A palladium catalyst for anthraquinone hydrogenation and preparation method thereof

Abstract

The present invention belongs to the field of catalyst technology, specifically a palladium catalyst for anthraquinone hydrogenation and a preparation method thereof, comprising the following steps: using hexadecyltrimethylammonium bromide as a primary template and adding a small amount of polyethylene glycol to prepare a catalyst carrier with a high specific surface area; then impregnating the catalyst carrier with a palladium salt solution; and drying, calcining, and reducing the impregnated catalyst carrier to obtain a palladium catalyst for anthraquinone hydrogenation. The palladium catalyst for anthraquinone hydrogenation uses the prepared high specific surface area alumina as a carrier, which greatly improves the catalytic efficiency. The larger pore size of the catalyst carrier can reduce diffusion resistance and facilitate the transport of reactants; on the other hand, the anthraquinone generated by the reaction can more easily diffuse out of the larger pores, thereby avoiding its prolonged residence time in the pores and reducing its catalytic activity. At the same time, the larger specific surface area of ​​the catalyst carrier can better disperse the active components, thereby significantly improving the hydrogenation efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and specifically relates to a palladium catalyst for anthraquinone hydrogenation and a preparation method thereof. Background Art

[0002] Hydrogen peroxide is a crucial green chemical product, originally produced by reacting barium peroxide with nitric acid. Because hydrogen peroxide produces only oxygen and water during use, it poses virtually no environmental risk. It is a recognized environmentally friendly chemical reagent and is widely used in a variety of industries, including environmental protection, papermaking, textiles, chemical synthesis, disinfection, electronics, metallurgy, and aerospace.

[0003] The anthraquinone process is the industrially-scaled method for producing hydrogen peroxide. The hydrogenation process is the core step in the anthraquinone process, and catalysts are a key research focus. The development of anthraquinone hydrogenation catalysts with high catalytic activity, high selectivity, and low cost is a key research focus in the anthraquinone process, and holds significant promise for the efficient and cost-effective production of hydrogen peroxide.

[0004] Nickel, palladium, and platinum-based catalysts can all be used in anthraquinone hydrogenation. Historically, nickel-based catalysts have been used industrially, primarily in the form of Raney nickel, a porous nickel-aluminum alloy catalyst obtained by treating the alloy with alkaline (concentrated sodium hydroxide) solution. Although nickel is relatively inexpensive compared to precious metal catalysts like platinum, Raney nickel suffers from severe over-hydrogenation and rapid deactivation when used in anthraquinone hydrogenation. Furthermore, Raney nickel is prone to spontaneous combustion, is easily oxidized, and is difficult to regenerate, significantly limiting its use in anthraquinone hydrogenation reactions.

[0005] Palladium-based catalysts can also be used in anthraquinone hydrogenation reactions, particularly supported palladium-based catalysts. These catalysts are widely used in anthraquinone-based hydrogen peroxide production processes both domestically and internationally due to their advantages, such as low precious metal usage, high activity, easy regeneration after deactivation, and greater safety. Chinese invention patent application publication number CN113600157A provides a rare-earth-doped spherical alumina palladium-based catalyst, its preparation method, and applications. The catalyst is prepared by introducing a rare-earth source into an aluminum sol, and then the active component, palladium, is loaded onto the rare-earth-doped spherical alumina as a carrier to obtain the catalyst. The rare-earth elements are highly dispersed in the alumina, preventing agglomeration even after high-temperature calcination. The rare-earth elements not only prevent clogging the pores of the spherical alumina but also increase pore size and pore volume, providing good mass transfer space for the reactant macromolecules. This catalyst is suitable for the anthraquinone hydrogenation process to produce hydrogen peroxide and is suitable for both fixed-bed and fluidized-bed processes. The Chinese invention patent application, publication number CN118162130A, provides a method for preparing a palladium catalyst for anthraquinone hydrogenation reaction. The method uses a polyethylene glycol segment as a template, which undergoes thermal decomposition during high-temperature calcination, causing pore formation in the nano-alumina aggregates, forming a large number of porous structures, and obtaining porous nano-alumina with a high specific surface area. Using porous nano-alumina as a carrier allows palladium to be better dispersed on the carrier surface with a high specific surface area, resulting in more catalytically active sites for the catalyst. Although the above technology improves the catalytic activity of the palladium-based catalyst to a certain extent, the improvement in hydrogenation efficiency is limited, which limits its application in industrialization. Summary of the Invention

[0006] The invention provides a palladium catalyst for anthraquinone hydrogenation and a preparation method thereof, which solves the problem that traditional alumina-based palladium catalysts have low catalytic activity in anthraquinone hydrogenation reactions.

[0007] The technical solution provided by the present invention is:

[0008] A method for preparing a palladium catalyst for anthraquinone hydrogenation comprises the following steps:

[0009] (1) adding aluminum nitrate and hexadecyltrimethylammonium bromide to deionized water and stirring uniformly to obtain an aluminum nitrate mixed solution;

[0010] (2) Sodium aluminate and polyethylene glycol are added to deionized water, and the sodium aluminate mixed solution is homogenized by ultrasonication; the number average molecular weight of the polyethylene glycol is 200-2000; the mass ratio of the polyethylene glycol to the hexadecyltrimethylammonium bromide in step (1) is (0.1-0.4):1; in order to promote the dissolution of each component, appropriate heating can be performed to accelerate the dissolution rate;

[0011] Polyethylene glycol of an appropriate molecular weight ensures good solubility and dispersibility while ensuring the template effect, while also avoiding excessively high molecular weight, which may cause interaction with long-chain hexadecyltrimethylammonium bromide and affect the dispersion of crystals or precipitates. Furthermore, the molecular weight of the polyethylene glycol can be any value between 300-1800, 400-1500, 600-1400, or 800-1200.

[0012] (3) adding the sodium metaaluminate mixed solution dropwise to the aluminum nitrate mixed solution while stirring to obtain a final solution, and adjusting the pH of the final solution to be alkaline; heating the solution for a certain period of time, filtering, washing, drying, and calcining to obtain a catalyst support; the catalyst support is an alumina support;

[0013] To promote dispersion, the aluminum nitrate mixed solution can be heated to 50-70°C, and then the sodium metaaluminate mixed solution can be added dropwise at a dropping rate of 5-15 mL / min.

