Pd-based catalyst as well as preparation method and application thereof

Abstract

The invention relates to a Pd-based catalyst and a preparation method and application thereof, the catalyst comprises a carrier and oxides of active metal Pd and non-noble metal M loaded on the carrier, and the non-noble metal M is selected from one or more of non-noble metal elements in IIB-VIIB groups, IIIA group and VIII group. The oxide of the non-noble metal M serving as the active metal additive in the catalyst provided by the invention has an atomic cluster structure, so that the appearance of a PdM alloy is avoided, and the hydrogen peroxide yield and the effective anthraquinone selectivity can be effectively improved.

Description

Technical Field

[0001] The present disclosure relates to the field of fine chemicals, and in particular, to a Pd-based catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Among many hydrogen peroxide production processes, the anthraquinone process has become the most widely used hydrogen peroxide production process in industry at present due to its low production cost, high production efficiency and other characteristics. In the anthraquinone process, the selective hydrogenation of anthraquinone is the key to determine the hydrogen peroxide production efficiency of this process. In the process of preparing hydrogen peroxide by the anthraquinone method, the reaction working fluid is recycled. That is, the working fluid containing anthraquinone is hydrogenated after passing through the catalyst to generate a working fluid containing hydroanthraquinone, and the hydrogenated working fluid undergoes an oxidation process, in which the hydroanthraquinone generated by hydrogenation will regenerate anthraquinone. However, in the catalytic hydrogenation step of the above process, in addition to generating effective anthraquinones such as hydroanthraquinone that can produce hydrogen peroxide, over-hydrogenation of substances such as anthraquinone or hydroanthraquinone will also occur, generating by-products that cannot produce hydrogen peroxide. For the currently most widely used Pd / Al2O3 catalyst in industry, although it has certain advantages in activity and selectivity compared with other catalysts. However, due to its metal properties, by-products of C═C bond hydrogenation are inevitably generated during the hydrogenation process, resulting in degradation products during the recycling of the working fluid, thus significantly reducing the hydrogen peroxide yield. At the same time, due to the high price of Pd and the trend of increasing year by year, it has become increasingly important to improve the catalyst activity and reduce the active metal loading.

[0003] To address the above problems, researchers have improved catalytic performance by increasing the number of surface active sites, regulating the electronic structure of active metals, and enhancing the mass transfer effect of the reaction system through methods such as changing the surface acidity and basicity of the catalyst and regulating the pore structure of the support. Hong Runrun et al. studied the effects of the pore size and pore depth of the support on the dispersion of the active metal Pd and the performance of the anthraquinone hydrogenation reaction in "Controllable preparation and catalytic performance of Pd / anodic alumina oxide@Al catalyst for hydrogenation of ethylanthraquinone, 2015, 135, 274". The study shows that the larger the pore size and the deeper the pore depth of the support are, the more conducive it is to the diffusion of reactant and product molecules in the reaction system, thereby improving the reaction performance. However, a larger pore size and a deeper depth of the support will lead to a decrease in the specific surface area of the material, which is not conducive to the dispersion of the active components and will reduce the catalytic performance. The effect of surface acidic sites on catalytic performance was reported in "Pd / MgAl-LDH nanocatalyst with vacancy-rich sandwich structure: Insight into interfacial effect for selective hydrogenation, 2019, 370, 107". The study shows that while the interfacial acidity of the catalyst adjusts the electronic structure of the active components, it can also change the adsorption mode of anthraquinone molecules at the active sites, thereby promoting the adsorption activation of the C=O bond on the catalyst surface and the desorption of the products.

[0004] For supported catalysts, in addition to the regulation of the support structure, the regulation of the properties of the active metal itself is also particularly important. Li Dianqing et al. added the noble metal Ir as the second component to the catalyst in the article "Fabrication of Supported Pd–Ir / Al2O3 Bimetallic Catalysts for 2-Ethylanthraquinone Hydrogenation, AIChE J. 2017, 63.3955". By using the segmentation effect of the Ir component on the continuous sites of the Pd active metal and the charge transfer effect of Ir on Pd, a PdIr alloy catalyst with improved activity and a significant increase in the effective anthraquinone selectivity was successfully prepared. In addition to Ir, there are also many reports on preparing highly efficient anthraquinone selective hydrogenation catalysts with noble metals such as Pt, Au, and Ag as the second metal. However, considering the economic disadvantages of noble metals, catalysts with noble metals as the second component do not have the potential for industrial application. However, in current reports, non-noble metals are mostly introduced into the catalyst in the form of alloys with the Pd component, but the optimal performance of the catalyst cannot be achieved. Summary of the Invention

[0005] The purpose of the present disclosure is to provide a Pd-based catalyst, a preparation method and application thereof, in which the oxide of a non-precious metal M serving as an active metal additive has an atomic cluster structure, avoiding the formation of a PdM alloy, and can effectively improve the hydrogen peroxide yield and effective anthraquinone selectivity.

