Preparation method and application of high-hydrophobic aluminum-based composite material

Abstract

The application discloses a preparation method of a high-hydrophobic aluminum-based composite material and application thereof, and the preparation method comprises the following steps: (1) active carbon is soaked in acid, washed, dried, and expanded hole roasted to obtain expanded hole active carbon; (2) the expanded hole active carbon, a hydrothermal solvent, a pH regulator and an auxiliary metal salt are added into an aluminum salt solution, and a microwave hydrothermal reaction is carried out; (3) after the reaction is completed, washing and filtering are carried out to obtain a composite material precursor; (4) the composite material precursor obtained in the step (3) is roasted in a microwave environment to obtain a composite material; the molar ratio of aluminum atoms in the aluminum salt to the active carbon is 2:1-1:2; and the mass of the auxiliary metal salt is 9.5-38% of the mass of the aluminum atoms in the aluminum salt. The alkylanthraquinone hydrogenation palladium catalyst prepared by adopting the microwave hydrothermal method to synthesize the high-hydrophobic aluminum-based composite material as a carrier has excellent activity and stability.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation technology, specifically relating to a method for preparing a highly hydrophobic aluminum-based composite material and its application. Background Technology

[0002] Alumina (Al2O3) is an important inorganic chemical raw material with wide applications in ceramics, pharmaceuticals, electronics, machinery, catalysis, and other industries. The market demand for alumina has significant growth potential. In 2021, China's alumina production reached 77.475 million tons, a year-on-year increase of 5.94%, and in the first half of 2022, China's alumina production had already reached 40.204 million tons. In recent years, alumina materials, due to their excellent physicochemical properties and extremely high stability, have been widely used in various catalytic reactions such as alkane dehydrogenation, methane reforming, and selective hydrogenation.

[0003] Pd / Al₂O₃ catalysts, as a typical alkylanthraquinone hydrogenation catalyst system, possess characteristics such as high activity, operational tolerance, long lifespan, and easy recovery, making them the mainstream alkylanthraquinone hydrogenation catalysts on the market. However, currently available commercially available Pd / Al₂O₃ spherical catalysts still have many problems, such as difficulty in controlling the composition of surface acidic sites, poor hydrophobicity, and low specific surface area, which lead to a decrease in the activity and stability of palladium catalysts. Therefore, there is an urgent need to develop efficient Pd catalyst supports to improve the performance of alkylanthraquinone hydrogenation reactions.

[0004] Studies have found that the specific surface area, pore structure, and hydrophobicity of the support play a crucial role in the hydrogenation reaction of alkyl anthraquinones. For example, patent CN103623820B, by introducing carbides into an oxide support, not only improves the dispersibility of Pd and reduces the Pd loading while maintaining high activity and stability, significantly reducing production costs. However, due to the complexity of the preparation technology and the limited selection of carbide precursors, its application is severely restricted. Patent CN106693958B also reports a CNTs-TiO2 composite support, which has a larger specific surface area and weaker surface acidity compared to traditional alumina supports, promoting the dispersion of Pd metal while reducing the generation of degradation products. However, the catalyst preparation method is complex and the raw material cost is high, severely limiting the industrial application of this method. Patent CN107138131A also reports a carbon-alumina composite material for highly efficient adsorption of chromium ions. This patent uses sodium dodecyl sulfate as an organic modifier and glucose solution as a template, employing a hydrothermal method to prepare the composite material. Although it has a high specific surface area, this method requires a large amount of modifier, making it difficult to accurately control the pore structure of the material. Furthermore, the composition and structural distribution of carbon and alumina are uneven, making it unsuitable as a catalyst support. Patent CN112928290B uses cyclodextrin and other materials as carbon sources and employs a high-temperature pyrolysis method to prepare a series of carbon-oxide composite materials. After loading Pt onto these materials, a catalyst is obtained. This catalyst exhibits excellent performance in methanol fuel cell reactions, but the preparation process requires a large amount of organic pore expander and is relatively complex, making industrial-scale production difficult. Patents CN116041135A, CN117963843, CN116040582A, CN116037181A, CN116037213A, and CN116041142A report a method for preparing carbon-modified alumina microspheres, which are prepared by solvothermal reaction of alumina microspheres with nitrogen-containing polymers such as polyvinylimidazole. However, the carbon content of this support is less than 1%, which limits the space for modifying the hydrophobicity and pore structure of the aluminum-based support, thus restricting its application in the anthraquinone hydrogenation reaction.

[0005] Due to the unique energy transfer and conversion mechanisms of microwaves, compared with traditional methods, microwave technology offers significant advantages such as high efficiency, high speed, high resource recycling rate, low energy consumption, and no environmental pollution. For example, patent CN103769093B reports the preparation of nano-magnesium oxide supports using a low-temperature microwave drying method, followed by palladium loading to obtain a catalyst for anthraquinone hydrogenation reactions. However, the preparation process requires large amounts of organic dispersants and polymeric pore-expanding agents, resulting in complex processes and severe pollution, thus limiting the application of this support. Summary of the Invention

[0006] To address the issues of small specific surface area and poor hydrophobicity in alumina materials, this invention provides a method for preparing a highly hydrophobic aluminum-based composite material and its application. The composite material is synthesized using a microwave hydrothermal method, which offers advantages such as simple process, no pollution, easy scale-up, and high controllability. The composite material serves as a support for an alkylanthraquinone hydrogenation palladium catalyst. Combined with an impregnation method, the resulting alkylanthraquinone hydrogenation palladium catalyst exhibits excellent anthraquinone hydrogenation activity and relatively high stability, providing a new approach for developing highly efficient alkylanthraquinone hydrogenation catalyst systems.

