Preparation method and application of low-temperature methanol steam reforming hydrogen production catalyst

Abstract

The invention relates to the field of catalyst preparation, and discloses a preparation method of a high-activity and high-dispersity copper-based catalyst for hydrogen production through low-temperature methanol steam reforming, and the preparation method at least comprises the following steps: mixing a titanium source solution, a silicon source solution and the like for reaction, and then carrying out roasting treatment to synthesize a titanium silicalite molecular sieve carrier; the preparation method comprises the following steps: dropwise adding a copper salt solution on a molecular sieve carrier by adopting an isopyknic impregnation method to obtain a primary copper-loaded titanium silicalite molecular sieve catalyst, and carrying out aging, drying and other treatment to obtain a final powder catalyst. The catalyst is a molecular sieve carrier copper-based catalyst dominated by high-dispersion framework titanium, and can be used for low-temperature methanol steam reforming hydrogen production reaction. The copper-based catalyst designed by the invention has the advantages of simple preparation mode, high hydrogen production efficiency, high CO2 selectivity, low cost and the like, and is easy for industrial production and popularization.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of catalysts for hydrogen production from low-temperature methanol steam, and particularly relates to a preparation method and application of a catalyst for low-temperature methanol steam reforming for hydrogen production. Background Art

[0002] In recent years, due to the depletion of traditional fossil energy and environmental pollution problems, it is urgent for humans to develop new recyclable, clean and efficient energy sources to achieve sustainable development. Hydrogen energy has important potential for energy development due to its high energy density, environmental friendliness and other characteristics. At present, the main problems of this technology are difficult safe storage and transportation and high cost.

[0003] The technology of hydrogen production by methanol steam reforming can effectively solve the above problems. Methanol has a high hydrogen content, relatively safe storage and transportation and a wide source, and is an ideal hydrogen storage carrier. Compared with the hydrogen production conditions of other hydrogen storage carriers such as ethanol and cyclohexane, the technology of hydrogen production by methanol steam reforming has mild reaction conditions and a high hydrogen-carbon ratio, and is a simple and efficient on-site hydrogen production method. The technology of low-temperature methanol steam reforming for hydrogen production has a low reaction temperature, low energy consumption and few CO by-products, and can produce directly utilizable hydrogen-rich gas, and is currently the most promising hydrogen production method.

[0004] At present, the catalysts applied to the technology of low-temperature methanol steam reforming for hydrogen production are mainly of two types: noble metal catalysts and non-noble metal copper catalysts. Noble metal catalysts generally have the problem of high cost of CO content and are difficult to be applied to industrial large-scale production. Copper-based catalysts have high low-temperature activity and low cost, and are relatively ideal catalysts in industry. However, the main problems they face are high CO selectivity at high temperatures, serious sintering of copper particles and poor stability. Further reducing the reaction temperature to achieve low-temperature methanol steam reforming for hydrogen production can effectively solve the above problems. Therefore, developing a copper-based catalyst with high low-temperature hydrogen production activity, low CO selectivity and good stability can effectively promote the large-scale application of hydrogen energy in the future. Summary of the Invention

[0005] The key problem solved by the present invention is that in view of the technical problems of low catalytic activity, high content of CO by-products and poor stability of existing industrial catalysts, the present invention provides a catalyst for low-temperature methanol steam reforming for hydrogen production with high hydrogen production activity and stability and a preparation method thereof. It is a molecular sieve supported catalyst dominated by framework titanium, which can better improve the dispersion of copper and its interaction with the surface of the support, and has the advantages of high and low-temperature activity, hydrogen production selectivity and stability, and can be used for optimizing industrial methanol hydrogen production processes or supporting distributed methanol hydrogen production fuel cell systems.

[0006] The technical solution adopted by the present invention:

[0007] In view of the above technical problems of the existing catalysts, the object of the present invention is to prepare a molecular sieve supported catalyst dominated by framework titanium. A titanium silicate molecular sieve support is synthesized by a hydrothermal method, and then an equal volume impregnation method is used to synthesize a copper loaded titanium silicate molecular sieve catalyst.

[0008] The preparation process flow of the above copper-based catalyst for low-temperature methanol steam reforming to produce hydrogen specifically includes the following processes:

[0009] (1) Mix the titanium source solution, silicon source solution, deionized water, and organic template agent and stir evenly. Then, perform crystallization, washing, drying, and calcination treatments in sequence to obtain a white powder titanium silicate molecular sieve TS.

[0010] (2) Prepare a copper loaded titanium silicate molecular sieve catalyst by the equal volume impregnation method. Drop the corresponding copper salt solution on the molecular sieve support, and then obtain the catalyst through aging, drying, grinding, and tabletting treatments.

