Palladium-based hydrogenation catalyst, preparation method thereof and application of palladium-based hydrogenation catalyst in production of hydrogen peroxide by anthraquinone method
By controlling the distribution of Pd activity centers on the support surface, an efficient palladium-based hydrogenation catalyst was prepared, which solved the problems of insufficient catalyst activity and excessive degradation in the prior art, and achieved efficient production in the anthraquinone method The effect of hydrogen peroxide.
Patent Information
- Application Number
- CN202411610470.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-12
- Publication Date
- 2025-02-18
AI Technical Summary
The prior art is difficult to achieve the controllable distribution of Pd active centers on the support surface, resulting in insufficient catalyst hydrogenation activity and excessive generation of degradable substances.
By immersing the porous support in the pre-impregnation solution for impregnation, then adding the Pd precursor solution for secondary impregnation, followed by rotary evaporation, drying and calcination, a palladium-based hydrogenation catalyst with a Pd active center located on the shallow surface of the support was prepared.
The controllable load of the Pd activity center is achieved, the hydrogenation activity of the catalyst is improved, the generation of degradable substances is reduced, and the preparation process is simplified, making it easy for industrial application.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of hydrogen peroxide preparation, and in particular relates to a palladium-based hydrogenation catalyst, a preparation method thereof and application thereof in producing hydrogen peroxide by an anthraquinone process. Background Art
[0002] The reduction product of hydrogen peroxide is water, which is more environmentally friendly than other traditional oxidants (hypochlorous acid, sodium hypochlorite). As an important green chemical, it is widely used in chemical, electronic, medical, food, environmental protection and other fields.
[0003] Anthraquinone method is the mainstream industrial technology for hydrogen peroxide production due to its low energy consumption and high economic value. Anthraquinone hydrogenation is the core step of hydrogen peroxide production process, and hydrogenation catalyst is the key to the hydrogenation efficiency and hydrogen peroxide production capacity of the device. Developing efficient catalysts to improve the activation of C=O in anthraquinone molecules and reduce the production of degradation products is an effective way to improve the operation capacity of the device.
[0004] Supported Pd-based catalysts have become the main catalytic system for anthraquinone hydrogenation to hydrogen peroxide, replacing Ni-based catalysts due to their easy recycling and environmentally friendly preparation process. The chemical environment, dispersion, and electronic properties of the Pd active center are all key factors affecting the catalytic hydrogenation performance of anthraquinone. Studies have found that when the Pd active center is located on the shallow surface of the carrier, the diffusion restriction of the carrier pore structure on the hydrogenation product can be weakened, the possibility of contact between the anthraquinone reactant and the Pd active center can be increased, thereby improving the catalyst hydrogenation activity and inhibiting the formation of degradation products. However, conventional catalyst preparation technology makes it difficult to achieve a controllable distribution of metal active centers on the carrier surface. Summary of the invention
[0005] The purpose of the present invention is to provide a palladium-based hydrogenation catalyst, a preparation method thereof and application thereof in the production of hydrogen peroxide by anthraquinone method. The Pd active center of the palladium-based hydrogenation catalyst of the present invention is located on the shallow surface of a carrier, which can reduce the diffusion restriction of the pore structure on hydrogenation products, inhibit the generation of degradation products, and exhibit higher anthraquinone catalytic hydrogenation activity.
[0006] The present invention provides a method for preparing a palladium-based hydrogenation catalyst, comprising the following steps:
[0007] A) immersing the porous support into a pre-impregnation liquid for impregnation;
[0008] The pre-impregnation liquid includes one or more of n-pentanol, 3-hexanol, toluene, ethylbenzene and xylene;
[0009] B) adding the Pd precursor solution into the impregnation system in step A) for secondary impregnation;
[0010] C) subjecting the impregnation system obtained in step B) to rotary evaporation, and then drying and calcining the sample after rotary evaporation to obtain a palladium-based hydrogenation catalyst;
[0011] The temperature of the rotary evaporation is 40-90° C., and the time of the rotary evaporation is 0.5-2 hours.