[0007] The first aspect of this invention provides a method for preparing a highly hydrophobic aluminum-based composite material, comprising the following steps: (1) Activated carbon is obtained by acid soaking, washing, drying, and pore-expanding calcination; (2) Add pore-expanding activated carbon, hydrothermal solvent, pH adjuster and auxiliary metal salt to aluminum salt solution and carry out microwave hydrothermal reaction; (3) After the reaction is complete, wash and filter to obtain the composite material precursor; (4) The composite material precursor obtained in step (3) is calcined in a microwave environment to obtain the composite material; The molar ratio of aluminum atoms to activated carbon in aluminum salts is 2:1 to 1:2.

[0008] The mass of the auxiliary metal salt is 9.5-38% of the mass of aluminum atoms in the aluminum salt, and can also be 15-30% or 20-25%.

[0009] Preferably, in step (1), the activated carbon is industrial grade with a specific surface area of ​​300~1000 m². 2 ·g -1 The acid used to soak the activated carbon is selected from at least one of phosphoric acid, nitric acid, hydrochloric acid, etc., and the soaking time is 1-5 hours. The pore-expansion calcination temperature is 500-900℃, the pore-expansion calcination atmosphere is an inert gas, such as nitrogen or argon, and the pore-expansion calcination time is 1-2 hours. This invention obtains a clean activated carbon carrier by soaking the activated carbon in acid, so that the specific surface area will not decrease due to the unclean surface of the carrier during calcination and pore expansion, which would affect the dispersion of Pd metal and the hydrogenation activity of anthraquinone.

[0010] Preferably, in step (2), the aluminum salt is selected from inorganic aluminum salts and / or organic aluminum salts; the inorganic aluminum salt is selected from at least one of aluminum chloride, aluminum nitrate, aluminum sulfate, etc., and the organic aluminum salt is selected from at least one of aluminum isopropoxide, aluminum sec-butoxide, aluminum acetate, etc.

[0011] Preferably, in step (2), the pH adjuster is selected from at least one of alkali or salt; the pH adjuster is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, urea, ammonia, ammonium carbonate, etc.; the pH adjustment range should be 8~11.

[0012] Preferably, in step (2), the hydrothermal solvent is selected from at least one of organic compounds such as alcohols, aldehydes, esters, amines, and ethers, including but not limited to ethanol, ethylene glycol, polyethylene glycol, formaldehyde, acetaldehyde, ethyl formate, propyl acetate, ethylenediamine, formamide, ethylamine, and diethyl ether. The amount of hydrothermal solvent used is 5-20% (volume fraction) of the aluminum salt solution.

[0013] Preferably, in step (2), the auxiliary metal salt is selected from at least one of alkaline earth (Group IIA) or transition metal (Groups IB-VIIB and VIII) salts; the types of metal salts include chlorides, sulfates, acetates, nitrates, etc. Preferably, the alkaline earth metal is selected from magnesium and / or calcium, and the transition metal is selected from one or more of copper, zinc, lanthanum, manganese, nickel, zirconium, cerium, and tungsten. More preferably, the auxiliary metal salt is selected from one or more of magnesium chloride, lanthanum nitrate, manganese acetate, nickel sulfate, zirconium oxynitrate, cerium nitrate, calcium nitrate, copper nitrate, zinc chloride, magnesium nitrate, and tungsten nitrate.

[0014] Preferably, in step (2), the microwave hydrothermal reaction time is 1~48h, the reaction temperature is 100~250℃, and the reaction pressure is 0.2~1.00MPa. The microwave hydrothermal reaction is carried out in a microwave reactor. The purpose of introducing microwaves into the hydrothermal reaction in this invention is to promote the formation of surface hydroxyl-rich species of aluminum salts during the precipitation-dissolution process. The formation of these species can better interact with the hydrothermal solvent to form metastable aluminum salt species containing organic groups. With the help of these organic groups, the aluminum salts, the treated activated carbon species, and the auxiliary metal salts can achieve a stronger binding effect. At the same time, due to the steric hindrance of the organic groups, the aluminum salts, the auxiliary metal salts, and the activated carbon can achieve a uniform binding and distribution state.

[0015] Preferably, in step (4), the microwave calcination time is 2~48h, the microwave calcination temperature is 500~900℃, and the microwave calcination atmosphere is an inert gas, such as nitrogen or argon. This invention achieves the effects of drying and adjusting the pore structure and specific surface area of ​​aluminum-based composite materials through microwave calcination.

[0016] A second aspect of the present invention provides an application of the highly hydrophobic aluminum-based composite material prepared by the preparation method described above, wherein the highly hydrophobic aluminum-based composite material is used as a support for an alkyl anthraquinone hydrogenation palladium catalyst.

[0017] Preferably, the alkylanthraquinone hydrogenation palladium catalyst is prepared by an impregnation method, comprising the following steps: adding the highly hydrophobic aluminum-based composite material to a palladium precursor solution, impregnating, filtering, washing, drying, and reducing to obtain the alkylanthraquinone hydrogenation palladium catalyst.

[0018] Preferably, the palladium precursor is a palladium salt. The palladium salt is selected from at least one of palladium chloride, palladium acetate, palladium nitrate, and sodium chloropalladium.

[0019] Preferably, the palladium loading in the alkylanthraquinone hydrogenation palladium catalyst is 0.5-5% of the support mass, and the mass of palladium is calculated based on the mass of the active metal palladium.

[0020] Preferably, the impregnation temperature is 25~30℃ and the impregnation time is 0.5~2.5h; the drying temperature is 50~120℃ and the drying time is 1~4h.

[0021] Preferably, the reduction operation conditions are as follows: the dried catalyst is subjected to a hydrogen-containing reducing atmosphere at 1~5℃ for 1 minute. -1 Heat to 25~400℃, and reduce for 1~4 hours.

