Platinum-rare earth alloy for liquid organic hydrogen storage and method of making and using same

Abstract

This invention discloses a method for preparing platinum-rare earth alloys for liquid organic hydrogen storage, specifically as follows: Step 1, preparing a Y / SiO2 precursor; Step 2, preparing a platinum-rare earth alloy Pt-Y / SiO2 based on the product obtained in Step 1. This invention also discloses the platinum-rare earth alloy for liquid organic hydrogen storage and its applications. This invention solves the problems of high precious metal content, low catalytic efficiency, and insufficient long-term stability in the preparation of existing dehydrogenation materials.

Description

Technical Field

[0001] This invention belongs to the field of catalytic material preparation and hydrogen energy chemical technology, and relates to platinum-rare earth alloys for liquid organic hydrogen storage. This invention also relates to the preparation method and application of platinum-rare earth alloys for liquid organic hydrogen storage. Background Technology

[0002] Liquid organic hydrogen carriers (LOHC) technology provides an important alternative route for the safe storage and transportation of hydrogen. Among them, methylcyclohexane (MCH) is considered one of the most promising liquid organic hydrogen carriers due to its high hydrogen storage density, stability under ambient temperature and pressure conditions, and good compatibility with existing petrochemical storage and transportation infrastructure. Currently, noble metal materials, especially Pt / Al₂O₃ systems, exhibit good CH bond activation ability and catalytic performance in the dehydrogenation reaction of methylcyclohexane. However, these materials still have problems such as high noble metal loading, high preparation cost, easy migration and agglomeration of metal particles under high temperature reaction conditions, and limited thermal conductivity of conventional carriers, which can easily lead to local overheating and material deactivation, thus limiting their application in large-scale industrialization. To further improve dehydrogenation efficiency, in addition to optimizing the process by extending the residence time of reactants in the catalyst bed, developing low platinum loading and improving metal utilization efficiency and catalytic performance through material structure regulation have become important directions for overcoming existing technological bottlenecks.

[0003] Fumed silica (SiO2), as a nanoscale oxide carrier, possesses a high specific surface area and excellent thermal stability, effectively dispersing and stabilizing metal nanoparticles. Its abundant silanol groups (Si-OH) serve as effective anchoring sites for metal precursors, exhibiting particularly strong electrostatic adsorption for platinum cations, which is beneficial for the high dispersion and stable loading of active components. Simultaneously, SiO2 possesses good thermal conductivity, facilitating rapid heat transfer during reaction and mitigating deactivation caused by localized heat accumulation during high-temperature dehydrogenation. Furthermore, introducing rare earth metal Y and forming an alloy structure with Pt can effectively regulate the electronic structure of Pt, enhancing its catalytic activity and structural stability for dehydrogenation reactions while reducing the amount of precious metal used. Therefore, developing a low-Pt-loading Pt-Y / SiO2 fumed silica-based alloy material for achieving efficient and stable dehydrogenation of methylcyclohexane is of significant practical importance for promoting the industrial application of liquid organic hydrogen storage technology. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing platinum-rare earth alloys for liquid organic hydrogen storage, which solves the problems of high precious metal content, low catalytic efficiency, and insufficient long-term stability in the preparation of existing dehydrogenation materials.

[0005] The first technical solution adopted in this invention is a method for preparing platinum-rare earth alloys for liquid organic hydrogen storage, as detailed below: Step 1: Prepare Y / SiO2 precursor; Step 2: Prepare platinum-rare earth alloy Pt-Y / SiO2 based on the product obtained in Step 1.

[0006] The first technical solution adopted in this invention is also characterized by: The specific process of step 1 is as follows: Step 1.1: Prepare a homogeneous yttrium salt impregnation system; Step 1.2: Prepare a Y / SiO2 precursor based on the product obtained in Step 1.1.

[0007] The specific process of step 1.1 is as follows: Yttrium chloride hexahydrate was used as a rare earth component precursor, dispersed in deionized water, and ultrasonically treated to obtain a homogenized yttrium salt impregnation system.

[0008] In step 1.1, the ultrasonic treatment time is 10 to 30 minutes.

[0009] The specific process of step 1.2 is as follows: the gaseous SiO2 support is introduced into the homogenized yttrium salt impregnation system, premixed for 10-20 min under stirring, followed by ultrasonic strengthening treatment for 60-120 min, the resulting mixture is transferred to a constant temperature oscillator and dried continuously at 60-80 ℃ and 160-180 rpm for 12-24 h, and the dried solid is ground and homogenized to obtain the Y / SiO2 precursor.

[0010] The specific process of step 2 is as follows: Step 2.1, prepare platinum precursor solution; Step 2.2: Add the Y / SiO2 precursor obtained in step 1 to the platinum precursor solution to prepare the platinum-rare earth alloy Pt-Y / SiO2.

[0011] The specific process of step 2.1 is as follows: Using chloroplatinic acid hexahydrate as the platinum source, it is dissolved in deionized water and ultrasonically treated for 10–30 min to form a uniform and transparent platinum precursor solution.

