Pt / cemoo2 catalyst for low-temperature methanol and water hydrogen production and preparation method thereof
A Pt/CeMoO2 catalyst was prepared by synthesizing CeMoO2 support via hydrothermal method and loading Pt via impregnation method. This solved the problem of insufficient activity and stability in the low-temperature methanol-water liquid-phase reforming hydrogen production reaction, and achieved efficient hydrogen production and good catalyst cycling performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NORTHWESTERN POLYTECHNICAL UNIV
- Filing Date
- 2023-04-10
- Publication Date
- 2026-07-14
AI Technical Summary
Existing catalysts have insufficient activity and stability in methanol-water liquid-phase reforming for hydrogen production under low-temperature conditions, and the large particle size of Pt particles leads to severe CO generation, hindering their commercial application.
CeMoO2 support was synthesized by hydrothermal method, and noble metal Pt was loaded by impregnation method to prepare Pt/CeMoO2 catalyst. The interaction between metal and support was optimized and the size of Pt nanoparticles was controlled at 1-2 nm.
Under normal pressure and 60℃ conditions, the Pt/CeMoO2 catalyst exhibits high hydrogen production and good stability, with a hydrogen yield of 379.93 mol molPt⁻¹, and maintains high activity during recycling, avoiding CO generation.
Smart Images
Figure CN118304884B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst preparation technology, and relates to a platinum-based catalyst Pt / CeMoO2 for low-temperature methanol and water hydrogen production and its preparation method. Background Technology
[0002] With rapid population and economic development, energy plays an increasingly important role in human society, and its demand is also increasing. However, the overexploitation and utilization of non-renewable fossil fuels such as oil, natural gas, and coal have led to energy shortages. Furthermore, under the policy framework of "carbon peaking" and "carbon neutrality," the use of traditional fossil fuels will be significantly restricted.
[0003] To address the dual challenges of energy shortages and environmental pollution, developing clean, renewable energy sources to replace non-renewable fossil fuels holds significant promise. Hydrogen is widely available, has high energy density, and is pollution-free and environmentally friendly. Using hydrogen as a renewable energy source to replace non-renewable fossil fuels can greatly alleviate human society's dependence on fossil fuels, further promoting socio-economic development while protecting the environment.
[0004] However, the current utilization of hydrogen energy still faces challenges such as high costs associated with hydrogen production, storage, and transportation. Using liquid chemicals as hydrogen carriers and then releasing hydrogen in situ through catalytic reactions to provide fuel for power equipment can simply and effectively solve the problems of high storage and transportation costs. Methanol, due to its low cost and availability, high hydrogen storage density per unit volume, and low dehydrogenation activation temperature, can be used as a liquid hydrogen storage carrier. Reforming methanol and water to produce hydrogen can further increase hydrogen release and effectively solve the hydrogen production problem, greatly promoting the utilization of hydrogen energy, especially in the application of on-board fuel cells.
[0005] To achieve efficient utilization of the produced hydrogen, it is still urgent to develop a catalyst that can improve the activity and stability of the methanol-water liquid-phase reforming hydrogen production reaction under milder reaction conditions, while further reducing the particle size of metal Pt particles in the catalyst to suppress CO generation. Summary of the Invention
[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:
[0007] First, this invention provides a method for preparing a platinum-based catalyst Pt / CeMoO2, comprising the following steps:
[0008] S1. Synthesize CeMoO2 support;
[0009] S2. The noble metal Pt is loaded onto the CeMoO2 support described in S1 to prepare a Pt / CeMoO2 supported catalyst.
[0010] Preferably, step S1 further includes:
[0011] S11. Prepare an aqueous solution of ammonium molybdate, and use the resulting solution as solution A;
[0012] S12. Prepare an aqueous solution of cerium nitrate, and use the resulting solution as solution B.
[0013] S13. Mix solutions A and B uniformly, and synthesize CeMoO2 support by hydrothermal method.
[0014] Preferably, the concentration of ammonium molybdate in solution A is 0.03-0.6 mmol / mL, and the solution volume is 50-120 mL.
[0015] Preferably, the concentration of cerium nitrate in solution B is 0.01-0.2 mmol / mL, and the solution volume is 50-120 mL.
[0016] Preferably, the synthesis temperature of the hydrothermal method is 100-150℃.
[0017] Preferably, step S2 further includes: mixing a platinum nitrate aqueous solution, ethanol and the CeMoO2 support, removing the solvent from the mixture and then calcining it to obtain a Pt / CeMoO2 catalyst.