[0012] Preferably, the porous carrier comprises any one or more of silicon oxide, aluminum oxide, alkaline earth metal oxide and SBA-15;
[0013] The solid-liquid ratio of the porous carrier to the pre-impregnation liquid is 1 g: (0.3-1.5) mL.
[0014] Preferably, the immersion temperature in step A) is 20 to 30° C., and the immersion time in step A) is 2 to 10 hours.
[0015] Preferably, the Pd precursor solution comprises a Pd precursor and water, and the Pd precursor comprises one or more of palladium chloride, palladium nitrate, tetraammine palladium nitrate, tetraammine palladium chloride and sodium chloropalladate;
[0016] The mass of the Pd precursor is 0.15-5% of the mass of the porous support.
[0017] Preferably, the temperature of the secondary immersion in step B) is 30 to 65° C., and the time of the secondary immersion in step B) is 5 to 24 hours.
[0018] Preferably, the drying temperature in step C) is 100-150° C., and the drying time in step C) is 5-12 hours.
[0019] Preferably, the calcination temperature in step C) is 300-550° C., and the calcination time in step C) is 3-6 hours.
[0020] The present invention provides a palladium-based hydrogenation catalyst, which is prepared according to the preparation method described above.
[0021] Preferably, the palladium-based hydrogenation catalyst comprises a carrier and Pd loaded on the surface of the carrier, and the loading amount of the Pd is 0.1-2% of the mass of the carrier.
[0022] The present invention provides the use of the palladium-based hydrogenation catalyst as described above in producing hydrogen peroxide by anthraquinone process.
[0023] The invention provides a preparation method of a palladium-based hydrogenation catalyst, comprising the following steps: A) immersing a porous carrier in a pre-impregnation liquid for impregnation; the pre-impregnation liquid comprises one or more of n-pentanol, 3-hexanol, toluene, ethylbenzene and xylene; B) adding a Pd precursor solution into the impregnation system in the step A) for secondary impregnation; C) performing rotary evaporation on the impregnation system obtained in the step B), and then drying and calcining the sample after rotary evaporation to obtain a palladium-based hydrogenation catalyst; the rotary evaporation temperature is 40-90°C, and the rotary evaporation time is 0.5-2 hours.
[0024] Compared with the prior art, the present invention has the following beneficial effects:
[0025] (1) The preparation method of the Pd-based catalyst provided by the present invention has the advantages of simple and safe preparation process and easy industrial scale-up;
[0026] (2) The present invention uses the pre-impregnation liquid to occupy the carrier pores, and the immersion depth of the Pd active center can be changed by adjusting the solid-liquid ratio of the carrier and the pre-impregnation liquid on the basis of controlling the drying conditions. Compared with commercial Pd-based catalysts, the catalyst prepared by the present invention can greatly improve the effective utilization rate of the Pd active center and inhibit the generation of degradation products.
[0027] (3) The raw materials required for the present invention are all bulk chemicals, which are cheap and easily available. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.
[0029] Figure 1 This is the HAADF-STEM image of the catalyst in Example 8 of the present invention. DETAILED DESCRIPTION
[0030] The present invention provides a method for preparing a palladium-based hydrogenation catalyst, comprising the following steps:
[0031] A) immersing the porous support into a pre-impregnation liquid for impregnation;
[0032] The pre-impregnation liquid includes one or more of n-pentanol, 3-hexanol, toluene, ethylbenzene and xylene;
[0033] B) adding the Pd precursor solution into the impregnation system in step A) for secondary impregnation;
[0034] C) subjecting the impregnation system obtained in step B) to rotary evaporation, and then drying and calcining the sample after rotary evaporation to obtain a palladium-based hydrogenation catalyst;
[0035] The temperature of the rotary evaporation is 40-90° C., and the time of the rotary evaporation is 0.5-2 hours.
[0036] The present invention preferably first vacuum treats the porous carrier, and then immerses the vacuum treated porous carrier in a pre-impregnation liquid for impregnation, so that the pre-impregnation liquid occupies part of the pores of the carrier to form an impregnation system containing the pre-impregnation liquid and the porous carrier immersed in the pre-impregnation liquid.