[0022] Compared with existing technologies, the beneficial effects of the catalyst prepared by this invention include: 1. The preparation method of the highly hydrophobic aluminum-based composite material of the present invention is obtained by microwave hydrothermal-microwave calcination. This method not only efficiently achieves the adjustment of parameters such as hydrophobicity and specific surface area of ​​the carrier, but is also more energy-saving and environmentally friendly, while avoiding the collapse of the alumina pore structure during the calcination process. 2. The preparation method described in this invention is simple, safe, energy-saving, and environmentally friendly. It allows for precise adjustment of the carrier structure and is easy to scale up. The raw materials used are all bulk chemicals, which are inexpensive and have the advantage of large-scale production. 3. Compared with Pd / Al2O3 and Pd / C catalysts with the same loading, the palladium-supported catalyst prepared by the method of the present invention using the highly hydrophobic aluminum-based composite material as a support has the characteristics of rich pore structure, large specific surface area and strong hydrophobicity, which makes it have higher activity and stability in the anthraquinone hydrogenation reaction. Attached Figure Description

[0023] Figure 1 The results are the cycle performance test results of the anthraquinone hydrogenation reaction catalysts in Examples 1 and 3, and Comparative Examples 1-5 and 8. Detailed Implementation

[0024] The present invention is described in detail below with reference to embodiments, but is not limited to the embodiments described. Unless otherwise specified, all figures appearing in the specification and claims of this invention, such as load, temperature, time, etc., should not be construed as absolutely precise values, as the measured values ​​will inevitably contain a certain degree of experimental error due to the standard deviation of measurement techniques.

[0025] The palladium loading was measured using inductively coupled plasma atomic emission spectrometry to obtain the actual loading after the catalyst reaction.

[0026] The reaction performance of the prepared catalyst was evaluated using an alkylanthraquinone hydrogenation apparatus, which consisted of a 1000 mL fiberglass reaction tube. Before the reaction, N2 was bubbled through the tube multiple times to purge the oxygen until the oxygen volume fraction was <2%, at which point H2 was introduced. The working solution consisted of heavy aromatics, tetrabutylurea, and 2-ethylanthraquinone, with an Ar to TBU volume ratio of 3:1 and a 2-ethylanthraquinone concentration of 120 g·L⁻¹. -1 Add 0.3g of catalyst to the reactor, stop the gas flow after reacting for 30 min, extract the hydrogen peroxide, and calculate the hydrogenation efficiency by titration with standard potassium permanganate solution.

[0027] The dispersion of Pd was tested by CO chemisorption. Before the test, a pre-reduction was performed. The final Pd dispersion was calculated based on a Pd atom to CO molecule ratio of 1:1 (i.e., one palladium atom adsorbs one CO molecule).

[0028] The pore structure of the support was tested using N2 isothermal adsorption-desorption curves: Before the test, the catalyst sample was degassed in a vacuum at 300℃, and then N2 adsorption-desorption tests were performed at room temperature. The pore size and specific surface area were calculated using the BET model.

[0029] Hydrophobicity was tested using an OSA200 measuring instrument: the catalyst sample was laid flat on a clean platform, and then water droplets were added to the surface of the catalyst sample using a syringe. After the instrument was calibrated, the contact angle between the water droplets and the tableted sample was tested.

[0030] Example 1

[0031] Preparation of highly hydrophobic aluminum-based composite materials: 4g of activated carbon (specific surface area approximately 302m²) was used. 2 ·g -1The activated carbon sample was soaked in nitric acid for 2 hours, then washed, dried, and set aside for later use. It was then calcined in a muffle furnace under Ar atmosphere at 500℃ for 2 hours to obtain a pore-expanded activated carbon sample. 31.9 g of aluminum chloride was dissolved in 100 mL of water, along with 12.3 mL of ethylene glycol solvent, the pore-expanded activated carbon sample, and 0.34 g of magnesium chloride. While stirring, 3.0 g of potassium carbonate was added to the aluminum chloride solution, and the pH was adjusted to approximately 8. The solution was then transferred to a microwave reactor and reacted at 100℃ and 0.2 MPa for 12 hours. After removal, washing and filtration, the sample was calcined in a microwave reactor under N2 atmosphere at 500℃ for 48 hours and then cooled to room temperature to obtain the carrier aluminum-based composite material. Preparation of Pd nanoparticle supported catalyst: 0.7 g of palladium chloride was dissolved in 40 mL of water. The support composite material was added to the solution containing palladium chloride under stirring. After impregnation and adsorption at room temperature for 1 h, the mixture was filtered. The product was washed with deionized water until the solution was neutral, and then dried in an oven at 50 °C for 2 h. After drying, the product was reduced in a hydrogen atmosphere at 50 °C for 2 h to obtain an aluminum-based composite material supported Pd nanoparticle catalyst (2 wt.% Pd / C-Al2O3-MgO) with a palladium loading of 2 wt.%.

[0032] The catalyst prepared was evaluated for its reactivity in an alkylanthraquinone hydrogenation unit. Under reaction conditions of 0.1 MPa and 50 °C, the hydrogenation efficiency was measured to be 13.11 g / L. -1 .

[0033] Table 1 shows that the Pd / C-Al2O3-MgO catalyst prepared by the microwave hydrothermal-impregnation method has a specific surface area as high as 213 m². 2 It has an average pore size of approximately 26.2 nm and a hydrophobic angle of up to 143°.

