precipitates containing mesoporous silicon oxide; then wash, dry, roast and granulate to obtain the catalyst.

In the above preparation method, the aqueous solution of sodium carbonate and nitrates containing copper, zinc and aluminum can be added at one time, or slowly added dropwise at a certain speed. The concentration of sodium carbonate and nitrate solution is between 0.05M-0.5M, preferably 0.1M-0.3M. The nitrate solution and the sodium carbonate solution are poured into the reactor preset with the metered mesoporous silica at the same speed to carry out the co-precipitation reaction, the pH value is controlled at 7.0-7.2, and the stirring is continued for 3-5 hours after the reaction is completed. The precipitated liquid is washed with distilled water, fully beaten and filtered. Then bake and dry at a temperature of 100-120°C. The dried catalyst is then calcined under a given atmosphere. The atmosphere for firing is generally air, oxygen, nitrogen, argon or carbon dioxide, preferably air. The calcination temperature is generally 250-600°C, and the better temperature is 300-400°C. The roasting time is 2-10 hours. The calcined catalyst is made into a sample with an average particle size of 60-80 mesh through procedures such as tableting and granulation.

The activity of the catalyst provided by the present invention can be tested by the following methods: the catalyst activity evaluation is carried out in the normal pressure fixed bed flow reaction system, the stainless steel reactor (300mm * Ф10mm), the reaction temperature is controlled between 180～250 ℃, the catalyst bed temperature It is controlled by a chrome-aluminum thermocouple through a program temperature controller. When evaluating the activity, mix the catalyst with the same volume of quartz sand and put it into the constant temperature zone of the reactor. First, 5% H ₂ /Ar mixed gas is passed into the reactor, the flow rate is 80mL/min, and the temperature is programmed to 250°C to reduce and activate the catalyst for 8 hours. , then lower the temperature of the reaction furnace to the set reaction temperature, switch the argon gas, and adjust the flow rate to 30mL/min, and the argon flow will introduce the mixed solution of water and methanol into the reaction system to start the reaction. The reaction is sampled and analyzed after the set reaction temperature is stable for 2 hours. The gas produced is first cooled by the condenser, and the tail gas is sampled by the six-way valve and then enters the GC122 for online analysis. Unreacted water and methanol are injected and analyzed, and detected by a thermal conductivity detector (TCD). A workstation is used to control the sampling process and perform data processing. Two parallel chromatographic columns (Poropak-Q and TDX-01, 2m) are used to separate CH ₃ OH, higher alcohols and CO, CO ₂ , H ₂ and other products. The catalyst prepared by the invention has high low-temperature activity, good stability, high selectivity to hydrogen, simple catalyst preparation process and good repeatability. The hydrogen content in the reformed gas is 50-75vol%, and the CO concentration is 0.08-0.3vol%, which is easy to purify.

Detailed ways

The present invention will be further described below with embodiment.

Example 1

Firstly, 7.26g Cu(NO ₃ ) ₂ ·3H ₂ O, 8.91g Zn(NO ₃ ) ₂ ·6H ₂ O, 2.50g Al(NO ₃ ) ₃ ·9H ₂ O (AR grade) were respectively prepared into 0.1M The solution was post _- mixed and 7.42 g of AR grade anhydrous _Na2CO3 was made into a 0.1M solution. Then, under strong stirring conditions, the above-mentioned nitrate solution and sodium carbonate solution were dripped into the 100mL aqueous solution preset with 0.16g SBA-15 (400-600 mesh), the solution temperature was controlled at 60°C, and the pH was 7.0- 7.2. After the reaction, continue to stir for 4 hours, then wash with deionized water, fully beat, filter, and finally dry at 110°C for 12 hours, and roast at 360°C for 4 hours under the protection of nitrogen to prepare the precursor of the catalyst in the oxidation state. Cu/Zn in the sample /Al=45/45/10 (molar ratio), the weight content of SBA-15 in the catalyst oxidation state precursor is 3wt%.