[0037] In the present invention, the porous carrier is preferably any one or more of silicon oxide, aluminum oxide, alkaline earth metal oxide and SBA-15; the pre-impregnation liquid is preferably a non-water-soluble solvent, that is, the pre-impregnation liquid and the Pd precursor solution are immiscible, and the boiling point of the pre-impregnation liquid is higher than the boiling point of the Pd precursor solution, so that in the subsequent rotary evaporation process, the rotary evaporation conditions can be controlled to ensure that the water in the Pd precursor solution evaporates before the pre-impregnation liquid, so that the Pd precursor is loaded on the shallow surface of the carrier, and the phenomenon of the Pd precursor solution migrating into the pores due to the pre-evaporation of the pre-impregnation liquid is avoided. Preferably, the pre-impregnation liquid is preferably one or more of n-pentanol, 3-hexanol, toluene, ethylbenzene and xylene.
[0038] In the present invention, the solid-liquid ratio of the porous carrier to the pre-impregnation liquid is preferably 1g: (0.3-1.5) mL, more preferably 1g: (0.5-1.2) mL, such as 1g: 0.3 mL, 1g: 0.4 mL, 1g: 0.5 mL, 1g: 0.6 mL, 1g: 0.7 mL, 1g: 0.8 mL, 1g: 0.9 mL, 1g: 1.0 mL, 1g: 1.1 mL, 1g: 1.2 mL, 1g: 1.3 mL, 1g: 1.4 mL, 1g: 1.5 mL, preferably a range value with any of the above values as the upper or lower limit.
[0039] In the present invention, the immersion temperature is preferably room temperature, such as 20 to 30° C., and the immersion time is preferably 2 to 10 hours, more preferably 6 to 8 hours.
[0040] The present invention adds the Pd precursor solution into the impregnation system and performs secondary impregnation under stirring conditions.
[0041] In the present invention, the Pd precursor solution includes a Pd precursor and water, and the Pd precursor includes one or more of palladium chloride, palladium nitrate, tetraammine palladium nitrate, tetraammine palladium chloride and sodium chloropalladate; the present invention has no special limitation on the concentration of the Pd precursor solution.
[0042] In the present invention, the mass of the Pd precursor is 0.15-5% of the mass of the porous carrier, and more preferably 0.3-3.5%, such as 0.15%, 0.3%, 0.5%, 0.8%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, preferably a range value with any of the above values as the upper or lower limit.
[0043] In the present invention, the stirring is preferably magnetic stirring, shaking table stirring or rotary stirring; the temperature of the secondary impregnation is preferably 30-65°C, more preferably 35-60°C, such as 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, preferably a range value with any of the above values as the upper or lower limit; the time of the secondary impregnation is preferably 5-24 hours, more preferably 8-18 hours.
[0044] After completing the above-mentioned secondary impregnation, the present invention transfers the secondary impregnation system to a rotary evaporator and performs rotary evaporation under vacuum conditions. By controlling the rotary evaporation conditions, it is ensured that the water in the Pd precursor evaporates before the pre-impregnation liquid, so that the Pd species is located on the surface of the carrier, avoiding the phenomenon that the Pd precursor solution migrates into the pores due to the pre-impregnation liquid volatilizing first.
[0045] In the present invention, the temperature of the rotary evaporation is preferably 40-90°C, more preferably 50-80°C, such as 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, preferably a range value with any of the above values as the upper or lower limit; the time of the rotary evaporation is preferably 0.5-2 hours, more preferably 0.5-1.5 hours; the vacuum degree of the rotary evaporation is preferably 50-500mbar, more preferably 100-400mbar.
[0046] After the rotary evaporation is completed, the present invention dries the sample after the rotary evaporation. During the drying process, a relatively high drying temperature is set to volatilize the pre-impregnation liquid.
[0047] In the present invention, the drying temperature is preferably 100-150°C, more preferably 120-150°C, such as 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, preferably a range value with any of the above values as the upper or lower limit; the drying time is preferably 5-12 hours, more preferably 8-10 hours.