[0014] (4) dispersing the palladium salt in an acetone solvent to obtain a palladium salt solution, and then impregnating the catalyst support with the palladium salt solution;

[0015] (5) The impregnated catalyst carrier is dried, calcined, and reduced to obtain a palladium catalyst for anthraquinone hydrogenation.

[0016] For supported catalysts, the support ensures high dispersion of the active metal, reducing the amount of active component used. Furthermore, the strong interaction between the active metal and the support enhances catalyst activity. Alumina, due to its excellent mechanical strength and acid and alkali resistance, is often used as a support in the preparation of anthraquinone hydrogenation catalysts. However, existing alumina supports have small pores and specific surface areas, resulting in limited improvements in catalytic performance.

[0017] According to the different surfactant templates used, the commonly used synthesis methods of alumina carriers can be divided into: cationic template method, anionic template method, and nonionic template method. Among them, nonionic surfactants are not suitable for industrial production because their polymer molecular weight is usually large and their solubility is poor, and many types of nonionic surfactants are relatively expensive. Therefore, the present invention selects hexadecyltrimethylammonium bromide as a cationic template. The alumina material synthesized using hexadecyltrimethylammonium bromide as a template has the advantages of regular mesopores, high order, and easy control of pore size distribution and pore size. However, the pore size formed by using hexadecyltrimethylammonium bromide alone as a template is relatively small, and the specific surface area is low. In actual production tests, the specific surface area of ​​alumina prepared by using hexadecyltrimethylammonium bromide alone as a template in the aluminum nitrate-sodium aluminate reaction system can only reach 200m 2 / g, and the pore size is relatively low. Therefore, the present invention adds a small amount of polyethylene glycol nonionic surfactant to the hexadecyltrimethylammonium bromide template to address the problems of hexadecyltrimethylammonium bromide as a cationic template. Polyethylene glycol nonionic surfactants typically produce larger pores and higher specific surface areas, and the pore size can be adjusted by changing the chain length of the molecule.

[0018] By combining cetyltrimethylammonium bromide with polyethylene glycol, the alumina material prepared not only has a large specific surface area but also exhibits a large pore size and a regular pore structure. This allows for the smooth passage of larger molecules and groups, significantly reducing internal diffusion resistance during reactions, making it an ideal catalyst support. The mass ratio of cetyltrimethylammonium bromide to aluminum nitrate is (0.04-0.2):1; specific values ​​include 0.05:1, 0.07:1, 0.1:1, 0.12:1, 0.14:1, and 0.17:1. By controlling the cetyltrimethylammonium bromide dosage within an appropriate range, smaller crystals can be formed while preventing pore collapse during calcination after template removal.

[0019] The simultaneous addition of hexadecyltrimethylammonium bromide and polyethylene glycol, two cationic and nonionic surfactants, can fully utilize the advantages of both: the hexadecyltrimethylammonium bromide cationic surfactant easily combines with the aluminum source during the hydrolysis process, and the polyethylene glycol nonionic surfactant helps to form pores during the precipitation and drying processes, thereby preparing an alumina product with a high surface area and pore volume.

[0020] In a specific embodiment of the present invention, the concentration of aluminum nitrate in the aluminum nitrate mixed solution in step (1) is 10-30 g / L, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum nitrate is (0.04-0.2):1; the concentration of sodium metaaluminate in the sodium metaaluminate mixed solution in step (2) is 5-30 g / L, and the mass ratio of sodium metaaluminate to the aluminum nitrate in step (1) is (0.1-1):1.

[0021] Adding cetyltrimethylammonium bromide and polyethylene glycol to aluminum nitrate and sodium metaaluminate solutions, respectively, can better promote the dispersion of crystals and prevent agglomeration. Since the aluminum ions in both cetyltrimethylammonium bromide and aluminum nitrate solutions are positively charged, pre-adding cetyltrimethylammonium bromide to the aluminum nitrate solution can better promote the dispersion of micelles. Adding a nonionic surfactant (polyethylene glycol) to the sodium metaaluminate solution not only maximizes the polyethylene glycol's templating function but also fully utilizes its dispersing properties, promoting crystal dispersion. Adding cetyltrimethylammonium bromide to the sodium metaaluminate solution or polyethylene glycol to the aluminum nitrate solution not only renders the polyethylene glycol ineffective, but also pre-empts strong electrostatic interactions between the positively charged cetyltrimethylammonium bromide and the sodium metaaluminate, hindering crystal dispersion and reducing the specific surface area of ​​the alumina product.

[0022] In a specific embodiment of the present invention, the pH value in step (3) is 7.5-11; the heating reaction temperature is 80-90°C, the reaction time is 1-3 hours; the calcination temperature is 550-650°C, and the calcination time is 4-6 hours. The method for adjusting the pH is not particularly limited, and it can be adjusted by adding an acid or a base. Specifically, an acidic substance selected from hydrochloric acid, sulfuric acid, or nitric acid, or an alkaline substance selected from sodium hydroxide, potassium hydroxide, or ammonia water is used for adjustment.

[0023] In a specific embodiment of the present invention, the palladium salt in step (4) is palladium acetate. Compared with nickel catalysts, palladium catalysts have higher anthraquinone hydrogenation activity and are more widely used in anthraquinone hydrogenation.

[0024] In a specific embodiment of the present invention, the impregnation in step (4) adopts an equal volume impregnation process. The equal volume impregnation process can more accurately control the solution volume and conveniently adjust the palladium loading. Furthermore, multiple equal volume impregnation processes can be used.

[0025] In a specific embodiment of the present invention, step (4) prepares a palladium salt solution based on a palladium loading of 0.1-1 wt% on the catalyst support. Generally speaking, as the palladium loading increases, the number of active centers increases, and the hydrogenation efficiency increases accordingly. However, when the loading is too high, agglomeration tends to occur on the catalyst surface, resulting in decreased catalyst activity.