[0018] Preferably, the calcination treatment should be carried out in a 5% H2 / Ar mixed gas, with the temperature increased to 350°C at a rate of 5°C / min, and calcined for 2 hours.
[0019] Furthermore, this invention also discloses a Pt / CeMoO2 catalyst, characterized in that, when the catalyst reacts with methanol-water liquid-phase reforming to produce hydrogen under mild conditions of atmospheric pressure and 60°C for 6 hours, its hydrogen production can reach 379.93 mol / mol. Pt -1 .
[0020] Preferably, a Pt / CeMoO2 catalyst is characterized in that the size of the metal Pt nanoparticles supported on the catalyst is 1-2 nm, which has high dispersion and better activity compared with the prior art.
[0021] Preferably, the catalyst is obtained by any of the above-described preparation methods.
[0022] Furthermore, the present invention discloses an application of a Pt / CeMoO2 catalyst, characterized in that the application includes its use in the methanol-water liquid-phase reforming hydrogen production reaction.
[0023] Preferably, the present invention provides a method for preparing a platinum-based catalyst Pt / CeMoO2, comprising the following steps:
[0024] (1) Preparation of CeMoO2 support:
[0025] First, measure 50 mL of 0.3 mmol / mL ammonium molybdate solution, then mix it evenly with 50 mL of aqueous solution containing 0.1 mmol / mL cerium nitrate. After aging at room temperature for 30 min, place it in an oven for hydrothermal treatment at 120℃ for 12 h, then centrifuge, collect the precipitate, wash it with water and ethanol, and finally place it in an oven to dry for 12 h.
[0026] (2) Preparation of Pt / CeMoO2 catalyst:
[0027] At room temperature, 300 mg of CeMoO2 was weighed and uniformly dispersed in 30 mL of ethanol. After stirring for 1 h, 600 μL of a 5 mg / mL platinum nitrate aqueous solution was added dropwise to the suspension. Stirring continued for 2 h, followed by heating to 80 °C and maintaining this temperature until the ethanol was completely evaporated, yielding a yellow powder. This powder was then calcined in a 5% H2 / Ar mixed gas at a rate of 5 °C / min to 350 °C for 2 h. The noble metal loading at this point was 1 wt%.
[0028] The beneficial effects of the above technical solution are as follows: The high cost, poor CO poisoning resistance, and poor stability of Pt severely hinder the commercial application of Pt-based catalysts. Therefore, adding a co-catalyst improves the activity and stability of the catalyst. Existing studies have shown that using CeO2 and MoO3 as co-catalysts can not only improve the stability of the catalyst but also enhance the CO resistance of Pt-based catalysts, thereby improving the selectivity of Pt-based catalysts in the methanol-water liquid-phase hydrogen production reaction. The inventors noted that Pt nanoparticles have good CH activation ability, and therefore selected Pt nanoparticles as typical metal active sites. Furthermore, this invention uses a hydrothermal synthesis method to prepare the support CeMoO2, and then uses a traditional impregnation method to load the noble metal Pt, achieving excellent catalytic activity in the methanol-water system. Under mild reaction conditions of atmospheric pressure and 60℃, compared with traditional CeO2 or MoO2 supports, the Pt / CeMoO2 catalyst prepared using CeMoO2 as the support has a significantly higher hydrogen production rate from methanol and water, reaching 379.93 mol / mol after 6 hours of reaction. Pt -1 Meanwhile, this Pt / CeMoO2 catalyst exhibits excellent catalytic stability.
[0029] This invention also provides an application of the noble metal platinum-based catalyst Pt / CeMoO2 in hydrogen production in a methanol-aqueous liquid phase system, for example, by operating as follows:
[0030] (1) Measure 10 mL of methanol and water in a volume ratio of 7:3 and pour it into a 100 mL flask. Then add 8.0 mol / L KOH (molar concentration based on total MeOH / H2O volume) to form a mixture.
[0031] (2) Weigh 20 mg of catalyst and disperse it evenly in the mixture in (1) above, and seal it with a rubber stopper. Purge the atmosphere with Ar for 30 min, and then allow the system to react in an Ar atmosphere. Place the flask on a magnetic stirrer that has been preheated to 60 °C and stir.
[0032] (3) The gas composition was quantitatively analyzed and recorded using gas chromatography. The hydrogen yield on the Pt / CeMoO2 catalyst was measured to be 47.94 mol / mol after 4 hours of reaction. Pt -1 h -1 .
