Preparation method of supported hydrogen production catalyst for methanol steam reforming

Abstract

The present invention relates to the technical field of hydrogen production catalysts, and specifically, to a preparation method of a supported methanol steam reforming hydrogen production catalyst. The method includes the following steps: S1, dissolve a copper salt, add indium oxide, evaporate water by water bath heating, and perform carbonization after drying to obtain a Cu / In2O3 catalyst; S2, add the Cu / In2O3 catalyst and tris(hydroxymethyl)aminomethane into water, then add dopamine hydrochloride for reaction, and after centrifuging, washing, and drying, obtain a precipitate; S3, grind and carbonize the precipitate to obtain a nitrogen-doped carbon modified Cu / In2O3 catalyst. After the carbon modifies the surface of the Cu / In2O3 catalyst, there is a strong electronic interaction between the carbon and the metallic copper, which promotes the transfer of electrons from the metallic Cu to the nitrogen-doped carbon, and the formed Cu + species enhances the catalytic activity of catalytic methanol steam reforming for hydrogen production and the selectivity to hydrogen.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen production catalysts, and in particular to a method for preparing a supported methanol steam reforming hydrogen production catalyst. Background Art

[0002] As the global energy transition accelerates, hydrogen energy has become a key development direction due to its clean and efficient characteristics. Methanol has become an ideal hydrogen energy carrier with its advantages such as convenient storage and transportation, wide sources, and high hydrogen-to-carbon ratio. Among them, methanol steam reforming hydrogen production technology is regarded as one of the optimal paths for distributed hydrogen production due to its low reaction temperature, high hydrogen production rate and mature process. Catalysts are the core of methanol reforming technology, and their performance directly affects the efficiency and cost of hydrogen production. Although Cu-based catalysts have higher activity and selectivity, they have problems such as poor thermal stability and easy sintering. Although precious metal catalysts (such as platinum group) have excellent anti-carbon deposition performance, their high cost limits their industrial application. Ni-based catalysts are widely used due to their low cost and high initial activity, but they face two major bottlenecks: one is that the sintering of active components at high temperatures leads to a decrease in specific surface area and poor stability; the other is that carbon deposition covers active sites during the reaction, causing catalyst deactivation. In order to break through the technical bottlenecks currently faced by Ni-based catalysts in methanol steam reforming hydrogen production technology and achieve the high efficiency, stability and sustainable development of this technology, it has become a top priority to develop Ni-based catalysts with high activity, high stability and strong anti-carbon deposition performance.

[0003] Chinese invention patent CN114192151B, March 18, 2022, discloses a methanol steam reforming hydrogen production catalyst synthesized by PCVD method and its preparation method, the preparation method comprising: obtaining a mixed solution of metal nitrate salts, the metal nitrate salts comprising at least copper nitrate, aluminum nitrate and zinc nitrate; adjusting the pH value of the mixed solution of metal nitrate salts to obtain a metal salt precipitate; drying and crushing the metal salt precipitate as a catalyst precursor; reducing the lanthanide metal precursor to a lanthanum metal element and depositing it on the surface of the catalyst precursor and then oxidizing it to obtain a catalyst. The above catalyst is used for methanol reforming hydrogen production to reduce the CO content in the reformed gas. However, the catalytic activity of hydrogen production and the selectivity for hydrogen have not been studied. Summary of the invention

[0004] The present invention provides a method for preparing a supported methanol steam reforming hydrogen production catalyst, comprising the following steps:

[0005] S1, dissolving copper salt, adding indium oxide, heating in a water bath to evaporate water, and carbonizing after drying to obtain a Cu / In2O3 catalyst;

[0006] S2. Add the Cu / In₂O₃ catalyst and tris(hydroxymethyl)aminomethane into water, then add dopamine hydrochloride for reaction. After centrifugation, washing, and drying, a precipitate is obtained.

[0007] S3. Grind the precipitate and then carbonize it to obtain a nitrogen-doped carbon-modified Cu / In₂O₃ catalyst.