[0011] Among them, in step (1), the titanium source solution is tetrabutyl titanate, the silicon source solution is tetraethyl orthosilicate, and the organic template agent is tetrapropylammonium hydroxide solution.

[0012] Among them, in step (1), the molar ratio of each component is: titanium source / silicon source = 0 - 0.013, and organic template agent / silicon source = 0.3.

[0013] Among them, in step (1), the stirring time of the mixed solution on a magnetic stirrer after mixing is 10 - 20 min; the vigorous stirring time under the irradiation of an ultraviolet lamp is 1 - 1.5 h; then, the clarified mixed solution is filled into a reaction kettle for crystallization, the crystallization temperature is 150 - 200 °C, and the time is 3 days; the drying temperature is 80 - 100 °C; the calcination temperature is 500 - 550 °C.

[0014] Among them, in step (2), the copper salt solution is copper nitrate solution, and the molar ratio of copper to silicon in the prepared catalyst is 0.03.

[0015] Among them, in step (2), corresponding amounts of copper nitrate solution with different loadings are dropped on molecular sieve supports with different titanium contents; the aging temperature is room temperature °C, and the time is 10 - 15 h; the drying temperature is 80 - 100 °C, and the time is 10 - 15 h.

[0016] Among them, in the catalyst prepared in step (2), the preferred copper loading is 20 wt%.

[0017] As an innovative solution of the copper-based catalyst for low-temperature methanol steam reforming to produce hydrogen of the present invention, it is characterized in that: the molecular sieve support dominated by titanium in the catalyst can efficiently cooperate with the copper active center to catalyze the reaction, and can catalyze the methanol steam reforming to produce hydrogen with high selectivity at low temperature, and the content of CO by-products in the products is low.

[0018] As an innovative solution for the preparation method of the copper-based catalyst for low-temperature methanol steam reforming to produce hydrogen in the present invention, the following steps are included: The copper-based catalyst is loaded into a tube and fixed in a reaction furnace, and a mixed solution of water and methanol is added with a liquid phase rate of 30 μl / min. The molar ratio of methanol to water vapor is 1:2. At the same time, N2 is introduced at a rate of 30 ml / min, and the reaction temperature ranges between 180 - 240 °C, and the reaction pressure is normal pressure.

[0019] Gas and liquid samples are collected at the sampling port of the reactor, and gas chromatography-mass spectrometry is used to qualitatively and quantitatively analyze the composition of the product.

[0020] As described above, the advantages and positive effects of the present invention in the methanol reforming to produce hydrogen catalyst and its preparation method are as follows:

[0021] The copper-based catalyst for low-temperature methanol steam reforming to produce hydrogen designed by the present invention has extremely high catalytic activity. In this catalyst, titanium in silicon mainly exists in the form of framework titanium. The titanium silicate molecular sieve support dominated by framework titanium can well enhance the interaction with the carrier surface and the dispersion of copper, thus significantly enhancing the performance of low-temperature methanol steam reforming to produce hydrogen. Specifically, the introduction of framework titanium effectively increases the density of weak acid sites, optimizes the adsorption configuration of formic acid intermediates in the MSR reaction, and accelerates the conversion process of reaction intermediates. In addition, a rich microporous structure with a size of 0.4 - 0.6 nm is formed in the catalyst, which can efficiently disperse the catalytic active center copper particles, inhibit the aggregation of copper nanoparticles, and thus promote the formation of stable and abundant active sites. These structural features play a positive role in improving the catalytic activity and long-term stability of the catalyst.

[0022] The preparation and synthesis method of the copper-based catalyst for low-temperature methanol steam reforming to produce hydrogen in the present invention is simple, has high reaction activity at low temperature, low raw material and synthesis costs, high selectivity for main products in the catalytic reaction, long service life of the catalyst, is not easily poisoned and deactivated, can effectively reduce industrial production costs, improve comprehensive benefits, and is easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for description in the embodiments. The drawings in the following description only represent some embodiments of the present application. For professionals in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 It is the N2 physical adsorption and desorption, BET analysis result of the methanol reforming to produce hydrogen catalyst of the present invention;

[0025] Figure 2 It is the XRD pattern of the catalyst in the embodiment of the present invention;

[0026] Figure 3 This is the H2-TPR graph of the catalyst in the embodiments of the present invention; Detailed implementation manners

[0027] In order to more clearly illustrate the objectives, technical solutions and advantages of the embodiments of the present invention, the implementation of the present invention will be described below through specific and particular examples. At the same time, the present invention can also be implemented or applied through other different specific embodiments. Combining the accompanying drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly described. The described embodiments only represent some embodiments of the present invention, rather than all embodiments.

