Catalysts for methanol cracking or methanol reforming to produce hydrogen, their preparation methods, and methods for methanol cracking and reforming to produce hydrogen.

Abstract

This invention relates to the field of catalysts and discloses a catalyst for methanol cracking to produce hydrogen or methanol reforming to produce hydrogen. The catalyst comprises an active component, an additive, and a support. The active component is copper, and the support is silica. The additive includes any one of nickel, zirconium, cobalt, and zinc. Based on the mass of the catalyst, the content of the active component is 25%-55 wt%, the content of the additive is 1 wt%-7 wt%, and the content of the support is 44 wt%-68 wt%. When used for methanol cracking to produce hydrogen and methanol reforming to produce hydrogen, the catalyst achieves methanol conversion rates of up to 99.8% and 100%, respectively, and H2 selectivity of up to 99.5% and 99.2%, respectively. Furthermore, the catalyst retains high catalytic activity after 220 hours of operation.

Description

Technical Field

[0001] This invention relates to the field of catalysts, specifically to a catalyst for methanol cracking and methanol reforming to produce hydrogen, a method for preparing the catalyst, and a method for methanol cracking and reforming to produce hydrogen. Background Technology

[0002] Hydrogen is abundant on Earth and produces only water when burned, making it one of the cleanest energy sources. Compared to traditional fossil fuels, hydrogen combustion has a thermal efficiency approximately 15% higher. Currently, hydrogen fuel cells, using hydrogen as a feedstock, offer advantages such as high efficiency, zero pollution, and low noise, attracting widespread attention from the automotive industry. Hydrogen is also a fundamental industrial raw material, widely used in petrochemicals, fine chemicals, and metallurgy. However, while hydrogen is an ideal energy source and a basic chemical feedstock, its incompressibility and difficulty in storage limit its widespread application. Therefore, finding an efficient hydrogen production process has become a hot research topic in recent years.

[0003] Hydrogen can be produced by various methods, and methanol-to-hydrogen is one of the most convenient. The methanol-to-hydrogen process has the following advantages: (1) Methanol, as a basic raw material in the chemical industry, can be obtained from traditional energy sources such as coal and natural gas; (2) Methanol is easy to package, transport, store, and transport, and is inexpensive, making it suitable for a wide range of small and medium-sized hydrogen-consuming enterprises; (3) Methanol has a high carbon-to-hydrogen ratio, making it easy to reform and decompose to produce hydrogen; (4) The products of methanol-to-hydrogen are simple and do not contain nitrogen or sulfur polluting compounds; (5) Methanol, as a hydrogen source storage medium, has high hydrogen storage density and does not require high-pressure storage. Therefore, methanol has received widespread attention as a hydrogen supply raw material.

[0004] The main methods for producing hydrogen from methanol include methanol cracking and methanol steam reforming. The main products of methanol cracking are hydrogen and carbon monoxide syngas, while the main products of methanol steam reforming are hydrogen and carbon dioxide. The core research focus for both methods lies in catalyst development. Currently, traditional copper-zinc-aluminum catalysts still face several challenges in methanol cracking. Excessive reaction temperatures can lead to catalyst sintering and deactivation, and copper-based catalysts suffer from coking and spontaneous combustion in air. Furthermore, due to the slight differences between methanol cracking and methanol steam reforming, there are few reports on copper-based catalysts used in either reaction system.

[0005] Therefore, the development of novel bifunctional catalysts for methanol cracking and methanol steam reforming is of profound significance in the fields of fuel cells and fine chemicals. Summary of the Invention

[0006] The purpose of this invention is to overcome the problem of low activity of methanol-to-hydrogen catalysts in the prior art, and to provide a catalyst for methanol cracking and methanol reforming to produce hydrogen, a method for preparing the catalyst, and a method for methanol cracking and reforming to produce hydrogen.

[0007] To achieve the above objectives, the first aspect of the present invention provides a catalyst for methanol cracking to produce hydrogen or methanol reforming to produce hydrogen, wherein the catalyst comprises: an active component, an additive, and a support;

[0008] The active component is copper, and the carrier is silicon dioxide.

[0009] The additives include any one of nickel, zirconium, cobalt and zinc;

[0010] Specifically, based on the mass of the catalyst, the content of the active component is 25wt%-55wt%, the content of the auxiliary agent is 1wt%-7wt%, and the content of the support is 44wt%-68wt%.

[0011] A second aspect of the present invention provides a method for preparing a catalyst for methanol cracking to produce hydrogen or methanol reforming to produce hydrogen, wherein the method includes the following steps:

[0012] (1) Dissolve the copper precursor and the precursor of the active component in water to prepare a first mixture;

[0013] (2) Mix the first mixture, ammonia and silica sol to obtain the second mixture;

[0014] (3) The second mixture is heated and aged;

[0015] (4) The product obtained in step (3) is subjected to reduction treatment to obtain a solid catalyst;

[0016] The active ingredient includes at least one of nickel, zirconium, and zinc.

[0017] The amount of the copper precursor and the precursor of the co-active component is such that, based on the total weight of the solid catalyst, the copper content is 25wt%-55wt% and the co-active component, calculated as metal element, is 1wt%-7wt%.