[0048] After drying, the present invention calcines the dried sample to obtain a palladium-based hydrogenation catalyst.
[0049] In the present invention, the calcination temperature is preferably 300-550°C, more preferably 300-500°C, such as 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, preferably a range value with any of the above values as the upper or lower limit; the calcination time is preferably 3-6 hours, more preferably 3-5 hours. The present invention preferably performs calcination in a muffle furnace, the initial calcination atmosphere is an air atmosphere, and no additional gas is required during the calcination process.
[0050] The method of the present invention can realize the controllable placement of the Pd active center, and in particular can regulate the controllable loading of the Pd active center on the surface of the porous catalyst carrier.
[0051] The present invention also provides a palladium-based hydrogenation catalyst, which is prepared according to the preparation method described above. The palladium-based hydrogenation catalyst comprises a carrier and Pd loaded on the surface of the carrier, and the loading amount of the Pd is 0.1-2% of the mass of the carrier, preferably 0.25-2%.
[0052] The present invention also provides an application of the above-mentioned palladium-based hydrogenation catalyst in the production of hydrogen peroxide by hydrogenation of anthraquinone. The Pd active center in the palladium-based hydrogenation catalyst prepared by the present invention is located on the shallow surface of the carrier, which can reduce the diffusion restriction of the pore structure on the hydrogenation product, inhibit the generation of degradation products, and show higher anthraquinone catalytic hydrogenation activity.
[0053] In the present invention, the anthraquinone is preferably one or more of 2-ethyl anthraquinone, tetrahydro-2-ethyl anthraquinone, 2-pentyl anthraquinone, tetrahydro-2-pentyl anthraquinone, 2-tert-butyl anthraquinone and tetrahydro-2-tert-butyl anthraquinone; the reaction temperature of anthraquinone hydrogenation to produce hydrogen peroxide is preferably 30 to 80°C, more preferably 40 to 70°C, such as 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, preferably with any of the above values as the upper or lower limit of the range value; the reaction mass space velocity of anthraquinone hydrogenation to produce hydrogen peroxide is preferably 5 to 70h -1 , more preferably 10 to 60 hours -1 , such as 5h -1 , 10h -1 , 15h -1 , 20h -1 , 25h -1 , 30h -1 , 35h -1 , 40h -1 , 45h -1 , 50h -1 , 55h -1 , 60h -1 , 65h -1 , 70h -1, preferably a range value with any of the above values as the upper or lower limit; the reaction pressure of anthraquinone hydrogenation to produce hydrogen peroxide is preferably 0.1-1MPa, more preferably 0.3-0.8MPa, such as 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa, 1.0MPa, preferably a range value with any of the above values as the upper or lower limit.
[0054] The invention provides a preparation method of a palladium-based hydrogenation catalyst, comprising the following steps: A) immersing a porous carrier in a pre-impregnation liquid for impregnation; the pre-impregnation liquid comprises one or more of n-pentanol, 3-hexanol, toluene, ethylbenzene and xylene; B) adding a Pd precursor solution into the impregnation system in the step A) for secondary impregnation; C) performing rotary evaporation on the impregnation system obtained in the step B), and then drying and calcining the sample after rotary evaporation to obtain a palladium-based hydrogenation catalyst; the rotary evaporation temperature is 40-90°C, and the rotary evaporation time is 0.5-2 hours.
[0055] Compared with the prior art, the present invention has the following beneficial effects:
[0056] (1) The preparation method of the Pd-based catalyst provided by the present invention has the advantages of simple and safe preparation process and easy industrial scale-up;
[0057] (2) The present invention uses the pre-impregnation liquid to occupy the carrier pores, and the immersion depth of the Pd active center can be changed by adjusting the solid-liquid ratio of the carrier and the pre-impregnation liquid on the basis of controlling the drying conditions. Compared with commercial Pd-based catalysts, the catalyst prepared by the present invention can greatly improve the effective utilization rate of the Pd active center and inhibit the generation of degradation products.
[0058] (3) The raw materials required for the present invention are all bulk chemicals, which are cheap and easily available.