[0012] The specific process of step 2.2 is as follows: The Y / SiO2 precursor obtained in step 1 is added to the platinum precursor solution and ultrasonically impregnated for 60–120 min. The resulting mixture is then transferred to a constant-temperature oscillator and dried at 60–80 ℃ and 160–180 rpm for 12–24 h. The resulting solid is then ground and placed in a tube furnace for thermal reduction under a H2 / Ar mixed reducing atmosphere. The heat treatment conditions are: heating rate 5–10 ℃ / min, reduction temperature 700–800 ℃, reduction time 90–150 min, and reduction pressure 0.1–0.13 MPa. After the sample cools to room temperature, it is removed to obtain the platinum-rare earth alloy Pt-Y / SiO2.

[0013] The second technical solution adopted in this invention is a platinum-rare earth alloy for liquid organic hydrogen storage, which is prepared by the above-mentioned preparation method of platinum-rare earth alloy for liquid organic hydrogen storage.

[0014] The third technical solution adopted in this invention is the application of platinum-rare earth alloys for liquid organic hydrogen storage in MCH dehydrogenation.

[0015] The beneficial effects of this invention are as follows: (1) The formation of an alloy structure between Y and Pt is beneficial for controlling the electronic structure of Pt and improving the dispersibility of the active components; (2) Using gaseous SiO2 as a support is beneficial to improving the uniformity of the distribution of active components on the support surface and enhancing the structural stability of the material; (3) Under low Pt loading conditions, the prepared material can still exhibit high conversion rate, high hydrogen release rate and good continuous operation stability in the dehydrogenation reaction of methylcyclohexane. Attached Figure Description

[0016] Figure 1 The image shows an HRTEM image of a Pt-Y / SiO2 material sample obtained in Example 1 of the preparation method of the platinum-rare earth alloy for liquid organic hydrogen storage according to the present invention. Figure 2 HAADF-STEM image of Pt-Y / SiO2 material sample obtained in Example 1 of the preparation method of platinum-rare earth alloy for liquid organic hydrogen storage of the present invention; Pt-Y particle size distribution. Figure 3 The XRD comparison diagrams are of the Pt-Y / SiO2 material obtained in Example 1 of the preparation method of the platinum-rare earth alloy for liquid organic hydrogen storage of the present invention and the Pt / SiO2 material obtained in Comparative Example 4. Figure 4 The diagram shows the catalytic MCH dehydrogenation performance of the Pt-Y / SiO2 material obtained in Example 1 of the preparation method of the platinum-rare earth alloy for liquid organic hydrogen storage according to the present invention. Figure 5 The image shows the Raman spectroscopy of the Pt-Y / SiO2 material before and after catalytic MCH dehydrogenation obtained in Example 1 of the preparation method of the platinum-rare earth alloy for liquid organic hydrogen storage according to the present invention. Detailed Implementation

[0017] The following detailed description is provided in conjunction with specific implementation methods.

[0018] The present invention relates to a method for preparing a platinum-rare earth alloy for liquid organic hydrogen storage. The method uses gaseous SiO2 as a carrier, first introducing rare earth metal Y to form a Y / SiO2 precursor, then introducing a Pt precursor through impregnation, and obtaining a Pt-Y / SiO2 alloy material after drying, grinding and reduction treatment.

[0019] Step 1, Preparation of Y / SiO2 precursor, the specific process is as follows: Yttrium chloride hexahydrate was used as a rare earth component precursor. 1–7 mg of the precursor was weighed and dispersed in 15–20 mL of deionized water. The mixture was then placed in a 50 mL container and sonicated for 10–30 min to obtain a homogenized yttrium salt impregnation system. Subsequently, 100–600 mg of fumed SiO2 support was introduced into the system. The mixture was premixed for 10–20 min under stirring, followed by ultrasonic treatment for 60–120 min. The resulting mixture was then transferred to a constant-temperature oscillator and dried continuously at 60–80 °C and 160–180 rpm for 12–24 h. The dried solid was then ground and homogenized to obtain the Y / SiO2 precursor material.

[0020] Step 2, the preparation of Pt-Y / SiO2 material, is as follows: Using chloroplatinic acid hexahydrate as the platinum source, 0.5–3.5 mg was weighed and dissolved in 15–20 mL of deionized water. The solution was ultrasonically treated for 10–30 min to form a homogeneous and transparent platinum precursor solution. The Y / SiO2 precursor obtained in step 1 was added to the platinum precursor solution (molar ratio of Y / SiO2 precursor to platinum precursor solution was 4:1), and ultrasonically impregnated for 60–120 min. The resulting mixture was transferred to a constant-temperature oscillator and dried at 60–80 °C and 160–180 rpm for 12–24 h. The resulting solid was ground and then placed in a tube furnace for thermal reduction under a H2 / Ar mixed reducing atmosphere. The heat treatment conditions were: heating rate 5–10 °C / min, reduction temperature 700–800 °C, reduction time 90–150 min, and reduction pressure 0.1–0.13 MPa. After the sample cools to room temperature, it is removed to obtain the Pt-Y / SiO2 material (platinum-rare earth alloy material).