[0033] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a method for loading noble metal Pt onto CeMoO2 catalyst material by impregnation and its application in hydrogen production in a methanol-water liquid phase system, which has the following advantages:
[0034] In catalyst preparation, the first step involves synthesizing a CeMoO2 support via a hydrothermal method. Both Mo and Ce are used to enhance the activity of Pt-based catalysts, and this step is simple, mild, and uses readily available raw materials. The second step involves loading the noble metal Pt onto the CeMoO2 support obtained in the first step through an impregnation method to prepare a Pt / CeMoO2 supported catalyst. In the reaction system, the interaction between the metal and the support enables the catalyst to exhibit high activity.
[0035] In the catalytic production of hydrogen from methanol-water liquid phase, this invention uses methanol and water as reactants, which aligns with the principles of green chemistry. Compared to existing catalysts for methanol-water liquid phase hydrogen production, this invention features a simpler preparation method and higher catalyst selectivity. Therefore, the catalyst in this invention boasts high catalytic efficiency, is more environmentally friendly and energy-saving, and has promising prospects for industrial application. Attached Figure Description
[0036] To more clearly illustrate the application of this invention in catalysis, the main catalytic effect diagrams are briefly introduced below.
[0037] Figure 1 Transmission electron microscope images (a) and (b) provided for Example 1;
[0038] Figure 2 This is a schematic diagram of the catalyst cycle stability test results in Example 3. Detailed Implementation
[0039] This invention discloses a method for loading noble metal Pt onto CeMoO2 catalyst material via impregnation and its application in hydrogen production in a methanol-water liquid phase system. The following will be discussed in conjunction with the attached... Figure 1 (a) to Figure 2 The technical solutions in this invention will be clearly and completely described with reference to specific embodiments.
[0040] Preparation of Pt / MoO3 catalyst (reference example 1)
[0041] First, 1 g of (NH4)6Mo7O·4H2O was directly calcined in air at 500℃ for 4 h to prepare the supported MoO3. Then, Pt / MoO3 was prepared using a traditional impregnation method. At room temperature, 300 mg of MoO3 was weighed and uniformly dispersed in 30 mL of ethanol. After stirring for 1 h, 600 μL of a 5 mg / mL platinum nitrate aqueous solution was added dropwise to the suspension. Stirring was continued for 12 h, followed by heating to 90℃ and maintaining this temperature until the ethanol was completely evaporated. Finally, the mixture was calcined at 500℃ in air for 4 h to obtain the Pt / MoO3 catalyst. The noble metal loading at this point was 1 wt%.
[0042] Reference ratio 2: Hydrogen production using Pt / MoO3 catalyst in a methanol-water liquid phase system.
[0043] (1) Measure 10 mL of methanol to water in a volume ratio of 7:3 and pour it into a 100 mL flask, then add 8.0 mol / L KOH (molar concentration based on total MeOH / H2O volume);
[0044] (2) Weigh 20 mg of catalyst Pt / MoO3 and uniformly disperse it in the above (1) mixture and seal it with a rubber stopper. Purge the atmosphere with Ar for 30 min and then allow the system to react in an Ar atmosphere. Place the flask on a magnetic stirrer that has been preheated to 60 °C and stir.
[0045] (3) The gas composition was quantitatively analyzed using gas chromatography and recorded. The hydrogen yield on the Pt / MoO3 catalyst was measured to be 3.64 mol / mol after 4 hours of reaction. Pt -1 h -1 .
[0046] Preparation of Pt / CeO2 catalyst (reference example 3)
[0047] First, 1 g of Ce(NO3)3·6H2O was directly calcined in air at 500℃ for 2 h to prepare the CeO2 support. Then, Pt / CeO2 was prepared using a traditional impregnation method. At room temperature, 300 mg of CeO2 was weighed and uniformly dispersed in 30 mL of ethanol. After stirring for 1 h, 600 μL of a 5 mg / mL platinum nitrate aqueous solution was added dropwise to the suspension. Stirring continued for 2 h, followed by heating to 80℃ and maintaining this temperature until the ethanol was completely evaporated, yielding a yellow powder. This powder was then calcined in a 5% H2 / Ar mixed gas at a rate of 5℃ / min to 350℃ for 2 h. At this point, the noble metal loading was 1 wt%.
[0048] Reference Example 4: Hydrogen production from Pt / CeO2 catalyst in a methanol-water liquid phase system
[0049] (1) Measure 10 mL of methanol to water in a volume ratio of 7:3 and pour it into a 100 mL flask, then add 8.0 mol / L KOH (molar concentration based on total MeOH / H2O volume);
[0050] (2) Weigh 20 mg of catalyst Pt / CeO2 and uniformly disperse it in the above (1) mixture and seal it with a rubber stopper. Purge the atmosphere with Ar for 30 min and then allow the system to react in an Ar atmosphere. Place the flask on a magnetic stirrer that has been preheated to 60 °C and stir.