[0034] Example 2

[0035] Preparation of highly hydrophobic aluminum-based composite materials: 4g of activated carbon (specific surface area approximately 573m²) was used. 2 ·g -1 The activated carbon sample was soaked in phosphoric acid for 5 hours, then washed, dried, and set aside for later use. It was then calcined in a muffle furnace at 900℃ for 2 hours to obtain a pore-expanded activated carbon sample. 36.7 g of aluminum nitrate was dissolved in 100 mL of water, along with 15.7 mL of formamide solvent, the pore-expanded activated carbon sample, and 1.0 g of lanthanum nitrate. While stirring, 5.0 g of sodium bicarbonate was added to the aluminum nitrate solution, adjusting the pH to approximately 11. The solution was then transferred to a microwave reactor and reacted at 150℃ and 1.0 MPa for 48 hours. After removal, washing and filtration, the sample was calcined in an Ar atmosphere microwave reactor at 500℃ for 2 hours and then cooled to room temperature to obtain the carrier aluminum-based composite material. Preparation of Pd nanoparticle supported catalyst: 0.18 g of palladium chloride was dissolved in 40 mL of water. The support composite material was added to the palladium chloride solution under stirring. After impregnation and adsorption at 30 °C for 2.5 h, the mixture was filtered. The product was washed with deionized water until the solution was neutral, and then dried in an oven at 120 °C for 1 h. After drying, the product was reduced in a hydrogen atmosphere at 25 °C for 1 h to obtain a Pd nanoparticle supported catalyst (0.5 wt.% Pd / C-Al2O3-La2O3) with a palladium loading of 0.5 wt.%.

[0036] The catalyst prepared was evaluated for its reactivity in an alkylanthraquinone hydrogenation unit. Under reaction conditions of 0.1 MPa and 50 °C, the hydrogenation efficiency was measured to be 11.51 g / L. -1 .

[0037] Table 1 shows that the Pd / C-Al2O3-La2O3 catalyst prepared by the microwave hydrothermal-impregnation method has a specific surface area as high as 202 m². 2 It has an average pore size of approximately 27.6 nm and a hydrophobic angle of up to 131°.

[0038] Example 3

[0039] Preparation of highly hydrophobic aluminum-based composite materials: 4g of activated carbon (specific surface area approximately 998m²) was used. 2 ·g -1 The activated carbon sample was soaked in hydrochloric acid for 1 hour, then washed and dried for later use. It was then calcined in a muffle furnace at 700℃ for 2 hours to obtain the expanded-pore activated carbon sample. 45.9 g of aluminum isopropoxide was dissolved in 100 mL of water, along with 12.3 mL of ethyl formate solvent, the expanded-pore activated carbon sample, and 1.5 g of manganese acetate. While stirring, 6.0 g of ammonia was added to the solution containing the aluminum salt, adjusting the pH to approximately 10. The solution was then transferred to a microwave reactor and reacted at 250℃ and 0.7 MPa for 1 hour. After removal, washing and filtration, the mixture was calcined in an Ar atmosphere microwave reactor at 800℃ for 4 hours and then cooled to room temperature to obtain the carrier composite material. Preparation of Pd nanoparticle supported catalyst: 1.8 g of palladium chloride was dissolved in 40 mL of water. The support composite material was added to the palladium chloride solution under stirring. After impregnation and adsorption at 25 °C for 0.5 h, the mixture was filtered. The product was washed with deionized water until the solution was neutral, and then dried in an oven at 50 °C for 4 h. After drying, the product was reduced at 400 °C in a hydrogen atmosphere for 4 h to obtain an aluminum-based composite supported Pd nanoparticle catalyst (5 wt.% Pd / C-Al2O3-MnO2) with a palladium loading of 5 wt.%.

[0040] The catalyst prepared was evaluated for its reactivity in an alkylanthraquinone hydrogenation unit. The hydrogenation efficiency was measured to be 14.88 g / L under reaction conditions of 0.1 MPa and 50 °C. -1 .

[0041] Table 1 shows that the Pd / C-Al2O3-MnO2 catalyst prepared by the microwave hydrothermal-impregnation method has a specific surface area as high as 180 m². 2 ·g, with an average pore size of approximately 34.2 nm and a hydrophobic angle of up to 171°.

[0042] Example 4

[0043] Preparation of highly hydrophobic aluminum-based composite materials: 4g of activated carbon (specific surface area approximately 612m²) was used. 2 ·g -1 The activated carbon sample was soaked in nitric acid for 2 hours, then washed, dried, and set aside for later use. It was then calcined in a muffle furnace at 800℃ for 2 hours to obtain the expanded-pore activated carbon sample. 52.9 g of aluminum sec-butoxide was dissolved in 100 mL of water, along with 10.4 mL of diethyl ether solvent, the expanded-pore activated carbon sample, and 1.6 g of nickel sulfate. While stirring, 4.0 g of potassium hydroxide was added to the solution containing the aluminum salt, adjusting the pH to approximately 8. The solution was then transferred to a microwave reactor and reacted at 130℃ and 0.4 MPa for 18 hours. After removal, washing and filtration, the sample was calcined in a microwave reactor under N2 atmosphere at 800℃ for 8 hours, and then cooled to room temperature to obtain the carrier composite material. Preparation of Pd nanoparticle supported catalyst: 0.8 g of sodium chloropalladium was dissolved in 40 mL of water. The support composite material was added to the solution containing sodium chloropalladium under stirring. After impregnation and adsorption at room temperature for 1 h, the mixture was filtered. The product was washed with deionized water until the solution was neutral, and then dried in an oven at 90 °C for 2 h. After drying, the product was reduced at 150 °C in a hydrogen atmosphere for 2 h to obtain an aluminum-based composite supported Pd nanoparticle catalyst (2 wt.% Pd / C-Al2O3-Ni2O3) with a palladium loading of 2 wt.%.

[0044] The catalyst prepared was evaluated for its reactivity in an alkylanthraquinone hydrogenation unit. Under reaction conditions of 0.1 MPa and 50 °C, the hydrogenation efficiency was measured to be 10.11 g / L. -1 .

[0045] Table 1 shows that the Pd / C-Al2O3-Ni2O3 catalyst prepared by the microwave hydrothermal-impregnation method has a specific surface area as high as 260 m². 2 ·g, with an average pore size of approximately 13.1 nm and a hydrophobic angle of up to 131°.