[0021] The Pt-Y / SiO2 catalytic dehydrogenation of MCH is as follows: 0.3 g of the prepared Pt-Y / SiO2 material was thoroughly mixed with 2–4 g of quartz sand and packed into a high-pressure fixed-bed reactor. MCH dehydrogenation was carried out at 250–425 °C under conditions of 0.3–0.5 MPa reaction pressure, 15–35 mL / min gas flow rate, and 0.05–0.15 mL / min methylcyclohexane injection rate.

[0022] Example 1 Step 1, the preparation of the Y / SiO2 precursor, is as follows: Yttrium chloride hexahydrate was used as a rare earth component precursor. 3.7 mg of the precursor was weighed and dispersed in 18 mL of deionized water. The mixture was then placed in a 50 mL container and sonicated for 20 min to obtain a homogenized yttrium salt impregnation system. Subsequently, 300 mg of fumed SiO2 support was introduced into the system, premixed for 15 min with stirring, followed by sonication for 90 min. The resulting mixture was then transferred to a constant-temperature oscillator and dried continuously at 70 °C and 170 rpm for 18 h. The dried solid was then ground and homogenized to obtain the Y / SiO2 precursor material.

[0023] Step 2, the preparation of Pt-Y / SiO2 material, is as follows: Using chloroplatinic acid hexahydrate as the platinum source, 1.6 mg was weighed and dissolved in 18 mL of deionized water. The solution was ultrasonically treated for 20 min to form a homogeneous and transparent platinum precursor solution. The Y / SiO2 precursor obtained in step 1 was added to the platinum precursor solution (the molar ratio of Y / SiO2 precursor to platinum precursor was 4:1), and ultrasonically impregnated for 90 min. The resulting mixture was transferred to a constant-temperature oscillator and dried at 70 ℃ and 170 rpm for 18 h. The resulting solid was ground and then placed in a tube furnace for thermal reduction under a H2 / Ar mixed reducing atmosphere. The heat treatment conditions were: heating rate 8 ℃ / min, reduction temperature 750 ℃, reduction time 120 min, and reduction pressure 0.12 MPa. After the sample cooled to room temperature, it was removed to obtain the Pt-Y / SiO2 material.

[0024] The Pt-Y / SiO2 catalytic dehydrogenation of MCH is as follows: 0.3 g of the prepared Pt-Y / SiO2 material was thoroughly mixed with 3 g of quartz sand and packed into a high-pressure fixed-bed reactor. MCH dehydrogenation was carried out at 350 °C under the conditions of a reaction pressure of 0.4 MPa, a gas flow rate of 25 mL / min, and a methylcyclohexane injection rate of 0.1 mL / min.

[0025] Example 2 Step 1, Preparation of Y / SiO2 precursor, the specific process is as follows: Yttrium chloride hexahydrate was used as a rare earth component precursor. 1 mg of the precursor was weighed and dispersed in 15 mL of deionized water. The mixture was then placed in a 50 mL container and sonicated for 10 min to obtain a homogenized yttrium salt impregnation system. Subsequently, 100 mg of fumed SiO2 support was introduced into the system, premixed for 10 min with stirring, followed by sonication for 60 min. The resulting mixture was then transferred to a constant-temperature oscillator and dried continuously at 80 °C and 160 rpm for 12 h. The dried solid was then ground and homogenized to obtain the Y / SiO2 precursor material.

[0026] Step 2, the preparation of Pt-Y / SiO2 material, is as follows: Using chloroplatinic acid hexahydrate as the platinum source, 0.5 mg was weighed and dissolved in 15 mL of deionized water. The solution was ultrasonically treated for 10 min to form a homogeneous and transparent platinum precursor solution. The Y / SiO2 precursor obtained in step 1 was added to the platinum precursor solution (the molar ratio of Y / SiO2 precursor to platinum precursor was 4:1), and ultrasonically impregnated for 60 min. The resulting mixture was transferred to a constant-temperature oscillator and dried at 80 ℃ and 160 rpm for 12 h. The resulting solid was ground and then placed in a tube furnace for thermal reduction under a H2 / Ar mixed reducing atmosphere. The heat treatment conditions were: heating rate 5 ℃ / min, reduction temperature 800 ℃, reduction time 90 min, and reduction pressure 0.1 MPa. After the sample cooled to room temperature, it was removed to obtain the Pt-Y / SiO2 material.

[0027] The Pt-Y / SiO2 catalytic dehydrogenation of MCH is as follows: 0.3 g of the prepared Pt-Y / SiO2 material was thoroughly mixed with 2 g of quartz sand and packed into a high-pressure fixed-bed reactor. MCH dehydrogenation was carried out at 250 °C under the conditions of a reaction pressure of 0.3 MPa, a gas flow rate of 15 mL / min, and a methylcyclohexane injection rate of 0.05 mL / min.