[0018] A third aspect of the present invention provides a method for producing hydrogen from methanol through cracking or reforming, wherein the method includes: reacting a cracking or reforming catalyst with methanol through cracking; or reacting a cracking or reforming catalyst with methanol through reforming.

[0019] The cracking or reforming catalyst is the catalyst described in the first aspect of the present invention or the catalyst prepared by the method described in the second aspect.

[0020] Through the above technical solution, the present invention achieves the following beneficial effects:

[0021] (1) The catalyst prepared by the method of the present invention has a uniformly dispersed active component, good low-temperature activity and high stability, and is a bifunctional catalyst that can be used for methanol cracking to produce hydrogen and methanol steam reforming to produce hydrogen.

[0022] (2) The catalyst preparation method of the present invention is simple. When the catalyst is used for methanol cracking to produce hydrogen, the methanol conversion rate can reach 99.8%, the H2 selectivity is as high as 99.5%, the CH4 and CO2 concentrations are 0.30% and 0.41%, respectively, and the catalyst still has high catalytic activity after continuous reaction for 220 hours, which is suitable for industrial production requirements.

[0023] (3) When the catalyst of the present invention is used for methanol steam reforming to produce hydrogen, the methanol conversion rate is as high as 100%, the H2 selectivity is as high as 99.2%, the CO concentration of the product gas is only 0.51%, and the catalyst still has high catalytic activity after continuous reaction for 260 hours, which is suitable for industrial production requirements. Attached Figure Description

[0024] Figure 1 The images show the X-ray diffraction patterns of the calcined powders of the catalysts in Comparative Examples 1-4.

[0025] Figure 2 The H2-TPR spectra of the catalysts in Comparative Examples 1-4 are shown.

[0026] Figure 3 The images show the X-ray diffraction patterns of the calcined powders of the catalysts in Examples 2-4 and Comparative Example 3.

[0027] Figure 4 The images show X-ray diffraction patterns of the reduced powder catalysts in Examples 2-4 and Comparative Example 3.

[0028] Figure 5 This is a TEM image of the calcined catalyst in Example 2.

[0029] Figure 6 The graph shows the relationship between the methanol cracking activity of the catalysts in Example 2 and Comparative Example 3 and time.

[0030] Figure 7 The graph shows the relationship between the methanol steam reforming activity of the catalysts in Example 2 and Comparative Example 3 and time. Detailed Implementation

[0031] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0032] The first aspect of the present invention provides a catalyst for methanol cracking to produce hydrogen or methanol reforming to produce hydrogen, wherein the catalyst comprises: an active component, an additive, and a support;

[0033] The active component is copper, and the carrier is silicon dioxide.

[0034] The additives include at least one of nickel, zirconium, cobalt and zinc;

[0035] Specifically, based on the mass of the catalyst, the content of the active component is 25wt%-55wt%, the content of the auxiliary agent is 1wt%-7wt%, and the content of the support is 44wt%-68wt%.

[0036] According to some embodiments of the present invention, the mass ratio of the active component to the carrier is (0.33-1.2):1; the mass ratio of the adjuvant to the carrier is (0.01-0.1):1.

[0037] In this invention, when the amounts of the active component, additive, and support meet the above-mentioned limits, the methanol conversion rate is as high as 99.8% and 100% respectively, and the H2 selectivity is as high as 99.5% and 99.2% respectively when the catalyst is used for methanol cracking to produce hydrogen and methanol reforming to produce hydrogen. Moreover, the catalyst still has high catalytic activity after running for 220 hours. When the above limits are not met, the activity will decrease.

[0038] According to some embodiments of the present invention, the additive is nickel and / or zirconium.

[0039] According to some embodiments of the present invention, the catalyst has a specific surface area of ​​400-600 m². 2 / g, pore volume 0.3-1cm 3 / g, with a pore size of 2.5-8.5nm.

[0040] A second aspect of the present invention provides a method for preparing a catalyst for methanol cracking to produce hydrogen or methanol reforming to produce hydrogen, wherein the method includes the following steps:

[0041] (1) Dissolve the copper precursor and the precursor of the active component in water to prepare a first mixture;

[0042] (2) Mix the first mixture, ammonia and silica sol to obtain the second mixture;

[0043] (3) The second mixture is heated and aged;

[0044] (4) The product obtained in step (3) is subjected to reduction treatment to obtain a solid catalyst;

[0045] The auxiliary active component includes any one of nickel, zirconium, cobalt and zinc;

[0046] The amount of the copper precursor and the precursor of the co-active component is such that, based on the total weight of the solid catalyst, the copper content is 25wt%-55wt% and the co-active component, calculated as metal element, is 1wt%-7wt%.

[0047] According to some embodiments of the present invention, the mass percentage of silicon dioxide in the silica sol is 44-68%.

[0048] In this invention, there is no particular limitation on the method of preparing the first mixture. For example, the precursors of the active component and the precursors of the co-active component can be dissolved in deionized water to prepare solutions, and then the aqueous solution containing the active component and the aqueous solution containing the co-active component can be mixed to form a mixed salt solution. Alternatively, the precursors of the active component and the precursors of the co-active component can be mixed and then deionized water can be added to prepare a mixed salt solution.

