Highly active platinum on carbon catalysts and methods for their preparation
By treating with ATMP and TiOSO4 to form N/P co-doped carbon layers and Ti-PO hybrid layers, the problem of easy migration and agglomeration of platinum-carbon catalysts under high temperature and high pressure was solved, the stability and activity of the catalyst were improved, and green preparation and efficient hydrogenation reaction were realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHAANXI ROCK NEW MATERIALS CO LTD
- Filing Date
- 2026-05-11
- Publication Date
- 2026-06-09
AI Technical Summary
Existing platinum-carbon catalysts are prone to Pt particle migration and agglomeration under high temperature, high pressure and water-containing conditions, resulting in a reduction of active sites and a decrease in catalyst stability. In addition, traditional preparation processes use highly toxic reducing agents, which have poor process safety and make it difficult to meet the requirements of green preparation and industrial application.
The carbon support is synergistically treated with ATMP solution and TiOSO4 to form an N/P co-doped carbon layer and a Ti-PO hybrid layer. Stable anchoring points are generated in situ to enhance the interfacial interaction between Pt and the support. Heat treatment under Ar/H2 atmosphere achieves uniform dispersion and stabilization of Pt, avoiding over-reduction. The process is simple and does not require strong liquid-phase reducing agents.
The catalyst's resistance to high-temperature sintering, resistance to chemical media erosion, and stability during recycling were improved, while the dispersibility and catalytic activity of Pt were enhanced, resulting in highly efficient hydrogenation reaction performance.
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Figure CN122164468A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst technology, specifically to a highly active platinum-carbon catalyst and its preparation method. Background Technology
[0002] Supported platinum-based catalysts play a crucial role in the chemical industry. Especially in hydrogenation reactions, platinum-carbon catalysts are commonly used in fine chemical processes such as the hydrogenation of nitro compounds, the synthesis of haloaryl amines, and the hydrogenation of unsaturated hydrocarbons. In fuel cells, platinum-carbon catalysts are also important catalytic materials for the oxygen reduction reaction at the cathode of proton exchange membrane fuel cells. In hydrogenation applications, catalysts are often subjected to high temperature, high pressure, H2, and aqueous systems, which can lead to platinum particle migration, ripening, and agglomeration. Furthermore, long-term cyclic use can cause platinum particle detachment, resulting in a reduction of active sites and decreased catalyst stability.
[0003] While existing technologies have proposed some improvements to address the aforementioned problems, significant shortcomings remain. For instance, while ultra-high temperature graphitization of carbon supports improves their corrosion resistance, it typically requires temperatures exceeding 2000°C. This not only demands sophisticated equipment and high energy consumption but also easily leads to a decrease in the specific surface area of the support, hindering the high dispersion and loading of active components. Furthermore, patent application CN110538651A discloses a highly active and selective platinum-carbon catalyst and its preparation method. This method modifies an ultrafine carbon black support, dispersing the active metal and support in an "interlocking" manner, thereby inhibiting metal particle aggregation during the reaction and improving catalytic performance to some extent. However, under harsh conditions such as high-temperature, high-pressure hydrogenation, aqueous conditions, and reaction-regeneration cycles, the carbon support and its metal-support interface are still prone to thermally induced structural degradation and chemical erosion, leading to Pt particle shedding, intensified sintering, reduced active sites, and insufficient catalyst durability.
[0004] Furthermore, the preparation of traditional platinum-carbon catalysts often relies on highly toxic reducing agents such as sodium borohydride and hydrazine hydrate to reduce platinum precursors, which not only results in poor process safety but also hinders green preparation and industrial application. Therefore, there is a need to provide a highly active platinum-carbon catalyst and its preparation method to solve the aforementioned technical problems. Summary of the Invention
[0005] In view of this, the present invention provides a highly active platinum-carbon catalyst and its preparation method, which can maintain high activity while improving the catalyst's resistance to chemical media erosion and high-temperature sintering performance.
[0006] To achieve the above objectives, the present invention provides a method for preparing a highly active platinum-carbon catalyst, comprising the following steps: S1. Add carbon support to deionized water, sonicate, add ATMP solution and stir to obtain ATMP carbon support dispersion; dissolve TiOSO4 in deionized water and add it dropwise to ATMP carbon support dispersion. After the addition is complete, stir magnetically to obtain mixed dispersion. S2. Add chloroplatinic acid hexahydrate to deionized water, stir, pour into the mixed dispersion, seal and protect from light, continue stirring, filter, wash, and vacuum dry to obtain precursor powder; S3. Place the precursor powder in a tubular furnace quartz tube, first introduce high-purity Ar, heat up and hold, then cool down, then switch the atmosphere to a mixed atmosphere of H2 / Ar, hold, and finally switch back to Ar atmosphere and cool to room temperature to obtain a highly active platinum-carbon catalyst.
[0007] In this invention, aminotrimethylenephosphonic acid (ATMP) simultaneously provides a P source, an N source, and a carbon framework in one step. During pyrolysis, an N / P co-doped carbon layer is spontaneously generated, and further, in synergy with a titanium source, a Ti-PO hybrid layer is generated in situ. The coordination environment containing N and P heteroatoms provides more stable anchoring sites for the Pt active component and enhances the interfacial interaction between the active component and the support. This is beneficial for improving the dispersion state of Pt on the support surface and reducing its migration and aggregation tendency during subsequent heat treatment and reaction processes, thereby improving the catalyst's resistance to high-temperature sintering and its high-temperature structural stability. Simultaneously, the interfacial environment containing N and P components also helps to regulate the electronic structure of the Pt surface, improving Pt's adsorption and activation ability for reactant molecules, thus enhancing the catalyst's hydrogenation reaction activity. Furthermore, the in-situ formed Ti-PO hybrid layer of this invention helps to extend the diffusion path of water, oxygen, and other corrosive media to the carbon support surface, thereby mitigating hydrothermal corrosion and oxidation loss of the carbon support under high-temperature and high-pressure hydrogenation conditions, and thus improving the catalyst's resistance to chemical media erosion.