[0026] In a specific embodiment of the present invention, the drying temperature in step (5) is 100-130°C.

[0027] In a specific embodiment of the present invention, the calcination temperature in step (5) is 300-350°C, and the calcination time is 3-4 hours.

[0028] In a specific embodiment of the present invention, the reduction in step (5) is carried out using a 10 vol% hydrogen / argon mixture at 160-200°C for 2.5-3.5 hours. Proper control of the reduction temperature can further enhance catalyst activity and prevent excessive growth of palladium grains on the catalyst surface during high-temperature reduction, which reduces dispersion and results in decreased activity.

[0029] In another aspect, the present invention also provides a palladium catalyst for anthraquinone hydrogenation obtained by the above-described preparation method, using the prepared high-specific-surface-area alumina as a support. Compared to conventional alumina, the alumina prepared in the present invention exhibits a higher surface area and a more regular mesoporous structure. The active components in the catalyst exhibit a higher dispersion, which increases the number of catalytically active sites and significantly improves hydrogenation efficiency.

[0030] Beneficial effects:

[0031] Using hexadecyltrimethylammonium bromide as the main template and modifier and adding a small amount of polyethylene glycol, the technical problems of low specific surface area and small pore size of the alumina material prepared with hexadecyltrimethylammonium bromide were solved. The palladium catalyst for anthraquinone hydrogenation uses the prepared high specific surface area alumina as a carrier, greatly improving the catalytic efficiency.

[0032] The larger pore size of the alumina support in the present invention reduces diffusion resistance, facilitating the transport of reactants. Furthermore, the generated anthrahydroquinone diffuses more easily from the larger pores, preventing the anthrahydroquinone from remaining in the pores for an extended period and thus reducing catalytic activity. Furthermore, the high specific surface area of ​​the alumina support allows for better dispersion of the active components, thereby improving hydrogenation efficiency. DETAILED DESCRIPTION

[0033] The examples are provided to better illustrate the present invention, but are not intended to limit the present invention to the examples. Therefore, non-essential improvements and adjustments to the embodiments made by those skilled in the art based on the above-mentioned invention still fall within the scope of protection of the present invention.

[0034] Example 1

[0035] A method for preparing a palladium catalyst for anthraquinone hydrogenation comprises the following steps:

[0036] (1) adding aluminum nitrate and hexadecyltrimethylammonium bromide to deionized water and stirring uniformly to obtain an aluminum nitrate mixed solution; the aluminum nitrate concentration in the aluminum nitrate mixed solution is 19 g / L, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum nitrate is 0.07:1;

[0037] (2) adding sodium aluminate and polyethylene glycol to deionized water, and ultrasonically homogenizing to obtain a sodium aluminate mixed solution; the number average molecular weight of the polyethylene glycol is 2000; the mass ratio of the polyethylene glycol to the hexadecyltrimethylammonium bromide in step (1) is 0.12:1; the concentration of sodium aluminate in the sodium aluminate mixed solution is 12.5 g / L; the mass ratio of the sodium aluminate to the aluminum nitrate in step (1) is 0.62:1;

[0038] (3) First, the aluminum nitrate mixed solution was heated to 60°C, and the sodium aluminate mixed solution was added dropwise to the aluminum nitrate mixed solution while stirring at a dropping rate of 10 mL / min to obtain a final solution, and the pH value of the final solution was adjusted to 7.8; the reaction was heated for a certain time, and the catalyst carrier was obtained through filtering, washing, drying, and calcining processes; the heating reaction temperature was 80°C, the reaction time was 2.8 h; the calcination temperature was 560°C, and the calcination time was 6 h; the catalyst carrier was an alumina carrier;

[0039] (4) preparing a palladium salt solution according to a palladium loading of 0.2 wt% in the catalyst support, specifically dispersing palladium acetate in an acetone solvent to obtain a palladium salt solution, and then impregnating the catalyst support with the palladium salt solution using an equal volume impregnation process;

[0040] (5) The impregnated catalyst support was dried, calcined, and reduced to obtain a palladium catalyst for anthraquinone hydrogenation; the drying temperature was 100°C; the calcination temperature was 300°C, and the calcination time was 4 hours; and the reduction was carried out using a 10 vol% hydrogen / argon mixture at 160°C for 3.5 hours.

[0041] Example 2

[0042] A method for preparing a palladium catalyst for anthraquinone hydrogenation comprises the following steps:

[0043] (1) adding aluminum nitrate and hexadecyltrimethylammonium bromide to deionized water and stirring uniformly to obtain an aluminum nitrate mixed solution; the aluminum nitrate concentration in the aluminum nitrate mixed solution is 19 g / L, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum nitrate is 0.14:1;

[0044] (2) sodium aluminate and polyethylene glycol are added to deionized water, and ultrasonically homogenized to obtain a sodium aluminate mixed solution; the number average molecular weight of the polyethylene glycol is 800; the mass ratio of the polyethylene glycol to the hexadecyltrimethylammonium bromide in step (1) is 0.40:1; the concentration of sodium aluminate in the sodium aluminate mixed solution is 12.5 g / L; the mass ratio of the sodium aluminate to the aluminum nitrate in step (1) is 0.85:1;

[0045] (3) First, the aluminum nitrate mixed solution was heated to 60°C, and the sodium aluminate mixed solution was added dropwise to the aluminum nitrate mixed solution while stirring at a dropping rate of 10 mL / min to obtain a final solution, and the pH value of the final solution was adjusted to 10.2; the heating reaction was carried out for a certain time, and the catalyst carrier was obtained through filtering, washing, drying, and calcining processes; the heating reaction temperature was 90°C, the reaction time was 1.5 h; the calcination temperature was 640°C, and the calcination time was 4 h; the catalyst carrier was an alumina carrier;

[0046] (4) preparing a palladium salt solution according to a palladium loading of 0.2 wt% in the catalyst support, specifically dispersing palladium acetate in an acetone solvent to obtain a palladium salt solution, and then impregnating the catalyst support with the palladium salt solution using an equal volume impregnation process;

[0047] (5) The impregnated catalyst support was dried, calcined, and reduced to obtain a palladium catalyst for anthraquinone hydrogenation; the drying temperature was 130°C; the calcination temperature was 350°C, and the calcination time was 3 hours; and the reduction was performed using a 10 vol% hydrogen / argon mixture at 200°C for 2.5 hours.

