阅读说明：本技术 一种铜基复合金属催化剂的制备方法 (Preparation method of copper-based composite metal catalyst ) 是由 高继明 王小鹏 沈志杰 蒋彪 于 2020-07-01 设计创作，主要内容包括：本发明公开了一种铜基复合金属催化剂的制备方法,所述铜基复合金属催化剂用于甲醇水重整制氢技术中,其中SBA-15分子筛为载体,ZnO为助催化剂,CuO为主催化剂,本发明经过活化后的SBA-15分子筛在表面活性剂CTAB的作用下,铜离子与锌离子经高温焙烧氧化后的得到不同活性组份负载量的CuO-ZnO/SBA-15,金属粒子的均匀分布代表更多的接触活性位点,从而表现出优异的催化活性。活化后的SBA-15存在大量微孔和介孔,表面积增大有利于催化剂的局部散热,且具有很好的机械性能,分子筛中少量的金属氧化物和二氧化硅增加整体催化剂的热稳定性。在甲醇水蒸气重整制氢反应中,在较高反应温度的条件下,表现出高氢气选择性和低一氧化碳选择性,以及较长的使用寿命。(The invention discloses a preparation method of a copper-based composite metal catalyst, which is used in the technology of hydrogen production by reforming methanol water, wherein an SBA-15 molecular sieve is used as a carrier, ZnO is used as an auxiliary catalyst, and CuO is used as a main catalyst. The activated SBA-15 has a large number of micropores and mesopores, the surface area is increased, the local heat dissipation of the catalyst is facilitated, the catalyst has good mechanical properties, and the thermal stability of the whole catalyst is improved by a small amount of metal oxide and silicon dioxide in the molecular sieve. In the methanol steam reforming hydrogen production reaction, high hydrogen selectivity and low carbon monoxide selectivity are shown under the condition of higher reaction temperature, and the service life is longer.)

1. A preparation method of a copper-based composite metal catalyst is used in a methanol-water reforming hydrogen production technology, wherein an SBA-15 molecular sieve is used as a carrier, and the SBA-15 molecular sieve contains SiO₂And a small amount of metal oxide, ZnO is taken as an auxiliary catalyst, CuO is taken as a main catalyst, and the method is characterized by comprising the following operation steps:

s1: firstly preparing a solution A of zinc salt and copper salt precursor ethanol/water, wherein the concentration of copper ions and the concentration of zinc ions in the solution A are both 0.1-1mol/L, the volume of the solution A is the volume of a mixed solution of ethanol and water, then transferring the mixed solution into a three-neck flask, setting the temperature of an oil bath, carrying out thermal stirring and heating, wherein the temperature of the oil bath is 40-100 ℃, and the time is 20-60 min;

s2: dispersing a quantitatively prepared SBA-15 molecular sieve in 20-100mL of water by ultrasonic, stirring at room temperature for 2-45min, adding 0.1-5mL of 0.05M sodium hydroxide solution, continuously stirring at room temperature for 0-5min, washing with deionized water for three times, and freeze-drying in a freeze-drying box for 12h to obtain activated SBA-15 and solid powder B;

s3: dispersing 0.1-1g of the solid powder B in 20-100mL of water, placing the mixture in an oil bath pan, stirring at a constant temperature of 65 ℃ for 2-15min, adding 0.01-0.1g of hexadecyl trimethyl ammonium bromide, and continuously stirring for 2-15min to obtain a suspension C;

s4: dropwise adding a certain volume of the solution A into the suspension C, continuously stirring at a constant temperature of 65 ℃ for 1-20min after dropwise adding is finished, transferring to a 100mL tetrafluoroethylene removing kettle, placing in a constant temperature oven to react at 100 ℃ for 6-12h, naturally cooling, washing the dark gray product with water and ethanol for three times respectively, and drying to obtain a solid product D;

s5: and (3) placing the solid powder D in a muffle furnace, roasting under the air condition, heating to 200-800 ℃ at the heating rate of 1-10 ℃/min, preserving the temperature for 2-6h, and naturally cooling to obtain the CuOx-ZnOy/SBA-15 composite metal catalyst.

