Preparation method of supported catalyst for hydrogen production by methanol steam reforming

Abstract

The invention relates to the technical field of hydrogen production catalysts, in particular to a preparation method of a supported methanol steam reforming hydrogen production catalyst. Comprising the following steps: S1, dissolving copper salt, adding indium oxide, heating in a water bath to evaporate water, drying, and carbonizing to obtain a Cu / In2O3 catalyst; s2, adding the Cu / In2O3 catalyst and tris (hydroxymethyl) aminomethane into water, then adding dopamine hydrochloride for reaction, and performing centrifugal washing and drying to obtain a precipitate; and S3, grinding and carbonizing the precipitate to obtain the nitrogen-doped carbon modified Cu / In2O3 catalyst. After the surface of the Cu / In2O3 catalyst is modified by carbon, strong electron interaction exists between carbon and metal copper, metal Cu electrons are promoted to be transferred to nitrogen-doped carbon, and the formed Cu < + > species enhance the catalytic activity for catalyzing methanol steam reforming hydrogen production and the selectivity for 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: S1, dissolve the copper salt, add indium oxide, heat in a water bath to evaporate the water, and then carbonize after drying to obtain Cu / In 2 O 3 catalyst; S2, the Cu / In 2 O 3The catalyst and tris(hydroxymethyl)aminomethane are added to water, and then dopamine hydrochloride is added for reaction. After centrifugation, washing, and drying, a precipitate is obtained. S3. The precipitate is ground and carbonized to obtain a nitrogen-doped carbon-modified Cu / In 2 O 3 catalyst.

[0005] By adding the Cu / In 2 O 3 catalyst and tris(hydroxymethyl)aminomethane to water and then adding dopamine hydrochloride for reaction, the methanol conversion and hydrogen selectivity in the steam reforming of methanol to hydrogen can be improved. The nitrogen-doped carbon modifier effectively regulates the electronic structure of metallic copper, promotes the formation of oxygen vacancies in the In 2 O 3 support, forms a spatial shielding and protective effect on metallic Cu, and thus realizes the efficient catalytic conversion of the copper-based catalyst in the steam reforming of methanol to hydrogen; after carbon modifies the surface of the Cu / In 2 O 3 catalyst, there is a strong electronic interaction between carbon and metallic copper, which promotes the transfer of electrons from metallic Cu to the nitrogen-doped carbon. The formed Cu + species enhances the catalytic activity for the steam reforming of methanol to hydrogen 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 / In 2 O 3 catalyst, inhibits the sintering and agglomeration of Cu particles at high temperatures, and enhances the catalytic stability of Cu.

[0006] The molar ratio of the copper salt to indium oxide is (0.3 - 0.7):1.

[0007] Optionally, the molar ratio of the copper salt to indium oxide is (0.4 - 0.6):1.

[0008] The copper salt includes at least one of copper nitrate, copper sulfate, copper chloride, and copper acetate.

[0009] Optionally, the copper nitrate includes copper nitrate trihydrate.

[0010] The temperature of carbonization in S1 is 400 - 700 °C, and the time is 1 - 3 h.

[0011] Optionally, the temperature of carbonization in S1 is 400 - 600 °C, and the time is 1 - 2 h.

[0012] The temperature of the water bath is 50 - 90 °C.

[0013] Optionally, the temperature of the water bath is 60 - 80 °C.

[0014] The drying temperature is 80 - 120 °C and the time is 8 - 15 h.

[0015] Optionally, the drying temperature is 90 - 110 °C and the time is 10 - 15 h.

[0016] The mass ratio of the Cu / In 2 O 3 catalyst, tris(hydroxymethyl)aminomethane, and dopamine hydrochloride is 0.6:(0.05 - 0.3):(0.5 - 1).

[0017] Optionally, the mass ratio of the Cu / In 2 O 3 catalyst, tris(hydroxymethyl)aminomethane, and dopamine hydrochloride is 0.6:(0.1 - 0.2):(0.5 - 0.9).

[0018] The reaction time is 2 - 8 h.

[0019] Optionally, the reaction time is 2 - 5 h.

[0020] 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.

[0021] 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.

[0022] Beneficial effects 1. By adding the Cu / In 2 O 3 catalyst and tris(hydroxymethyl)aminomethane into 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.

[0023] 2. The mass ratio of the Cu / In 2 O 3 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.

[0024] 3. The mass ratio of the Cu / In 2 O 3 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% and the hydrogen selectivity is 100% at 200 °C.

[0025] 4. At 250 - 300 °C, in methanol steam reforming for hydrogen production, both the methanol conversion rate and the hydrogen selectivity can reach 100%.

[0026] 5. Nitrogen-doped carbon modified Cu / In 2 O 3 The preparation conditions of the catalyst are simple and the reaction conditions are mild. Description of the Drawings

[0027] Figure 1 The broken line of the methanol conversion rate of the catalysts prepared in the examples and comparative examples at different temperatures.