[0008] By adding the Cu / In₂O₃ catalyst and tris(hydroxymethyl)aminomethane into water and then adding dopamine hydrochloride for reaction, the methanol conversion and hydrogen selectivity in methanol steam reforming for hydrogen production can be improved. The nitrogen-doped carbon modifier effectively regulates the electronic structure of metallic copper, promotes the formation of oxygen vacancies on the In₂O₃ support, and forms a spatial shielding and protective effect on metallic Cu, thereby realizing the efficient catalytic conversion of the copper-based catalyst in methanol steam reforming for hydrogen production; after the carbon modifies the surface of the Cu / In₂O₃ catalyst, there is a strong electronic interaction between the carbon and metallic copper, which promotes the transfer of electrons from metallic Cu to the nitrogen-doped carbon, and the formed Cu + species enhances the catalytic activity for methanol steam reforming for hydrogen production and the selectivity for hydrogen; the carbon modifier has a spatial shielding and protective effect on the metallic Cu nanoparticles on the surface of the Cu / In₂O₃ catalyst, inhibits the sintering and agglomeration of Cu particles at high temperatures, and enhances the catalytic stability of Cu.

[0009] The molar ratio of the copper salt to indium oxide is (0.3 - 0.7):1.

[0010] Optionally, the molar ratio of the copper salt to indium oxide is (0.4 - 0.6):1.

[0011] The copper salt includes at least one of copper nitrate, copper sulfate, copper chloride, and copper acetate.

[0012] Optionally, the copper nitrate includes copper nitrate trihydrate.

[0013] The temperature of carbonization in S1 is 400 - 700 °C, and the time is 1 - 3 h.

[0014] Optionally, the temperature of carbonization in S1 is 400 - 600 °C, and the time is 1 - 2 h.

[0015] The temperature of the water bath is 50 - 90 °C.

[0016] Optionally, the temperature of the water bath is 60 - 80 °C.

[0017] The temperature of drying is 80 - 120 °C, and the time is 8 - 15 h.

[0018] Optionally, the temperature of drying is 90 - 110 °C, and the time is 10 - 15 h.

[0019] The mass ratio of the Cu / In2O3 catalyst, tris(hydroxymethyl)aminomethane, and dopamine hydrochloride is 0.6:(0.05 - 0.3):(0.5 - 1).

[0020] Optionally, the mass ratio of the Cu / In2O3 catalyst, tris(hydroxymethyl)aminomethane, and dopamine hydrochloride is 0.6:(0.1 - 0.2):(0.5 - 0.9).

[0021] The reaction time is 2 - 8 h.

[0022] Optionally, the reaction time is 2 - 5 h.

[0023] The carbonization in S3 includes: heating to 500 - 800 °C at a heating rate of 3 - 10 °C / min and maintaining for 1 - 3 h.

[0024] Optionally, the carbonization in S3 includes: heating to 500 - 700 °C at a heating rate of 5 - 10 °C / min and maintaining for 1 - 2 h.

[0025] Beneficial effects

[0026] 1. By adding the Cu / In2O3 catalyst and tris(hydroxymethyl)aminomethane to water and then adding dopamine hydrochloride for reaction, the methanol conversion rate and hydrogen selectivity in methanol steam reforming for hydrogen production can be improved.

[0027] 2. The mass ratio of the Cu / In2O3 catalyst, tris(hydroxymethyl)aminomethane, and dopamine hydrochloride is 0.6:(0.05 - 0.3):(0.5 - 1), which inhibits the sintering and agglomeration of Cu particles at high temperatures and enhances the catalytic stability of Cu.

[0028] 3. The mass ratio of the Cu / In2O3 catalyst, tris(hydroxymethyl)aminomethane, and dopamine hydrochloride is 0.6:(0.1 - 0.2):(0.5 - 0.9), and the methanol conversion rate reaches 77.2% at 200 °C, and the hydrogen selectivity is 100%.

[0029] 4. At 250 - 300 °C in methanol steam reforming for hydrogen production, both the methanol conversion rate and hydrogen selectivity can reach 100%.