The evaluation of the catalyst's hydrogen production activity in steam reforming of methanol was carried out in a fixed-bed continuous flow reactor system at atmospheric pressure (300mm×Ф10mm), and the catalyst dosage was 0.5 g. First pass 5% H ₂ /Ar mixed gas into the reactor, adjust the flow rate to 80mL/min, program the temperature to 250°C to reduce and activate the catalyst for 8 hours, then lower the temperature of the reactor to the set reaction temperature, switch the argon gas, and adjust the flow rate 30mL/min, the mixture of water and methanol was introduced into the reaction system by argon flow to start the reaction. The reaction is sampled and analyzed after the set reaction temperature is stable for 2 hours. The gas produced is first cooled by the condenser, and the tail gas is sampled by the six-way valve and then enters the GC122 for online analysis. The thermal conductivity detector (TCD) detects it. The workstation controls the sampling process and performs data processing. . The evaluation results show that under the reaction conditions of normal pressure, low temperature 230°C, n(H ₂ O)/n(CH ₃ OH)=1.1/1.0, WHSV=3.61h ^-1 , the conversion rate of methanol is 89.9%, and the hydrogen production The ratio is 0.3037, the hydrogen selectivity is 99.6%, the _CO2 selectivity is 99.4%, and the CO content in the reformed product gas is 0.14%. Compared with the experimental results in Comparative Example 1, after a small amount of SBA-15 is modified, the low-temperature activity of the catalyst is improved, the content of CO in the reformed gas is significantly reduced, and it is easy to purify.

Comparative Example 1

Conventional Cu/ZnO/ _Al2O3 catalysts with the same composition ratio and without silica mesoporous materials prepared under _the same experimental conditions. Catalytic activity evaluation is the same as in Example 1. Under the reaction conditions of normal pressure, low temperature 230°C, n(H ₂ O)/n(CH ₃ OH)=1.1/1.0, WHSV=3.61h ^-1 , the conversion rate of methanol is 83.1 %, the hydrogen yield is 0.2808, the hydrogen selectivity is 99.2%, the _CO2 selectivity is 99.0%, and the CO content in the reformed product gas is 0.25%.

Example 2

First, 7.26g Cu(NO ₃ ) ₂ ·3H ₂ O, 8.91g Zn(NO ₃ ) ₂ ·6H ₂ O, 2.50g Al(NO ₃ ) ₃ ·9H ₂ O (AR grade) were respectively prepared into 0.3M The solution was post _- mixed and 7.42 g of AR grade anhydrous _Na2CO3 was made into a 0.3M solution. Then, under strong stirring conditions, the above-mentioned nitrate solution and sodium carbonate solution were dripped into 100mL aqueous solution preset with 0.27g SBA-15, the solution temperature was controlled at 30°C, and the pH was 7.0-7.2. Continue to stir for 4 hours after the reaction, then wash with deionized water, fully beat, filter, and finally dry at 120°C for 12 hours, and bake at 300°C for 5 hours under the protection of nitrogen atmosphere to prepare the precursor of the catalyst in an oxidized state. Cu in the sample /Zn/Al=45/45/10 (molar ratio), the weight content of SBA-15 in the catalyst oxidation state precursor is 5wt%. Catalyst activity evaluation is the same as in Example 1, and the test results show that: under the reaction conditions of normal pressure, low temperature 230°C, n(H ₂ O)/n(CH ₃ OH)=1.1/1.0, WHSV=3.61h ^-1 , methanol The conversion rate was 93.4%, the hydrogen yield was 0.3156, the hydrogen selectivity was 99.9%, the _CO2 selectivity was 99.3%, and the CO content in the reformed product gas was 0.16%.