[0028] Figure 2 The broken line of the hydrogen selectivity of the catalysts prepared in the examples and comparative examples at different temperatures.

[0029] Figure 3 The X-ray diffraction (XRD) pattern of the product prepared in Example 1. Detailed Description of the Invention

[0030] Example 1 A preparation method of a supported hydrogen production catalyst by steam reforming of methanol, comprising 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 a drying oven at 100 °C for 12 h, and then put it into a muffle furnace, carbonize it at 500 °C for 2 h to obtain Cu / In 2 O 3 catalyst powder. Take 0.6 g of Cu / In 2 O 3 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 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 tubular furnace under nitrogen protection (30 mL / min) at a heating rate of 7 °C / min to finally obtain nitrogen-doped carbon modified Cu / In 2 O 3 -C 5 -600 catalyst.

[0031] Example 2 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 / In 2 O 3 catalyst powder. Take 0.6 g of Cu / In 2 O 3 catalyst powder and 0.15 g of tris(hydroxymethyl)aminomethane and add them to 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 / In 2 O 3 -C 2 -600 catalyst.

[0032] Example 3 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 / In 2 O 3 catalyst powder. Take 0.6 g of Cu / In 2 O 3 catalyst powder and 0.15 g of tris(hydroxymethyl)aminomethane and add them to 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 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 / In 2 O 3 -C 8 -600 catalyst.

[0033] Example 4 A preparation method of a supported hydrogen production catalyst by steam reforming of methanol 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 / In 2 O 3 catalyst powder. Take 0.6 g of CuIn 2 O 3 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 500 °C for 2 h to finally obtain nitrogen-doped carbon-modified Cu / In 2 O 3 -C 5 -500.

[0034] 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, and then put it into a muffle furnace and carbonize it at 500 °C for 2 h to prepare Cu / In 2 O 3 catalyst powder. Take 0.6 g of CuIn 2 O 3 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 700 °C for 2 h to finally obtain nitrogen-doped carbon-modified Cu / In 2 O 3 -C 5 -700.

[0035] Comparative Example 1 A preparation method of a supported methanol steam reforming hydrogen production catalyst comprises the following steps: weighing 0.2745 g of copper nitrate trihydrate, putting it into 50 mL of deionized water, stirring it at room temperature for 30 min, adding 0.65 g of commercial indium oxide powder, heating it to 80 ° C in a water bath to slowly evaporate its water, and then drying it in a 100 ° C drying oven for 12 h, putting it in a muffle furnace, and carbonizing it at 500 ° C for 2 h to obtain Cu / In 2 O 3 Catalyst powder.

[0036] Comparative Example 2 A preparation method of a supported methanol steam reforming hydrogen production catalyst comprises the following steps: weighing 0.2745 g of copper nitrate trihydrate, putting it into 50 mL of deionized water, stirring it at room temperature for 30 min, adding 0.65 g of commercial aluminum oxide powder, heating it to 80 ° C in a water bath to slowly evaporate its water, and then drying it in a 100 ° C drying oven for 12 h, putting it in a muffle furnace, and carbonizing it at 500 ° C for 2 h to prepare Cu / Al 2 O 3 Catalyst. Take 0.6 g Cu / Al 2 O 3 The catalyst powder and 0.15 g of tris(hydroxymethyl)aminomethane) were added to 50 mL of deionized water, stirred at room temperature for 30 min, and then 0.7 g of dopamine hydrochloride was added. The stirring was continued for 5 h to obtain a black suspension. The suspension was centrifuged and washed to obtain a black precipitate. The precipitate was placed in an oven at 100 °C for 12 h, then fully ground and placed in a porcelain boat. The precipitate was heated to 600 °C in a tubular furnace under nitrogen protection (30 mL / min) at a heating rate of 7 °C / min for carbonization for 2 h to finally obtain nitrogen-doped carbon-modified Cu / Al 2 O 3 -C 5 -600 catalyst.

[0037] Comparative Example 3 A preparation method of a supported methanol steam reforming hydrogen production catalyst comprises the following steps: weighing 0.2745 g of copper nitrate trihydrate, putting it into 50 mL of deionized water, stirring it at room temperature for 30 min, adding 0.65 g of commercial silicon dioxide powder, heating it to 80 ° C in a water bath to slowly evaporate its water, and then drying it in a 100 ° C drying oven for 12 h, putting it in a muffle furnace, and carbonizing it at 500 ° C for 2 h to obtain Cu / SiO 2 Catalyst powder. Take 0.6 g Cu / SiO 2The catalyst powder and 0.15 g of tris(hydroxymethyl)aminomethane were added to 50 mL of deionized water. After stirring at room temperature for 30 min, 0.7 g of dopamine hydrochloride was added, and stirring was continued for 5 h to obtain a black suspension. The suspension was centrifuged and washed to obtain a black precipitate. The precipitate was placed in an oven and dried at 100 °C for 12 h, then thoroughly ground, placed in a porcelain boat, and carbonized in a tube furnace under nitrogen protection (30 mL / min) at a heating rate of 7 °C / min to 600 °C for 2 h, finally obtaining a nitrogen-doped carbon-modified Cu / SiO 2 -C 5 -600 catalyst.