2. The method of claim 1, wherein the copper salt is one or more of copper dichloride, copper nitrate, copper sulfate pentahydrate, copper acetate, and copper nitrate.

3. The method for preparing the copper-based composite metal catalyst according to claim 1, wherein the zinc salt is one or more of zinc dichloride, zinc acetate and zinc nitrate.

4. The preparation method of the copper-based composite metal catalyst according to claim 1, wherein the water is deionized water, the ethanol is industrial ethanol with a purity of 98%, and the volume ratio of the water to the ethanol is 1-5.

5. The method for preparing the copper-based composite metal catalyst as recited in claim 1, wherein the muffle furnace is under air condition, the calcination temperature is 300-800 ℃, and the calcination time is 1-5 h.

6. The method for preparing a copper-based composite metal catalyst according to claim 1, wherein in the water bath heating stirring condition: the oil bath temperature is 40-150 ℃, the magnetons are stirred by magnetic force, and the stirring speed is 300-800 rmp/min.

7. The preparation method of the copper-based composite metal catalyst according to claim 1, wherein the mixture is ultrasonically dispersed in the water/ethanol mixed solution for 1-3 hours at an ultrasonic frequency of 50-150 kHz, 80-150 kHz, and/or 100-150 kHz.

8. The preparation method of the copper-based composite metal catalyst according to claim 1, wherein the mixture is washed and centrifuged three times by the deionized water and the ethanol in sequence, the centrifugation speed is 5000 to 10000rmp/min, the mixture is dried in the constant temperature oven at the constant temperature of 40 to 80 ℃ for 8 to 12 hours, the reaction temperature of the constant temperature oven ranges from 50 to 200 ℃, and the reaction time is 4 to 50 hours.

Technical Field

The invention relates to the technical field of catalyst preparation, in particular to a preparation method of a copper-based composite metal catalyst.

Background

The continuous development of social economy, the continuous improvement of the demand of people on primary fossil energy, and the subsequent serious environmental problems of greenhouse gas, acid rain, air pollution, unregulated emission of toxic and harmful wastes, and the like, are brought, so that a green new energy capable of replacing the fossil energy is urgently needed, the new energy is not only nontoxic, but also combustion products are nontoxic and harmless, and hydrogen is one of the most potential ideal energy in recent years.

The hydrogen production process by reforming methanol water is a main means for preparing hydrogen at present, has the advantages of simple raw materials (methanol and water), clean products and the like, is gradually mature in the development of the chemical field in the long term, is regarded as one of important hydrogen production means along with the advocation and continuous popularization of using novel green energy by the country, and can better exert the function and greatly improve the life of human beings by being combined with a fuel cell.

The methanol steam reforming reaction is a strongly endothermic reaction, and the reaction products are hydrogen and carbon monoxide/carbon dioxide. In the existing methanol water reforming hydrogen production technology, the copper-based catalyst has proved to be best in various reforming hydrogen production metal catalysts, wherein the copper-zinc-aluminum catalyst has wider application, but the further popularization is greatly limited due to the defects of no high temperature resistance, easy sintering and the like. Meanwhile, noble metals such as gold, silver, platinum, palladium and the like and transition metals are combined and loaded on one or more carriers to serve as composite metal methanol-water reforming hydrogen production catalysts, and the catalysts are excellent in high temperature resistance and service life, but the high cost hinders the popularization path.

In view of the above, there is an urgent need to develop a catalyst for methanol-water reforming hydrogen production with low carbon monoxide selectivity and better thermal stability.