[0048] Example 3

[0049] A method for preparing a palladium catalyst for anthraquinone hydrogenation comprises the following steps:

[0050] (1) adding aluminum nitrate and hexadecyltrimethylammonium bromide to deionized water and stirring uniformly to obtain an aluminum nitrate mixed solution; the aluminum nitrate concentration in the aluminum nitrate mixed solution is 19 g / L, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum nitrate is 0.04:1;

[0051] (2) sodium aluminate and polyethylene glycol are added to deionized water, and ultrasonically homogenized to obtain a sodium aluminate mixed solution; the number average molecular weight of the polyethylene glycol is 1400; the mass ratio of the polyethylene glycol to the hexadecyltrimethylammonium bromide in step (1) is 0.22:1; the concentration of sodium aluminate in the sodium aluminate mixed solution is 12.5 g / L; the mass ratio of the sodium aluminate to the aluminum nitrate in step (1) is 0.74:1;

[0052] (3) First, the aluminum nitrate mixed solution was heated to 60°C, and the sodium aluminate mixed solution was added dropwise to the aluminum nitrate mixed solution while stirring at a dropping rate of 10 mL / min to obtain a final solution, and the pH value of the final solution was adjusted to 9.5; the reaction was heated for a certain time, and the catalyst carrier was obtained through filtering, washing, drying, and calcining processes; the heating reaction temperature was 85°C, the reaction time was 2.2 h; the calcination temperature was 600°C, and the calcination time was 5 h; the catalyst carrier was an alumina carrier;

[0053] (4) preparing a palladium salt solution according to a palladium loading of 0.2 wt% in the catalyst support, specifically dispersing palladium acetate in an acetone solvent to obtain a palladium salt solution, and then impregnating the catalyst support with the palladium salt solution using an equal volume impregnation process;

[0054] (5) The impregnated catalyst carrier is dried, calcined, and reduced to obtain a palladium catalyst for anthraquinone hydrogenation; the drying temperature is 120°C; the calcination temperature is 330°C, and the calcination time is 3.5 hours; and the reduction is carried out using a 10 vol% hydrogen / argon mixture at 180°C for 3 hours.

[0055] Example 4

[0056] A method for preparing a palladium catalyst for anthraquinone hydrogenation comprises the following steps:

[0057] (1) adding aluminum nitrate and hexadecyltrimethylammonium bromide to deionized water and stirring uniformly to obtain an aluminum nitrate mixed solution; the aluminum nitrate concentration in the aluminum nitrate mixed solution is 19 g / L, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum nitrate is 0.08:1;

[0058] (2) adding sodium aluminate and polyethylene glycol to deionized water, and ultrasonically homogenizing to obtain a sodium aluminate mixed solution; the number average molecular weight of the polyethylene glycol is 1800; the mass ratio of the polyethylene glycol to the hexadecyltrimethylammonium bromide in step (1) is 0.15:1; the concentration of sodium aluminate in the sodium aluminate mixed solution is 12.5 g / L; the mass ratio of the sodium aluminate to the aluminum nitrate in step (1) is 0.82:1;

[0059] (3) First, the aluminum nitrate mixed solution was heated to 60°C, and the sodium aluminate mixed solution was added dropwise to the aluminum nitrate mixed solution while stirring at a dropping rate of 10 mL / min to obtain a final solution, and the pH value of the final solution was adjusted to 8.7; the reaction was heated for a certain time, and the catalyst carrier was obtained through filtering, washing, drying, and calcining processes; the heating reaction temperature was 82°C, the reaction time was 1.9 h; the calcination temperature was 610°C, and the calcination time was 4.6 h; the catalyst carrier was an alumina carrier;

[0060] (4) preparing a palladium salt solution according to a palladium loading of 0.2 wt% in the catalyst support, specifically dispersing palladium acetate in an acetone solvent to obtain a palladium salt solution, and then impregnating the catalyst support with the palladium salt solution using an equal volume impregnation process;

[0061] (5) The impregnated catalyst support was dried, calcined, and reduced to obtain a palladium catalyst for anthraquinone hydrogenation; the drying temperature was 100°C; the calcination temperature was 310°C, and the calcination time was 3.4 h; and the reduction was carried out using a 10 vol% hydrogen / argon mixture at 190°C for 2.9 h.

[0062] Example 5

[0063] A method for preparing a palladium catalyst for anthraquinone hydrogenation comprises the following steps:

[0064] (1) adding aluminum nitrate and hexadecyltrimethylammonium bromide to deionized water and stirring uniformly to obtain an aluminum nitrate mixed solution; the aluminum nitrate concentration in the aluminum nitrate mixed solution is 19 g / L, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum nitrate is 0.2:1;

[0065] (2) sodium aluminate and polyethylene glycol are added to deionized water, and ultrasonically homogenized to obtain a sodium aluminate mixed solution; the number average molecular weight of the polyethylene glycol is 1400; the mass ratio of the polyethylene glycol to the hexadecyltrimethylammonium bromide in step (1) is 0.22:1; the concentration of sodium aluminate in the sodium aluminate mixed solution is 12.5 g / L; the mass ratio of the sodium aluminate to the aluminum nitrate in step (1) is 0.74:1;

[0066] (3) First, the aluminum nitrate mixed solution was heated to 60°C, and the sodium aluminate mixed solution was added dropwise to the aluminum nitrate mixed solution while stirring at a dropping rate of 10 mL / min to obtain a final solution, and the pH value of the final solution was adjusted to 9.5; the reaction was heated for a certain time, and the catalyst carrier was obtained through filtering, washing, drying, and calcining processes; the heating reaction temperature was 85°C, the reaction time was 2.2 h; the calcination temperature was 600°C, and the calcination time was 5 h; the catalyst carrier was an alumina carrier;

[0067] (4) preparing a palladium salt solution according to a palladium loading of 0.2 wt% in the catalyst support, specifically dispersing palladium acetate in an acetone solvent to obtain a palladium salt solution, and then impregnating the catalyst support with the palladium salt solution using an equal volume impregnation process;

[0068] (5) The impregnated catalyst carrier is dried, calcined, and reduced to obtain a palladium catalyst for anthraquinone hydrogenation; the drying temperature is 120°C; the calcination temperature is 330°C, and the calcination time is 3.5 hours; and the reduction is carried out using a 10 vol% hydrogen / argon mixture at 180°C for 3 hours.