[0008] Furthermore, in the heat treatment process of step S3, the precursor pyrolysis and hybrid layer formation are first promoted under an Ar atmosphere, followed by reduction treatment under a H2 / Ar mixed atmosphere. This helps to ensure the stable formation of the interface structure while avoiding insufficient exposure of active sites due to excessive reduction or over-coating of the Pt active component, thus balancing the stability of Pt particles with the accessibility of surface active sites. Simultaneously, the synergistic effect of the phosphorus-containing component and the Ti component in ATMP also enhances the bonding strength between Pt and the support, further inhibiting the migration and growth of Pt particles under high temperature and high pressure conditions and in the reaction-regeneration cycle, thereby further improving the catalyst's resistance to high-temperature sintering and its stability in repeated use. Moreover, this invention primarily uses deionized water as the dispersion and loading medium, and does not require the introduction of additional liquid-phase strong reducing agents. The Pt active component can be reduced in situ through the heat treatment process, making the process relatively simple and environmentally friendly.
[0009] Optionally, the ATMP carbon support dispersion is obtained by adding 1.8 to 2.2 parts by weight of carbon support to 200 to 220 parts by weight of deionized water, ultrasonically dispersing at room temperature with a power of 300W for 30 to 40 minutes, then adding ATMP solution and magnetically stirring at 300 to 500 rpm at 25 to 30°C for 50 to 70 minutes.
[0010] Optionally, the ATMP solution is obtained by mixing 0.08-0.15 parts by weight of aminotrimethylenephosphonic acid with 15-30 parts by weight of deionized water and stirring for 10-15 minutes.
[0011] Optionally, the carbon support is a nitrogen-doped carbon support, which is obtained by mixing and grinding g-C3N4 powder and Mg powder under Ar atmosphere for 20-30 minutes, placing it in a tube furnace, heating it to 650℃ at 5℃ / min under Ar atmosphere protection and holding it at that temperature for 2-2.5 hours; after the holding period, cooling it to room temperature under Ar atmosphere, slowly adding it to 0.5mol / L dilute hydrochloric acid, stirring and washing it at room temperature for 30-60 minutes, filtering it, washing it 3-5 times with deionized water, placing it in 5wt% hydrogen peroxide aqueous solution, stirring it at 55-60℃ for 50-70 minutes, filtering it, washing it with deionized water until neutral, and vacuum drying it at 70-80℃ for 10-14 hours.
[0012] By heat-treating g-C3N4 powder and Mg powder under an inert atmosphere, a porous nitrogen-doped carbon support with a certain degree of graphitization is formed. Graphitized carbon has a lower surface defect density and higher resistance to electrochemical / chemical oxidation, which fundamentally improves the support's resistance to chemical media erosion. At the same time, further use of nitrogen-doped carbon support not only helps to enhance the metal-support interaction with Pt, but also transfers electrons to Pt through π-bond conjugation, forming a dual N-doping synergistic effect with the N / P co-doped carbon layer generated by ATMP pyrolysis.
[0013] Optionally, the nitrogen-doped carbon support comprises the following raw materials in parts by weight: 4-5 parts by weight of g-C3N4 powder and 2-3 parts by weight of Mg powder.
[0014] Optionally, in step S1, 0.18~0.25 parts by weight of TiOSO4 are dissolved in 20~30 parts by weight of deionized water, and added dropwise to the ATMP carbon support dispersion at a rate of 1 mL / min using a constant pressure dropping funnel. After the addition is complete, the mixture is magnetically stirred at 300~500 rpm for 120~180 minutes at 25~30℃ to obtain a mixed dispersion.
[0015] Optionally, in step S1, 0.05~0.1 parts by mass of ZrOCl2·8H2O are added when adding TiOSO4.
[0016] This invention further introduces ZrOCl2·8H2O into TiOSO4, making Zr 4+ With Ti 4+ Both can participate in the coordination assembly of ATMP, which is beneficial for forming a Zr-Ti-ATMP bimetallic coordination thin layer on the carbon support surface, and then generating a Zr-Ti-PO composite layer in situ through pyrolysis. Since zirconium-based phosphate / phosphonate systems generally have good chemical stability and hydrolysis resistance, the introduction of Zr components helps to enhance the structural stability of the interface layer and mitigate the tendency of Ti-based phosphate structures to undergo partial hydrolysis and structural degradation under high temperature, high pressure or hydrothermal environments.
[0017] Optionally, in step S2, 1.3-1.5 parts by weight of chloroplatinic acid hexahydrate are added to 50-60 parts by weight of deionized water, stirred at room temperature for 10-15 minutes, and poured into the mixed dispersion in two portions. The mixture is sealed and protected from light, and stirred at 25-30°C for 100-150 minutes. After filtration, the mixture is washed 3-5 times with 150-200 mL of deionized water each time, and dried at 60-70°C and a vacuum degree ≤100 Pa for 10-12 hours to obtain the precursor powder.