[0046] Example 5

[0047] Preparation of highly hydrophobic aluminum-based composite materials: 4g of activated carbon (specific surface area approximately 439m²) was used. 2 ·g -1 The activated carbon sample was soaked in nitric acid for 2 hours, then washed, dried, and set aside for later use. It was then calcined in a muffle furnace at 900℃ for 2 hours to obtain the expanded-pore activated carbon sample. 38.9 g of aluminum acetate was dissolved in 100 mL of water, along with 13.4 mL of ethylenediamine solvent, the expanded-pore activated carbon sample, and 0.9 g of zirconium oxynitrate. While stirring, 3.6 g of potassium hydroxide was added to the solution containing the aluminum salt, adjusting the pH to approximately 8. The solution was then transferred to a microwave reactor and reacted at 130℃ and 0.4 MPa for 18 hours. After removal, washing and filtration, the mixture was calcined in a microwave reactor under N2 atmosphere at 600℃ for 8 hours, and then cooled to room temperature to obtain the carrier composite material. Preparation of Pd nanoparticle supported catalyst: 0.85 g of palladium acetate was dissolved in 40 mL of water. The composite material support was added to the palladium acetate solution under stirring. After impregnation and adsorption at 27 °C for 1.5 h, the mixture was filtered. The product was washed with deionized water until the solution was neutral, and then dried in an oven at 110 °C for 2 h. After drying, the product was reduced at 90 °C in a hydrogen atmosphere for 2 h to obtain a composite material supported Pd nanoparticle catalyst (2 wt.% Pd / C-Al2O3-ZrO2) with a palladium loading of 2 wt.%.

[0048] The catalyst prepared was evaluated for its reactivity in an alkylanthraquinone hydrogenation unit. The hydrogenation efficiency was measured to be 11.27 g / L under reaction conditions of 0.1 MPa and 50 °C. -1 .

[0049] Table 1 shows that the Pd / C-Al2O3-ZrO2 catalyst prepared by the microwave hydrothermal-impregnation method has a specific surface area as high as 260 m². 2 It has an average pore size of approximately 11.6 nm and a hydrophobic angle of up to 121°.

[0050] Example 6

[0051] Preparation of highly hydrophobic aluminum-based composite materials: 4g of activated carbon (specific surface area approximately 537m²) was used. 2 ·g -1 The activated carbon sample was soaked in nitric acid for 2 hours, then washed and dried for later use. It was then calcined in a muffle furnace at 700℃ for 2 hours to obtain the expanded-pore activated carbon sample. 38.9 g of aluminum acetate was dissolved in 100 mL of water, along with 23.4 mL of polyethylene glycol solvent, the expanded-pore activated carbon sample, and 1.7 g of cerium nitrate. While stirring, 5.3 g of sodium hydroxide was added to the solution containing aluminum salts, adjusting the pH to approximately 9. The solution was then transferred to a microwave reactor and reacted at 180℃ and 0.6 MPa for 24 hours. After removal, washing and filtration, the mixture was calcined in a microwave reactor at 700℃ for 6 hours under N2 atmosphere, and then cooled to room temperature to obtain the carrier composite material. Preparation of Pd nanoparticle supported catalyst: 0.85 g of palladium nitrate was dissolved in 40 mL of water. The composite material support was added to the palladium nitrate solution under stirring. After impregnation and adsorption at 25 °C for 1.5 h, the mixture was filtered. The product was washed with deionized water until the solution was neutral, and then dried in an oven at 110 °C for 3 h. After drying, the product was reduced at 100 °C for 2 h in a hydrogen atmosphere to obtain a composite material supported Pd nanoparticle catalyst (2 wt.% Pd / C-Al2O3-CeO2) with a palladium loading of 2 wt.%.

[0052] The catalyst prepared was evaluated for its reactivity in an alkylanthraquinone hydrogenation unit. The hydrogenation efficiency was measured to be 10.98 g / L under reaction conditions of 0.1 MPa and 50 °C. -1 .

[0053] Table 1 shows that the Pd / C-Al2O3-CeO2 catalyst prepared by the microwave hydrothermal-impregnation method has a specific surface area as high as 300 m². 2 It has an average pore size of approximately 10.7 nm and a hydrophobic angle of up to 131°.

[0054] Example 7

[0055] Preparation of highly hydrophobic aluminum-based composite materials: 4g of activated carbon (specific surface area approximately 833m²) was used. 2 ·g -1 The activated carbon sample was soaked in nitric acid for 2 hours, then washed, dried, and set aside for later use. It was then calcined in a muffle furnace at 900℃ for 2 hours to obtain the expanded-pore activated carbon sample. 38.9 g of aluminum acetate was dissolved in 100 mL of water, along with 11.4 mL of ethanol solvent, the expanded-pore activated carbon sample, and 1.9 g of calcium nitrate. While stirring, 3.9 g of potassium carbonate was added to the solution containing aluminum salts, and the pH was adjusted to approximately 10. The solution was then transferred to a microwave reactor and reacted at 210℃ and 0.3 MPa for 19 hours. After removal, washing and filtration, the mixture was calcined in a microwave reactor under N2 atmosphere at 600℃ for 6 hours, and then cooled to room temperature to obtain the carrier composite material. Using the same catalyst impregnation method as in Example 1, a composite material-supported Pd nanoparticle catalyst (2wt.%Pd / C-Al2O3-CaO) with a palladium metal loading of 2wt.% was obtained.

[0056] The catalyst prepared was evaluated for its reactivity in an alkylanthraquinone hydrogenation unit. The hydrogenation efficiency was measured to be 12.81 g / L under reaction conditions of 0.1 MPa and 50 °C. -1 .

[0057] Table 1 shows that the Pd / C-Al2O3-CaO catalyst prepared by the microwave hydrothermal-impregnation method has a specific surface area as high as 203 m². 2It has an average pore size of approximately 24.9 nm and a hydrophobic angle of up to 142°.