[0006] In order to achieve the above-mentioned objectives, the first aspect of the present disclosure provides a Pd-based catalyst, which includes a carrier and an oxide of active metal Pd and a non-precious metal M supported on the carrier, wherein the non-precious metal M is selected from one or more non-precious metal elements in Groups IIB to VIIB, Group IIIA and Group VIII.

[0007] Optionally, based on the total weight of the Pd-based catalyst, the content of the active metal Pd is 0.05-5% by weight, the content of the oxide of the non-noble metal M is 0.005-5% by weight, and the content of the carrier is 90-99.945% by weight;

[0008] Preferably, the content of the active metal Pd is 0.25-1 wt %, the content of the oxide of the non-noble metal M is 0.025-0.5 wt %, and the content of the carrier is 98.5-99.725 wt %.

[0009] Optionally, the non-noble metal M is selected from one or more of Ga, Ti, Mn, Cr, In, Co, Ni and Zn;

[0010] The carrier is selected from one or more of transition metal oxides and inert oxides; preferably, the carrier is selected from one or more of MgO, Al2O3, TiO2, SiO2, ZnO2, ZrO2, CeO2 and Co2O;

[0011] Preferably, the non-noble metal oxide exists in the form of atomic clusters; preferably, no PdM alloy exists in the Pd-based catalyst;

[0012] Further preferably, the average particle size of the active metal in the Pd-based catalyst is 0.1 to 4.5 nm, preferably 0.1 to 1.5 nm;

[0013] Optionally, the BET specific surface area of the Pd-based catalyst is 100 to 300 m 2 / g, preferably 150 to 220 m 2 / g.

[0014] A second aspect of the present disclosure provides a method for preparing a Pd-based catalyst, comprising the following steps:

[0015] S1. Contact the carrier, palladium source, non-noble metal M source and water, and perform an adsorption treatment to obtain a loaded product; wherein the non-noble metal M is selected from one or more of the non-noble metal elements in Group IIB to VIIB, Group IIIA and Group VIII;

[0016] S2. Perform a first aging treatment, a first drying treatment and a first calcination treatment on the loaded product to obtain a catalyst precursor; the conditions of the first calcination treatment include: the calcination temperature is 350 - 650 °C, the calcination time is 0.5 - 8 h, and the calcination atmosphere is selected from one of air, nitrogen and oxygen;

[0017] S3. Perform a reduction treatment on the catalyst precursor; the conditions of the reduction treatment include: the reduction temperature is 50 - 250 °C, the reduction time is 0.5 - 8 h, and the reduction atmosphere is selected from hydrogen or a mixed gas containing hydrogen and nitrogen.

[0018] Optionally, in step S1, the carrier is selected from one or more of transition metal oxides and inert oxides; preferably, the carrier is selected from one or more of MgO, Al2O3, TiO2, SiO2, ZnO2, ZrO2, CeO2 and Co2O3;

[0019] The palladium source is selected from one or more of Pd(NH3)2Cl2, Pd(NO3)2, Na2PdCl4 and C 10 H 14 O4Pd;

[0020] The non-noble metal M source is selected from one or more of the nitrates, sulfates and chlorides of the non-noble metal M; preferably, the non-noble metal M is selected from one or more of Ga, Ti, Mn, Cr, In, Co, Ni and Zn; more preferably, the non-noble metal M source is selected from one or more of gallium nitrate, titanium tetrachloride, manganese chloride, chromium chloride, indium nitrate, cobalt chloride, nickel nitrate and zinc sulfate.

[0021] Optionally, in step S1, based on the total weight of the prepared Pd-based catalyst, the addition amount of the palladium source is such that the loading amount of Pd metal is 0.05 - 5 wt%, preferably 0.25 - 1 wt%; the addition amount of the non-noble metal M source is such that the loading amount of the non-noble metal M is 0.005 - 5 wt%, preferably 0.025 - 0.5 wt%;

[0022] Preferably, the molar ratio of the Pd atoms of the palladium source to the M atoms of the non-noble metal M source is 1:0.01 - 1, preferably 1:0.1 - 0.5;

[0023] Optionally, the palladium source is used in the form of a solution, and the concentration of the palladium source solution is 0.1 - 5 M; the non-noble metal M source is used in the form of a solution, and the concentration of the non-noble metal M source solution is 0.01 - 5 M.