[0030] 5. The preparation conditions of the nitrogen-doped carbon-modified Cu / In2O3 catalyst are simple, and the reaction conditions are mild. Description of the drawings

[0031] Figure 1 It is a broken line of the methanol conversion rate of the catalysts prepared in the examples and comparative examples at different temperatures.

[0032] Figure 2 It is a broken line of the hydrogen selectivity of the catalysts prepared in the examples and comparative examples at different temperatures.

[0033] Figure 3 Prepare the X-ray diffraction (XRD) pattern of the product for Example 1. Detailed implementation manners

[0034] Example 1

[0035] A preparation method of a supported hydrogen production catalyst for methanol steam reforming comprises the following steps: Weigh 0.2745 g of copper nitrate trihydrate, put it into 50 mL of deionized water, stir at room temperature for 30 min, then add 0.65 g of commercial indium oxide powder (Aladdin CAS: 1314-23-4), heat it in a water bath to 80 °C to slowly evaporate the water, then dry it in an oven at 100 °C for 12 h, put it into a muffle furnace, and carbonize it at 500 °C for 2 h to prepare Cu / In2O3 catalyst powder. Take 0.6 g of Cu / In2O3 catalyst powder and 0.15 g of tris(hydroxymethyl)aminomethane and add them into 50 mL of deionized water, stir at room temperature for 30 min, then add 0.7 g of dopamine hydrochloride, and continue to stir for 5 h to obtain a black suspension. Centrifuge and wash it to obtain a black precipitate. Place the precipitate in an oven and dry it at 100 °C for 12 h, then grind it thoroughly, put it into a porcelain boat, and carbonize it in a tube furnace under nitrogen protection (30 mL / min) at a heating rate of 7 °C / min to 600 °C for 2 h to finally obtain a nitrogen-doped carbon-modified Cu / In2O3-C5-600 catalyst.

[0036] Example 2

[0037] A preparation method of a supported hydrogen production catalyst for methanol steam reforming comprises the following steps: Weigh 0.2745 g of copper nitrate trihydrate, put it into 50 mL of deionized water, stir at room temperature for 30 min, then add 0.65 g of commercial indium oxide powder, heat it in a water bath to 80 °C to slowly evaporate the water, then dry it in an oven at 100 °C for 12 h, put it into a muffle furnace, and carbonize it at 500 °C for 2 h to prepare Cu / In2O3 catalyst powder. Take 0.6 g of Cu / In2O3 catalyst powder and 0.15 g of tris(hydroxymethyl)aminomethane and add them into 50 mL of deionized water, stir at room temperature for 30 min, then add 0.7 g of dopamine hydrochloride, and continue to stir for 2 h to obtain a black suspension. Centrifuge and wash it to obtain a black precipitate. Place the precipitate in an oven and dry it at 100 °C for 12 h, then grind it thoroughly, put it into a porcelain boat, and carbonize it in a tube furnace under nitrogen protection (30 mL / min) at a heating rate of 7 °C / min to 600 °C for 2 h to finally obtain a nitrogen-doped carbon-modified Cu / In2O3-C2-600 catalyst.

[0038] Example 3

[0039] A preparation method of a supported hydrogen production catalyst for methanol steam reforming comprises the following steps: Weigh 0.2745 g of copper nitrate trihydrate, put it into 50 mL of deionized water, stir at room temperature for 30 min, then add 0.65 g of commercial indium oxide powder, heat it in a water bath to 80 °C to slowly evaporate the water, then dry it in an oven at 100 °C for 12 h, and then put it into a muffle furnace and carbonize it at 500 °C for 2 h to prepare Cu / In2O3 catalyst powder. Take 0.6 g of Cu / In2O3 catalyst powder and 0.15 g of tris(hydroxymethyl)aminomethane and add them into 50 mL of deionized water, stir at room temperature for 30 min, then add 0.7 g of dopamine hydrochloride, and continue to stir for 8 h to obtain a black suspension. Centrifuge and wash it to obtain a black precipitate. Place the precipitate in an oven and dry it at 100 °C for 12 h, then grind it thoroughly, put it into a porcelain boat, and carbonize it at 600 °C for 2 h in a tube furnace under nitrogen protection (30 mL / min) at a heating rate of 7 °C / min to finally obtain the nitrogen-doped carbon-modified Cu / In2O3-C8-600 catalyst.