[0069] Example 6

[0070] A method for preparing a palladium catalyst for anthraquinone hydrogenation comprises the following steps:

[0071] (1) adding aluminum nitrate and hexadecyltrimethylammonium bromide to deionized water and stirring uniformly to obtain an aluminum nitrate mixed solution; the aluminum nitrate concentration in the aluminum nitrate mixed solution is 19 g / L, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum nitrate is 0.09:1;

[0072] (2) sodium aluminate and polyethylene glycol are added to deionized water, and ultrasonically homogenized to obtain a sodium aluminate mixed solution; the number average molecular weight of the polyethylene glycol is 1400; the mass ratio of the polyethylene glycol to the hexadecyltrimethylammonium bromide in step (1) is 0.21:1; the concentration of sodium aluminate in the sodium aluminate mixed solution is 12.5 g / L; the mass ratio of the sodium aluminate to the aluminum nitrate in step (1) is 0.68:1;

[0073] (3) First, the aluminum nitrate mixed solution was heated to 60°C, and the sodium aluminate mixed solution was added dropwise to the aluminum nitrate mixed solution while stirring at a dropping rate of 10 mL / min to obtain a final solution, and the pH value of the final solution was adjusted to 9.5; the reaction was heated for a certain time, and the catalyst carrier was obtained through filtering, washing, drying, and calcining processes; the heating reaction temperature was 83°C, the reaction time was 2.4 h; the calcination temperature was 590°C, and the calcination time was 5.6 h; the catalyst carrier was an alumina carrier;

[0074] (4) preparing a palladium salt solution according to a palladium loading of 0.2 wt% in the catalyst support, specifically dispersing palladium acetate in an acetone solvent to obtain a palladium salt solution, and then impregnating the catalyst support with the palladium salt solution using an equal volume impregnation process;

[0075] (5) The impregnated catalyst carrier was dried, calcined, and reduced to obtain a palladium catalyst for anthraquinone hydrogenation; the drying temperature was 110°C; the calcination temperature was 320°C, and the calcination time was 3.2 h; and the reduction was carried out using a 10 vol% hydrogen / argon mixture at 170°C for 3.2 h.

[0076] Example 7

[0077] A method for preparing a palladium catalyst for anthraquinone hydrogenation comprises the following steps:

[0078] (1) adding aluminum nitrate and hexadecyltrimethylammonium bromide to deionized water and stirring uniformly to obtain an aluminum nitrate mixed solution; the aluminum nitrate concentration in the aluminum nitrate mixed solution is 19 g / L, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum nitrate is 0.11:1;

[0079] (2) sodium aluminate and polyethylene glycol are added to deionized water, and ultrasonically homogenized to obtain a sodium aluminate mixed solution; the number average molecular weight of the polyethylene glycol is 200; the mass ratio of the polyethylene glycol to the hexadecyltrimethylammonium bromide in step (1) is 0.22:1; the concentration of sodium aluminate in the sodium aluminate mixed solution is 12.5 g / L; the mass ratio of the sodium aluminate to the aluminum nitrate in step (1) is 0.74:1;

[0080] (3) First, the aluminum nitrate mixed solution was heated to 60°C, and the sodium aluminate mixed solution was added dropwise to the aluminum nitrate mixed solution while stirring at a dropping rate of 10 mL / min to obtain a final solution, and the pH value of the final solution was adjusted to 9.5; the reaction was heated for a certain time, and the catalyst carrier was obtained through filtering, washing, drying, and calcining processes; the heating reaction temperature was 85°C, the reaction time was 2.2 h; the calcination temperature was 600°C, and the calcination time was 5 h; the catalyst carrier was an alumina carrier;

[0081] (4) preparing a palladium salt solution according to a palladium loading of 0.2 wt% in the catalyst support, specifically dispersing palladium acetate in an acetone solvent to obtain a palladium salt solution, and then impregnating the catalyst support with the palladium salt solution using an equal volume impregnation process;

[0082] (5) The impregnated catalyst carrier is dried, calcined, and reduced to obtain a palladium catalyst for anthraquinone hydrogenation; the drying temperature is 120°C; the calcination temperature is 330°C, and the calcination time is 3.5 hours; and the reduction is carried out using a 10 vol% hydrogen / argon mixture at 180°C for 3 hours.

[0083] Example 8

[0084] A method for preparing a palladium catalyst for anthraquinone hydrogenation comprises the following steps:

[0085] (1) adding aluminum nitrate and hexadecyltrimethylammonium bromide to deionized water and stirring uniformly to obtain an aluminum nitrate mixed solution; the aluminum nitrate concentration in the aluminum nitrate mixed solution is 19 g / L, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum nitrate is 0.12:1;

[0086] (2) adding sodium aluminate and polyethylene glycol to deionized water, and ultrasonically homogenizing to obtain a sodium aluminate mixed solution; the number average molecular weight of the polyethylene glycol is 1000; the mass ratio of the polyethylene glycol to the hexadecyltrimethylammonium bromide in step (1) is 0.36:1; the concentration of sodium aluminate in the sodium aluminate mixed solution is 12.5 g / L; the mass ratio of the sodium aluminate to the aluminum nitrate in step (1) is 0.82:1;