[0059] In order to further illustrate the present invention, a palladium-based hydrogenation catalyst provided by the present invention, its preparation method and application in the production of hydrogen peroxide by the anthraquinone process are described in detail below in conjunction with examples, but it should not be construed as limiting the scope of protection of the present invention.
[0060] The catalyst evaluation method is:
[0061] 80g of 2-ethylanthraquinone, 500g of trioctyl phosphate and 500g of mesitylene were mixed and added to the liquid storage tank of the horizontal flow pump. 1.0g of the prepared Pd-based catalyst was loaded into a fixed bed reaction tube and reduced at 80°C for 2h at a H2 gas rate of 50mL / min. After the reduction was completed, the temperature of the reaction tube was lowered to 45°C, the pressure was adjusted to 0.5MPa, and the H2 flow rate was adjusted to 5mL / min. Subsequently, the liquid pump was turned on and the liquid flow rate was 0.3mL / min. During the reaction process, the liquid product was taken into a separatory funnel every 1h, and high-purity O2 was passed through to oxidize to light yellow, and then extracted with 20mL of deionized water multiple times. Among them, the aqueous phase was titrated with potassium permanganate solution to determine the hydrogenation efficiency of the catalyst, and the organic phase was analyzed by high-performance liquid chromatography to determine the effective anthraquinone selectivity.
[0062] Example 1
[0063] 1. Carrier pretreatment: Take an appropriate amount of alumina and treat it under 100 Pa vacuum for 10 hours. Weigh 1 g of vacuum-treated alumina and place it in 0.3 mL of toluene. Immerse it at room temperature for 12 hours to obtain an alumina carrier with partially occupied pores.
[0064] 2. Catalyst preparation: Weigh 0.0070g of PdNO3 and ultrasonically disperse it in 1mL of deionized water to prepare a PdNO3 aqueous solution, and add the prepared solution to the above-mentioned pretreated carrier, and impregnate it at room temperature for 8h using magnetic stirring. After the impregnation is completed, transfer the above system to a rotary evaporator, and rotary evaporate it at 20KPa and 45℃ for 30min. Place the rotary evaporated sample in an oven and dry it at 150℃ for 12h, and then place it in a muffle furnace at 450℃ for calcination for 3h.
[0065] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 5.4 g / L and the effective anthraquinone selectivity was 95.3%.
[0066] Embodiment 2:
[0067] 1. Carrier pretreatment: Take an appropriate amount of alumina and treat it under 100 Pa vacuum for 10 hours. Weigh 1g of vacuum-treated alumina and place it in 0.5mL of toluene. Immerse it at room temperature for 12 hours to obtain an alumina carrier with partially occupied pores.
[0068] 2. Catalyst preparation: Weigh 0.0070g of PdNO3 and ultrasonically disperse it in 1mL of deionized water to prepare a PdNO3 aqueous solution, and add the prepared solution to the above-mentioned pretreated carrier, and impregnate it at room temperature for 8h using magnetic stirring. After the impregnation is completed, transfer the above system to a rotary evaporator, and rotary evaporate it at 20KPa and 45℃ for 30min. Place the rotary evaporated sample in an oven and dry it at 150℃ for 12h, and then place it in a muffle furnace at 450℃ for calcination for 3h.
[0069] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 6.7 g / L and the effective anthraquinone selectivity was 96.5%.
[0070] Embodiment 3:
[0071] 1. Carrier pretreatment: Take an appropriate amount of alumina and treat it under 100 Pa vacuum for 10 hours. Weigh 1 g of vacuum-treated alumina and place it in 0.8 mL of toluene. Immerse it at room temperature for 12 hours to obtain an alumina carrier with partially occupied pores.
[0072] 2. Catalyst preparation: Weigh 0.0070g of PdNO3 and ultrasonically disperse it in 1mL of deionized water to prepare a PdNO3 aqueous solution, and add the prepared solution to the above-mentioned pretreated carrier, and impregnate it at room temperature for 8h using magnetic stirring. After the impregnation is completed, transfer the above system to a rotary evaporator, and rotary evaporate it at 20KPa and 45℃ for 30min. Place the rotary evaporated sample in an oven and dry it at 150℃ for 12h, and then place it in a muffle furnace at 450℃ for calcination for 3h.