[0049] In this invention, in order to obtain more copper ammonia complex and copper hydroxide, preferably, 20-35% ammonia water by mass is added to the first mixture to make the pH of the first mixture alkaline, and then silica sol is added.

[0050] According to some embodiments of the present invention, in step (2), the amount of ammonia water used is such that the pH value of the second mixture is 10-12.

[0051] According to some embodiments of the present invention, the copper precursor is selected from soluble copper salts.

[0052] According to some embodiments of the present invention, the nickel precursor is selected from soluble nickel salts.

[0053] According to some embodiments of the present invention, the zirconium precursor is selected from soluble zirconium salts.

[0054] According to some embodiments of the present invention, the precursor of cobalt is selected from soluble cobalt salts.

[0055] According to some embodiments of the present invention, the zinc precursor is selected from soluble zinc salts.

[0056] According to some embodiments of the present invention, the copper precursor is selected from at least one of copper chloride, copper nitrate and copper sulfate, preferably copper nitrate.

[0057] According to some embodiments of the present invention, the nickel precursor is selected from at least one of nickel chloride, nickel nitrate and nickel sulfate, preferably nickel nitrate.

[0058] According to some embodiments of the present invention, the precursor of cobalt is cobalt nitrate.

[0059] According to some embodiments of the present invention, the zirconium precursor is selected from zirconium chloride and / or zirconium nitrate, preferably zirconium nitrate.

[0060] According to some embodiments of the present invention, the zinc precursor is selected from at least one of zinc chloride, zinc nitrate and zinc sulfate, preferably zinc nitrate.

[0061] According to some embodiments of the present invention, the heating conditions include: a temperature of 80-100°C and a time of 6-8 hours.

[0062] According to some embodiments of the present invention, the aging conditions include: a temperature of 80-100°C and a time of 10-12 hours.

[0063] In this invention, the purpose of heating the second mixture is to evaporate the ammonia gas in the mixture. This process is carried out in a water bath. When the pH of the second mixture drops to 6-7, the heating and ammonia evaporation are stopped.

[0064] According to some embodiments of the present invention, the reduction treatment method includes: introducing hydrogen gas at a flow rate of 100-150 mL / min, heating to 240-250 °C at a heating rate of 1-2 °C / min, and holding at the temperature for 5-6 h.

[0065] In this invention, after the second mixture is steamed to remove ammonia, and after aging treatment, the resulting product still needs to be washed, dried, roasted and shaped.

[0066] In a preferred embodiment, the drying conditions include: a temperature of 100-120°C and a time of 10-12 hours.

[0067] In a preferred embodiment, the calcination conditions include: a temperature of 400-450°C and a time of 3.5-4 hours.

[0068] In this invention, the molding process includes grinding the solid catalyst into powder using a mortar and pestle, and then pressing the powder into tablets using an automatic tablet press for later use.

[0069] A third aspect of the present invention provides a method for producing hydrogen from methanol through cracking or reforming, wherein the method includes: reacting a cracking or reforming catalyst with methanol through cracking; or reacting a cracking or reforming catalyst with methanol through reforming.

[0070] The cracking or reforming catalyst is the catalyst described in the first aspect of the present invention or the catalyst prepared by the method described in the second aspect.

[0071] According to some embodiments of the present invention, the conditions for the pyrolysis reaction include: a temperature of 220-280°C, a pressure of 0.1-1 MPa, and a mass hourly space velocity of 0.2-0.8 h⁻¹. -1 .

[0072] According to some embodiments of the present invention, the conditions for the reforming reaction include: a temperature of 220-260°C, a pressure of 0.1-1 MPa, and a mass hourly space velocity (HSV) of 0.2-0.6 h⁻¹. -1 The water-to-alcohol ratio is (0.5-1.5):1.

[0073] According to a particularly preferred embodiment of the present invention, a method for producing hydrogen from methanol through methanol cracking or methanol reforming is provided, the method comprising:

[0074] Weigh out a certain mass of Cu(NO3)2·3H2O, Zr(NO3)4·5H2O / Ni(NO3)2·6H2O and silica sol, where m(CuO):m(SiO2) = (0.33-1.2):1 and m(NiO / ZrO2):m(SiO2) = (0.01-0.1):1. First, mix Cu(NO3)2·3H2O and Zr(NO3)4·5H2O / Ni(NO3)2·6H2O, then add deionized water to prepare a mixed salt solution. Add ammonia to the mixed salt solution until the pH reaches 10-12, then add the silica sol mixture and stir well. Transfer the four-necked flask to a water bath at 80-100℃ to begin ammonia evaporation. Stop ammonia evaporation when the pH reaches 6-7. Age at 80-100℃ for 10-12 hours. After filtering and washing the precipitate mixture, dry it in an oven at 100-120℃ for 10-12 hours, and calcine it in a muffle furnace at 400-450℃ for 3.5-4 hours. Finally, use an automatic tablet press to form tablets for later use. The obtained catalyst contains 25wt%-55wt% of active components, 1wt%-7wt% of additives, and 44wt%-68wt% of support.

[0075] The present invention will be described in detail below through embodiments.