[0040] Example 4

[0041] A preparation method of a supported hydrogen production catalyst for methanol steam reforming comprises the following steps: Weigh 0.2745 g of copper nitrate trihydrate, put it into 50 mL of deionized water, stir at room temperature for 30 min, then add 0.65 g of commercial indium oxide powder, heat it in a water bath to 80 °C to slowly evaporate the water, then dry it in an oven at 100 °C for 12 h, and then put it into a muffle furnace and carbonize it at 500 °C for 2 h to prepare Cu / In2O3 catalyst powder. Take 0.6 g of CuIn2O3 catalyst powder and 0.15 g of tris(hydroxymethyl)aminomethane and add them into 50 mL of deionized water, stir at room temperature for 30 min, then add 0.7 g of dopamine hydrochloride, and continue to stir for 5 h to obtain a black suspension. Centrifuge and wash it to obtain a black precipitate. Place the precipitate in an oven and dry it at 100 °C for 12 h, then grind it thoroughly, put it into a porcelain boat, and carbonize it at 500 °C for 2 h in a tube furnace under nitrogen protection (30 mL / min) at a heating rate of 7 °C / min to finally obtain the nitrogen-doped carbon-modified Cu / In2O3-C5-500.

[0042] Example 5: Weigh 0.2745 g of copper nitrate trihydrate, put it into 50 mL of deionized water, stir at room temperature for 30 min, then add 0.65 g of commercial indium oxide powder, heat it in a water bath to 80 °C to slowly evaporate the water, then dry it in an oven at 100 °C for 12 h, put it into a muffle furnace, and carbonize it at 500 °C for 2 h to prepare Cu / In2O3 catalyst powder. Take 0.6 g of CuIn2O3 catalyst powder and 0.15 g of tris(hydroxymethyl)aminomethane and add them to 50 mL of deionized water. After stirring at room temperature for 30 min, add 0.7 g of dopamine hydrochloride and continue stirring for 5 h to obtain a black suspension. Centrifuge and wash it to obtain a black precipitate. Place the precipitate in an oven and dry it at 100 °C for 12 h, then grind it thoroughly, put it into a porcelain boat, and carbonize it at 700 °C for 2 h in a tubular furnace under nitrogen protection (30 mL / min) at a heating rate of 7 °C / min to finally obtain nitrogen-doped carbon-modified Cu / In2O3-C5-700.

[0043] Comparative Example 1

[0044] A preparation method of a supported hydrogen production catalyst for methanol steam reforming comprises the following steps: Weigh 0.2745 g of copper nitrate trihydrate, put it into 50 mL of deionized water, stir at room temperature for 30 min, then add 0.65 g of commercial indium oxide powder, heat it in a water bath to 80 °C to slowly evaporate the water, then dry it in an oven at 100 °C for 12 h, put it into a muffle furnace, and carbonize it at 500 °C for 2 h to prepare Cu / In2O3 catalyst powder.

[0045] Comparative Example 2

[0046] A preparation method of a supported hydrogen production catalyst for methanol steam reforming comprises the following steps: Weigh 0.2745 g of copper nitrate trihydrate, put it into 50 mL of deionized water, stir at room temperature for 30 min, then add 0.65 g of commercial aluminum oxide powder, heat it in a water bath to 80 °C to slowly evaporate the water, then dry it in an oven at 100 °C for 12 h, put it into a muffle furnace, and carbonize it at 500 °C for 2 h to prepare Cu / Al2O3 catalyst. Take 0.6 g of Cu / Al2O3 catalyst powder and 0.15 g of tris(hydroxymethyl)aminomethane and add them to 50 mL of deionized water. After stirring at room temperature for 30 min, add 0.7 g of dopamine hydrochloride and continue stirring for 5 h to obtain a black suspension. Centrifuge and wash it to obtain a black precipitate. Place the precipitate in an oven and dry it at 100 °C for 12 h, then grind it thoroughly, put it into a porcelain boat, and carbonize it at 600 °C for 2 h in a tubular furnace under nitrogen protection (30 mL / min) at a heating rate of 7 °C / min to finally obtain nitrogen-doped carbon-modified Cu / Al2O3-C5-600 catalyst.