[0028] Example 3 Step 1, Preparation of Y / SiO2 precursor, the specific process is as follows: Yttrium chloride hexahydrate was used as a rare earth component precursor. 7 mg of the precursor was weighed and dispersed in 20 mL of deionized water. The mixture was then placed in a 50 mL container and sonicated for 30 min to obtain a homogenized yttrium salt impregnation system. Subsequently, 600 mg of fumed SiO2 support was introduced into the system, premixed for 20 min with stirring, followed by sonication for 120 min. The resulting mixture was then transferred to a constant-temperature oscillator and dried continuously at 60 °C and 180 rpm for 24 h. The dried solid was then ground and homogenized to obtain the Y / SiO2 precursor material.

[0029] Step 2, the preparation of Pt-Y / SiO2 material, is as follows: Using chloroplatinic acid hexahydrate as the platinum source, 3.5 mg was weighed and dissolved in 20 mL of deionized water. The solution was ultrasonically treated for 30 min to form a homogeneous and transparent platinum precursor solution. The Y / SiO2 precursor obtained in step 1 was added to the platinum precursor solution (the molar ratio of Y / SiO2 precursor to platinum precursor was 4:1), and ultrasonically impregnated for 120 min. The resulting mixture was transferred to a constant-temperature oscillator and dried at 60 ℃ and 180 rpm for 24 h. The resulting solid was ground and then placed in a tube furnace for thermal reduction under a H2 / Ar mixed reducing atmosphere. The heat treatment conditions were: heating rate 10 ℃ / min, reduction temperature 700 ℃, reduction time 150 min, and reduction pressure 0.13 MPa. After the sample cooled to room temperature, it was removed to obtain the Pt-Y / SiO2 material.

[0030] The Pt-Y / SiO2 catalytic dehydrogenation of MCH is as follows: 0.3 g of the prepared Pt-Y / SiO2 material was thoroughly mixed with 4 g of quartz sand and packed into a high-pressure fixed-bed reactor. MCH dehydrogenation was carried out at 425 °C under the conditions of a reaction pressure of 0.5 MPa, a gas flow rate of 35 mL / min, and a methylcyclohexane injection rate of 0.15 mL / min.

[0031] Comparative Example 1 (Preparation of yttrium chloride precursor and chloroplatinic acid precursor using anhydrous ethanol) Step 1, the preparation of the Y / SiO2 precursor, is as follows: Yttrium chloride hexahydrate was used as a rare earth component precursor. 3.7 mg of the precursor was weighed and dispersed in 18 mL of anhydrous ethanol. The mixture was then placed in a 50 mL container and sonicated for 20 min to obtain a homogenized yttrium salt impregnation system. Subsequently, 300 mg of fumed SiO2 support was introduced into the system, premixed for 15 min with stirring, followed by sonication for 90 min. The resulting mixture was then transferred to a constant-temperature oscillator and dried continuously at 70 °C and 170 rpm for 18 h. The dried solid was then ground and homogenized to obtain the Y / SiO2 precursor material.

[0032] Step 2, the preparation of Pt-Y / SiO2 material, is as follows: Using chloroplatinic acid hexahydrate as the platinum source, 1.6 mg was weighed and dissolved in 18 mL of anhydrous ethanol. The solution was ultrasonically treated for 20 min to form a homogeneous and transparent platinum precursor solution. The Y / SiO2 precursor obtained in step 1 was added to the platinum precursor solution (the molar ratio of Y / SiO2 precursor to platinum precursor was 4:1), and ultrasonically impregnated for 90 min. The resulting mixture was transferred to a constant-temperature oscillator and dried at 70 ℃ and 170 rpm for 18 h. The resulting solid was ground and then placed in a tube furnace for thermal reduction under a H2 / Ar mixed reducing atmosphere. The heat treatment conditions were: heating rate 8 ℃ / min, reduction temperature 750 ℃, reduction time 120 min, and reduction pressure 0.12 MPa. After the sample cooled to room temperature, it was removed to obtain the Pt-Y / SiO2 material.

[0033] Step 3, Pt-Y / SiO2 catalyzed MCH dehydrogenation, as detailed below: 0.3 g of the prepared Pt-Y / SiO2 material was thoroughly mixed with 3 g of quartz sand and packed into a high-pressure fixed-bed reactor. MCH dehydrogenation was carried out at 350 °C under the conditions of a reaction pressure of 0.4 MPa, a gas flow rate of 25 mL / min, and a methylcyclohexane injection rate of 0.1 mL / min.

[0034] Comparative Example 2 (Pt-Y / SiO2 material without the addition of quartz sand, directly placed into a high-pressure catalytic fixed bed) Step 1, the preparation of the Y / SiO2 precursor, is as follows: Yttrium chloride hexahydrate was used as a rare earth component precursor. 3.7 mg of the precursor was weighed and dispersed in 18 mL of deionized water. The mixture was then placed in a 50 mL container and sonicated for 20 min to obtain a homogenized yttrium salt impregnation system. Subsequently, 300 mg of fumed SiO2 support was introduced into the system, premixed for 15 min with stirring, followed by sonication for 90 min. The resulting mixture was then transferred to a constant-temperature oscillator and dried continuously at 70 °C and 170 rpm for 18 h. The dried solid was then ground and homogenized to obtain the Y / SiO2 precursor material.