[0018] The present invention adds chloroplatinic acid hexahydrate in two stages, which helps to reduce the aggregation of Pt precursors caused by excessively high local concentrations, allowing them to be more uniformly adsorbed and anchored on the surface of the modified support, thereby improving the dispersibility and loading stability of Pt.
[0019] Optionally, in step S3, the precursor powder is placed in a tubular furnace quartz tube, and high-purity Ar is first introduced at a flow rate of 100 mL / min. The temperature is raised to 540~560℃ at a heating rate of 5℃ / min and held for 1.5~2.5 hours. After the holding period, the temperature is lowered to 245~255℃ with the furnace. Then, the atmosphere is switched to a mixed atmosphere consisting of 5% H2 and 95% Ar by volume at a flow rate of 50 mL / min. The temperature is held at 245~255℃ for 30~40 minutes. Finally, the atmosphere is switched back to Ar and cooled to room temperature to obtain a highly active platinum-carbon catalyst.
[0020] During the heating and holding phase at 540–560 °C, the ATMP organic framework undergoes carbonization, which facilitates the formation of an N / P co-doped carbon layer on the support surface. Simultaneously, the Ti-ATMP precursor network can generate a Ti-PO hybrid layer in situ after pyrolysis. Subsequently, under a mixed H2 / Ar atmosphere, the platinum precursor can be reduced to Pt nanoparticles, which then form Pt-P-Ti ternary interface chemical bonds with P atoms and Ti in the ATMP, thereby improving the dispersion stability and bonding strength of the Pt active component.
[0021] The present invention also provides a highly active platinum-carbon catalyst, which is prepared by the above preparation method.
[0022] The highly active platinum-carbon catalyst prepared using the above preparation method and component ratio not only improves the catalytic activity of the catalyst, but also enhances its resistance to high-temperature sintering, corrosion resistance, and cycle stability, thus exhibiting good comprehensive performance.
[0023] The above-described technical solution of the present invention has at least the following beneficial effects: 1. In this invention, ATMP simultaneously provides a P source, an N source, and a carbon framework in one step. During pyrolysis, an N / P co-doped carbon layer is spontaneously generated, and a Ti-PO hybrid layer is further generated in situ in synergy with the titanium source. This is beneficial for extending the diffusion path of water, oxygen, and corrosive media, and for mitigating hydrothermal corrosion and oxidation loss of the support under high temperature and high pressure conditions. At the same time, it also helps to provide stable anchoring points for the Pt active component, enhances the metal-support interaction, improves Pt dispersion, and inhibits migration and aggregation, thereby improving catalytic activity and resistance to high temperature sintering.
[0024] 2. In step S3, the Ti-PO hybrid layer is first heat-treated in an Ar atmosphere to promote its formation, and then gently reduced in a H2 / Ar mixed atmosphere. This helps to balance the stability of the interface with the accessibility of Pt active sites and inhibit the growth of Pt particles. Furthermore, this invention mainly uses deionized water as the medium, which does not require additional liquid-phase strong reducing agents. The process is relatively simple and environmentally friendly. Attached Figure Description
[0025] Figure 1 The figures show the experimental results of the highly active platinum-carbon catalysts prepared in Example 3 and Comparative Examples 1-3 of this invention during the cycle stability test. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.
[0027] Example 1 4 g g-C3N4 powder and 2 g Mg powder were mixed and ground for 20 minutes under Ar atmosphere. The mixture was placed in a tube furnace and heated to 650℃ at 5℃ / min under Ar atmosphere protection and held for 2 hours. After the holding period, the mixture was cooled to room temperature under Ar atmosphere and slowly added to 0.5 mol / L dilute hydrochloric acid. The mixture was stirred and washed for 30 minutes at room temperature, filtered, and washed three times with deionized water. The mixture was then placed in a 5 wt% hydrogen peroxide aqueous solution, stirred at 55℃ for 50 minutes, filtered, and washed with deionized water until neutral. The mixture was then vacuum dried at 70℃ for 10 hours to obtain a nitrogen-doped carbon support.
[0028] 0.08 g of aminotrimethylenephosphonic acid (ATMP) was added to 15 mL of deionized water and stirred for 10 minutes to obtain an ATMP solution. 1.8 g of nitrogen-doped carbon support was added to 200 mL of deionized water and ultrasonically dispersed at 300 W for 30 minutes at room temperature. Then, the ATMP solution was added and the mixture was magnetically stirred at 300 rpm for 50 minutes at 25 °C to obtain an ATMP carbon support dispersion. 0.18 g of TiOSO4 and 0.05 g of ZrOCl2·8H2O were dissolved in 20 mL of deionized water and added dropwise to the ATMP carbon support dispersion at a rate of 1 mL / min using a constant pressure dropping funnel. After the addition was complete, the mixture was magnetically stirred at 300 rpm for 120 minutes at 25 °C to obtain a mixed dispersion.
[0029] Add 1.3g of chloroplatinic acid hexahydrate to 50mL of deionized water and stir at room temperature for 10 minutes. Pour the mixture into the mixed dispersion in two portions, seal and protect from light, and continue stirring at 25℃ for 100 minutes. Filter the mixture and wash it three times with 150mL of deionized water each time. Dry the mixture at 60℃ and vacuum degree ≤100Pa for 10 hours to obtain the precursor powder.
[0030] The precursor powder was placed in a quartz tube of a tubular furnace. High-purity Ar was first introduced at a flow rate of 100 mL / min, and the temperature was raised to 540 °C at a rate of 5 °C / min and held for 1.5 hours. After the holding period, the temperature was lowered to 245 °C with the furnace. The atmosphere was then switched to a mixed atmosphere of 5% H2 and 95% Ar at a flow rate of 50 mL / min and held at 245 °C for 30 minutes. Finally, the atmosphere was switched back to Ar and cooled to room temperature to obtain a highly active platinum-carbon catalyst.