Example 3

First, 7.26g Cu(NO ₃ ) ₂ ·3H ₂ O, 8.91g Zn(NO ₃ ) ₂ ·6H ₂ O, 2.50g Al(NO ₃ ) ₃ ·9H ₂ O (AR grade) were respectively prepared into 0.5M The solution was post _- mixed and 7.42 g of AR grade anhydrous _Na2CO3 was made into a 0.5M solution. Then, under strong stirring conditions, the above-mentioned nitrate solution and sodium carbonate solution were dripped into 100mL aqueous solution preset with 0.45g SBA-15, the solution temperature was controlled at 80°C, and the pH was 7.0-7.2. After the reaction, continue to stir for 4 hours, then wash with deionized water, fully beat, filter, and finally dry at 100°C for 12 hours, and roast at 250°C for 5 hours under the protection of nitrogen to prepare the catalyst oxidation state precursor. Cu/Zn in the sample /Al=45/45/10 (mass ratio), the weight content of SBA-15 in the catalyst oxidation state precursor is 8wt%. Catalyst activity evaluation is the same as in Example 1, and the test results show that: under the reaction conditions of normal pressure, low temperature 230°C, n(H ₂ O)/n(CH ₃ OH)=1.1/1.0, WHSV=3.61h ^-1 , methanol The conversion rate was 97.1%, the hydrogen yield rate was 0.3281, the hydrogen selectivity was 99.9%, the _CO2 selectivity was 99.4%, and the CO content in the reformed product gas was 0.15%.

Example 4

Firstly, 7.26g Cu(NO ₃ ) ₂ ·3H ₂ O, 8.91g Zn(NO ₃ ) ₂ ·6H ₂ O, 2.50g Al(NO ₃ ) ₃ ·9H ₂ O (AR grade) were respectively prepared into 0.1M The solution was post _- mixed and 7.42 g of AR grade anhydrous _Na2CO3 was made into a 0.1M solution. Then, under strong stirring conditions, the above-mentioned nitrate solution and sodium carbonate solution were dripped into 100mL aqueous solution preset with 0.71g SBA-15, the solution temperature was controlled at 55°C, and the pH was 7.0-7.2. Continue to stir for 4 hours after the reaction, then wash with deionized water, fully beat, filter, and finally dry at 100°C for 12 hours, and roast at 600°C for 3 hours under the protection of nitrogen to prepare the precursor of the catalyst in the oxidation state. Cu/Zn in the sample /Al=45/45/10 (molar ratio), the weight content of SBA-15 in the catalyst oxidation state precursor is 12wt%. Catalyst activity evaluation is the same as in Example 1, and the test results show that: under the reaction conditions of normal pressure, low temperature 230°C, n(H ₂ O)/n(CH ₃ OH)=1.1/1.0, WHSV=3.61h ^-1 , methanol The conversion rate was 95.2%, the hydrogen yield was 0.3217, the hydrogen selectivity was 99.9%, the _CO2 selectivity was 99.6%, and the CO content in the reformed product gas was 0.11%.

Example 5

Firstly, 7.26g Cu(NO ₃ ) ₂ ·3H ₂ O, 8.91g Zn(NO ₃ ) ₂ ·6H ₂ O, 2.50g Al(NO ₃ ) ₃ ·9H ₂ O (AR grade) were respectively prepared into 0.1M The solution was post _- mixed and 7.42 g of AR grade anhydrous _Na2CO3 was made into a 0.1M solution. Then, under strong stirring conditions, the above-mentioned nitrate solution and sodium carbonate solution were dripped into 100mL aqueous solution preset with 0.99g SBA-15, the solution temperature was controlled at 60°C, and the pH was 7.0-7.2. Continue to stir for 4 hours after the reaction, then wash with deionized water, fully beat, filter, and finally dry at 110°C for 12h, and roast at 500°C for 3h under the protection of nitrogen to prepare the precursor of the catalyst in the oxidation state. Cu/Zn/ Al=45/45/10 (molar ratio), the weight content of SBA-15 in the catalyst oxidation state precursor is 16wt%. Catalyst activity evaluation is the same as in Example 1, and the test results show that: under the reaction conditions of normal pressure, low temperature 230°C, n(H ₂ O)/n(CH ₃ OH)=1.1/1.0, WHSV=3.61 h ^-1 , methanol The conversion rate was 87.5%, the hydrogen yield was 0.2956, the hydrogen selectivity was 99.9%, the _CO2 selectivity was 99.5%, and the CO concentration in the reformed product gas was 0.12%.