[0035] Step 2, the preparation of Pt-Y / SiO2 material, is as follows: Using chloroplatinic acid hexahydrate as the platinum source, 1.6 mg was weighed and dissolved in 18 mL of deionized water. The solution was ultrasonically treated for 20 min to form a homogeneous and transparent platinum precursor solution. The Y / SiO2 precursor obtained in step 1 was added to the platinum precursor solution (the molar ratio of Y / SiO2 precursor to platinum precursor was 4:1), and ultrasonically impregnated for 90 min. The resulting mixture was transferred to a constant-temperature oscillator and dried at 70 ℃ and 170 rpm for 18 h. The resulting solid was ground and then placed in a tube furnace for thermal reduction under a H2 / Ar mixed reducing atmosphere. The heat treatment conditions were: heating rate 8 ℃ / min, reduction temperature 750 ℃, reduction time 120 min, and reduction pressure 0.12 MPa. After the sample cooled to room temperature, it was removed to obtain the Pt-Y / SiO2 material.

[0036] The Pt-Y / SiO2 catalytic dehydrogenation of MCH is as follows: 0.3 g of the prepared Pt-Y / SiO2 material was packed into a high-pressure fixed-bed reactor. MCH dehydrogenation was carried out at 350 °C under the conditions of a reaction pressure of 0.4 MPa, a gas flow rate of 25 mL / min, and a methylcyclohexane injection rate of 0.1 mL / min, using methylcyclohexane as the liquid hydrogen donor substrate.

[0037] Comparative Example 3 (Y / SiO2 material without Pt) Step 1, the preparation of Y / SiO2 material, is as follows: Yttrium chloride hexahydrate was weighed at a dosage of 3.7 mg and dispersed in 18 mL of deionized water. The solution was then placed in a 50 mL container and sonicated for 20 min to obtain a homogenized yttrium salt impregnation system. Subsequently, 300 mg of fumed SiO2 support was introduced into the system, premixed for 15 min with stirring, followed by sonication for 90 min. The resulting mixture was transferred to a constant-temperature oscillator and dried continuously at 70 °C and 170 rpm for 18 h. The resulting solid was then ground and placed in a tube furnace for thermal reduction in a H2 / Ar mixed reducing atmosphere. The heat treatment conditions were: heating rate 8 °C / min, reduction temperature 750 °C, reduction time 120 min, and reduction pressure 0.12 MPa. After cooling to room temperature, the sample was removed to obtain the Y / SiO2 material.

[0038] Step 2, Y / SiO2 catalyzed MCH dehydrogenation, as detailed below: 0.3 g of the prepared Y / SiO2 material was thoroughly mixed with 3 g of quartz sand and packed into a high-pressure fixed-bed reactor. MCH dehydrogenation was carried out at 350 °C under the conditions of a reaction pressure of 0.4 MPa, a gas flow rate of 25 mL / min, and a methylcyclohexane injection rate of 0.1 mL / min.

[0039] Comparative Example 4 (Pt / SiO2 material without Y) Step 1, the preparation of the Pt / SiO2 precursor, is detailed below: Chloroplatinic acid hexahydrate was weighed at a dosage of 1.6 mg and dispersed in 18 mL of deionized water. The solution was then placed in a 50 mL container and sonicated for 20 min to form a homogeneous and transparent platinum precursor solution. Subsequently, 300 mg of fumed SiO2 support was introduced into the system and premixed for 15 min with stirring, followed by sonication for 90 min. The resulting mixture was transferred to a constant-temperature oscillator and dried continuously at 70 °C and 170 rpm for 18 h. The resulting solid was then ground and placed in a tube furnace for thermal reduction in a H2 / Ar mixed reducing atmosphere. The heat treatment conditions were: heating rate 8 °C / min, reduction temperature 750 °C, reduction time 120 min, and reduction pressure 0.12 MPa. After the sample cooled to room temperature, it was removed to obtain the Pt / SiO2 material.

[0040] Step 1, Pt / SiO2 catalyzed MCH dehydrogenation, is detailed below: 0.3 g of the prepared Pt / SiO2 material was thoroughly mixed with 3 g of quartz sand and packed into a high-pressure fixed-bed reactor. MCH dehydrogenation was carried out at 350 °C under the conditions of a reaction pressure of 0.4 MPa, a gas flow rate of 25 mL / min, and a methylcyclohexane injection rate of 0.1 mL / min.

[0041] Comparative Example 5 (Preparation of Pt-Cr / SiO2 material by replacing Y with metallic Cr) Step 1, preparation of the Cr / SiO2 precursor, is as follows: Chromium nitrate nonahydrate was used as the metal precursor. 3.7 mg of the precursor was weighed and dispersed in 18 mL of deionized water. The mixture was then placed in a 50 mL container and sonicated for 20 min to obtain a homogenized chromium salt impregnation system. Subsequently, 300 mg of fumed SiO2 support was introduced into the system, premixed for 15 min with stirring, followed by sonication for 90 min. The resulting mixture was then transferred to a constant-temperature oscillator and dried continuously at 70 °C and 170 rpm for 18 h. The dried solid was then ground and homogenized to obtain the Cr / SiO2 precursor material.