[0031] Example 2 5 g of g-C3N4 powder and 3.0 g of Mg powder were mixed and ground for 30 minutes under Ar atmosphere. The mixture was placed in a tube furnace and heated to 650 °C at 5 °C / min under Ar atmosphere protection and held for 2.5 hours. After the holding period, the mixture was cooled to room temperature under Ar atmosphere and slowly added to 0.5 mol / L dilute hydrochloric acid. The mixture was stirred and washed for 60 minutes at room temperature, filtered, and washed 5 times with deionized water. The mixture was then placed in a 5 wt% hydrogen peroxide aqueous solution, stirred at 60 °C for 70 minutes, filtered, and washed with deionized water until neutral. The mixture was then vacuum dried at 80 °C for 14 hours to obtain a nitrogen-doped carbon support.
[0032] 0.15 g of aminotrimethylenephosphonic acid (ATMP) was added to 30 mL of deionized water and stirred for 15 minutes to obtain an ATMP solution. 2.2 g of nitrogen-doped carbon support was added to 220 mL of deionized water and ultrasonically dispersed at 300 W for 40 minutes at room temperature. Then, the ATMP solution was added and the mixture was magnetically stirred at 500 rpm for 70 minutes at 30 °C to obtain an ATMP carbon support dispersion. 0.25 g of TiOSO4 and 0.1 g of ZrOCl2·8H2O were dissolved in 30 mL of deionized water and added dropwise to the ATMP carbon support dispersion at a rate of 1 mL / min using a constant pressure dropping funnel. After the addition was complete, the mixture was magnetically stirred at 500 rpm for 180 minutes at 30 °C to obtain a mixed dispersion.
[0033] Add 1.5g of chloroplatinic acid hexahydrate to 60mL of deionized water and stir at room temperature for 15 minutes. Pour the mixture into the mixed dispersion in two portions, seal and protect from light, and continue stirring at 30℃ for 150 minutes. Filter the mixture and wash it 5 times with 200mL of deionized water each time. Dry it at 70℃ and vacuum degree ≤100Pa for 12 hours to obtain the precursor powder.
[0034] The precursor powder was placed in a quartz tube of a tubular furnace. High-purity Ar was first introduced at a flow rate of 100 mL / min, and the temperature was raised to 560 °C at a rate of 5 °C / min and held for 2.5 hours. After the holding period, the temperature was lowered to 255 °C with the furnace. The atmosphere was then switched to a mixed atmosphere of 5% H2 and 95% Ar at a flow rate of 50 mL / min and held at 255 °C for 40 minutes. Finally, the atmosphere was switched back to Ar and cooled to room temperature to obtain a highly active platinum-carbon catalyst.
[0035] Example 3 4.5 g g-C3N4 powder and 2.5 g Mg powder were mixed and ground for 25 minutes under Ar atmosphere. The mixture was placed in a tube furnace and heated to 650 °C at 5 °C / min under Ar atmosphere protection and held for 2.2 hours. After the holding period, the mixture was cooled to room temperature under Ar atmosphere and slowly added to 0.5 mol / L dilute hydrochloric acid. The mixture was stirred and washed at room temperature for 45 minutes, filtered, and washed four times with deionized water. The mixture was then placed in a 5 wt% hydrogen peroxide aqueous solution, stirred at 58 °C for 60 minutes, filtered, and washed with deionized water until neutral. The mixture was then vacuum dried at 75 °C for 12 hours to obtain a nitrogen-doped carbon support.
[0036] 0.12 g of aminotrimethylenephosphonic acid (ATMP) was added to 22 mL of deionized water and stirred for 12 minutes to obtain an ATMP solution. 2.0 g of nitrogen-doped carbon support was added to 210 mL of deionized water and ultrasonically dispersed at 300 W for 35 minutes at room temperature. Then, the ATMP solution was added and the mixture was magnetically stirred at 400 rpm for 60 minutes at 28 °C to obtain an ATMP carbon support dispersion. 0.22 g of TiOSO4 and 0.08 g of ZrOCl2·8H2O were dissolved in 25 mL of deionized water and added dropwise to the ATMP carbon support dispersion at a rate of 1 mL / min using a constant pressure dropping funnel. After the addition was complete, the mixture was magnetically stirred at 400 rpm for 150 minutes at 28 °C to obtain a mixed dispersion.
[0037] Add 1.4 g of chloroplatinic acid hexahydrate to 55 mL of deionized water and stir at room temperature for 12 minutes. Pour the mixture into the mixed dispersion in two portions, seal and protect from light, and continue stirring at 28 °C for 125 minutes. Filter the mixture and wash it with 180 mL of deionized water four times each time. Dry the mixture at 65 °C and a vacuum degree ≤100 Pa for 11 hours to obtain the precursor powder.
[0038] The precursor powder was placed in a quartz tube of a tubular furnace. High-purity Ar was first introduced at a flow rate of 100 mL / min, and the temperature was raised to 550 °C at a rate of 5 °C / min and held for 2 hours. After the holding period, the temperature was lowered to 250 °C with the furnace. Then, the atmosphere was switched to a mixed atmosphere of 5% H2 and 95% Ar by volume at a flow rate of 50 mL / min and held at 250 °C for 35 minutes. Finally, the atmosphere was switched back to Ar and cooled to room temperature to obtain a highly active platinum-carbon catalyst.