Example 6

Firstly, 7.26g Cu(NO ₃ ) ₂ ·3H ₂ O, 8.91g Zn(NO ₃ ) ₂ ·6H ₂ O, 2.50g Al(NO ₃ ) ₃ ·9H ₂ O (AR grade) were respectively prepared into 0.05M The solution was post _- mixed and 7.42 g of AR grade anhydrous _Na2CO3 was made into a 0.01M solution. Then, under strong stirring conditions, the above-mentioned nitrate solution and sodium carbonate solution were dripped into 100mL aqueous solution preset with 0.45g SiO ₂ , the solution temperature was controlled at 60°C, and the pH was 7.0-7.2. Continue to stir for 4 hours after the reaction, then wash with deionized water, fully beat, filter, and finally dry at 110°C for 12h, and bake at 360°C for 4h in an air atmosphere to prepare the precursor of the catalyst in an oxidized state. Cu/Zn/ Al=45/45/10 (molar ratio), the weight content of SiO ₂ airgel in the catalyst oxidation state precursor is 8wt%. Catalyst activity evaluation is the same as in Example 1, and the test results show that: under the reaction conditions of normal pressure, low temperature 230°C, n(H ₂ O)/n(CH ₃ OH)=1.1/1.0, WHSV=3.61h ^-1 , methanol The conversion rate was 86.3%, the hydrogen yield was 0.2916, the hydrogen selectivity was 99.6%, the _CO2 selectivity was 99.4%, and the CO content in the reformed gas was 0.14%.

Example 7

Firstly, 7.26g Cu(NO ₃ ) ₂ ·3H ₂ O, 8.91g Zn(NO ₃ ) ₂ ·6H ₂ O, 2.50g Al(NO ₃ ) ₃ ·9H ₂ O (AR grade) were respectively prepared into 0.1M The solution was post _- mixed and 7.42 g of AR grade anhydrous _Na2CO3 was made into a 0.1M solution. Then, under strong stirring conditions, the above nitrate solution and sodium carbonate solution were added dropwise into 100mL aqueous solution pre-prepared with 0.45g MCM-41, the solution temperature was controlled at 65°C, and the pH was 7.0-7.2. Continue to stir for 4 hours after the reaction, then wash with deionized water, fully beat, filter, and finally dry at 110°C for 12h, and roast at 400°C for 4h under the protection of argon to prepare the precursor of the catalyst in the oxidation state. Cu/Zn in the sample /Al=45/45/10 (molar ratio), the weight content of MCM-41 in the catalyst oxidation state precursor is 8wt%. Catalyst activity evaluation is the same as in Example 1, and the test results show that: under the reaction conditions of normal pressure, low temperature 230°C, n(H ₂ O)/n(CH ₃ OH)=1.1/1.0, WHSV=3.61h ^-1 , methanol The conversion rate was 87.9%, the hydrogen yield was 0.2970, the hydrogen selectivity was 99.7%, the _CO2 selectivity was 99.5%, and the CO content in the reformed gas was 0.13%. Referring to comparative experiment 1, the low-temperature catalytic performance of the catalyst after MCM-41 modification is improved, and the content of CO in the reformed gas is reduced to a considerable extent.