[0028] Example 1

[0029] A preparation method of a copper-based catalyst catalytic material for low-temperature methanol steam reforming to produce hydrogen, the steps are as follows:

[0030] (1) Mix 25-30 g of tetrapropylammonium hydroxide solution, 10-15 g of water, 25-30 g of tetraethyl orthosilicate and 0.65 g of tetrabutyl titanate and stir evenly. Subsequently, place the mixed solution under the irradiation of an ultraviolet lamp and stir vigorously for 1 h.

[0031] (2) Crystallize the mixed solution obtained in step (1) at 150-200 °C for 3 days. Then, wash the obtained white solid, dry it at 80-100 °C, and finally calcine it at 500-550 °C to remove the template agent.

[0032] (3) Using the equal-volume impregnation method, dropwise add a 3.5-6.5 mol / L copper nitrate solution to the solid product obtained after calcination in an equal volume of 0.8-1.2 g.

[0033] (4) Let the supported catalyst obtained in step (3) stand at room temperature for aging for 10-15 h, dry it at 80-100 °C for 10-15 h, and finally obtain a powdery catalyst.

[0034] Example 2

[0035] A preparation method of a copper-based catalyst catalytic material for low-temperature methanol steam reforming to produce hydrogen, the steps are as follows:

[0036] (1) Mix 25-30 g of tetrapropylammonium hydroxide solution, 10-15 g of water, 25-30 g of tetraethyl orthosilicate and 0.5 g of tetrabutyl titanate and stir evenly. Subsequently, place the mixed solution under the irradiation of an ultraviolet lamp and stir vigorously for 1 h.

[0037] (2) Crystallize the mixed solution obtained in step (1) at 150 - 200 °C for 3 days, then wash the obtained white solid and dry it at 80 - 100 °C, and finally calcine it at 500 - 550 °C to remove the template agent.

[0038] (3) Using the equal - volume impregnation method, dropwise add a 3.5 - 6.5 mol / L copper nitrate solution in an equal volume on the 0.8 - 1.2 g of the solid product obtained after calcination.

[0039] (4) Let the supported catalyst obtained in step (3) stand for aging at room temperature for 10 - 15 h, dry it at 80 - 100 °C for 10 - 15 h, and finally obtain a powdery catalyst.

[0040] Example 3

[0041] A preparation method of a copper - based catalyst catalytic material for low - temperature steam reforming of methanol to produce hydrogen, the steps are as follows:

[0042] (1) Mix 25 - 30 g of tetrapropylammonium hydroxide solution, 10 - 15 g of water, 25 - 30 g of tetraethyl orthosilicate and 0.25 g of tetrabutyl titanate and stir evenly. Subsequently, place the mixed solution under the irradiation of an ultraviolet lamp and stir vigorously for 1 h.

[0043] (2) Crystallize the mixed solution obtained in step (1) at 150 - 200 °C for 3 days, then wash the obtained white solid and dry it at 80 - 100 °C, and finally calcine it at 500 - 550 °C to remove the template agent.

[0044] (3) Using the equal - volume impregnation method, dropwise add a 3.5 - 6.5 mol / L copper nitrate solution in an equal volume on the 0.8 - 1.2 g of the solid product obtained after calcination.

[0045] (4) Let the supported catalyst obtained in step (3) stand for aging at room temperature for 10 - 15 h, dry it at 80 - 100 °C for 10 - 15 h, and finally obtain a powdery catalyst.

[0046] Example 4

[0047] A preparation method of a copper - based catalyst catalytic material for low - temperature steam reforming of methanol to produce hydrogen, the steps are as follows:

[0048] (1) Mix 25 - 30 g of tetrapropylammonium hydroxide solution, 10 - 15 g of water, 25 - 30 g of tetraethyl orthosilicate and 0.25 g of tetrabutyl titanate and stir evenly. Subsequently, place the mixed solution under the irradiation of an ultraviolet lamp and stir vigorously for 1 h.

[0049] (2) Crystallize the mixed solution obtained in step (1) at 150 - 200 °C for 3 days, then wash the obtained white solid and dry it at 80 - 100 °C, and finally calcine it at 500 - 550 °C to remove the template agent.

[0050] (3) Adopt the equal-volume impregnation method, and dropwise add a copper nitrate solution with a concentration of 3.5 - 6.5 mol / L to the solid product obtained after calcination in an equal volume of 0.8 - 1.2 g.