[0047] Comparative Example 3

[0048] A preparation method of a supported hydrogen production catalyst for methanol steam reforming comprises the following steps: Weigh 0.2745 g of copper nitrate trihydrate, put it into 50 mL of deionized water, stir at room temperature for 30 min, then add 0.65 g of commercial silica powder, heat it in a water bath to 80 °C to slowly evaporate the water, then dry it in an oven at 100 °C for 12 h, and then put it into a muffle furnace and carbonize it at 500 °C for 2 h to obtain Cu / SiO2 catalyst powder. Take 0.6 g of Cu / SiO2 catalyst powder and 0.15 g of tris(hydroxymethyl)aminomethane and add them into 50 mL of deionized water, stir at room temperature for 30 min, then add 0.7 g of dopamine hydrochloride, and continue to stir for 5 h to obtain a black suspension. Centrifuge and wash it to obtain a black precipitate. Place the precipitate in an oven at 100 °C and dry it for 12 h, then grind it thoroughly, put it into a porcelain boat, and carbonize it at 600 °C for 2 h in a tube furnace under nitrogen protection (30 mL / min) at a heating rate of 7 °C / min to finally obtain a nitrogen-doped carbon modified Cu / SiO2-C5-600 catalyst.

[0049] Comparative Example 4

[0050] A preparation method of a supported hydrogen production catalyst for methanol steam reforming comprises the following steps: Weigh 0.2745 g of copper nitrate trihydrate, put it into 50 mL of deionized water, stir at room temperature for 30 min, then add 0.65 g of commercial indium oxide powder, heat it in a water bath to 80 °C to slowly evaporate the water, then dry it in an oven at 100 °C for 12 h, and then put it into a muffle furnace and carbonize it at 500 °C for 2 h to obtain Cu / In2O3 catalyst powder. Take 0.6 g of Cu / In2O3 catalyst powder and 0.02 g of activated carbon, put them in a ball mill and ball mill and mix them for 1 h. Put the mixed powder into a tube furnace under nitrogen protection (30 mL / min) and heat it to 600 °C at a heating rate of 7 °C / min and carbonize it for 2 h to finally obtain a nitrogen-doped carbon modified Cu / In2O3@C5-600 catalyst.

[0051] Performance testing method

[0052] Catalyst performance test: The activity evaluation of methanol steam reforming hydrogen production catalyst adopts a fixed bed reactor. The specific evaluation process is as follows: weigh 0.05 g catalyst (50 mesh) and 1 g quartz sand, mix them thoroughly and fill them into a quartz tube reactor with an inner diameter of 8 mm, an outer diameter of 10 mm, and a length of 40 cm. Quartz sand is used to fill the upper and lower ends of the catalyst bed. For the catalysts of Examples 1-5 and Comparative Examples 2-4, there is no need to perform H2 pre-reduction before the reaction. Under the protection of N2, the catalyst bed is heated to the reaction temperature (200°C, 250°C, 300°C), and then water and methanol are injected into the steam generator using a liquid phase pump, and the water and methanol mixed gas is loaded into the reactor through N2 for catalytic hydrogen production reaction; for Comparative Example 1, the catalyst needs to be reduced with hydrogen before the catalytic reaction. The temperature is raised to 500°C under H2 atmosphere, reduced at this temperature for 2 hours, and then cooled to the reaction temperature, and then switched to N2, and water and methanol are injected into the steam generator using a liquid phase pump, and the water and methanol mixed gas is loaded into the reactor through N2 for catalytic hydrogen production reaction. The outlet gas is detected and analyzed by online gas chromatography. The test data are listed in Table 1 and a broken line of methanol conversion rate and reaction temperature is drawn ( Figure 1 ) and the broken line of hydrogen selective reaction temperature ( Figure 2 ).