[0076] The contents of copper, nickel, zirconium, zinc and silica in the catalyst were determined by ICP emission spectroscopy.

[0077] Methanol conversion rate (%) = (m methanol inlet - m methanol outlet) / m methanol inlet.

[0078] H2 selectivity (%) = (nCO2 + nCO) * n(H2) / 3.

[0079] CO concentration (%), CO2 concentration (%), and CH4 concentration (%) were determined by gas chromatography.

[0080] The specific surface area, pore volume, and average pore size of the catalyst were measured using a physical adsorption analyzer.

[0081] In the examples and comparative examples, all raw materials were commercially available.

[0082] Example 1

[0083] According to the mass ratio m(CuO):m(ZrO2):m(SiO2)=45:3:55, accurately weigh 22g Cu(NO3)2·3H2O, 1.5g Zr(NO3)4·5H2O and 37g silica sol. First, mix Cu(NO3)2·3H2O and Zr(NO3)4·5H2O and then add deionized water to prepare a 0.5mol / L mixed salt solution. Ammonia was added to the mixed salt solution until pH=11. After stirring for 20 min, silica sol mixture was added and stirred for 4 h. The four-necked flask was then transferred to an 80°C water bath to begin ammonia evaporation. Ammonia evaporation was stopped when pH=6. The mixture was aged at 80°C for 12 h. The precipitate mixture was filtered and washed, then dried in a 100°C oven for 12 h, calcined in a 400°C muffle furnace for 4 h, and finally pressed into tablets using an automatic tablet press for later use. The resulting catalyst was named Cu45 / Zr3 / SiO2 (where “45” and “3” represent the contents of the active component copper and the auxiliary agent zirconium, respectively, which are 45 wt% and 3 wt%), respectively.

[0084] The specific surface area, pore volume, and average pore size of the catalyst Cu45 / Zr3 / SiO2 were measured, and the results are shown in Table 1.

[0085] Example 2

[0086] According to the mass ratio m(CuO):m(NiO):m(SiO2)=45:3:55, accurately weigh 22g Cu(NO3)2·3H2O, 1.5g Ni(NO3)2·6H2O and 37g silica sol. First, mix Cu(NO3)2·3H2O and Ni(NO3)2·6H2O and then add deionized water to prepare a 0.5mol / L mixed salt solution. Ammonia was added to the mixed salt solution until pH=12. After stirring for 20 min, silica sol mixture was added and stirred for 4 h. The four-necked flask was transferred to an 80°C water bath to start ammonia evaporation. Ammonia evaporation was stopped when pH=7. The mixture was aged at 90°C for 11 h. The precipitate mixture was filtered and washed, then dried in an oven at 110°C for 11 h, calcined in a muffle furnace at 430°C for 3.5 h, and finally pressed into tablets using an automatic tablet press for later use. The resulting catalyst was named Cu45 / Ni3 / SiO2.

[0087] The specific surface area, pore volume, and average pore size of the catalyst Cu45 / Ni3 / SiO2 were measured, and X-ray diffraction analysis of the calcined powder and the reduced powder was performed. The results are shown in Table 1 and 2. Figure 3-4.

[0088] Example 3

[0089] According to the mass ratio m(CuO):m(NiO):m(SiO2)=45:5:55, accurately weigh 22g Cu(NO3)2·3H2O, 2.5g Ni(NO3)2·6H2O and 37g silica sol. First, mix Cu(NO3)2·3H2O and Ni(NO3)2·6H2O and then add deionized water to prepare a 0.5mol / L mixed salt solution. Ammonia was added to the mixed salt solution until pH=12. After stirring for 20 min, silica sol mixture was added and stirred for 4 h. The four-necked flask was transferred to a water bath at 100 °C to start ammonia evaporation. Ammonia evaporation was stopped when pH=7. The mixture was aged at 100 °C for 10 h. After filtration and washing, the precipitate mixture was dried in an oven at 120 °C for 10 h and calcined in a muffle furnace at 450 °C for 4 h. Finally, it was pressed into tablets using an automatic tablet press for later use. The resulting catalyst was named Cu45 / Ni5 / SiO2.

[0090] The specific surface area, pore volume, and average pore size of the Cu45 / Ni5 / SiO2 catalyst were measured, and X-ray diffraction analysis of the calcined and reduced powders was performed. The results are shown in Table 1 and 2. Figure 3-4 .

[0091] Example 4

[0092] According to the mass ratio m(CuO):m(NiO):m(SiO2)=45:1:55, accurately weigh 22g Cu(NO3)2·3H2O, 0.5g Ni(NO3)2·6H2O and 37g silica sol. First, mix Cu(NO3)2·3H2O and Ni(NO3)2·6H2O and then add deionized water to prepare a 0.5mol / L mixed salt solution. Ammonia was added to the mixed salt solution until the pH reached 11.5. After stirring for 20 minutes, silica sol mixture was added and stirred for 4 hours. The four-necked flask was then transferred to a water bath at 90°C to begin ammonia evaporation. Ammonia evaporation was stopped when the pH reached 6.5. The mixture was aged at 90°C for 12 hours. The precipitate mixture was filtered and washed, then dried in an oven at 120°C for 12 hours and calcined in a muffle furnace at 450°C for 4 hours. Finally, it was pressed into tablets using an automatic tablet press for later use, and the catalyst was named Cu45 / Ni1 / SiO2.