[0024] Optionally, step S1 includes the following steps a1 - a3:

[0025] a1. Contact the carrier with water for soaking treatment to obtain the soaked carrier;

[0026] a2. Add the palladium source solution to the soaked carrier, perform the first adsorption treatment and the first solid-liquid separation treatment; the obtained solid product is subjected to the second aging treatment, the second drying treatment and the second calcination treatment to obtain the palladium source-loaded product;

[0027] a3. Contact the non-noble metal M source solution with the palladium source-loaded product, perform the second adsorption treatment and the second solid-liquid separation treatment to obtain the loaded product;

[0028] Alternatively, step S1 includes the following steps b1 - b2:

[0029] b1. Contact the carrier with water for soaking treatment to obtain the soaked carrier;

[0030] b2. Add the palladium source solution and the non-noble metal M source solution to the soaked carrier, perform the third adsorption treatment and the third solid-liquid separation treatment to obtain the loaded product.

[0031] Optionally, in step a1 or step b1, relative to 1 g of the carrier, the amount of water used is 1.2 - 10 mL, preferably 1.5 - 5 mL, and the conditions of the soaking treatment include: the soaking temperature is 20 - 95 °C, and the soaking time is 10 - 360 min; preferably, the soaking temperature is 25 - 80 °C, and the soaking time is 30 - 120 min; optionally, step a1 or step b1 includes: performing solid-liquid separation on the suspension obtained by soaking the carrier with water, and contacting the obtained solid with water to continue the soaking treatment, repeating multiple times, preferably repeating 3 - 10 times;

[0032] The conditions of the first adsorption treatment in step a2, the second adsorption treatment in step a3, and the third adsorption treatment in step b2 each independently include: the adsorption temperature is 20 - 95 °C, the adsorption time is 30 - 360 min, and the rotation rate is 10 - 1000 r / min; preferably, the adsorption temperature is 25 - 80 °C, the adsorption time is 30 - 240 min, and the rotation rate is 50 - 200 r / min;

[0033] Optionally, in step a2, the conditions for the second aging treatment include: an aging temperature of 20 to 90 °C and an aging time of 2 to 48 h; preferably, an aging temperature of 20 to 35 °C and an aging time of 2 to 6 h;

[0034] The conditions for the second drying treatment include: a drying temperature of 90 to 180 °C and a drying time of 6 to 48 h; preferably, a drying temperature of 100 to 120 °C and a drying time of 10 to 18 h;

[0035] The conditions for the second calcination treatment include: a calcination temperature of 350 to 650 °C, a calcination time of 0.5 to 8 h, and the calcination atmosphere is selected from one of air, nitrogen, and oxygen; preferably, a calcination temperature of 350 to 500 °C and a calcination time of 3 to 5 h.

[0036] Optionally, in step S2, the conditions for the first aging treatment include: an aging temperature of 20 to 90 °C and an aging time of 2 to 48 h; preferably, an aging temperature of 20 to 35 °C and an aging time of 2 to 6 h;

[0037] The conditions for the first calcination include: a calcination temperature of 350 to 450 °C and a calcination time of 0.5 to 4 h; preferably, the purity of the nitrogen is above 99.9 vol%, and the purity of the oxygen is above 99.9 vol%;

[0038] The conditions for the first drying treatment include: a drying temperature of 9 to 180 °C and a drying time of 12 to 48 h; preferably, a drying temperature of 100 to 120 °C and a drying time of 10 to 18 h.

[0039] Optionally, in step S3, the conditions for the reduction treatment include: a reduction temperature of 100 to 150 °C and a reduction time of 2 to 6 h;

[0040] Preferably, when using a mixed gas containing hydrogen and nitrogen as the reduction atmosphere, the volume ratio of hydrogen to nitrogen is 1:1 to 10, preferably 1:3 to 5.

[0041] The third aspect of the present disclosure provides a Pd-based catalyst prepared by the method according to the second aspect of the present disclosure.

[0042] The fourth aspect of the present disclosure provides the application of the Pd-based catalyst according to the first aspect or the third aspect of the present disclosure in the reaction of selective hydrogenation of anthraquinone to prepare hydrogen peroxide.

[0043] Through the above technical solutions, the present disclosure provides a Pd-based catalyst, a preparation method thereof, and an application thereof. The catalyst is a Pd-based catalyst modified by non-precious metal oxide MOx clusters, and does not have a PdM alloy structure. The active metal of the catalyst modified by non-precious metal oxide MOx clusters as an additive has the characteristics of better dispersion degree, better geometric structure and electronic structure, and stronger anti-migration and sintering ability. The catalyst can have excellent catalytic performance in the field of selective hydrogenation represented by the selective hydrogenation of anthraquinone to prepare hydrogen peroxide, effectively improving the hydrogen peroxide yield and the effective anthraquinone selectivity in the reaction of preparing hydrogen peroxide by anthraquinone hydrogenation; and using non-precious metal M to replace the active component in Pd in the catalyst can also reduce the catalyst preparation cost.