[0038] Comparative Example 4 A preparation method of a supported hydrogen production catalyst by steam reforming of methanol 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 in a water bath to 80 °C to slowly evaporate the water, then dry in an oven at 100 °C for 12 h, and then put it into a muffle furnace and carbonize at 500 °C for 2 h to prepare a Cu / In 2 O 3 catalyst powder. Take 0.6 g of Cu / In 2 O 3 catalyst powder and 0.02 g of activated carbon, put them in a ball mill and ball mill and mix for 1 h. The mixed powder is put into a tube furnace under nitrogen protection (30 mL / min) and heated at a heating rate of 7 °C / min to 600 °C for 2 h, finally obtaining a nitrogen-doped carbon-modified Cu / In 2 O 3 @C 5 -600 catalyst.

[0039] Performance test method Catalyst performance test: The activity evaluation of the hydrogen production catalyst by steam reforming of methanol was carried out using a fixed-bed reactor. The specific evaluation process is as follows: Weigh 0.05 g of the catalyst (50 mesh) and 1 g of 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 was used for filling at both the upper and lower ends of the catalyst bed. For the catalysts of Examples 1-5 and Comparative Examples 2-4, no pre-reduction of H 2 was required before the reaction. Under the protection of N 2 , the catalyst bed was heated to the reaction temperature (200 °C, 250 °C, 300 °C), and then a liquid-phase pump was used to inject water and methanol into the steam generator, and through N 2Load the water and methanol mixture into the reactor for catalytic hydrogen production reaction; for Comparative Example 1, the catalyst needs to be reduced by hydrogen before the catalytic reaction. Heat it to 500 °C under H 2 atmosphere, reduce it at this temperature for 2 h, then cool it to the reaction temperature, and then switch to N 2 , use a liquid-phase pump to inject water and methanol into the steam generator, and pass through N 2 to load the water and methanol mixture into the reactor for catalytic hydrogen production reaction. The outlet gas is detected and analyzed by an on-line gas chromatograph. The test data are listed in Table 1 and the broken lines of methanol conversion rate and reaction temperature ( Figure 1 ) and the broken line of hydrogen selectivity and reaction temperature ( Figure 2 ) are plotted.

[0040] Perform X-ray diffraction (XRD) analysis on the product prepared in Example 1. The results confirm (as Figure 3 ), high-temperature carbonization leads to the formation of metallic Cu.

[0041] Performance test data Table 1

[0042] It can be seen from the data in Table 1 that at a reaction temperature of 200 °C, the catalytic activity of the catalyst is relatively low. The Cu / In 2 O 3 catalyst without carbon modification has a methanol conversion rate of only 45.8%, and a hydrogen selectivity of 90.2%; the optimal catalyst (Cu / In 2 O 3 -C 5 -600) with carbon modification has a methanol conversion rate of 77.2% and a hydrogen selectivity of 100%. When the reaction temperature rises to 250 °C, the methanol conversion rate and hydrogen selectivity of Cu / In 2 O 3 -C 5 -600 both reach 100%, which is better than other Cu / In 2 O 3 catalysts with carbon modification, and much higher than the Cu / In 2 O 3 catalyst without carbon modification (methanol conversion rate 72.4%, hydrogen selectivity 84.2%).

Claims

1. A method for preparing a supported methanol steam reforming hydrogen production catalyst, characterized in that: The following steps are involved: 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; S2, adding the Cu / In2O3 catalyst and trishydroxymethylaminomethane into water, and then adding dopamine hydrochloride to react, and obtaining a precipitate after centrifugation, washing, and drying; S3, grinding the precipitate and carbonizing it to obtain a nitrogen-doped carbon-modified Cu / In2O3 catalyst.

2. The method for preparing a supported methanol steam reforming hydrogen production catalyst 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 method for preparing a supported methanol steam reforming hydrogen production catalyst 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 method for preparing the supported methanol steam reforming hydrogen production catalyst according to claim 1 or 3, characterized in that: The carbonization temperature in S1 is 400-700° C. and the time is 1-3 hours.

5. The method for preparing a supported methanol steam reforming hydrogen production catalyst according to claim 4, characterized in that: The temperature of the water bath is 50-90°C.

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

7. The method for preparing a supported methanol steam reforming hydrogen production catalyst 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 method for preparing a supported methanol steam reforming hydrogen production catalyst 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 method for preparing a supported methanol steam reforming hydrogen production catalyst according to claim 8, characterized in that: The reaction time is 2-8h.

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

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