[0042] Step 2, the preparation of Pt-Cr / SiO2 material, is as follows: Using chloroplatinic acid hexahydrate as the platinum source, 1.6 mg was weighed and dissolved in 18 mL of deionized water. The solution was ultrasonically treated for 20 min to form a homogeneous and transparent platinum precursor solution. The Cr / SiO2 precursor obtained in step 1 was added to the platinum precursor solution (the molar ratio of Cr / SiO2 precursor to platinum precursor was 4:1), and ultrasonically impregnated for 90 min. The resulting mixture was transferred to a constant-temperature oscillator and dried at 70 ℃ and 170 rpm for 18 h. The resulting solid was ground and then placed in a tube furnace for thermal reduction under a H2 / Ar mixed reducing atmosphere. The heat treatment conditions were: heating rate 8 ℃ / min, reduction temperature 750 ℃, reduction time 120 min, and reduction pressure 0.12 MPa. After the sample cooled to room temperature, it was removed to obtain the Pt-Cr / SiO2 material.

[0043] The Pt-Cr / SiO2 catalytic dehydrogenation of MCH is as follows: 0.3 g of the prepared Pt-Cr / SiO2 material was thoroughly mixed with 3 g of quartz sand and packed into a high-pressure fixed-bed reactor. MCH dehydrogenation was carried out at 350 °C under the conditions of a reaction pressure of 0.4 MPa, a gas flow rate of 25 mL / min, and a methylcyclohexane injection rate of 0.1 mL / min.

[0044] Comparative Example 6 (Preparation of Pt-Sm / SiO2 material by replacing Y with rare earth metal Sm) Step 1, preparation of the Sm / SiO2 precursor, is as follows: Using samarium chloride hexahydrate as a rare earth component precursor, 3.7 mg was weighed and dispersed in 18 mL of deionized water. The mixture was then placed in a 50 mL container and sonicated for 20 min to obtain a homogenized samarium salt impregnation system. Subsequently, 300 mg of fumed SiO2 support was introduced into the system, premixed for 15 min under stirring, and then sonicated for 90 min. The resulting mixture was transferred to a constant-temperature oscillator and dried continuously at 70 °C and 170 rpm for 18 h. The dried solid was then ground and homogenized to obtain the Sm / SiO2 precursor material.

[0045] Step 2, the preparation of Pt-Sm / SiO2 materials, is as follows: Using chloroplatinic acid hexahydrate as the platinum source, 1.6 mg was weighed and dissolved in 18 mL of deionized water. The solution was ultrasonically treated for 20 min to form a homogeneous and transparent platinum precursor solution. The Sm / SiO2 precursor obtained in step 1 was added to the platinum precursor solution (the molar ratio of Sm / SiO2 precursor to platinum precursor was 4:1), and ultrasonically impregnated for 90 min. The resulting mixture was transferred to a constant-temperature oscillator and dried at 70 ℃ and 170 rpm for 18 h. The resulting solid was ground and then placed in a tube furnace for thermal reduction under a H2 / Ar mixed reducing atmosphere. The heat treatment conditions were: heating rate 8 ℃ / min, reduction temperature 750 ℃, reduction time 120 min, and reduction pressure 0.12 MPa. After the sample cooled to room temperature, it was removed to obtain the Pt-Sm / SiO2 material.

[0046] The Pt-Sm / SiO2 catalytic dehydrogenation of MCH is as follows: 0.3 g of the prepared Pt-Sm / SiO2 material was thoroughly mixed with 3 g of quartz sand and packed into a high-pressure fixed-bed reactor. MCH dehydrogenation was carried out at 350 °C under the conditions of a reaction pressure of 0.4 MPa, a gas flow rate of 25 mL / min, and a methylcyclohexane injection rate of 0.1 mL / min.

[0047] Comparative Example 7 (using traditional non-gas phase SiO2 as a support) Step 1, the preparation of the Y / SiO2 precursor, is as follows: Yttrium chloride hexahydrate was used as a rare earth component precursor. 3.7 mg of the precursor was weighed and dispersed in 18 mL of deionized water. The mixture was then placed in a 50 mL container and sonicated for 20 min to obtain a homogenized yttrium salt impregnation system. Subsequently, 300 mg of non-gas phase SiO2 support was introduced into the system, premixed for 15 min under stirring, followed by ultrasonic strengthening treatment for 90 min. The resulting mixture was transferred to a constant temperature oscillator and dried continuously at 70 ℃ and 170 rpm for 18 h. The dried solid was then ground and homogenized to obtain the Y / SiO2 precursor material.