[0039] Example 4 4.7 g g-C3N4 powder and 2.7 g Mg powder were mixed and ground for 27 minutes under Ar atmosphere. The mixture was placed in a tube furnace and heated to 650 °C at 5 °C / min under Ar atmosphere protection and held for 2.3 hours. After the holding period, the mixture was cooled to room temperature under Ar atmosphere and slowly added to 0.5 mol / L dilute hydrochloric acid. The mixture was stirred and washed for 50 minutes at room temperature, filtered, and washed four times with deionized water. The mixture was then placed in a 5 wt% hydrogen peroxide aqueous solution and stirred for 65 minutes at 59 °C. The mixture was filtered, washed with deionized water until neutral, and vacuum dried at 77 °C for 12 hours to obtain a nitrogen-doped carbon support.
[0040] 0.13 g of aminotrimethylenephosphonic acid (ATMP) was added to 25 mL of deionized water and stirred for 13 minutes to obtain an ATMP solution. 2.05 g of nitrogen-doped carbon support was added to 215 mL of deionized water and ultrasonically dispersed at 300 W for 37 minutes at room temperature. Then, the ATMP solution was added and the mixture was magnetically stirred at 450 rpm for 63 minutes at 29 °C to obtain an ATMP carbon support dispersion. 0.23 g of TiOSO4 and 0.09 g of ZrOCl2·8H2O were dissolved in 27 mL of deionized water and added dropwise to the ATMP carbon support dispersion at a rate of 1 mL / min using a constant pressure dropping funnel. After the addition was complete, the mixture was magnetically stirred at 450 rpm for 165 minutes at 29 °C to obtain a mixed dispersion.
[0041] Add 1.45g of chloroplatinic acid hexahydrate to 57mL of deionized water and stir at room temperature for 13 minutes. Pour the mixture into the mixed dispersion in two portions, seal and protect from light, and continue stirring at 29℃ for 135 minutes. Filter the mixture and wash it with 190mL of deionized water four times each time. Dry the mixture at 67℃ and vacuum degree ≤100Pa for 12 hours to obtain the precursor powder.
[0042] The precursor powder was placed in a quartz tube of a tubular furnace. High-purity Ar was first introduced at a flow rate of 100 mL / min, and the temperature was raised to 555 °C at a rate of 5 °C / min and held for 2.2 hours. After the holding period, the furnace was cooled to 252 °C. The atmosphere was then switched to a mixed atmosphere of 5% H2 and 95% Ar at a flow rate of 50 mL / min and held at 252 °C for 37 minutes. Finally, the atmosphere was switched back to Ar and cooled to room temperature to obtain a highly active platinum-carbon catalyst.
[0043] Example 5 4.2 g g-C3N4 powder and 2.2 g Mg powder were mixed and ground for 22 minutes under Ar atmosphere. The mixture was placed in a tube furnace and heated to 650 °C at 5 °C / min under Ar atmosphere protection and held for 2.1 hours. After the holding period, the mixture was cooled to room temperature under Ar atmosphere and slowly added to 0.5 mol / L dilute hydrochloric acid. The mixture was stirred and washed at room temperature for 40 minutes, filtered, and washed four times with deionized water. The mixture was then placed in a 5 wt% hydrogen peroxide aqueous solution, stirred at 56 °C for 55 minutes, filtered, and washed with deionized water until neutral. The mixture was then vacuum dried at 72 °C for 11 hours to obtain a nitrogen-doped carbon support.
[0044] 0.10 g of aminotrimethylenephosphonic acid (ATMP) was added to 18 mL of deionized water and stirred for 11 minutes to obtain an ATMP solution. 1.9 g of nitrogen-doped carbon support was added to 205 mL of deionized water and ultrasonically dispersed at 300 W for 32 minutes at room temperature. Then, the ATMP solution was added and the mixture was magnetically stirred at 350 rpm for 55 minutes at 26 °C to obtain an ATMP carbon support dispersion. 0.20 g of TiOSO4 and 0.06 g of ZrOCl2·8H2O were dissolved in 22 mL of deionized water and added dropwise to the ATMP carbon support dispersion at a rate of 1 mL / min using a constant pressure dropping funnel. After the addition was complete, the mixture was magnetically stirred at 350 rpm for 135 minutes at 26 °C to obtain a mixed dispersion.
[0045] 1.35 g of chloroplatinic acid hexahydrate was added to 52 mL of deionized water and stirred at room temperature for 11 minutes. The mixture was poured into the mixed dispersion in two portions, sealed and protected from light, and stirred at 26 °C for 115 minutes. The mixture was then filtered and washed four times with 160 mL of deionized water each time. The mixture was dried at 62 °C and a vacuum degree ≤100 Pa for 11 hours to obtain the precursor powder.
[0046] The precursor powder was placed in a quartz tube of a tubular furnace. High-purity Ar was first introduced at a flow rate of 100 mL / min, and the temperature was raised to 545 °C at a rate of 5 °C / min and held for 1.8 hours. After the holding period, the furnace was cooled to 248 °C. The atmosphere was then switched to a mixed atmosphere of 5% H2 and 95% Ar at a flow rate of 50 mL / min and held at 248 °C for 33 minutes. Finally, the atmosphere was switched back to Ar and cooled to room temperature to obtain a highly active platinum-carbon catalyst.