[0051] (4) Let the supported catalyst obtained in step (3) stand for aging at room temperature for 10 - 15 h, dry it at 80 - 100 °C for 10 - 15 h, and finally obtain a powdery catalyst.

[0052] Perform a catalyst activity test for hydrogen production by methanol steam reforming on the catalysts prepared in Examples 1 - 4 above.

[0053] In this example, the catalyst activity test was carried out in a quartz tube fixed-bed reactor. The specific steps are as follows: Mix 0.2 g of the granular catalyst prepared in the above examples with 0.2 g of quartz sand (20 - 40 mesh) and fix it in the middle position of the quartz tube. Introduce N2 into the reactor at a flow rate of 30 mL / min. Heat it up to 220 °C at a rate of 2 °C / min using a programmed temperature rise; switch to the methanol-water mixed solution. After heating up, introduce methanol steam into the quartz tube to start the reaction. The flow rate of methanol steam is set to 30 μl / min, and the molar ratio of water to alcohol is 2:1. Collect gas and liquid samples at the sampling port of the reactor, and use gas chromatography-mass spectrometry to qualitatively and quantitatively analyze the composition of the products.

[0054] Table 1 shows the catalytic activity test results of each catalyst tested:

[0055]

[0056] The test results in Table 1 show that in the low-temperature methanol steam reforming for hydrogen production reaction, the test results show that the catalyst prepared in this application has a lower reaction temperature, higher hydrogen production activity, and lower CO selectivity. And the above preparation method is simple and easy to realize industrial production. The above description is only an example of this application and does not limit the patent scope of this application. Any equivalent structural or equivalent process transformation made using the content of the specification and drawings of this application, such as the mutual combination of technical features between various examples, or direct or indirect application in other related technical fields, is equally included in the patent protection scope of this application.

Claims

1. Preparation of a hydrogen production catalyst by low-temperature steam reforming of methanol with water, comprising the following steps: (1) Mix a titanium source solution, a silicon source solution, deionized water, and an organic template agent and stir evenly. Then, perform crystallization, washing, drying, and calcination treatments in sequence to obtain white powder titanium silicate molecular sieve. (2) Prepare a copper-loaded titanium silicate molecular sieve catalyst by the equal-volume impregnation method. Drop the corresponding copper salt solution on the molecular sieve support, and then obtain the catalyst through aging, drying, grinding, and tabletting treatments.

2. The preparation process of the copper-based catalyst according to claim 1, characterized in that: In step (1), the titanium source solution is tetrabutyl titanate, the silicon source solution is tetraethyl orthosilicate, and the organic template agent is tetrapropylammonium hydroxide solution.

3. The preparation process of the copper-based catalyst according to claim 1, characterized in that: In step (1), the molar ratio of each component is: titanium source / silicon source = 0 - 0.013, organic template agent / silicon source = 0.

300.

4. The preparation process of the copper-based catalyst according to claim 1, characterized in that: In step (1), after the solutions are mixed, stir on a magnetic stirrer for 10 - 20 min; then place the mixed solution under the irradiation of an ultraviolet lamp and stir vigorously for 1 - 1.5 h; then load the clarified mixed solution into a reaction kettle for crystallization, with the crystallization temperature being 150 - 200 °C and the time being 3 days; the drying temperature is 80 - 100 °C; the calcination temperature is 500 - 550 °C.

5. The preparation process of the copper-based catalyst according to claim 1, characterized in that: In step (2), the copper salt solution is copper nitrate solution, and the molar ratio of copper to silicon in the prepared catalyst is 0.

03.

6. The preparation process of the copper-based catalyst according to claim 1, characterized in that: In step (2), drop the corresponding loading amount of copper nitrate solution on the molecular sieve support with different titanium contents; the aging temperature is room temperature °C, and the time is 10 - 15 h; the drying temperature is 80 - 100 °C, and the time is 10 - 15 h.

7. The preparation process of the copper-based catalyst according to claim 1, characterized in that: In the catalyst described in step (2), the preferred copper loading amount is 20 wt%.

8. Use of a copper-loaded titanium silicate molecular sieve catalyst for hydrogen production by low-temperature methanol steam reforming according to claim 1, characterized in that Comprising the following steps: Fix the catalyst in a fixed-bed reactor. Methanol and water with a water-alcohol molar ratio of 2:1 are used as raw materials. The reaction pressure includes atmospheric pressure, and the reaction temperature is 160 - 240 °C. Collect gas and liquid samples at the reactor sampling port, and use gas chromatography-mass spectrometry to qualitatively and quantitatively analyze the composition of the product.

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