[0087] (3) First, the aluminum nitrate mixed solution was heated to 60°C, and the sodium aluminate mixed solution was added dropwise to the aluminum nitrate mixed solution while stirring at a dropping rate of 10 mL / min to obtain a final solution, and the pH value of the final solution was adjusted to 10.2; the reaction was heated for a certain time, and the catalyst carrier was obtained through filtering, washing, drying, and calcining processes; the heating reaction temperature was 88°C, the reaction time was 1.8 h; the calcination temperature was 630°C, and the calcination time was 4.5 h; the catalyst carrier was an alumina carrier;

[0088] (4) preparing a palladium salt solution according to a palladium loading of 0.2 wt% in the catalyst support, specifically dispersing palladium acetate in an acetone solvent to obtain a palladium salt solution, and then impregnating the catalyst support with the palladium salt solution using an equal volume impregnation process;

[0089] (5) The impregnated catalyst carrier was dried, calcined, and reduced to obtain a palladium catalyst for anthraquinone hydrogenation; the drying temperature was 120°C; the calcination temperature was 340°C, and the calcination time was 3.2 h; and the reduction was carried out using a 10 vol% hydrogen / argon mixture at 185°C for 2.8 h.

[0090] Example 9

[0091] A method for preparing a palladium catalyst for anthraquinone hydrogenation comprises the following steps:

[0092] (1) adding aluminum nitrate and hexadecyltrimethylammonium bromide to deionized water and stirring uniformly to obtain an aluminum nitrate mixed solution; the aluminum nitrate concentration in the aluminum nitrate mixed solution is 19 g / L, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum nitrate is 0.11:1;

[0093] (2) sodium aluminate and polyethylene glycol are added to deionized water, and ultrasonically homogenized to obtain a sodium aluminate mixed solution; the number average molecular weight of the polyethylene glycol is 2000; the mass ratio of the polyethylene glycol to the hexadecyltrimethylammonium bromide in step (1) is 0.22:1; the concentration of sodium aluminate in the sodium aluminate mixed solution is 12.5 g / L; the mass ratio of the sodium aluminate to the aluminum nitrate in step (1) is 0.74:1;

[0094] (3) First, the aluminum nitrate mixed solution was heated to 60°C, and the sodium aluminate mixed solution was added dropwise to the aluminum nitrate mixed solution while stirring at a dropping rate of 10 mL / min to obtain a final solution, and the pH value of the final solution was adjusted to 9.5; the reaction was heated for a certain time, and the catalyst carrier was obtained through filtering, washing, drying, and calcining processes; the heating reaction temperature was 85°C, the reaction time was 2.2 h; the calcination temperature was 600°C, and the calcination time was 5 h; the catalyst carrier was an alumina carrier;

[0095] (4) preparing a palladium salt solution according to a palladium loading of 0.2 wt% in the catalyst support, specifically dispersing palladium acetate in an acetone solvent to obtain a palladium salt solution, and then impregnating the catalyst support with the palladium salt solution using an equal volume impregnation process;

[0096] (5) The impregnated catalyst carrier is dried, calcined, and reduced to obtain a palladium catalyst for anthraquinone hydrogenation; the drying temperature is 120°C; the calcination temperature is 330°C, and the calcination time is 3.5 hours; and the reduction is carried out using a 10 vol% hydrogen / argon mixture at 180°C for 3 hours.

[0097] Example 10

[0098] A method for preparing a palladium catalyst for anthraquinone hydrogenation comprises the following steps:

[0099] (1) adding aluminum nitrate and hexadecyltrimethylammonium bromide to deionized water and stirring uniformly to obtain an aluminum nitrate mixed solution; the aluminum nitrate concentration in the aluminum nitrate mixed solution is 19 g / L, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum nitrate is 0.13:1;

[0100] (2) sodium aluminate and polyethylene glycol are added to deionized water, and ultrasonically homogenized to obtain a sodium aluminate mixed solution; the number average molecular weight of the polyethylene glycol is 800; the mass ratio of the polyethylene glycol to the hexadecyltrimethylammonium bromide in step (1) is 0.33:1; the concentration of sodium aluminate in the sodium aluminate mixed solution is 12.5 g / L; the mass ratio of the sodium aluminate to the aluminum nitrate in step (1) is 0.81:1;

[0101] (3) First, the aluminum nitrate mixed solution was heated to 60°C, and the sodium aluminate mixed solution was added dropwise to the aluminum nitrate mixed solution while stirring at a dropping rate of 10 mL / min to obtain a final solution, and the pH value of the final solution was adjusted to 8.7; the reaction was heated for a certain time, and the catalyst carrier was obtained through filtering, washing, drying, and calcining processes; the heating reaction temperature was 86°C, the reaction time was 2.1 hours, the calcination temperature was 605°C, and the calcination time was 4.9 hours; the catalyst carrier was an alumina carrier;

[0102] (4) preparing a palladium salt solution according to a palladium loading of 0.2 wt% in the catalyst support, specifically dispersing palladium acetate in an acetone solvent to obtain a palladium salt solution, and then impregnating the catalyst support with the palladium salt solution using an equal volume impregnation process;

[0103] (5) The impregnated catalyst carrier was dried, calcined, and reduced to obtain a palladium catalyst for anthraquinone hydrogenation; the drying temperature was 120°C; the calcination temperature was 345°C, and the calcination time was 3.7 hours; and the reduction was carried out using a 10 vol% hydrogen / argon mixture at 165°C for 3.2 hours.