Example 8

Firstly, 7.26g Cu(NO ₃ ) ₂ ·3H ₂ O, 8.91g Zn(NO ₃ ) ₂ ·6H ₂ O, 2.50g Al(NO ₃ ) ₃ ·9H ₂ O (AR grade) were respectively prepared into 0.1M The solution was post _- mixed and 7.42 g of AR grade anhydrous _Na2CO3 was made into a 0.1M solution. Then, under strong stirring conditions, the above-mentioned nitrate solution and sodium carbonate solution were added dropwise into 100 mL aqueous solution pre-prepared with 0.45 g of mesoporous silica gel. The temperature of the solution was controlled at 50° C., and the pH was 7.0-7.2. Continue to stir for 4 hours after the reaction, then wash with deionized water, fully beat, filter, and finally dry at 110°C for 12 hours, and roast at 360°C for 4 hours under the protection of nitrogen to prepare the precursor of the catalyst in the oxidation state. Cu/Zn/ Al=45/45/10 (molar ratio), the weight content of the mesoporous silica gel in the catalyst oxidation state precursor is 8wt%. Catalyst activity evaluation is the same as in Example 1, and the test results show that: under the reaction conditions of normal pressure, low temperature 230°C, n(H ₂ O)/n(CH ₃ OH)=1.1/1.0, WHSV=3.61h ^-1 , methanol The conversion rate was 85.7%, the hydrogen yield rate was 0.2970, the hydrogen selectivity was 99.7%, the _CO2 selectivity was 99.5%, and the CO content in the reformed gas was 0.19%.

Example 9

Firstly, 9.68g Cu(NO ₃ ) ₂ ·3H ₂ O, 5.94g Zn(NO ₃ ) ₂ ·6H ₂ O, 2.50g Al(NO ₃ ) ₃ ·9H ₂ O (AR grade) were respectively prepared into 0.1M The solution was post _- mixed and 7.42 g of AR grade anhydrous _Na2CO3 was made into a 0.1M solution. Then, under strong stirring conditions, the above-mentioned nitrate solution and sodium carbonate solution were dripped into 100mL aqueous solution preset with 0.71g SBA-15, the solution temperature was controlled at 60°C, and the pH was 7.0-7.2. Continue to stir for 4 hours after the reaction, then wash with deionized water, fully beat, filter, and finally dry at 110°C for 12 hours, and bake at 360°C for 4 hours in an air atmosphere to prepare the precursor of the catalyst in an oxidized state. Cu/Zn in the sample /Al=60/30/10 (molar ratio), the weight content of SBA-15 in the catalyst oxidation state precursor is 12wt%. Catalyst activity evaluation is the same as in Example 1, and the test results show that: under the reaction conditions of normal pressure, low temperature 230°C, n(H ₂ O)/n(CH ₃ OH)=1.1/1.0, WHSV=3.61h ^-1 , methanol The conversion rate was 90.2%, the hydrogen yield was 0.3048, the hydrogen selectivity was 99.9%, the _CO2 selectivity was 99.6%, and the CO content in the reformed gas was 0.08%.

Example 10

First, 7.26g Cu(NO ₃ ) ₂ ·3H ₂ O, 8.91g Zn(NO ₃ ) ₂ ·6H ₂ O, 2.50g Al(NO ₃ ) ₃ ·9H ₂ O (AR grade) were respectively prepared into 0.3M After the solution was mixed, 7.42g of AR grade anhydrous Na ₂ CO ₃ was prepared into a 0.3]M solution. Then, under strong stirring conditions, the above-mentioned nitrate solution and sodium carbonate solution were dripped into 100mL aqueous solution preset with 1.48g SBA-15, the solution temperature was controlled at 60°C, and the pH was 7.0-7.2. Continue to stir for 4 hours after the reaction, then wash with deionized water, fully beat, filter, and finally dry at 110°C for 12 hours, and bake at 500°C for 4 hours in an air atmosphere to prepare the catalyst oxidation state precursor. Cu/Zn in the sample /Al=45/45/10 (molar ratio), the weight content of SBA-15 in the catalyst oxidation state precursor is 25wt%. Catalyst activity evaluation is the same as in Example 1, and the test results show that: under the reaction conditions of normal pressure, low temperature 230°C, n(H ₂ O)/n(CH ₃ OH)=1.1/1.0, WHSV=3.61h ^-1 , methanol The conversion rate was 89.2%, the hydrogen yield was 0.3007, the hydrogen selectivity was 99.9%, the _CO2 selectivity was 99.6%, and the CO content in the reformed gas was 0.13%.