[0047] Example 6 4.9 g g-C3N4 powder and 2.9 g Mg powder were mixed and ground for 29 minutes under Ar atmosphere. The mixture was placed in a tube furnace and heated to 650 °C at 5 °C / min under Ar atmosphere protection and held for 2.4 hours. After the holding period, the mixture was cooled to room temperature under Ar atmosphere and slowly added to 0.5 mol / L dilute hydrochloric acid. The mixture was stirred and washed at room temperature for 55 minutes, filtered, and washed 5 times with deionized water. The mixture was then placed in a 5 wt% hydrogen peroxide aqueous solution, stirred at 60 °C for 68 minutes, filtered, and washed with deionized water until neutral. The mixture was then vacuum dried at 79 °C for 13 hours to obtain a nitrogen-doped carbon support.
[0048] 0.14 g of aminotrimethylenephosphonic acid (ATMP) was added to 28 mL of deionized water and stirred for 14 minutes to obtain an ATMP solution. 2.1 g of nitrogen-doped carbon support was added to 218 mL of deionized water and ultrasonically dispersed at 300 W for 39 minutes at room temperature. Then, the ATMP solution was added and the mixture was magnetically stirred at 480 rpm for 68 minutes at 30 °C to obtain an ATMP carbon support dispersion. 0.24 g of TiOSO4 and 0.095 g of ZrOCl2·8H2O were dissolved in 29 mL of deionized water and added dropwise to the ATMP carbon support dispersion at a rate of 1 mL / min using a constant pressure dropping funnel. After the addition was complete, the mixture was magnetically stirred at 480 rpm for 175 minutes at 30 °C to obtain a mixed dispersion.
[0049] 1.48 g of chloroplatinic acid hexahydrate was added to 59 mL of deionized water and stirred at room temperature for 14 minutes. The mixture was then poured into the mixed dispersion in two portions, sealed and protected from light. After stirring at 30 °C for 145 minutes, the mixture was filtered and washed five times with 195 mL of deionized water each time. The mixture was then dried at 69 °C and a vacuum degree ≤100 Pa for 12 hours to obtain the precursor powder.
[0050] The precursor powder was placed in a quartz tube of a tubular furnace. High-purity Ar was first introduced at a flow rate of 100 mL / min, and the temperature was raised to 558 °C at a rate of 5 °C / min and held for 2.4 hours. After the holding period, the furnace was cooled to 254 °C. The atmosphere was then switched to a mixed atmosphere of 5% H2 and 95% Ar at a flow rate of 50 mL / min and held at 254 °C for 39 minutes. Finally, the atmosphere was switched back to Ar and cooled to room temperature to obtain a highly active platinum-carbon catalyst.
[0051] The present invention also includes comparative examples and related experiments.
[0052] Comparative Example 1 Compared with Example 3, the only difference is that conventional heat treatment was used at the end, that is: the precursor powder was prepared by the same method and composition as in the previous stage; the precursor powder was placed in a quartz tube of a tubular furnace, and a mixed atmosphere of 5% H2 and 95% Ar by volume was first introduced at a flow rate of 50 mL / min, and the temperature was raised to 550°C at a heating rate of 5°C / min and held for 2 hours, and then cooled to room temperature to obtain a highly active platinum-carbon catalyst.
[0053] Comparative Example 2 Compared with Example 3, the only difference is that an ATMP carbon support dispersion was used instead of a mixed dispersion. Specifically, 1.4 g of chloroplatinic acid hexahydrate was added to 55 mL of deionized water and stirred at room temperature for 12 minutes. The mixture was then poured into the ATMP carbon support dispersion in two batches, sealed, and protected from light. After stirring at 28°C for 125 minutes, the mixture was filtered and washed four times with 180 mL of deionized water each time. The powder was then dried at 65°C and a vacuum degree ≤100 Pa for 11 hours to obtain the precursor powder. The precursor powder was placed in a tubular furnace quartz tube, and high-purity Ar was first introduced at a flow rate of 100 mL / min. The temperature was increased to 550°C at a rate of 5°C / min and held for 2 hours. After the holding period, the temperature was lowered to 250°C with the furnace. The atmosphere was then switched to a mixed atmosphere of 5% H2 and 95% Ar at a flow rate of 50 mL / min and held at 250°C for 35 minutes. Finally, the atmosphere was switched back to Ar and cooled to room temperature to obtain a highly active platinum-carbon catalyst.
[0054] Comparative Example 3 Compared to Example 3, the only difference was that the ATMP carbon support dispersion was not prepared. Specifically, 2.0 g of nitrogen-doped carbon support was added to 210 mL of deionized water and ultrasonically dispersed at 300 W for 35 minutes at room temperature to obtain a nitrogen-doped carbon support dispersion. 0.22 g of TiOSO4 and 0.08 g of ZrOCl2·8H2O were dissolved in 25 mL of deionized water and added dropwise to the nitrogen-doped carbon support dispersion at a rate of 1 mL / min using a constant pressure dropping funnel. After the addition was complete, the mixture was magnetically stirred at 400 rpm for 150 minutes at 28°C to obtain a mixed dispersion. Subsequent preparation methods and compositions were completely consistent, ultimately yielding a highly active platinum-carbon catalyst.
[0055] Performance testing To verify the structural characteristics, activity, and stability of the highly active platinum-carbon catalyst prepared in this invention, the highly active platinum-carbon catalysts prepared in Examples 1-6 and Comparative Examples 1-3 were subjected to physicochemical performance tests, hydrogenation performance tests, high-temperature sintering resistance tests, chemical media erosion resistance tests, and cycle stability tests.