[0058] Example 8

[0059] Preparation of highly hydrophobic aluminum-based composite materials: 4g of activated carbon (specific surface area approximately 339m²) was used. 2 ·g -1 The activated carbon sample was soaked in phosphoric acid for 2 hours, then washed, dried, and set aside for later use. It was then calcined in a muffle furnace at 500℃ for 12 hours to obtain the expanded-pore activated carbon sample. 38.9 g of aluminum acetate was dissolved in 100 mL of water, along with 14.4 mL of diethyl ether solvent, the expanded-pore activated carbon sample, and 1.23 g of copper nitrate. While stirring, 5.7 g of sodium hydroxide was added to the solution containing the aluminum salt, adjusting the pH to approximately 11. The solution was then transferred to a microwave reactor and reacted at 150℃ and 0.4 MPa for 16 hours. After removal, washing and filtration, the mixture was calcined in a microwave reactor under N2 atmosphere at 700℃ for 3 hours, and then cooled to room temperature to obtain the carrier composite material. Using the same catalyst impregnation method as in Example 1, a composite material-supported Pd nanoparticle catalyst (2wt.%Pd / C-Al2O3-CuO) with a palladium metal loading of 2wt.% was obtained.

[0060] The catalyst prepared was evaluated for its reactivity in an alkylanthraquinone hydrogenation unit. The hydrogenation efficiency was measured to be 12.01 g / L under reaction conditions of 0.1 MPa and 50 °C. -1 .

[0061] Table 1 shows that the Pd / C-Al2O3-CuO catalyst prepared by the microwave hydrothermal-impregnation method has a specific surface area as high as 202 m². 2 ·g, with an average pore size of approximately 21.5nm and a hydrophobic angle of up to 141°.

[0062] Example 9

[0063] Preparation of highly hydrophobic aluminum-based composite materials: 4g of activated carbon (specific surface area approximately 539m²) was used. 2 ·g -1 The activated carbon sample was soaked in nitric acid for 2 hours, then washed, dried, and set aside for later use. It was then calcined in a muffle furnace at 700℃ for 2 hours to obtain the expanded-pore activated carbon sample. 38.9 g of aluminum acetate was dissolved in 100 mL of water, along with 23.4 mL of polyethylene glycol solvent, the expanded-pore activated carbon sample, and 1.3 g of zinc chloride. While stirring, 3.9 g of sodium hydroxide was added to the solution containing aluminum salts, adjusting the pH to approximately 9. The solution was then transferred to a microwave reactor and reacted at 120℃ and 0.6 MPa for 24 hours. After removal, washing and filtration, the sample was calcined in a microwave reactor under N2 atmosphere at 850℃ for 6 hours and then cooled to room temperature to obtain the carrier composite material. Using the same catalyst impregnation method as in Example 1, a composite material-supported Pd nanoparticle catalyst (2wt.%Pd / C-Al2O3-ZnO) with a palladium metal loading of 2wt.% was obtained.

[0064] The catalyst prepared was evaluated for its reactivity in an alkylanthraquinone hydrogenation unit. Under reaction conditions of 0.1 MPa and 50 °C, the hydrogenation efficiency was measured to be 11.23 g / L. -1 .

[0065] Table 1 shows that the Pd / C-Al2O3-ZnO catalyst prepared by the microwave hydrothermal-impregnation method has a specific surface area as high as 270 m². 2 ·g, with an average pore size of approximately 11.3 nm and a hydrophobic angle of up to 134°.

[0066] Example 10

[0067] Preparation of highly hydrophobic aluminum-based composite materials: 4g of activated carbon (specific surface area approximately 439m²) was used. 2 ·g -1 The activated carbon sample was soaked in nitric acid for 2 hours, then washed, dried, and set aside for later use. It was then calcined in a muffle furnace at 700℃ for 2 hours to obtain the expanded-pore activated carbon sample. 34.9 g of aluminum sulfate was dissolved in 100 mL of water, and 23.4 mL of polyethylene glycol solvent, the expanded-pore activated carbon sample, 0.4 g of magnesium nitrate, and 0.8 g of cerium nitrate were added simultaneously. 6.5 g of sodium hydroxide was added to the solution containing aluminum salts while stirring, and the pH was adjusted to approximately 9. The solution was then transferred to a microwave reactor and reacted at 190℃ and 0.2 MPa for 12 hours. After removal, washing and filtration, the solution was calcined in a microwave reactor under N2 atmosphere at 800℃ for 12 hours and then cooled to room temperature to obtain the carrier composite material. Using the same catalyst impregnation method as in Example 1, a composite material-supported Pd nanoparticle catalyst (2wt.%Pd / C-Al2O3-MgO-CeO2) with a palladium metal loading of 2wt.% was obtained.

[0068] The catalyst prepared was evaluated for its reactivity in an alkylanthraquinone hydrogenation unit. The hydrogenation efficiency was measured to be 12.81 g / L under reaction conditions of 0.1 MPa and 50 °C. -1 .

[0069] Table 1 shows that the Pd / C-Al2O3-MgO-CeO2 catalyst prepared by the microwave hydrothermal-impregnation method has a specific surface area as high as 130 m². 2 ·g, with an average pore size of approximately 31.8 nm and a hydrophobic angle of up to 142°.