Disclosure of Invention

The invention aims to solve the technical problem of providing a preparation method of a copper-based composite metal catalyst with better thermal stability, high activity and high hydrogen selectivity.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a preparation method of a copper-based composite metal catalyst, which comprises the following stepsThe copper-based composite metal catalyst is used in methanol water reforming hydrogen production technology, wherein the SBA-15 molecular sieve is used as a carrier, and the SBA-15 molecular sieve contains SiO₂And a small amount of metal oxide, ZnO as an auxiliary catalyst and CuO as a main catalyst, and the method specifically comprises the following operation steps:

s1: firstly preparing a solution A of zinc salt and copper salt precursor ethanol/water, wherein the concentration of copper ions and the concentration of zinc ions in the solution A are both 0.1-1mol/L, the volume of the solution A is the volume of a mixed solution of ethanol and water, then transferring the mixed solution into a three-neck flask, setting the temperature of an oil bath, carrying out thermal stirring and heating, wherein the temperature of the oil bath is 40-100 ℃, and the time is 20-60 min;

s2: dispersing a quantitatively prepared SBA-15 molecular sieve in 20-100mL of water by ultrasonic, stirring at room temperature for 2-45min, adding 0.1-5mL of 0.05M sodium hydroxide solution, continuously stirring at room temperature for 0-5min, washing with deionized water for three times, and freeze-drying in a freeze-drying box for 12h to obtain activated SBA-15 and solid powder B;

s3: dispersing 0.1-1g of the solid powder B in 20-100mL of water, placing the mixture in an oil bath pan, stirring at a constant temperature of 65 ℃ for 2-15min, adding 0.01-0.1g of hexadecyl trimethyl ammonium bromide, and continuously stirring for 2-15min to obtain a suspension C;

s4: dropwise adding a certain volume of the solution A into the suspension C, continuously stirring at a constant temperature of 65 ℃ for 1-20min after dropwise adding is finished, transferring to a 100mL tetrafluoroethylene removing kettle, placing in a constant temperature oven to react at 100 ℃ for 6-12h, naturally cooling, washing the dark gray product with water and ethanol for three times respectively, and drying to obtain a solid product D;

s5: placing the solid powder D in a muffle furnace, roasting under the air condition, heating up to 200-800 ℃ at the heating rate of 1-10 ℃/min, keeping the temperature for 2-6h, and naturally cooling to obtain CuO_x-ZnO_yThe catalyst is a composite metal catalyst of SBA-15.

Preferably, the copper salt is one or more of copper dichloride, and/or copper nitrate, and/or copper sulfate pentahydrate, and/or copper acetate, and/or copper nitrate.

Preferably, the zinc salt is one or more of zinc dichloride, zinc acetate and zinc nitrate.

Preferably, the water is deionized water, the ethanol is industrial ethanol with the purity of 98%, and the volume ratio of the water to the ethanol is 1-5.

Preferably, the muffle furnace is in an air condition, the roasting temperature is 300-800 ℃, and the roasting time is 1-5 h;

preferably, in the water bath heating and stirring condition: the oil bath temperature is 40-150 ℃, the magnetons are stirred by magnetic force, and the stirring speed is 300-800 rmp/min.

Preferably, the mixture is subjected to ultrasonic dispersion in a water/ethanol mixed solution, the ultrasonic dispersion time is 1-3 hours, and the ultrasonic frequency is 50-150 kHz, 80-150 kHz and/or 100-150 kHz.

Preferably, the mixture is washed and centrifuged for three times by the deionized water and the ethanol in sequence, the centrifugation speed is 5000 to 10000rmp/min, the mixture is dried in the constant-temperature oven at the constant temperature of 40 to 80 ℃ for 8 to 12 hours, the reaction temperature range of the constant-temperature oven is 50 to 200 ℃, and the reaction time is 4 to 50 hours.

The invention has the advantages and beneficial effects that:

(1) in the composite metal catalyst prepared by the invention, CuO and ZnO metals are uniformly dispersed in the porous SBA-15 pore channel and on the surface of the pore channel, and the uniform distribution of metal particles represents more contact active sites, thereby showing excellent catalytic activity.