[0056] I. Catalyst Physicochemical Performance Testing The specific surface area and pore volume of the highly active platinum-carbon catalyst samples prepared in Examples 1-6 and Comparative Examples 1-3 were calculated according to GB / T19587-2017 "Determination of Specific Surface Area of Solid Substances by Gas Adsorption BET Method" using the t-plot method and BJH model. In addition, the Pt dispersion of the catalyst samples was tested by CO pulse chemisorption method, and the average Pt particle size was tested by JEOL JEM-2100F field emission transmission electron microscope. The specific test results are shown in Table 1.
[0057] Table 1
[0058] As shown in Table 1, the highly active platinum-carbon catalysts prepared in Examples 1-6 of this invention all have high specific surface area, large total pore volume, and high Pt dispersion, and the average Pt particle size is generally small. In contrast, Comparative Example 3 lacks ATMP, resulting in a significant decrease in Pt dispersion and a significant increase in the average Pt particle size. The use of conventional heat treatment methods in Comparative Example 1 and the absence of the Ti-PO interface layer in Comparative Example 2 also have a significant impact on Pt dispersion and average Pt particle size.
[0059] II. Hydrogenation Performance Test The intrinsic hydrogenation activity of the highly active platinum-carbon catalyst samples prepared in Examples 1-6 and Comparative Examples 1-3 was evaluated by a model nitrobenzene hydrogenation reaction. The conversion rate (%) of nitrobenzene and the selectivity (%) of aniline were tested. The specific test method is as follows: 5.0 g of nitrobenzene and 50 mL of anhydrous ethanol were added to a 100 mL stainless steel high-pressure reactor, and then 0.050 g of the catalyst to be tested was added. After sealing, the reactor was purged with nitrogen twice, and then purged with H2 three times. Subsequently, H2 was introduced to 0.6 MPa, and the reactor was reacted at 60 °C and 800 r / min for 40 min. After the reaction was completed, the reactor was cooled and depressurized. The catalyst was separated by filtration, and the supernatant was analyzed by gas chromatography with external standard method for nitrobenzene conversion and aniline selectivity. The specific test results are shown in Table 2.
[0060] Table 2
[0061] As shown in Table 2, the highly active platinum-carbon catalysts prepared in Examples 1-6 of this invention all exhibited high nitrobenzene conversion and high aniline selectivity in the hydrogenation reaction of nitrobenzene, with Examples 3 and 4 showing the best overall hydrogenation performance. In contrast, Comparative Example 3 lacked ATMP, resulting in a weaker bond strength between Pt and the support, which significantly reduced its nitrobenzene conversion and aniline selectivity. Comparative Example 1, due to the use of conventional heat treatment methods, had its Pt dispersion and average particle size affected, leading to a decrease in both its nitrobenzene conversion and aniline selectivity. Comparative Example 2, lacking a Ti-PO interface layer, also exhibited catalytic performance inferior to the examples of this invention.
[0062] III. Tests on resistance to high-temperature sintering and resistance to chemical corrosion Take 0.3 g of each of the highly active platinum-carbon catalyst samples prepared in Examples 1-6 and Comparative Examples 1-3, place them in a quartz boat of a tubular furnace, heat them to 600 °C at 10 °C / min under Ar atmosphere and hold for 2 h, then cool to room temperature to obtain aged samples. Measure the average particle size of Pt and the dispersion of Pt after aging. Perform nitrobenzene hydrogenation tests under the same conditions as in Experiment (II) and test the retention rate of hydrogenation activity after aging. The calculation formula is as follows: Retention rate of hydrogenation activity (%) = (Conversion rate of nitrobenzene after aging / Conversion rate of nitrobenzene before aging) × 100%; Another 0.3 g of the highly active platinum-carbon catalyst sample prepared in Examples 1-6 and Comparative Examples 1-3 was added to 100 mL of 5 wt% hydrochloric acid solution and magnetically stirred at 60 °C for 6 h. After the reaction was completed, the sample was filtered and washed with deionized water until neutral. It was then vacuum dried at 80 °C for 6 h to obtain the acid-treated sample. The hydrogenation activity retention rate of nitrobenzene after acid treatment was tested under the same conditions as in Experiment (II). The calculation formula is as follows: Activity retention rate (%) = (Nitrobenzene conversion rate after acid treatment / Nitrobenzene conversion rate before acid treatment) × 100%; The specific test results are shown in Table 3.
[0063] Table 3
[0064] As shown in Table 3, the high-activity platinum-carbon catalysts prepared in Examples 1-6 of this invention exhibited a relatively small increase in average Pt particle size after high-temperature aging, and the Pt dispersion remained at a high level after aging, with an overall high retention rate of hydrogenation activity. Furthermore, after treatment with 5wt% hydrochloric acid solution, the hydrogenation activity retention rate of Examples 1-6 of this invention remained at a high level of 95.8%-97.6%. In contrast, Comparative Example 3, lacking ATMP, showed a significant decrease in activity retention rate after both high-temperature aging and acid treatment, with a significant increase in Pt particle size and a significant decrease in Pt dispersion. Comparative Example 1, due to the use of conventional heat treatment methods, and Comparative Example 2, lacking the Ti-PO interface layer, also showed a significant increase in Pt particle size and a significant decrease in Pt dispersion after aging, with a significantly lower activity retention rate after both high-temperature aging and acid treatment.