[0070] Example 11

[0071] Preparation of highly hydrophobic aluminum-based composite materials: 4g of activated carbon (specific surface area approximately 312m²) was used. 2 ·g -1 The activated carbon sample was soaked in nitric acid for 2 hours, then washed, dried, and set aside for later use. It was then calcined in a muffle furnace under Ar atmosphere at 600℃ for 2 hours to obtain the expanded-pore activated carbon sample. 44.3 g of aluminum chloride and 82.6 g of aluminum sec-butoxide were dissolved in 100 mL of water, along with 35.3 mL of ethylene glycol solvent, the expanded-pore activated carbon sample, 1.2 g of calcium nitrate, and 1.4 g of tungsten nitrate. While stirring, 9.4 g of potassium carbonate was added to the aluminum chloride solution, and the pH was adjusted to approximately 8. The mixture was then transferred to a microwave reactor and reacted at 150℃ and 0.4 MPa for 12 hours. After removal, washing and filtration, the mixture was calcined in a microwave reactor under N2 atmosphere at 600℃ for 2 hours and then cooled to room temperature to obtain the carrier composite material. Preparation of Pd nanoparticle supported catalyst: 0.7 g of palladium chloride was dissolved in 40 mL of water. The support composite material was added to the solution containing palladium chloride under stirring. After impregnation and adsorption at room temperature for 1 h, the mixture was filtered. The product was washed with deionized water until the solution was neutral, and then dried in an oven at 50 °C for 2 h. After drying, the product was reduced in a hydrogen atmosphere at 50 °C for 2 h to obtain a composite material supported Pd nanoparticle catalyst (2 wt.% Pd / C-Al2O3-CaO-Sm2O3) with a palladium loading of 2 wt.%.

[0072] The catalyst prepared was evaluated for its reactivity in an alkylanthraquinone hydrogenation unit. The hydrogenation efficiency was measured to be 11.76 g / L under reaction conditions of 0.1 MPa and 50 °C. -1 .

[0073] Table 1 shows that the Pd / C-Al2O3-CaO-Sm2O3 catalyst prepared by the microwave hydrothermal-impregnation method has a specific surface area as high as 208 m². 2 It has an average pore size of approximately 23.6 nm and a hydrophobic angle of up to 160°.

[0074] Comparative Example 1

[0075] First, take 4g of activated carbon (specific surface area approximately 302m²) 2 ·g -1 The activated carbon sample was soaked in nitric acid for 2 hours, then washed, dried, and set aside for later use. It was then calcined at 500°C for 2 hours in an Ar atmosphere muffle furnace to obtain the expanded-pore activated carbon sample. After washing and filtration, it was calcined at 500°C for 48 hours in a N2 atmosphere microwave reactor and then cooled to room temperature to obtain the carrier carbon material.

[0076] Using the same catalyst impregnation method as in Example 1, except that the support was replaced with a carbon support, a carbon-supported Pd nanoparticle catalyst with a metal loading of 2 wt.% (2 wt.% Pd / C) was obtained.

[0077] The catalyst prepared was evaluated for its reactivity in an alkylanthraquinone hydrogenation unit. Under reaction conditions of 0.1 MPa and 50 °C, the hydrogenation efficiency was measured to be only 3.01 g / L. -1 .

[0078] Comparative Example 2

[0079] 31.9 g of aluminum chloride was dissolved in 100 mL of water. 2.0 g of potassium carbonate was added to the solution containing aluminum chloride while stirring. The pH was adjusted to about 8. After precipitation reaction for 2 h, the solution was washed, filtered, and calcined at 500 °C for 48 h in a microwave reactor under N2 atmosphere. The solution was then cooled to room temperature to obtain the carrier alumina material.

[0080] Using the same catalyst impregnation method as in Example 1, except that the support was replaced with an Al2O3 support, a carbon-alumina supported Pd nanoparticle catalyst with a metal loading of 2 wt.% (2 wt.% Pd / Al2O3) was obtained.

[0081] The catalyst prepared was evaluated for its reactivity in an alkylanthraquinone hydrogenation unit. Under reaction conditions of 0.1 MPa and 50 °C, the hydrogenation efficiency was measured to be only 4.31 g / L. -1 .

[0082] Comparative Example 3 Remove "4g of activated carbon (specific surface area approximately 998m²)" from Example 3. 2 ·g -1 The activated carbon sample was soaked in hydrochloric acid for 1 hour, then washed, dried, and set aside for later use. It was then calcined in a muffle furnace at 700°C for 2 hours to obtain the expanded-pore activated carbon sample. The activated carbon was used directly, and the remaining operations were the same as in Example 3.

[0083] Comparative Example 4 Replace "transfer it to a microwave reactor and react at 250°C and 0.7MPa for 1 hour" in Example 3 with "transfer it to a regular reactor and react at 250°C and 0.7MPa for 1 hour", and the rest of the operation is the same as in Example 3.

[0084] Comparative Example 5 Replace "washing and filtering, then calcining at 800°C for 4 hours in an Ar atmosphere microwave reactor" in Example 3 with "washing and filtering, then microwave drying at 300°C for 1 hour in an Ar atmosphere, followed by calcination at 800°C for 4 hours in an Ar atmosphere muffle furnace", and the rest of the operation is the same as in Example 3.

[0085] Comparative Example 6 In Example 3, palladium chloride was replaced with ferric chloride, and the remaining operations were the same as in Example 3. As shown in Table 1, the hydrogen efficiency of the iron-supported catalyst in Comparative Example 6 for the anthraquinone hydrogenation reaction was 0.21 g / L. -1This catalyst has almost no catalytic effect on the hydrogenation of anthraquinone.

[0086] Comparative Example 7 In Example 3, "aluminum isopropoxide" was replaced with "magnesium chloride," and the remaining operations were the same as in Example 3. As shown in Table 1, the catalyst prepared using magnesium oxide as a support in Comparative Example 7 had an average pore size of approximately 11.3 nm and a hydrogen efficiency of 3.33 g / L for the anthraquinone hydrogenation reaction. -1 This is because nano-magnesium oxide is an alkaline oxide with a small pore size, and therefore does not have a good adsorption and activation ability for anthraquinone macromolecules, resulting in low hydrogen efficiency.

[0087] Comparative Example 8 Remove "0.9 g magnesium chloride" from Example 1, and follow the same procedure as in Example 1. As shown in Table 1, although the hydrophobic angle slightly increased after removing the auxiliary metal salt in Comparative Example 8, the Pd metal dispersion decreased significantly. This indicates that changes in the support surface structure lead to reduced Pd dispersion, thereby decreasing the anthraquinone hydrogenation reactivity.