[0048] Step 2, the preparation of Pt-Y / SiO2 material, is as follows: Using chloroplatinic acid hexahydrate as the platinum source, 1.6 mg was weighed and dissolved in 18 mL of deionized water. The solution was ultrasonically treated for 20 min to form a homogeneous and transparent platinum precursor solution. The Y / SiO2 precursor obtained in step 1 was added to the platinum precursor solution (the molar ratio of Y / SiO2 precursor to platinum precursor was 4:1), and ultrasonically impregnated for 90 min. The resulting mixture was transferred to a constant-temperature oscillator and dried at 70 ℃ and 170 rpm for 18 h. The resulting solid was ground and then placed in a tube furnace for thermal reduction under a H2 / Ar mixed reducing atmosphere. The heat treatment conditions were: heating rate 8 ℃ / min, reduction temperature 750 ℃, reduction time 120 min, and reduction pressure 0.12 MPa. After the sample cooled to room temperature, it was removed to obtain the Pt-Y / SiO2 material.

[0049] The Pt-Y / SiO2 catalytic dehydrogenation of MCH is as follows: 0.3 g of the prepared Pt-Y / SiO2 material was thoroughly mixed with 3 g of quartz sand and packed into a high-pressure fixed-bed reactor. MCH dehydrogenation was carried out at 350 °C under the conditions of a reaction pressure of 0.4 MPa, a gas flow rate of 25 mL / min, and a methylcyclohexane injection rate of 0.1 mL / min.

[0050] Table 1 Comparison of dehydrogenation effects of materials under different conditions

[0051] As shown in Table 1, the Pt-Y / SiO2 material obtained in Example 1 exhibited the highest methylcyclohexane conversion, hydrogen release rate, and excellent dehydrogenation selectivity. In Comparative Example 1, the impregnation medium was anhydrous ethanol, which may have resulted in weaker interactions between the precursor and the hydroxyl groups on the support surface, leading to a decrease in the uniformity of the active component distribution. Ultimately, this resulted in inferior alloy formation, particle dispersion, and effective active site exposure compared to Example 1. Mixing the material with quartz sand typically improves bed uniformity, reduces local overheating, local concentration gradients, and uneven flow, and makes the reaction stream and heat distribution more stable. However, in Comparative Example 2, no quartz sand was added; 0.3 g of the material was directly loaded into the fixed bed. Direct loading is more likely to cause local hot spots or limited mass transfer, thereby reducing apparent activity. Comparative Examples 3 and 4 verified the irreplaceable roles of Y and Pt, respectively. Comparative Example 3, a Y / SiO2 material without Pt, showed zero conversion, hydrogen release rate, and selectivity, indicating that the material has almost no MCH dehydrogenation ability when only Y is present without Pt. This suggests that Pt is the core active center for this reaction. Comparative Example 4, a Pt / SiO2 material without Y, performed significantly worse than Example 1, indicating that Y is not an independent active center but an important alloying component: it significantly improves the catalytic efficiency per unit Pt by forming an alloy with Pt, regulating the electronic structure, surface adsorption-desorption behavior, and particle stability of Pt. Comparative Examples 5 and 6 were both significantly worse than Example 1, especially the performance after Sm substitution, indicating that the structural or electronic synergistic effect between Y and Pt is unique. On the one hand, different metals have different alloying tendencies, electron donation and acceptance characteristics, atomic radius matching, and surface stabilization effects with Pt; on the other hand, their interactions with the SiO2 support also differ. In Comparative Example 7, the use of traditional non-gas-phase SiO2 instead of fumed silica may not provide a high specific surface area and abundant surface silanol groups, resulting in insufficient formation of the Pt-Y active phase and a significant decrease in activity. This indicates that the superior performance of the material of this invention stems from the synergistic effect of the solvent system, Pt-Y alloy composition, fumed SiO2 support, and reaction bed configuration.

[0052] Figure 1 This is an HRTEM image of a Pt-Y / SiO2 material sample obtained in Example 1 of the preparation method of Pt-Y / SiO2 material of the present invention. It can be seen that the Pt-Y alloy particles are small and uniformly dispersed.

[0053] Figure 2 The image shows the HAADF-STEM image of the Pt-Y / SiO2 material sample obtained in Example 1 of the preparation method of the Pt-Y / SiO2 material of the present invention, and the Pt-Y particle size distribution. Fitting analysis revealed that the average Pt-Y particle size is 2.43 nm. This indicates that the active site design was successful, resulting in a highly dispersed Pt-Y alloy with a small size.

[0054] Figure 3 The images show a comparison of the XRD patterns of the Pt-Y / SiO2 material obtained in Example 1 of the preparation method of the present invention and the Pt / SiO2 material obtained in Comparative Example 4. According to the XRD patterns, the Pt-Y alloy is more uniformly dispersed compared to the Pt / SiO2 material.

[0055] Figure 4 The image shows the catalytic performance of the Pt-Y / SiO2 material for MCH dehydrogenation obtained in Example 1 of the preparation method of the Pt-Y / SiO2 material of this invention. It can be seen that the material maintains good stability and activity during the 48-hour reaction, with the conversion rate remaining at around 80%. Its highest hydrogen release rate reaches 1719.71 mmol·g. Pt -1 ·min -1 And it never fell below 1500 mmol·g Pt -1 ·min -1 This also illustrates that the design of alloy materials is crucial for improving the activity of MCH materials.