[0053] The product prepared in Example 1 was subjected to X-ray diffraction (XRD) analysis, and the results confirmed that ( Figure 3 ), high temperature carburization leads to the formation of metallic Cu.

[0054] Performance test data

[0055] Table 1

[0056]

[0057] From the data in Table 1, it can be seen that at 200℃, the catalytic activity of the catalyst is relatively low. The conversion rate of methanol for the non-carbon-modified Cu / In2O3 catalyst is only 45.8%, and the hydrogen selectivity is 90.2%. The methanol conversion rate of the carbon-modified optimal catalyst (Cu / In2O3-C5-600) reaches 77.2%, and the hydrogen selectivity is 100%. When the reaction temperature is increased to 250℃, the conversion rate of methanol and the hydrogen selectivity of Cu / In2O3-C5-600 reach 100%, which is better than other carbon-modified Cu / In2O3 catalysts and much higher than the non-carbon-modified Cu / In2O3 catalyst (methanol conversion rate 72.4%, hydrogen selectivity 84.2%).

Claims

1. A preparation method of a supported hydrogen production catalyst for methanol steam reforming, characterized in that, It includes the following steps: S1. Dissolve the copper salt, add indium oxide, evaporate water by heating in a water bath, perform carbonization after drying to obtain a Cu / In2O3 catalyst; S2. Add the Cu / In2O3 catalyst and tris(hydroxymethyl)aminomethane into water, then add dopamine hydrochloride for reaction, and obtain a precipitate after centrifugation, washing, and drying; S3. Grind the precipitate and perform carbonization to obtain a nitrogen-doped carbon modified Cu / In2O3 catalyst.

2. The preparation method of the supported hydrogen production catalyst by methanol steam reforming according to claim 1, characterized in that, The molar ratio of the copper salt to indium oxide is (0.3 - 0.7):

1.

3. The preparation method of the supported hydrogen production catalyst for methanol steam reforming according to claim 2, characterized in that, The copper salt includes at least one of copper nitrate, copper sulfate, copper chloride, and copper acetate.

4. The preparation method of the supported hydrogen production catalyst for methanol steam reforming according to claim 1 or 3, characterized in that In S1, the temperature of carbonization is 400 - 700 °C, and the time is 1 - 3 h.

5. The preparation method of the supported hydrogen production catalyst for methanol steam reforming according to claim 4, wherein The temperature of the water bath is 50 - 90 °C.

6. The preparation method of the supported hydrogen production catalyst for methanol steam reforming according to claim 5, characterized in that, The temperature of drying is 80 - 120 °C, and the time is 8 - 15 h.

7. The preparation method of the supported hydrogen production catalyst for methanol steam reforming according to claim 6, characterized in that, The mass ratio of the Cu / In2O3 catalyst, tris(hydroxymethyl)aminomethane, and dopamine hydrochloride is 0.6:(0.05 - 0.3):(0.5 - 1).

8. The preparation method of the supported hydrogen production catalyst by methanol steam reforming according to claim 7, characterized in that, The mass ratio of the Cu / In2O3 catalyst, tris(hydroxymethyl)aminomethane, and dopamine hydrochloride is 0.6:(0.1 - 0.2):(0.5 - 0.9).

9. The preparation method of the supported hydrogen production catalyst by methanol steam reforming according to claim 8, characterized in that, The time of the reaction is 2 - 8 h.

10. The preparation method of the supported hydrogen production catalyst for methanol steam reforming according to claim 9, wherein, The carbonization in S3 includes: heating up to 500 - 800 °C at a heating rate of 3 - 10 °C / min and maintaining for 1 - 3 h.

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