(2) The activated and modified SBA-15 has a large number of micropores and mesopores, the surface area is increased, the local heat dissipation of the catalyst is facilitated, the catalyst has good mechanical properties, and the thermal stability of the whole catalyst is improved by a small amount of metal oxide and silicon dioxide in the molecular sieve.

(3) In the methanol steam reforming hydrogen production reaction, high hydrogen selectivity and low carbon monoxide selectivity are shown under the condition of higher reaction temperature, and the service life is longer.

Drawings

FIG. 1 is a flow chart of an embodiment of a method for preparing a copper-based composite metal catalyst according to the present invention.

Detailed Description

The following further describes embodiments of the present invention with reference to the drawings. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

As shown in figure 1, the preparation method of the copper-based composite metal catalyst is used in the technology of hydrogen production by methanol-water reforming, wherein the SBA-15 molecular sieve is used as a carrier, and the SBA-15 molecular sieve contains SiO₂And a small amount of metal oxide, ZnO as an auxiliary catalyst and CuO as a main catalyst, and the method specifically comprises the following operation steps:

s1: firstly preparing a solution A of zinc salt and a precursor ethanol/water of copper salt, wherein the concentration of copper ions and the concentration of zinc ions in the solution A are both 0.1-1mol/L, the volume of the solution A is the volume of a mixed solution of ethanol and water, then transferring the mixed solution into a three-neck flask, setting the temperature of an oil bath, heating by stirring, and setting the temperature of the oil bath to be 40-100 ℃ for 20-60 min;

s2: and (2) dispersing a quantitatively prepared SBA-15 molecular sieve in 20-100mL of water by ultrasonic, stirring at room temperature for 2-45min, adding 0.1-5mL of 0.05M sodium hydroxide solution, continuously stirring at room temperature for 0-5min, washing with deionized water for three times, and then placing in a freeze drying box for freeze drying for 12h to obtain the activated SBA-15 and solid powder B.

S3: dispersing 0.1-1g of the solid powder B in 20-100mL of water, placing the mixture in an oil bath pan, stirring at a constant temperature of 65 ℃ for 2-15min, adding 0.01-0.1g of hexadecyl trimethyl ammonium bromide, and continuously stirring for 2-15min to obtain a suspension C;

s4: dropwise adding a certain volume of the solution A into the suspension C, continuously stirring at a constant temperature of 65 ℃ for 1-20min after dropwise adding is finished, transferring to a 100mL tetrafluoroethylene removing kettle, placing in a constant-temperature oven to react at 100 ℃ for 6-12h, naturally cooling, washing the dark gray product with water and ethanol for three times respectively, and drying to obtain a solid product D;

s5: and (3) placing the solid powder D in a muffle furnace, roasting under the air condition, heating to 200-800 ℃ at the heating rate of 1-10 ℃/min, preserving the temperature for 2-6h, and naturally cooling to obtain the CuOx-ZnOy/SBA-15 composite metal catalyst.

Specifically, the invention provides a novel metal composite catalyst aiming at the high-temperature sintering problem generated in the reforming hydrogen production reaction of a copper-based catalyst, the main active components are CuO and ZnO, the carrier is a porous SBA-15 molecular sieve, under the action of a surfactant CTAB, copper ions and zinc ions can be attached to the inner wall and outer wall pore channels of the molecular sieve, CuO-ZnO/SBA-15/SBA-15 with different active component loading amounts obtained after high-temperature roasting and oxidation is used as the carrier, SiO2 in the molecular sieve and a small amount of metal oxide in the molecular sieve also play a role in heat conduction and improve the local sintering problem, and the CuO-ZnO/SBA-15 composite metal catalyst with high activity and high hydrogen selectivity has better thermal stability.

In a preferred embodiment of the invention, the copper salt is one or more of copper dichloride, and/or copper nitrate, and/or copper sulfate pentahydrate, and/or copper acetate, and/or copper nitrate.

In a preferred embodiment of the invention, the zinc salt is one or more of zinc dichloride, zinc acetate and zinc nitrate.