[0093] The specific surface area, pore volume, and average pore size of the catalyst Cu45 / Ni1 / SiO2 were measured, and X-ray diffraction analysis of the calcined powder and the reduced powder was performed. The results are shown in Table 1 and 2. Figure 3-4 .

[0094] Example 5

[0095] According to the mass ratio m(CuO):m(CoO):m(SiO2)=45:3:55, accurately weigh 22g Cu(NO3)2·3H2O, 1.5g Co(NO3)2·6H2O and 37g silica sol. First, mix Cu(NO3)2·3H2O and Co(NO3)2·6H2O and then add deionized water to prepare a 0.5mol / L mixed salt solution. Ammonia was added to the mixed salt solution until the pH reached 11.5. After stirring for 20 minutes, silica sol mixture was added and stirred for 4 hours. The four-necked flask was then transferred to a water bath at 90°C to begin ammonia evaporation. Ammonia evaporation was stopped when the pH reached 6.5. The mixture was aged at 90°C for 12 hours. The precipitate mixture was filtered and washed, then dried in an oven at 120°C for 12 hours and calcined in a muffle furnace at 450°C for 4 hours. Finally, it was pressed into tablets using an automatic tablet press for later use, and the catalyst was named Cu45 / Co3 / SiO2.

[0096] The specific surface area, pore volume, and average pore size of the catalyst Cu45 / Co3 / SiO2 were measured, and the results are shown in Table 1.

[0097] Example 6

[0098] According to the mass ratio m(CuO):m(ZnO):m(SiO2)=45:3:55, accurately weigh 22g Cu(NO3)2·3H2O, 1.5g Zn(NO3)2·6H2O and 37g silica sol. First, mix Cu(NO3)2·3H2O and Zn(NO3)2·6H2O and then add deionized water to prepare a 0.5mol / L mixed salt solution. Ammonia was added to the mixed salt solution until the pH reached 11.5. After stirring for 20 minutes, silica sol mixture was added and stirred for 4 hours. The four-necked flask was then transferred to a water bath at 90°C to begin ammonia evaporation. Ammonia evaporation was stopped when the pH reached 6.5. The mixture was aged at 90°C for 12 hours. The precipitate mixture was filtered and washed, then dried in an oven at 120°C for 12 hours and calcined in a muffle furnace at 450°C for 4 hours. Finally, it was pressed into tablets using an automatic tablet press for later use, and the catalyst was named Cu45Zn3 / SiO2.

[0099] The specific surface area, pore volume and average pore size of the catalyst Cu45Zn3 / SiO2 were measured, and the results are shown in Table 1.

[0100] Comparative Example 1

[0101] According to the mass ratio m(CuO):m(SiO2) = 25:75, accurately weigh 10.7g Cu(NO3)2·3H2O and 50g silica sol. First, add deionized water to Cu(NO3)2·3H2O to prepare a 0.5mol / L metal salt solution. Then, add ammonia to the metal salt solution until pH = 11, stir for 20 min, add the silica sol mixture and stir for 4 h. Transfer the four-necked flask to a 90℃ water bath to start ammonia evaporation. Stop ammonia evaporation when pH = 6. Age at 90℃ for 12 h. After filtering and washing the precipitate mixture, dry it in an oven at 120℃ for 12 h, calcine it in a muffle furnace at 450℃ for 4 h, and finally use an automatic tablet press to form tablets for later use. The resulting catalyst is named Cu25 / SiO2.

[0102] The specific surface area, pore volume, and average pore size of the Cu25 / SiO2 catalyst were determined, and X-ray diffraction and H2-TRR analysis were performed simultaneously. The results are shown in Table 1 and... Figure 1-2 .

[0103] Comparative Example 2

[0104] According to the mass ratio m(CuO):m(SiO2) = 35:65, 17.1g of Cu(NO3)2·3H2O and 43g of silica sol were accurately weighed. First, Cu(NO3)2·3H2O was added to deionized water to prepare a 0.5mol / L metal salt solution. Then, ammonia water was added to the metal salt solution until the pH = 11. After stirring for 20 min, the silica sol mixture was added and stirred for 4 h. The four-necked flask was transferred to a 90℃ water bath to start ammonia evaporation. Ammonia evaporation was stopped when the pH = 6. The mixture was aged at 90℃ for 12 h. After filtering and washing the precipitate mixture, it was dried in an oven at 120℃ for 12 h and calcined in a muffle furnace at 450℃ for 4 h. Finally, it was pressed into tablets using an automatic tablet press for later use, and the catalyst was named Cu35 / SiO2.

[0105] The specific surface area, pore volume, and average pore size of the Cu35 / SiO2 catalyst were determined, and X-ray diffraction and H2-TRR analysis were performed simultaneously. The results are shown in Table 1 and... Figure 1-2 .