[0104] Example 11

[0105] A method for preparing a palladium catalyst for anthraquinone hydrogenation comprises the following steps:

[0106] (1) adding aluminum nitrate and hexadecyltrimethylammonium bromide to deionized water and stirring uniformly to obtain an aluminum nitrate mixed solution; the aluminum nitrate concentration in the aluminum nitrate mixed solution is 19 g / L, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum nitrate is 0.11:1;

[0107] (2) sodium aluminate and polyethylene glycol are added to deionized water, and ultrasonically homogenized to obtain a sodium aluminate mixed solution; the number average molecular weight of the polyethylene glycol is 1400; the mass ratio of the polyethylene glycol to the hexadecyltrimethylammonium bromide in step (1) is 0.22:1; the concentration of sodium aluminate in the sodium aluminate mixed solution is 12.5 g / L; the mass ratio of the sodium aluminate to the aluminum nitrate in step (1) is 0.74:1;

[0108] (3) First, the aluminum nitrate mixed solution was heated to 60°C, and the sodium aluminate mixed solution was added dropwise to the aluminum nitrate mixed solution while stirring at a dropping rate of 10 mL / min to obtain a final solution, and the pH value of the final solution was adjusted to 9.5; the reaction was heated for a certain time, and the catalyst carrier was obtained through filtering, washing, drying, and calcining processes; the heating reaction temperature was 85°C, the reaction time was 2.2 h; the calcination temperature was 600°C, and the calcination time was 5 h; the catalyst carrier was an alumina carrier;

[0109] (4) preparing a palladium salt solution according to a palladium loading of 0.2 wt% in the catalyst support, specifically dispersing palladium acetate in an acetone solvent to obtain a palladium salt solution, and then impregnating the catalyst support with the palladium salt solution using an equal volume impregnation process;

[0110] (5) The impregnated catalyst carrier is dried, calcined, and reduced to obtain a palladium catalyst for anthraquinone hydrogenation; the drying temperature is 120°C; the calcination temperature is 330°C, and the calcination time is 3.5 hours; and the reduction is carried out using a 10 vol% hydrogen / argon mixture at 180°C for 3 hours.

[0111] Comparative Example 1

[0112] A method for preparing a palladium catalyst for anthraquinone hydrogenation comprises the following steps:

[0113] (1) adding aluminum nitrate and polyethylene glycol to deionized water and stirring uniformly to obtain an aluminum nitrate mixed solution; the aluminum nitrate concentration in the aluminum nitrate mixed solution is 19 g / L, and the number average molecular weight of the polyethylene glycol is 1400;

[0114] (2) adding sodium aluminate and hexadecyltrimethylammonium bromide to deionized water, and ultrasonically homogenizing to obtain a sodium aluminate mixed solution; the mass ratio of hexadecyltrimethylammonium bromide to the aluminum nitrate in step (1) is 0.11:1; the concentration of sodium aluminate in the sodium aluminate mixed solution is 12.5 g / L; the mass ratio of sodium aluminate to the aluminum nitrate in step (1) is 0.74:1;

[0115] The mass ratio of polyethylene glycol in step (1) to hexadecyltrimethylammonium bromide in step (2) is 0.22:1;

[0116] (3) First, the aluminum nitrate mixed solution was heated to 60°C, and the sodium aluminate mixed solution was added dropwise to the aluminum nitrate mixed solution while stirring at a dropping rate of 10 mL / min to obtain a final solution, and the pH value of the final solution was adjusted to 9.5; the reaction was heated for a certain time, and the catalyst carrier was obtained through filtering, washing, drying, and calcining processes; the heating reaction temperature was 85°C, the reaction time was 2.2 h; the calcination temperature was 600°C, and the calcination time was 5 h; the catalyst carrier was an alumina carrier;

[0117] (4) preparing a palladium salt solution according to a palladium loading of 0.2 wt% in the catalyst support, specifically dispersing palladium acetate in an acetone solvent to obtain a palladium salt solution, and then impregnating the catalyst support with the palladium salt solution using an equal volume impregnation process;

[0118] (5) The impregnated catalyst carrier is dried, calcined, and reduced to obtain a palladium catalyst for anthraquinone hydrogenation; the drying temperature is 120°C; the calcination temperature is 330°C, and the calcination time is 3.5 hours; and the reduction is carried out using a 10 vol% hydrogen / argon mixture at 180°C for 3 hours.

[0119] Comparative Example 2

[0120] A method for preparing a palladium catalyst for anthraquinone hydrogenation comprises the following steps:

[0121] (1) adding aluminum nitrate and hexadecyltrimethylammonium bromide to deionized water and stirring uniformly to obtain an aluminum nitrate mixed solution; the aluminum nitrate concentration in the aluminum nitrate mixed solution is 19 g / L, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum nitrate is 0.11:1;

[0122] (2) adding sodium aluminate and polyethylene glycol to deionized water, and ultrasonically homogenizing to obtain a sodium aluminate mixed solution; the number average molecular weight of the polyethylene glycol is 1400; the mass ratio of the polyethylene glycol to the hexadecyltrimethylammonium bromide in step (1) is 1:1; the concentration of sodium aluminate in the sodium aluminate mixed solution is 12.5 g / L; the mass ratio of the sodium aluminate to the aluminum nitrate in step (1) is 0.74:1;

[0123] (3) First, the aluminum nitrate mixed solution was heated to 60°C, and the sodium aluminate mixed solution was added dropwise to the aluminum nitrate mixed solution while stirring at a dropping rate of 10 mL / min to obtain a final solution, and the pH value of the final solution was adjusted to 9.5; the reaction was heated for a certain time, and the catalyst carrier was obtained through filtering, washing, drying, and calcining processes; the heating reaction temperature was 85°C, the reaction time was 2.2 h; the calcination temperature was 600°C, and the calcination time was 5 h; the catalyst carrier was an alumina carrier;

[0124] (4) preparing a palladium salt solution according to a palladium loading of 0.2 wt% in the catalyst support, specifically dispersing palladium acetate in an acetone solvent to obtain a palladium salt solution, and then impregnating the catalyst support with the palladium salt solution using an equal volume impregnation process;

[0125] (5) The impregnated catalyst carrier is dried, calcined, and reduced to obtain a palladium catalyst for anthraquinone hydrogenation; the drying temperature is 120°C; the calcination temperature is 330°C, and the calcination time is 3.5 hours; and the reduction is carried out using a 10 vol% hydrogen / argon mixture at 180°C for 3 hours.

[0126] Catalyst support performance: The specific surface area (m2) of the catalyst supports prepared in Examples 1 to 11 and Comparative Examples 1 and 2 was measured by BET gas adsorption method. 2 / g), pore size (nm), as shown in Table 1-Table 2.