In a preferred embodiment of the present invention, the water is deionized water, the ethanol is industrial ethanol with a purity of 98%, and the volume ratio of the water to the ethanol is 1-5.

5. The preparation method of the copper-based composite metal catalyst as claimed in claim 1, wherein the muffle furnace is in air condition, the calcination temperature is 300-800 ℃, and the calcination time is 1-5 h;

in the preferred embodiment of the present invention, in the water bath heating and stirring condition: the oil bath temperature is 40-150 ℃, the magnetons are stirred by magnetic force, and the stirring speed is 300-800 rmp/min.

In a preferred embodiment of the invention, the mixture is ultrasonically dispersed in the water/ethanol mixed solution, the ultrasonic dispersion time is 1-3 h, and the ultrasonic frequency is 50-150 kHz, 80-150 kHz and/or 100-150 kHz.

In a preferred embodiment of the invention, the mixture is washed and centrifuged for three times by deionized water and ethanol sequentially, the centrifugation speed is 5000 rmp/min-10000 rmp/min, the mixture is dried for 8-12 h at the constant temperature of 40-80 ℃ in a constant temperature oven, the reaction temperature range of the constant temperature oven is 50-200 ℃, and the reaction time is 4-50 h.

Specifically, in this embodiment, the reaction conditions for hydrogen production by methanol-water reforming are as follows: the hourly space velocity of the methanol water solution is 0.02-10kg/h × kgcat, the reaction temperature is 100-. The reaction conditions of the invention are as follows: the liquid hourly space velocity of the methanol/water is 2-5kg/h × kgcat, the reaction temperature is 180-.

Reforming reactor model: the inner diameter is 12mm, the catalyst filling amount is 4g, the raw material gas firstly passes through a thermal evaporator and then passes through a catalyst bed layer from top to bottom, a heating jacket is arranged around the reformer for providing reaction temperature, and the product gas is detected on line by Agilent GC-8860.

The methanol steam reforming hydrogen production reaction of the invention can be carried out in one or more combined devices of a fixed bed reactor, a fluidized bed reactor or a slurry bed reactor which meet the reaction conditions. In this example, a fixed bed reactor was selected.

Other embodiments of the invention are as follows:

the first embodiment:

(1) dissolving 5.6g of copper nitrate and 1.8g of zinc nitrate in a mixed solution of 40mL of water and 60mL of ethanol, placing the mixed solution in an oil bath kettle, keeping the temperature constant at 75 ℃, and stirring for 20min to obtain a mixed solution A;

(2) ultrasonically dissolving 2g of SBA-15 into 100mL of water, stirring for 15min at room temperature, adding 5mL of 0.05M sodium hydroxide solution, continuously stirring for 1min at room temperature, washing with deionized water for three times, and freeze-drying in a freeze-drying oven for 12h to obtain activated SBA-15 and solid powder B;

(3) dispersing the 0.8g of solid powder B in 100mL of water, placing the mixture in an oil bath kettle, stirring at the constant temperature of 65 ℃ for 15min, adding 0.05g of hexadecyl trimethyl ammonium bromide, and continuously stirring for 5min to obtain a suspension C;

(4) dropwise adding 10mL of the solution A into the suspension C, continuously stirring at a constant temperature of 75 ℃ for 20min after dropwise adding is finished, transferring the suspension C into a 100mL tetrafluoroethylene removing kettle, placing the kettle into a constant-temperature oven to react for 8h at a temperature of 100 ℃, naturally cooling, washing the dark gray product with water and ethanol for three times respectively, and drying to obtain a solid product D;

(5) placing the solid powder D in a muffle furnace, roasting under the air condition, heating to 300 ℃ at the heating rate of 2 ℃/min, keeping the temperature for 3h, and naturally cooling to obtain CuO_21.37-ZnO_6.6the/SBA-15 composite metal catalyst takes the mass sum of metal oxide and SBA-15 as the total mass, the mass fraction of copper oxide is 21.36 wt%, and the mass fraction of zinc oxide is 6.6 wt%.