[0106] Comparative Example 3

[0107] According to the mass ratio m(CuO):m(SiO2) = 45:55, 22g of Cu(NO3)2·3H2O and 37g of silica sol were accurately weighed. First, Cu(NO3)2·3H2O was added to deionized water to prepare a 0.5mol / L metal salt solution. Then, ammonia water was added to the metal salt solution until the pH = 11. After stirring for 20 min, the silica sol mixture was added and stirred for 4 h. The four-necked flask was transferred to a 90℃ water bath to start ammonia evaporation. Ammonia evaporation was stopped when the pH = 6. The mixture was aged at 90℃ for 12 h. After filtering and washing the precipitate mixture, it was dried in an oven at 120℃ for 12 h and calcined in a muffle furnace at 450℃ for 4 h. Finally, it was pressed into tablets using an automatic tablet press for later use, and the resulting catalyst was named Cu45 / SiO2.

[0108] The specific surface area, pore volume, and average pore size of the Cu45 / SiO2 catalyst were determined, and X-ray diffraction and H2-TRR analysis were performed simultaneously. The results are shown in Table 1 and... Figure 1-2 .

[0109] Comparative Example 4

[0110] According to the mass ratio m(CuO):m(SiO2) = 55:45, accurately weigh 27g Cu(NO3)2·3H2O and 30g silica sol. First, add deionized water to Cu(NO3)2·3H2O to prepare a 0.5mol / L metal salt solution. Then, add ammonia to the metal salt solution until pH = 11, stir for 20 min, add the silica sol mixture and stir for 4 h. Transfer the four-necked flask to a 90℃ water bath to start ammonia evaporation. Stop ammonia evaporation when pH = 6. Age at 90℃ for 12 h. After filtering and washing the precipitate mixture, dry it in an oven at 120℃ for 12 h, calcine it in a muffle furnace at 450℃ for 4 h, and finally use an automatic tablet press to form tablets for later use. The resulting catalyst is named Cu55 / SiO2.

[0111] The specific surface area, pore volume, and average pore size of the Cu55 / SiO2 catalyst were determined, and X-ray diffraction and H2-TRR analysis were performed simultaneously. The results are shown in Table 1 and... Figure 1-2 .

[0112] Test Example 1

[0113] The catalysts prepared in Examples 1-6 and Comparative Examples 1-4 were used in methanol cracking for hydrogen production and methanol steam reforming for hydrogen production, respectively, and their performance was evaluated.

[0114] Before the reaction, the catalyst needs to be reduced. The specific method is as follows: accurately weigh 7.9g of catalyst and put it into a stainless steel reaction tube with a length of 100cm and an inner diameter of 10cm. Before the reaction, hydrogen gas is introduced at 150mL / min, and the temperature is increased to 250℃ at 2℃ / min and maintained for 6h to reduce the catalyst.

[0115] The specific method for evaluating catalyst performance is as follows: the methanol cracking to hydrogen production reaction and the methanol steam reforming to hydrogen production reaction are carried out in a fixed-bed reactor. The feed is fed in using a constant flow pump. After the feed enters the reaction tube, it gradually cracks, causing the pressure to increase. After the pressure increases to 1 MPa, the pressure is kept constant by adjusting the back pressure valve. After the reaction stabilizes for 10 hours, samples are taken for analysis. The results are shown in Table 2 (methanol conversion rate, H2 selectivity, and concentrations of byproducts CH4 and CO2 in methanol cracking to hydrogen production) and Table 3 (methanol conversion rate, H2 selectivity, and CO concentration in methanol steam reforming to hydrogen production).

[0116] The methanol cracking reaction conditions for hydrogen production include: temperature 280℃, pressure 1MPa, and mass hourly space velocity (HHSV) 0.6h. -1 .

[0117] The reaction conditions for methanol steam reforming to produce hydrogen include: temperature 250℃, water-to-methanol ratio 1.5, pressure 1 MPa, and mass hourly space velocity (H₂Sv) 1.2 h⁻¹. -1 .

[0118] Test Example 2

[0119] The catalysts from Example 2 and Comparative 3 were tested for their catalytic activity in methanol cracking for hydrogen production and methanol steam reforming for hydrogen production, respectively. The methanol cracking reaction conditions included: temperature 280°C, pressure 1 MPa, and mass hourly space velocity (HHSV) 0.6 h⁻¹. -1 The reaction conditions for methanol steam reforming to produce hydrogen are: temperature 250℃, water-to-methanol ratio 1.5, pressure 1 MPa, and mass hourly space velocity (H₂Sv) 1.2 h⁻¹. -1 The result is as follows Figure 6-7 .

[0120] Table 1

[0121]

[0122] Table 2

[0123]

[0124] Table 3

[0125]

[0126]

[0127] As can be seen from the data in Comparative Examples 1-4 in Table 1, the specific surface area of ​​the Cu / SiO2 catalyst gradually increases when the copper oxide content in the catalyst increases from 25% to 45%. This is because the increased copper content raises the content of copper silicate, thereby increasing the specific surface area of ​​the catalyst. When the copper oxide content further increases to 55%, the specific surface area of ​​the catalyst increases from 580.6 m² / s². 2 ·g-1 Reduced to 446.3m 2 ·g -1 This indicates that excessively high copper loading is not conducive to increasing the specific surface area of ​​the catalyst.