[0127] Performance of palladium catalyst for anthraquinone hydrogenation: 2-Ethylanthraquinone was dissolved in a mixed solvent of 1,2,4-trimethylbenzene and trioctyl phosphate (volume ratio: 1:1) to prepare a working solution with a concentration of 120 g / L. 60 mL of the working solution and 1 g of palladium catalyst were added to a reactor. High-purity hydrogen was used as the feedstock, and the reaction temperature was set at 60°C, the pressure at 0.3 MPa, and the reaction time was 90 minutes. The working solution was then oxidized with oxygen, and the hydrogen peroxide content in the solution was determined by titration with potassium permanganate solution. The hydrogenation efficiency (g / L) was calculated, as shown in Tables 1 and 2.

[0128] Table 1 Catalyst supports prepared in Examples 1 to 7 and performance of palladium catalysts for anthraquinone hydrogenation

[0129]

[0130] Table 2 Performance of catalyst supports and palladium catalysts for anthraquinone hydrogenation prepared in Examples 8-11 and Comparative Examples 1-2

[0131]

[0132] As can be seen from Tables 1 and 2, the present invention uses hexadecyltrimethylammonium bromide as the primary template and modifier, and by adding a small amount of polyethylene glycol, solves the technical problems of low specific surface area and small pore size of the alumina material prepared with hexadecyltrimethylammonium bromide. The palladium catalyst for anthraquinone hydrogenation uses the prepared high specific surface area alumina as a carrier, greatly improving the catalytic efficiency. The catalyst carrier has a larger pore size, which, on the one hand, can reduce diffusion resistance and facilitate the transmission of the reactants; on the other hand, the anthrahydroquinone generated by the reaction can more easily diffuse out from the larger pores, thereby avoiding the anthrahydroquinone staying in the pores for too long and reducing the catalytic activity. At the same time, the catalyst carrier has a larger specific surface area, which can better disperse the active components, thereby significantly improving the hydrogenation efficiency.

[0133] Compared with Example 11, Comparative Example 1 adds cetyltrimethylammonium bromide to sodium metaaluminate solution, and polyethylene glycol is added to aluminum nitrate solution, not only polyethylene glycol cannot play a role, and easily causes positively charged cetyltrimethylammonium bromide and sodium metaaluminate to have strong electrostatic interaction, is unfavorable for the dispersion of crystal grains, affects the improvement of alumina product specific surface area, is unfavorable for the dispersion of palladium active components. Comparative Example 2 shows that because polyethylene glycol belongs to polymeric surfactant, its own consumption can strongly affect cetyltrimethylammonium bromide effect. Although polyethylene glycol has a template effect, in the reaction system of the present invention, the main effect of polyethylene glycol is to contribute to the formation of pores during precipitation and drying, thereby preparing an alumina product with high surface area and large pore size; When the amount of polyethylene glycol is too much, it will affect the formation of micelles, thereby causing the alumina carrier to show lower surface area and poor mesoporous structure, and the active component dispersion in the catalyst is low, thereby causing the hydrogenation efficiency to decrease.

[0134] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

Claims

1. A method for preparing a palladium catalyst for anthraquinone hydrogenation, characterized in that: The following steps are involved: (1) adding aluminum nitrate and hexadecyltrimethylammonium bromide to deionized water and stirring uniformly to obtain an aluminum nitrate mixed solution; (2) adding sodium aluminate and polyethylene glycol to deionized water, and ultrasonically homogenizing to obtain a sodium aluminate mixed solution; the number average molecular weight of the polyethylene glycol is 200-2000; The mass ratio of polyethylene glycol to hexadecyltrimethylammonium bromide in step (1) is (0.1-0.4):1; (3) adding the sodium metaaluminate mixed solution dropwise to the aluminum nitrate mixed solution while stirring to obtain a final solution, and adjusting the pH of the final solution to be alkaline; Heat the reaction for a certain period of time, and then filter, wash, dry, and calcine to obtain a catalyst carrier; (4) dispersing the palladium salt in an acetone solvent to obtain a palladium salt solution, and then impregnating the catalyst support with the palladium salt solution; (5) drying, calcining, and reducing the impregnated catalyst support to obtain a palladium catalyst for anthraquinone hydrogenation; The aluminum nitrate concentration of the aluminum nitrate mixed solution in step (1) is 10-30 g / L, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum nitrate is (0.04-0.2):1; the sodium metaaluminate concentration of the sodium metaaluminate mixed solution in step (2) is 5-30 g / L; and the mass ratio of sodium metaaluminate to the aluminum nitrate in step (1) is (0.1-1):

1.

2. The method for preparing a palladium catalyst for anthraquinone hydrogenation according to claim 1, wherein: In the step (3), the pH value is 7.5-11; the heating reaction temperature is 80-90°C, and the reaction time is 1-3 hours; the calcination temperature is 550-650°C, and the calcination time is 4-6 hours.

3. The method for preparing a palladium catalyst for anthraquinone hydrogenation according to claim 1, wherein The palladium salt in step (4) is palladium acetate.

4. The method for preparing a palladium catalyst for anthraquinone hydrogenation according to claim 1, wherein The impregnation in step (4) adopts an equal volume impregnation process.

5. The method for preparing a palladium catalyst for anthraquinone hydrogenation according to claim 1, wherein: In the step (4), a palladium salt solution is prepared according to the palladium loading amount in the catalyst carrier being 0.1-1 wt%.

6. The method for preparing a palladium catalyst for anthraquinone hydrogenation according to claim 1, wherein: The drying temperature in step (5) is 100-130°C.

7. The method for preparing a palladium catalyst for anthraquinone hydrogenation according to claim 1, wherein: In the step (5), the calcination temperature is 300-350° C. and the calcination time is 3-4 hours.

8. The method for preparing a palladium catalyst for anthraquinone hydrogenation according to claim 1, wherein: The reduction in step (5) is performed by using a 10 vol% hydrogen / argon mixture at 160-200° C. for 2.5-3.5 hours.

9. A palladium catalyst for anthraquinone hydrogenation, characterized in that The catalyst is prepared by the method for preparing a palladium catalyst for anthraquinone hydrogenation according to any one of claims 1 to 8.

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