[0051] (3) The gas composition was quantitatively analyzed using gas chromatography and recorded. The hydrogen yield on the Pt / CeO2 catalyst was measured to be 12.64 mol / mol after 4 hours of reaction. Pt -1 h -1 It is much higher than that of the catalyst Pt / MoO3.
[0052] Example 1: Preparation of the catalyst Pt / CeMoO2
[0053] (1) Preparation of CeMoO2 support:
[0054] First, measure 50 mL of 0.3 mmol / mL ammonium molybdate solution, then mix it evenly with 50 mL of aqueous solution containing 0.1 mmol / mL cerium nitrate. After aging at room temperature for 30 min, place it in an oven for hydrothermal treatment at 120℃ for 12 h, then centrifuge, collect the precipitate, wash it with water and ethanol, and finally place it in an oven to dry for 12 h.
[0055] (2) Preparation of Pt / CeMoO2 catalyst:
[0056] At room temperature, 300 mg of CeMoO2 was weighed and uniformly dispersed in 30 mL of ethanol. After stirring for 1 h, 600 μL of a 5 mg / mL platinum nitrate aqueous solution was added dropwise to the suspension. Stirring continued for 2 h, followed by heating to 80 °C and maintaining this temperature until the ethanol was completely evaporated, yielding a yellow powder. This powder was then calcined in a 5% H2 / Ar mixed gas at a rate of 5 °C / min to 350 °C for 2 h. The noble metal loading at this point was 1 wt%.
[0057] Figure 1 (a) Figure 1 (b) represents the particle size of Pt in the Pt / CeMoO2 catalyst. Figure 1 (a) and Figure 1 As shown in (b) in the figure, Figure 1 The high-resolution TEM measurement of the lattice fringe spacing of the small bright spots on the surface of the larger particles in (a) is 0.23 nm, corresponding to the (111) crystal plane of the Pt nanoparticles, indicating that... Figure 1 (a) The small bright spots on the surface of the larger particles are metal Pt nanoparticles, which were successfully loaded onto CeMoO2. The particle size distribution of the small particles in the figure shows that the size of the metal Pt nanoparticles is 1-2 nm. Compared with the prior art, this size has high dispersion and better activity.
[0058] Example 2 Hydrogen production from Pt / CeMoO2 catalyst in a methanol-water liquid phase system
[0059] (1) Measure 10 mL of methanol to water in a volume ratio of 7:3 and pour it into a 100 mL flask, then add 8.0 mol / L KOH (molar concentration based on total MeOH / H2O volume);
[0060] (2) Weigh 20 mg of catalyst and disperse it evenly in the mixture in (1) above, and seal it with a rubber stopper. Purge the atmosphere with Ar for 30 min, and then allow the system to react in an Ar atmosphere. Place the flask on a magnetic stirrer that has been preheated to 60 °C and stir.
[0061] (3) The gas composition was quantitatively analyzed using gas chromatography and recorded. The hydrogen yield on the Pt / CeMoO2 catalyst was measured to be 47.94 mol / mol after 4 hours of reaction. Pt -1 h -1 It exhibits significantly higher catalytic activity than the Pt / MoO3 and Pt / CeO2 catalysts, demonstrating excellent catalytic activity.
[0062] Preparation of Pt / CeMoO2-1 catalyst (reference ratio 5)
[0063] (1) Preparation of CeMoO2-1 support:
[0064] First, measure 50 mL of 0.3 mmol / mL ammonium molybdate solution, then mix it evenly with 50 mL of aqueous solution containing 0.1 mmol / mL cerium nitrate. After aging at room temperature for 30 min, place it in a 180℃ oven for hydrothermal treatment for 12 h, then centrifuge, collect the precipitate, wash it with water and ethanol, and finally place it in an oven to dry for 12 h.
[0065] (2) Preparation of Pt / CeMoO2-1 catalyst:
[0066] At room temperature, 300 mg of CeMoO2 was weighed and uniformly dispersed in 30 mL of ethanol. After stirring for 1 h, 600 μL of a 5 mg / mL platinum nitrate aqueous solution was added dropwise to the suspension. Stirring continued for 2 h, followed by heating to 80 °C and maintaining this temperature until the ethanol was completely evaporated, yielding a yellow powder. This powder was then calcined in a 5% H2 / Ar mixed gas at a rate of 5 °C / min to 350 °C for 2 h. The noble metal loading at this point was 1 wt%.