[0056] Figure 5 This is a Raman spectroscopy image of the Pt-Y / SiO2 material before and after catalytic MCH dehydrogenation obtained in Example 1 of the preparation method of the Pt-Y / SiO2 material of the present invention. According to the spectral analysis, the gaseous SiO2 support is predominantly amorphous, and the low-loaded Pt-Y species are well dispersed on the support surface, without forming detectable large-grained phases. After 48 h of reaction, the spectral fluctuations of the Pt-Y / SiO2 material are somewhat enhanced, but remain relatively stable at approximately 1350 cm⁻¹. -1 and 1580 cm -1 No obvious D-band and G-band characteristic peaks were observed nearby, indicating that no significant graphitization carbon deposits were formed on the surface of the Pt-Y / SiO2 material.

[0057] In some embodiments, when the Pt loading is 0.2 wt%, the conversion rate of methylcyclohexane can exceed 85%, and the hydrogen release rate can reach 1700 mmol·g. Pt -1 ·min -1 The above results were obtained, and the catalytic performance remained good even after 48 hours of continuous reaction.

[0058] Example 4 Compared with Example 1, the ultrasonic treatment time in step 1 is 25 minutes.

[0059] Example 5 Compared with Example 1, the reduction temperature in step 2 is 780°C.

[0060] Example 6 Compared with Example 1, the reduction time in step 2 is 100 min.

Claims

1. A method for preparing platinum-rare earth alloys for liquid organic hydrogen storage, characterized in that: Specifically as follows: Step 1: Prepare Y / SiO2 precursor; Step 2: Prepare platinum-rare earth alloy Pt-Y / SiO2 based on the product obtained in Step 1.

2. The method for preparing platinum-rare earth alloys for liquid organic hydrogen storage according to claim 1, characterized in that: The specific process of step 1 is as follows: Step 1.1: Prepare a homogeneous yttrium salt impregnation system; Step 1.2: Prepare a Y / SiO2 precursor based on the product obtained in Step 1.

1.

3. The method for preparing platinum-rare earth alloys for liquid organic hydrogen storage according to claim 2, characterized in that: The specific process of step 1.1 is as follows: Yttrium chloride hexahydrate was used as a rare earth component precursor, dispersed in deionized water, and ultrasonically treated to obtain a homogenized yttrium salt impregnation system.

4. The method for preparing platinum-rare earth alloys for liquid organic hydrogen storage according to claim 3, characterized in that: In step 1.1, the ultrasonic treatment time is 10 to 30 minutes.

5. The method for preparing platinum-rare earth alloys for liquid organic hydrogen storage according to claim 3, characterized in that: The specific process of step 1.2 is as follows: the gaseous SiO2 support is introduced into the homogenized yttrium salt impregnation system, premixed for 10-20 min under stirring, followed by ultrasonic strengthening treatment for 60-120 min, the resulting mixture is transferred to a constant temperature oscillator and dried continuously at 60-80 ℃ and 160-180 rpm for 12-24 h, and the dried solid is ground and homogenized to obtain the Y / SiO2 precursor.

6. The method for preparing platinum-rare earth alloys for liquid organic hydrogen storage according to claim 3, characterized in that: The specific process of step 2 is as follows: Step 2.1, prepare platinum precursor solution; Step 2.2: Add the Y / SiO2 precursor obtained in step 1 to the platinum precursor solution to prepare the platinum-rare earth alloy Pt-Y / SiO2.

7. The method for preparing platinum-rare earth alloys for liquid organic hydrogen storage according to claim 6, characterized in that: The specific process of step 2.1 is as follows: Using chloroplatinic acid hexahydrate as the platinum source, it is dissolved in deionized water and ultrasonically treated for 10–30 min to form a uniform and transparent platinum precursor solution.

8. The method for preparing platinum-rare earth alloys for liquid organic hydrogen storage according to claim 6, characterized in that: The specific process of step 2.2 is as follows: the Y / SiO2 precursor obtained in step 1 is added to the platinum precursor solution and ultrasonically impregnated for 60-120 min. The resulting mixture is transferred to a constant temperature oscillator and dried at 60-80 ℃ and 160-180 rpm for 12-24 h. The resulting solid is ground and then placed in a tube furnace for thermal reduction in a H2 / Ar mixed reducing atmosphere. The heat treatment conditions are as follows: heating rate 5-10 ℃ / min, reduction temperature 700-800 ℃, reduction time 90-150 min, and reduction pressure 0.1-0.13 MPa. After the sample is cooled to room temperature, it is taken out to obtain the platinum-rare earth alloy Pt-Y / SiO2.

9. A platinum-rare earth alloy for liquid organic hydrogen storage, prepared by the method for preparing a platinum-rare earth alloy for liquid organic hydrogen storage as described in any one of claims 1 to 8.

10. Application of platinum-rare earth alloys for liquid organic hydrogen storage in MCH dehydrogenation.

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