[0088] Table 1 shows the physicochemical properties of the catalysts in Examples 1-11 and Comparative Examples 1-8.

[0089] Table 1 Comparison of physicochemical properties of different catalysts

[0090] As shown in Table 1, the palladium-supported catalysts of Examples 1-11, which underwent microwave hydrothermal treatment, exhibited high dispersion, large specific surface area, good hydrophobicity, and high anthraquinone hydrogenation activity. In Comparative Example 1, the palladium-supported catalyst on activated carbon exhibited low dispersion and low anthraquinone hydrogenation activity. Similarly, the palladium-supported catalyst on alumina in Comparative Example 2 exhibited low dispersion, small specific surface area, poor hydrophobicity, and low anthraquinone hydrogenation activity. Compared to Example 3, the activated carbon in Comparative Example 3 was untreated, resulting in a significantly reduced specific surface area, decreased Pd dispersion, slightly reduced hydrophobicity, and decreased anthraquinone hydrogenation activity. Compared to Example 3, Comparative Example 4, using a conventional reactor, produced a catalyst with a pore size of only 4.6 nm, exhibiting a significant decrease in hydrophobicity and a Pd dispersion of 21.8%, resulting in a reduction in anthraquinone hydrogenation activity to 3.89 g / L. In Comparative Example 4, the removal of microwaves hindered the uniform bonding of aluminum and activated carbon, drastically altering the specific surface area, pore structure, and hydrophobicity of the composite material, further reducing Pd dispersion and impacting catalytic activity. In contrast, Comparative Example 5, employing low-temperature microwave drying and calcination, produced a catalyst with a specific surface area of ​​170 m². 2 / g, with a pore size of 32.9nm, the hydrophobic angle becomes 113°, and the Pd dispersion also decreases to 19.2%, resulting in a decrease in the anthraquinone hydrogenation activity to 8.98g / L. This may be due to the difference caused by the structural changes of the support caused by different microwave treatment temperatures. In Example 3, the direct microwave calcination method results in a larger specific surface area of ​​the carbon-alumina material, thus giving Pd better dispersion and higher anthraquinone hydrogenation reactivity.

[0091] Example 12: Cyclic Test of Anthraquinone Hydrogenation Reaction The catalysts in Examples 1 and 3, and Comparative Examples 1-5 and 8, were subjected to stability tests in an alkylanthraquinone hydrogenation unit. The catalysts were tested multiple times in the working solution, with the working solution replaced every 30 minutes, and the activity changes were tested cyclically. Figure 1 As shown.

[0092] from Figure 1 As can be seen, the catalysts in Examples 1 and 3 have higher stability and activity, which are significantly improved compared with the catalysts in Comparative Examples 1-5 and 8.

[0093] The above descriptions are merely a few embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any modifications or variations made by those skilled in the art without departing from the scope of the present invention using the disclosed technical content are equivalent to equivalent embodiments and fall within the scope of the technical solution.

Claims

1. A method for preparing a highly hydrophobic aluminum-based composite material, comprising the following steps: (1) Activated carbon is obtained by acid soaking, washing, drying, and pore-expanding calcination; (2) Add pore-expanding activated carbon, hydrothermal solvent, pH adjuster and auxiliary metal salt to aluminum salt solution and carry out microwave hydrothermal reaction; (3) After the reaction is complete, wash and filter to obtain the composite material precursor; (4) The composite material precursor obtained in step (3) is calcined in a microwave environment to obtain the composite material; The molar ratio of aluminum atoms to activated carbon in aluminum salts is 2:1 to 1:

2. The mass of the auxiliary metal salt is 9.5% to 38% of the atomic mass of aluminum in the aluminum salt; In step (2), the hydrothermal solvent is selected from at least one of alcohols, aldehydes, esters, amines, and ethers; the auxiliary metal salt is selected from at least one of alkaline earth or transition metal salts; and the pH adjustment range is 8 to 11. In step (4), the microwave roasting atmosphere is an inert gas.

2. The method for preparing a highly hydrophobic aluminum-based composite material according to claim 1, characterized in that, In step (2), the aluminum salt is selected from inorganic aluminum salts and / or organic aluminum salts.

3. The method for preparing a highly hydrophobic aluminum-based composite material according to claim 2, characterized in that, The inorganic aluminum salt is selected from at least one of aluminum chloride, aluminum nitrate, and aluminum sulfate, and the organic aluminum salt is selected from at least one of aluminum isopropoxide, aluminum sec-butoxide, and aluminum acetate.

4. The method for preparing a highly hydrophobic aluminum-based composite material according to claim 1, characterized in that, In step (2), the pH adjuster is selected from at least one of alkali or salt.

5. The method for preparing a highly hydrophobic aluminum-based composite material according to claim 1, characterized in that, In step (2), the types of metal salts include chlorides, sulfates, acetates, and nitrates.

6. The method for preparing a highly hydrophobic aluminum-based composite material according to claim 1, characterized in that, In step (2), the microwave hydrothermal reaction time is 1~48h, the reaction temperature is 100~250℃, and the reaction pressure is 0.2~1.00MPa.

7. The method for preparing a highly hydrophobic aluminum-based composite material according to claim 1, characterized in that, In step (4), the microwave roasting time is 2~48h and the microwave roasting temperature is 500~900℃.

8. An application of a highly hydrophobic aluminum-based composite material prepared by the preparation method according to any one of claims 1 to 7, wherein the highly hydrophobic aluminum-based composite material is used as a support for an alkyl anthraquinone hydrogenation palladium catalyst.

9. The application of the highly hydrophobic aluminum-based composite material according to claim 8, characterized in that, The alkylanthraquinone hydrogenation palladium catalyst is prepared by an impregnation method, comprising the following steps: adding the highly hydrophobic aluminum-based composite material to a palladium precursor solution, impregnating, filtering, washing, drying, and reducing to obtain the alkylanthraquinone hydrogenation palladium catalyst.

Images