[0067] Reference ratio 6: Hydrogen production from Pt / CeMoO2-1 catalyst in a methanol-water liquid phase system
[0068] (1) Measure 10 mL of methanol to water in a volume ratio of 7:3 and pour it into a 100 mL flask, then add 8.0 mol / L KOH (molar concentration based on total MeOH / H2O volume);
[0069] (2) Weigh 20 mg of catalyst and disperse it evenly in the mixture in (1) above, and seal it with a rubber stopper. Purge the atmosphere with Ar for 30 min, and then allow the system to react in an Ar atmosphere. Place the flask on a magnetic stirrer that has been preheated to 60 °C and stir.
[0070] (3) The gas composition was quantitatively analyzed using gas chromatography and recorded. The hydrogen yield on the Pt / CeMoO2-1 catalyst was measured to be 35.78 mol / mol after 4 hours of reaction. Pt -1 h -1 It is far lower than the Pt / CeMoO2 catalyst provided by this invention.
[0071] Example 3 Catalyst Cyclic Stability Test
[0072] Catalyst stability is also an important factor in evaluating catalyst performance. First, accurately weigh 20 mg of Pt / CeMoO2 catalyst and uniformly disperse it in 10 mL of a methanol-water mixed solution (V... 甲醇 :V 水=7:3), then add 8 mol / L KOH solution (molar concentration based on total MeOH / H2O volume), seal with a rubber stopper and ensure the system is in an Ar atmosphere, and react at 60℃. One reaction cycle is approximately 6-10 hours. The catalyst can be separated by centrifugation and recycled without further treatment. Three cycles were tested.
[0073] Figure 2 The results show the hydrogen yield at different reaction cycles and times on the Pt / CeMoO2 catalyst. The results indicate that the H2 yield of the Pt / CeMoO2 catalyst is 379.93 mol / mol after the initial 6 hours of reaction. Pt -1 Even after 13 hours of reaction, the H2 production still reached 325.37 mol / mol. Pt -1 The Pt / CeMoO2 catalyst maintained good hydrogen production activity and excellent catalytic stability even after 22.5 h of reaction. Furthermore, no CO byproduct was detected by chromatography throughout the reaction, demonstrating good selectivity. Therefore, the Pt / CeMoO2 catalyst exhibits good catalytic activity, selectivity, and stability in a low-temperature methanol-water liquid phase system.
[0074] The above experimental results show that the catalyst Pt / CeMoO2 has high reusability in the methanol-water liquid phase system. The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention, but it should not be construed as limiting the specific implementation of the invention to these descriptions. For those skilled in the art, various simple deductions and substitutions can be made without departing from the inventive concept, and all such modifications and substitutions should be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a Pt / CeMoO2 catalyst, characterized in that, The preparation method includes the following steps: S1. Synthesize CeMoO2 support; S2. The noble metal Pt is loaded onto the CeMoO2 support to prepare a Pt / CeMoO2 catalyst; Step S1 further includes: S11. Prepare an aqueous solution of ammonium molybdate, and use the resulting solution as solution A; S12. Prepare an aqueous solution of cerium nitrate, and use the resulting solution as solution B. S13. Mix solutions A and B uniformly, and synthesize CeMoO2 support by hydrothermal method using the resulting mixed solution. The concentration of ammonium molybdate in solution A is 0.03-0.6 mmol / mL, and the solution volume is 50-120 mL; The concentration of cerium nitrate in solution B is 0.01-0.2 mmol / mL, and the solution volume is 50-120 mL; The hydrothermal synthesis temperature is 100-150℃.
2. The preparation method according to claim 1, characterized in that, Step S2 also includes: A platinum nitrate aqueous solution, ethanol, and the CeMoO2 support were mixed, and the resulting mixture was calcined after removing the solvent to obtain a Pt / CeMoO2 catalyst.
3. The preparation method according to claim 2, characterized in that, The calcination process shall be carried out in a 5% H2 / Ar mixed gas, heated to 350°C at a rate of 5°C / min, and calcined for 2 h.
4. A Pt / CeMoO2 catalyst, characterized in that, The catalyst-supported metal Pt nanoparticles have a size of 1-2 nm.
5. A Pt / CeMoO2 catalyst, characterized in that, The catalyst is obtained by the preparation method according to any one of claims 1-3.
6. An application of a Pt / CeMoO2 catalyst, characterized in that, The applications include those in the methanol-water liquid-phase reforming hydrogen production reaction.