[0073] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 9.3 g / L and the effective anthraquinone selectivity was 98.7%.
[0074] Embodiment 4:
[0075] 1. Carrier pretreatment: Take an appropriate amount of alumina and treat it under 100 Pa vacuum for 10 hours. Weigh 1 g of vacuum-treated alumina and place it in 1.2 mL of toluene. Immerse it at room temperature for 12 hours to obtain an alumina carrier with partially occupied pores.
[0076] 2. Catalyst preparation: Weigh 0.0070g of PdNO3 and ultrasonically disperse it in 1mL of deionized water to prepare a PdNO3 aqueous solution, and add the prepared solution to the above-mentioned pretreated carrier, and impregnate it at room temperature for 8h using magnetic stirring. After the impregnation is completed, transfer the above system to a rotary evaporator, and rotary evaporate it at 20KPa and 45℃ for 30min. Place the rotary evaporated sample in an oven and dry it at 150℃ for 12h, and then place it in a muffle furnace at 450℃ for calcination for 3h.
[0077] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 7.8 g / L and the effective anthraquinone selectivity was 97.3%.
[0078] Embodiment 5:
[0079] 1. Carrier pretreatment: Take an appropriate amount of alumina and treat it under 100 Pa vacuum for 10 hours. Weigh 1 g of vacuum-treated alumina and place it in 0.8 mL of toluene. Immerse it at room temperature for 12 hours to obtain an alumina carrier with partially occupied pores.
[0080] 2. Catalyst preparation: Weigh 0.0070g of PdNO3 and ultrasonically disperse it in 1mL of deionized water to prepare a PdNO3 aqueous solution, and add the prepared solution to the above-mentioned pretreated carrier, and impregnate it at room temperature for 8h using magnetic stirring. After the impregnation is completed, transfer the above system to a rotary evaporator, and rotary evaporate it at 20KPa and 60℃ for 30min. Place the rotary evaporated sample in an oven and dry it at 150℃ for 12h, and then place it in a muffle furnace at 450℃ for calcination for 3h.
[0081] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 6.0 g / L and the effective anthraquinone selectivity was 95.9%.
[0082] Embodiment 6:
[0083] 1. Carrier pretreatment: Take an appropriate amount of alumina and treat it under 100 Pa vacuum for 10 hours. Weigh 1 g of vacuum-treated alumina and place it in 0.8 mL of toluene. Immerse it at room temperature for 12 hours to obtain an alumina carrier with partially occupied pores.
[0084] 2. Catalyst preparation: Weigh 0.0070g of PdNO3 and ultrasonically disperse it in 1mL of deionized water to prepare a PdNO3 aqueous solution, and add the prepared solution to the above-mentioned pretreated carrier, and impregnate it at room temperature for 8h using magnetic stirring. After the impregnation is completed, transfer the above system to a rotary evaporator, and rotary evaporate it at 20KPa and 75℃ for 30min. Place the rotary evaporated sample in an oven and dry it at 150℃ for 12h, and then place it in a muffle furnace at 450℃ for calcination for 3h.
[0085] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 5.5 g / L and the effective anthraquinone selectivity was 95.2%.
[0086] Example 7
[0087] 1. Carrier pretreatment: Take an appropriate amount of SBA-15 and treat it under 600Pa vacuum for 3h. Weigh 1g of vacuum-treated SBA-15 and place it in 0.8mL of toluene. Immerse it at room temperature for 12h to obtain an SBA-15 carrier with partially occupied pores.
[0088] 2. Catalyst preparation: Weigh 0.0070g of PdNO3 and ultrasonically disperse it in 1mL of deionized water to prepare a PdNO3 aqueous solution, and add the prepared solution to the pretreated SBA-15, and use a shaker to impregnate it at room temperature for 8h. After the impregnation is completed, transfer the above system to a rotary evaporator, and rotary evaporate it at 20KPa and 45℃ for 30min. Place the sample after rotary evaporation in an oven at 150℃ for 12h, and then place it in a muffle furnace at 450℃ for calcination for 3h.