[0065] In addition, to evaluate the activity decay of the catalyst during repeated use, the highly active platinum-carbon catalyst samples prepared in Example 3 and Comparative Examples 1-3 of this invention were subjected to nitrobenzene hydrogenation tests under the same conditions as in Experiment (II), and five consecutive cycles were conducted. The nitrobenzene conversion rate of each cycle was recorded. Specific test results are shown in [link to specific test results]. Figure 1 ,from Figure 1It can be clearly seen that the nitrobenzene conversion rate of Comparative Example 2, which lacks the Ti-PO interface layer, decreased the most, indicating that its activity decay rate was the fastest during repeated use. The nitrobenzene conversion rate of Comparative Example 1, which uses conventional heat treatment, and Comparative Example 3, which lacks ATMP, also decreased significantly more than that of Example 3 of the present invention.
[0066] The above are preferred embodiments of the present invention. Those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a highly active platinum-carbon catalyst, characterized in that, Includes the following steps: S1. Add carbon support to deionized water, sonicate, add ATMP solution and stir to obtain ATMP carbon support dispersion; dissolve TiOSO4 in deionized water and add it dropwise to ATMP carbon support dispersion. After the addition is complete, stir magnetically to obtain mixed dispersion. S2. Add chloroplatinic acid hexahydrate to deionized water, stir, pour into the mixed dispersion, seal and protect from light, continue stirring, filter, wash, and vacuum dry to obtain precursor powder; S3. Place the precursor powder in a tubular furnace quartz tube, first introduce high-purity Ar, heat up and hold, then cool down, then switch the atmosphere to a mixed atmosphere of H2 / Ar, hold, and finally switch back to Ar atmosphere and cool to room temperature to obtain a highly active platinum-carbon catalyst.
2. The method for preparing a highly active platinum-carbon catalyst according to claim 1, characterized in that, The ATMP carbon support dispersion is obtained by adding 1.8 to 2.2 parts by weight of carbon support to 200 to 220 parts by weight of deionized water, ultrasonically dispersing at room temperature with a power of 300W for 30 to 40 minutes, then adding ATMP solution and magnetically stirring at 300 to 500 rpm at 25 to 30°C for 50 to 70 minutes.
3. The method for preparing a highly active platinum-carbon catalyst according to claim 1, characterized in that, The ATMP solution is obtained by mixing 0.08-0.15 parts by weight of aminotrimethylenephosphonic acid with 15-30 parts by weight of deionized water and stirring for 10-15 minutes.
4. The method for preparing a highly active platinum-carbon catalyst according to claim 2, characterized in that, The carbon support is a nitrogen-doped carbon support, which is obtained by mixing and grinding g-C3N4 powder and Mg powder under Ar atmosphere for 20-30 minutes, placing it in a tube furnace, heating it to 650℃ at 5℃ / min under Ar atmosphere protection and holding it at that temperature for 2-2.5 hours; after holding, cooling it to room temperature under Ar atmosphere, slowly adding it to 0.5mol / L dilute hydrochloric acid, stirring and washing it at room temperature for 30-60 minutes, filtering it, washing it 3-5 times with deionized water, placing it in 5wt% hydrogen peroxide aqueous solution, stirring it at 55-60℃ for 50-70 minutes, filtering it, washing it with deionized water until neutral, and vacuum drying it at 70-80℃ for 10-14 hours.
5. The method for preparing a highly active platinum-carbon catalyst according to claim 4, characterized in that, The nitrogen-doped carbon support comprises the following raw materials in parts by weight: 4-5 parts by weight of g-C3N4 powder and 2-3 parts by weight of Mg powder.
6. The method for preparing a highly active platinum-carbon catalyst according to claim 1, characterized in that, In step S1, 0.18-0.25 parts by weight of TiOSO4 are dissolved in 20-30 parts by weight of deionized water, and added dropwise to the ATMP carbon carrier dispersion at a rate of 1 mL / min using a constant pressure dropping funnel. After the addition is complete, the mixture is magnetically stirred at 300-500 rpm for 120-180 minutes at 25-30°C to obtain a mixed dispersion.
7. The method for preparing a highly active platinum-carbon catalyst according to claim 1, characterized in that, In step S1, 0.05~0.1 parts by mass of ZrOCl2·8H2O were added when adding TiOSO4.
8. The method for preparing a highly active platinum-carbon catalyst according to claim 1, characterized in that, In step S2, 1.3-1.5 parts by weight of chloroplatinic acid hexahydrate are added to 50-60 parts by weight of deionized water and stirred at room temperature for 10-15 minutes. The mixture is then poured into the mixed dispersion in two portions, sealed and protected from light, and stirred at 25-30°C for 100-150 minutes. After filtration, the mixture is washed 3-5 times with 150-200 mL of deionized water each time, and dried at 60-70°C and a vacuum degree ≤100 Pa for 10-12 hours to obtain the precursor powder.
9. The method for preparing a highly active platinum-carbon catalyst according to claim 1, characterized in that, In step S3, the precursor powder is placed in a tubular furnace quartz tube. First, high-purity Ar is introduced at a flow rate of 100 mL / min, and the temperature is raised to 540~560℃ at a heating rate of 5℃ / min and held for 1.5~2.5 hours. After the holding period, the temperature is lowered to 245~255℃ along with the furnace. Then, the atmosphere is switched to a mixed atmosphere of 5% H2 and 95% Ar by volume at a flow rate of 50 mL / min, and the temperature is held at 245~255℃ for 30~40 minutes. Finally, the atmosphere is switched back to Ar and cooled to room temperature to obtain a highly active platinum-carbon catalyst.
10. A highly active platinum-carbon catalyst, characterized in that, It was prepared using the method for preparing a highly active platinum-carbon catalyst according to any one of claims 1 to 9.