Example 11

First, 11.30g Cu(NO ₃ ) ₂ ·3H ₂ O, 5.94g Zn(NO ₃ ) ₂ ·6H ₂ O (AR grade) were prepared into 0.1M solution and mixed, then 7.42g AR grade anhydrous Na ₂ CO ₃ was prepared as a 0.1M solution. Then, under strong stirring conditions, the above-mentioned nitrate solution and sodium carbonate solution were dripped into 100mL aqueous solution preset with 0.71g SBA-15, the solution temperature was controlled at 60°C, and the pH was 7.0-7.2. After the reaction, continue to stir for 4 hours, then wash with deionized water, fully beat, filter, and finally dry at 110°C for 12 hours, and bake at 360°C for 4 hours in a carbon dioxide atmosphere to prepare the precursor of the catalyst in an oxidized state. Cu/Zn in the sample /Al=70/30/0 (molar ratio), the weight content of SBA-15 in the catalyst oxidation state precursor is 12wt%. Catalyst activity evaluation is the same as in Example 1, and the test results show that: under the reaction conditions of normal pressure, low temperature 230°C, n(H ₂ O)/n(CH ₃ OH)=1.1/1.0, WHSV=3.61h ^-1 , methanol The conversion rate was 84.2%, the hydrogen yield rate was 0.2838, the hydrogen selectivity was 99.9%, the _CO2 selectivity was 99.6%, and the CO content in the reformed gas was 0.18%.

Comparing the low-temperature catalytic performance of copper-based methanol steam reforming hydrogen production catalysts modified by various new mesoporous silica materials, it can be seen that the new mesoporous molecular sieve SBA-15 with regular mesoporous pore structure, copper The activity of methanol-based steam reforming catalyst for hydrogen production is improved, and the content of CO in the gas is reduced. In particular, the new SBA-15 mesoporous molecular sieve modified copper-based catalyst shows the best catalytic performance, and the content of SBA-15 The performance of the catalyst is the best when it is 3-12wt.%.

Claims (6)

1, the silicon oxide mesoporous molecular sieve modified copper-based catalysts used of a kind of steam reformation of methanol to produce hydrogen is characterized in that by CuO/ZnO/Al ₂O ₃Active component and silicon oxide mesoporous molecular sieve are formed, wherein active component CuO/ZnO/Al ₂O ₃Weight percentage be 70-99wt%; Remaining 1-30wt% is silicon oxide mesoporous molecular sieve; Said CuO/ZnO/Al ₂O ₃CuO content is in the 30-70% mol ratio in the active component, and ZnO content is at 20-60% mol ratio, Al ₂O ₃Content is in the 0-15% mol ratio, and three's total amount satisfies 100% mol ratio.

2,, it is characterized in that said silicon oxide mesoporous molecular sieve is a kind of among SBA-15, the MCM-41 according to the described catalyst of claim 1.

3, the preparation method of the silicon oxide mesoporous molecular sieve modified copper-based catalysts used of a kind of steam reformation of methanol to produce hydrogen as claimed in claim 1, it is characterized in that: by usage ratio, under stirring, 30-80 ℃ condition, with the aqueous solution of sodium carbonate and contain copper, zinc and aluminium nitrate the aqueous solution with and the stream mode join in the pre-dispersed aqueous solution that the silicon oxide mesoporous molecular sieve of specified rate arranged, carry out coprecipitation reaction, aging; Wash again, drying, roasting, granulation promptly gets this catalyst.

4, Preparation of catalysts method according to claim 3, the concentration that it is characterized in that sodium carbonate and nitrate aqueous solution is 0.01-0.5M.

5, Preparation of catalysts method according to claim 3 is characterized in that calcination atmosphere is air, nitrogen, argon gas or carbon dioxide.

6, Preparation of catalysts method according to claim 3 is characterized in that sintering temperature is 250-600 ℃, and roasting time is 2-10 hour.