[0089] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 7.1 g / L and the effective anthraquinone selectivity was 96.5%.
[0090] Example 8
[0091] 1. Carrier pretreatment: Take an appropriate amount of SBA-15 and treat it under 600Pa vacuum for 5h. Weigh 1g of vacuum-treated SBA-15 and place it in 0.8mL of toluene. Immerse it at room temperature for 12h to obtain an SBA-15 carrier with partially occupied pores.
[0092] 2. Catalyst preparation: Weigh 0.0070g of PdNO3 and ultrasonically disperse it in 1mL of deionized water to prepare a PdNO3 aqueous solution, and add the prepared solution to the pretreated SBA-15, and use a shaker to impregnate it at room temperature for 8h. After the impregnation is completed, transfer the above system to a rotary evaporator, and rotary evaporate it at 20KPa and 45℃ for 30min. Place the sample after rotary evaporation in an oven at 150℃ for 12h, and then place it in a muffle furnace at 450℃ for calcination for 3h.
[0093] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 7.6 g / L and the effective anthraquinone selectivity was 97.0%.
[0094] The catalyst obtained in Example 8 was examined by high-angle annular dark-field scanning electron microscopy. Figure 1 As shown by Figure 1 It can be seen that the Pd active centers in this embodiment are distributed on the shallow surface of the carrier.
[0095] Comparative Example 1
[0096] The catalyst was prepared according to the method in Example 1, except that the carrier in Comparative Example 1 was directly used for impregnation without pretreatment.
[0097] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 5.0 g / L and the effective anthraquinone selectivity was 94.9%.
[0098] Comparative Example 2
[0099] 1. Carrier pretreatment: Take an appropriate amount of alumina and treat it under 100 Pa vacuum for 10 hours. Weigh 1 g of vacuum-treated alumina and place it in 0.8 mL of methanol. Immerse it at room temperature for 12 hours to obtain an alumina carrier with partially occupied pores.
[0100] 2. Catalyst preparation: Weigh 0.0070g of PdNO3 and ultrasonically disperse it in 1mL of deionized water to prepare a PdNO3 aqueous solution, and add the prepared solution to the above-mentioned pretreated carrier, and impregnate it at room temperature for 8h using magnetic stirring. After the impregnation is completed, transfer the above system to a rotary evaporator, and rotary evaporate it at 20KPa and 45℃ for 30min. Place the rotary evaporated sample in an oven and dry it at 150℃ for 12h, and then place it in a muffle furnace at 450℃ for calcination for 3h.
[0101] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 5.1 g / L and the effective anthraquinone selectivity was 95.0%.
[0102] Comparative Example 3
[0103] 1. Carrier pretreatment: Take an appropriate amount of alumina and treat it under 100 Pa vacuum for 10 hours. Weigh 1g of vacuum-treated alumina and place it in 0.8mL of n-butanol. Immerse it at room temperature for 12 hours to obtain an alumina carrier with partially occupied pores.
[0104] 2. Catalyst preparation: Weigh 0.0070g of PdNO3 and ultrasonically disperse it in 1mL of deionized water to prepare a PdNO3 aqueous solution, and add the prepared solution to the above-mentioned pretreated carrier, and impregnate it at room temperature for 8h using magnetic stirring. After the impregnation is completed, transfer the above system to a rotary evaporator, and rotary evaporate it at 20KPa and 45℃ for 30min. Place the rotary evaporated sample in an oven and dry it at 150℃ for 12h, and then place it in a muffle furnace at 450℃ for calcination for 3h.
[0105] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 6.0 g / L and the effective anthraquinone selectivity was 95.9%.
[0106] Comparative Example 4
[0107] 1. Carrier pretreatment: Take an appropriate amount of alumina and treat it under 100 Pa vacuum for 10 hours. Weigh 1 g of vacuum-treated alumina and place it in 0.8 mL of toluene. Immerse it at room temperature for 12 hours to obtain an alumina carrier with partially occupied pores.