[0128] Figure 1 In the diagram, a, b, c, and d correspond to the catalysts Cu25 / SiO2, Cu35 / SiO2, Cu45 / SiO2, and Cu55 / SiO2 in proportions 1-4, respectively. From... Figure 1 It can be seen that, except for the catalyst in Comparative Example 4, the diffraction peaks in the XRD patterns of Cu / SiO2 catalysts in Comparative Examples 1-3 are all very diffuse, indicating that when the copper oxide content is 45% or less, the copper species in the catalyst exist in a highly dispersed form. When the copper oxide content increases from 25% to 45%, the diffraction peaks of sheet-like copper silicate appear in the catalyst and the intensity gradually increases. However, when the copper oxide content is 55%, sharp copper oxide diffraction peaks appear in the catalyst, that is, the catalyst in Example 4 contains copper oxide particles with a large particle size, which is not conducive to improving catalytic activity.

[0129] Figure 2 In the diagram, a, b, c, and d correspond to the catalysts Cu25 / SiO2, Cu35 / SiO2, Cu45 / SiO2, and Cu55 / SiO2 in proportions 1-4, respectively. Figure 2 It can be seen that as the copper content in the catalyst increases, the reduction temperature of the catalyst gradually increases. For the catalysts in Comparative Examples 1-3 (copper oxide contents of 25%, 35%, and 45%, respectively), the two reduction peaks are attributed to the overlapping peak of the reduction of highly dispersed copper oxide and copper silicate at low temperature, and the reduction peak of large copper oxide particles at high temperature, respectively. For the catalyst in Comparative Example 4 (Cu55 / SiO2), its reduction temperature is relatively high at 229℃, and a distinct shoulder peak appears next to the main reduction peak, which is attributed to the reduction of low-dispersion large copper oxide particles.

[0130] Figure 3 In the figures, a, b, c, and d correspond to the catalysts Cu45 / SiO2, Cu45 / Ni1 / SiO2, Cu45 / Ni3 / SiO2, and Cu45 / Ni5 / SiO2 in Example 4, Example 4, Example 2, and Example 3, respectively. Figure 3 It can be seen that the diffraction peak at 2θ = 22° belongs to silicon dioxide; the diffraction peaks at 2θ = 30.8°, 35.9°, 57.1° and 63.4° belong to foliated copper silicate. Among them, no diffraction peaks of nickel silicate were found in the catalysts of Examples 2-4, indicating that the content of nickel species in the catalysts is low and highly dispersed, which is below the detection limit of XRD.

[0131] Figure 4In the figures, a, b, c, and d correspond to the catalysts Cu45 / SiO2, Cu45 / Ni1 / SiO2, Cu45 / Ni3 / SiO2, and Cu45 / Ni5 / SiO2 in Examples 3, 4, 2, and 3, respectively. Figure 4 It can be seen that the diffraction peak at 2θ = 22° belongs to silicon dioxide; the peaks at 2θ = 43.2°, 50.3° and 74° belong to Cu. 0 The diffraction peaks. Among them, the catalyst (Cu45 / Ni1 / SiO2) of Example 4 and the catalyst (Cu45 / Ni3 / SiO2) of Example 2 contain Cu... 0 The diffraction peak intensity of Cu in Example 3 was significantly weaker than that of the catalyst (Cu45 / SiO2) in Comparative Example 3; while the Cu in the catalyst (Cu45 / Ni5 / SiO2) of Example 3 was significantly weaker. 0 The diffraction peak intensity is significantly enhanced, indicating that the introduction of an appropriate amount of nickel can improve the dispersion of the active components in the Cu / SiO2 catalyst, while the introduction of excessive nickel can easily lead to the aggregation of copper particles in the catalyst. Figure 4 The diffraction peaks of elemental nickel cannot be observed because the nickel content in the catalyst is low and highly dispersed, below the detection limit of XRD.

[0132] Depend on Figure 5 It can be seen that the catalyst (Cu45 / Ni3 / SiO2) in Example 2 has a distinct fibrous copper silicate structure, which is conducive to the diffusion of reactants. At the same time, no large-diameter copper oxide particles are formed on the surface, making it less prone to particle agglomeration during high-temperature reactions.

[0133] Depend on Figure 6 It can be seen that the catalyst (Cu45 / SiO2) of Comparative Example 3 remained stable within 110 h of reaction, but its catalytic activity decreased significantly after 110 h, with the methanol conversion rate dropping to 60.5% within 220 h. In contrast, the catalyst (Cu45 / Ni3 / SiO2) of Example 2 maintained stable activity within 180 h of reaction, with methanol conversion and gas yield remaining above 96% and 95%, respectively. At the same reaction time, the methanol conversion and gas yield of the catalyst (Cu45 / SiO2) of Comparative Example 3 were only 74.1% and 71.8%, respectively. This is because the addition of an appropriate amount of Ni reduced the particle size of the metal particles, improved the dispersion of the active components, and generated suitable copper-nickel interactions. These factors prevented copper particles from agglomerating or migrating during the reaction, thus contributing to catalyst stability. With the passage of reaction time, the activity of the Cu45 / Ni3 / SiO2 catalyst gradually decreased, reaching 88.3% for methanol conversion and 86.1% for gas yield at 220 h.