[0108] 2. Catalyst preparation: Weigh 0.0070g of PdNO3 and ultrasonically disperse it in 1mL of deionized water to prepare a PdNO3 aqueous solution, and add the prepared solution to the above-mentioned pretreated carrier, and impregnate it at room temperature for 8h using magnetic stirring. After the impregnation is completed, transfer the above system to a rotary evaporator, and rotary evaporate it at 20KPa and 100℃ for 30min. Place the rotary evaporated sample in an oven and dry it at 150℃ for 12h, and then place it in a muffle furnace at 450℃ for calcination for 3h.
[0109] The reaction performance of the prepared catalyst was evaluated in an anthraquinone hydrogenation reaction device, and the hydrogenation efficiency was measured to be 6.7 g / L and the effective anthraquinone selectivity was 96.2%.
[0110] Table 1 Evaluation results of catalytic performance of catalysts in Examples and Comparative Examples
[0111] catalyst Pd loading (wt / %) Hydrogenation efficiency (g / L) Effective anthraquinone selectivity (%) Comparative Example 1 0.30 5.0 94.9 Comparative Example 2 0.28 5.1 95.0 Comparative Example 3 0.27 6.0 95.9 Comparative Example 4 0.29 6.7 96.2 Example 1 0.30 5.4 95.3 Example 2 0.28 6.7 96.5 Example 3 0.29 9.3 98.7 Example 4 0.30 7.8 97.3 Example 5 0.29 6.0 95.9 Example 6 0.29 5.5 95.2 Example 7 0.28 7.1 96.5 Example 8 0.29 7.6 97.0
[0112] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A method for preparing a palladium-based hydrogenation catalyst, comprising the following steps: A) immersing the porous support into a pre-impregnation liquid for impregnation; The pre-impregnation liquid includes one or more of n-pentanol, 3-hexanol, toluene, ethylbenzene and xylene; B) adding the Pd precursor solution into the impregnation system in step A) for secondary impregnation; C) subjecting the impregnation system obtained in step B) to rotary evaporation, and then drying and calcining the sample after rotary evaporation to obtain a palladium-based hydrogenation catalyst; The temperature of the rotary evaporation is 40-90° C., and the time of the rotary evaporation is 0.5-2 hours.
2. The preparation method according to claim 1, characterized in that: The porous carrier includes any one or more of silicon oxide, aluminum oxide, alkaline earth metal oxide and SBA-15; The solid-liquid ratio of the porous carrier to the pre-impregnation liquid is 1 g: (0.3-1.5) mL.
3. The preparation method according to claim 1, characterized in that: The immersion temperature in step A) is 20-30° C., and the immersion time in step A) is 2-10 hours.
4. The preparation method according to claim 1, characterized in that: The Pd precursor solution comprises a Pd precursor and water, wherein the Pd precursor comprises one or more of palladium chloride, palladium nitrate, tetraammine palladium nitrate, tetraammine palladium chloride and sodium chloropalladate; The mass of the Pd precursor is 0.15-5% of the mass of the porous support.
5. The preparation method according to claim 1, characterized in that: The temperature of the secondary immersion in step B) is 30-65° C., and the time of the secondary immersion in step B) is 5-24 hours.
6. The preparation method according to claim 1, characterized in that: The drying temperature in the step C) is 100 to 150° C., and the drying time in the step C) is 5 to 12 hours.
7. The preparation method according to claim 1, characterized in that: The calcination temperature in the step C) is 300-550° C., and the calcination time in the step C) is 3-6 hours.
8. A palladium-based hydrogenation catalyst prepared according to the preparation method according to any one of claims 1 to 7.
9. The palladium-based hydrogenation catalyst according to claim 8, characterized in that The palladium-based hydrogenation catalyst comprises a carrier and Pd loaded on the surface of the carrier, and the loading amount of the Pd is 0.1-2% of the mass of the carrier.
10. Use of the palladium-based hydrogenation catalyst as claimed in claim 8 or 9 in producing hydrogen peroxide by anthraquinone process.