[0134] Depend on Figure 7It can be seen that the catalyst (Cu45 / Ni3 / SiO2) in Example 2 has stable activity within 260 h of reaction and a methanol conversion rate of over 94%. Under the same reaction time, the methanol conversion rate of the catalyst (Cu45 / SiO2) in Comparative Example 3 is only 87.3%.

[0135] In summary, the Cu / M / SiO2 catalyst prepared using the method described in this invention exhibits uniform dispersion of active components, good low-temperature activity, and high stability, making it a bifunctional catalyst suitable for both methanol cracking and methanol steam reforming for hydrogen production. The catalyst preparation method in this invention is simple. Using Cu / Ni / SiO2 and Cu / Zr / SiO2 catalysts for methanol cracking to hydrogen production, conversion rates of 99.5% and 99.8% can be achieved at low reaction temperatures, respectively. Furthermore, using the above catalysts for methanol steam reforming to hydrogen production, 100% conversion can be achieved at a reaction temperature of 250°C, with CO concentration selectivity of only 0.5% and 0.53%, respectively. The Cu / Ni / SiO2 catalyst, in particular, exhibits excellent catalytic activity for methanol steam reforming after continuous reaction for 260 hours, making it suitable for industrial production requirements.

[0136] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A catalyst for hydrogen production through methanol cracking or methanol reforming, characterized in that, The catalyst comprises: an active component, an auxiliary agent, and a support; The active component is copper, and the carrier is silicon dioxide. The additive is nickel and / or zirconium; Specifically, based on the total amount of the catalyst, the content of the active component is 45wt%-55wt%, the content of the auxiliary agent is 1wt%-5wt%, and the content of the support is 44wt%-54wt%. The mass ratio of the active component to the carrier is (0.83-1.2):1; the mass ratio of the adjuvant to the carrier is (0.018-0.1):

1. The specific surface area of the catalyst is 565.4-600 m 2 / g, the pore volume is 0.59-0.65 cm 3 / g, and the pore size is 3.95-4.23 nm.

2. A method for preparing the catalyst for methanol cracking to hydrogen production or methanol reforming to hydrogen production as described in claim 1, characterized in that, The method includes the following steps: (1) Dissolve the copper precursor and the precursor of the auxiliary agent in water to prepare a first mixture; (2) The first mixture, ammonia and silica sol are mixed to obtain the second mixture; (3) The second mixture is heated and aged; (4) The product obtained in step (3) is subjected to reduction treatment to obtain a solid catalyst; The additive is nickel and / or zirconium; The amount of the copper precursor and the precursor of the auxiliary agent is such that, based on the total weight of the solid catalyst, the copper content is 45wt%-55wt% and the auxiliary agent content (calculated as metal element) is 1wt%-5wt%; The silica sol contains 44-68% silica by mass. The mass ratio of copper to silicon dioxide in the silica sol is (0.83-1.2):1; the mass ratio of metal elements in the additive to silicon dioxide in the silica sol is (0.018-0.1):

1.

3. The method according to claim 2, wherein, In step (2), the amount of ammonia water used makes the pH value of the second mixture 10-12.

4. The method according to claim 2, wherein, The copper precursor is selected from soluble copper salts; And / or, the nickel precursor is selected from soluble nickel salts; And / or, the zirconium precursor is selected from soluble zirconium salts.

5. The method according to claim 4, wherein, The copper precursor is selected from at least one of copper chloride, copper nitrate and copper sulfate; And / or, the nickel precursor is selected from at least one of nickel chloride, nickel nitrate, and nickel sulfate; And / or, the zirconium precursor is selected from zirconium chloride and / or zirconium nitrate.

6. The method according to claim 5, wherein, The copper precursor is copper nitrate; And / or, the precursor of said nickel is nickel nitrate; And / or, the precursor of the zirconium is zirconium nitrate.

7. The method according to any one of claims 2-6, wherein, The heating conditions include: a temperature of 80-100℃ and a time of 6-8 hours; And / or, the aging conditions include: a temperature of 80-100°C and a time of 10-12 hours.

8. The method according to any one of claims 2-6, wherein, The reduction treatment method includes: introducing hydrogen gas at a flow rate of 100-150 mL / min, heating to 240-250℃ at a heating rate of 1-2℃ / min, and holding at the temperature for 5-6 hours.

9. A method for producing hydrogen from methanol through cracking or reforming, characterized in that, The method includes: reacting a cracking or reforming catalyst with methanol in a cracking reaction; or, reacting a cracking or reforming catalyst with methanol in a reforming reaction; The cracking or reforming catalyst is the catalyst described in claim 1 or the catalyst prepared by the method described in any one of claims 2-8.

10. The method according to claim 9, wherein, The conditions of the cracking reaction include: temperature of 220-280℃, pressure of 0.1-1MPa, mass space velocity of 0.2-0.8h -1 ; And / or, the conditions of the reforming reaction include: temperature is 220-260℃, pressure is 0.1-1MPa, mass space velocity is 0.2-0.6h -1 , water-alcohol ratio is (0.5-1.5):1.

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