[0044] Other features and advantages of the present disclosure will be described in detail in the subsequent specific implementation section. Brief Description of the Drawings

[0045] The drawings are used to provide a further understanding of the present disclosure, and constitute a part of the specification. Together with the following specific implementation, they are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings:

[0046] Figure 1 It is the HRTEM photograph of the catalyst prepared in Example 2 of the present disclosure.

[0047] Figure 2 It is the Pd 3d XPS spectrum of the catalyst prepared in Example 3 of the present disclosure.

[0048] Figure 3 It is the XRD spectrum of the catalysts prepared in Example 4 and Example 5 of the present disclosure. Specific Embodiments

[0049] The following details the specific embodiments of the present disclosure. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0050] The first aspect of the present disclosure provides a Pd-based catalyst, which includes a carrier and active metal Pd and an oxide of non-precious metal M supported on the carrier, and the non-precious metal M is selected from one or more of non-precious metal elements in Group IIB to VIIB, Group IIIA, and Group VIII.

[0051] The present disclosure provides a Pd-based catalyst, which is a Pd-based catalyst modified by non-noble metal oxide MOx clusters and does not have a PdM alloy structure. The active metal of the catalyst modified by non-noble metal oxide MOx clusters has the characteristics of better dispersion degree, better geometric and electronic structures, and stronger anti-migration and sintering abilities. This catalyst can exhibit excellent catalytic performance in the field of selective hydrogenation represented by the selective hydrogenation of anthraquinone to prepare hydrogen peroxide, effectively improving the hydrogen peroxide yield and the effective anthraquinone selectivity in the reaction of preparing hydrogen peroxide by anthraquinone hydrogenation; and using non-noble metal M to replace the active component in Pd in the catalyst can also reduce the catalyst preparation cost.

[0052] In one embodiment, based on the total weight of the Pd-based catalyst, the content of the active metal Pd is 0.05 to 5% by weight, the content of the non-noble metal M is 0.005 to 5% by weight, and the content of the carrier is 90 to 99.945% by weight.

[0053] In a preferred embodiment, the content of the active metal Pd is 0.25 to 1% by weight, the content of the oxide of the non-noble metal M is 0.025 to 0.5% by weight, and the content of the carrier is 98.5 to 99.725% by weight. The catalyst provided in this embodiment with optimized component contents has more excellent catalytic performance.

[0054] In one embodiment, the non-noble metal M is selected from one or more of Ga, Ti, Mn, Cr, In, Co, Ni, and Zn;

[0055] The carrier is selected from one or more of transition metal oxides and inert oxides; preferably, the carrier is selected from one or more of MgO, Al2O3, TiO2, SiO2, ZnO2, ZrO2, CeO2, and Co2O3.

[0056] In a preferred embodiment, the oxide of the non-noble metal exists in the form of atomic clusters; preferably, there is no PdM alloy in the Pd-based catalyst.

[0057] In a specific embodiment, the average particle size of the active metal in the Pd-based catalyst is 0.1 to 4.5 nm, preferably 0.1 to 1.5 nm; optionally, the BET specific surface area of the Pd-based catalyst is 100 to 300 m 2 / g, preferably 150 to 220 m 2 / g; the total pore volume is 0.4 to 0.7 cm 3 / g, preferably 0.45 to 0.60 cm 3 / g. The catalyst provided by the present disclosure has an appropriate active metal particle size, as well as a BET specific surface area and pore volume of the catalyst, and can achieve appropriate and excellent catalytic performance in the reaction of selective hydrogenation of anthraquinone to prepare hydrogen peroxide.

[0058] The second aspect of the present disclosure provides a method for preparing a Pd-based catalyst, including the following steps:

[0059] S1. Contact a carrier, a palladium source, a non-noble metal M source, and water, and perform an adsorption treatment to obtain a loaded product, where the non-noble metal M is selected from one or more of non-noble metal elements in Groups IIB to VIIB, Group IIIA, and Group VIII;

[0060] S2. Perform a first aging treatment, a first drying treatment, and a first calcination treatment on the loaded product to obtain a catalyst precursor; the conditions of the first calcination treatment include: the calcination temperature is 350-650 °C, the calcination time is 0.5-8 h, and the calcination atmosphere is selected from one of air, high-purity nitrogen, and high-purity oxygen;

[0061] S3. Perform a reduction treatment on the catalyst precursor; the conditions of the reduction treatment include: the reduction temperature is 50-250 °C, the reduction time is 0.5-8 h, and the reduction atmosphere is selected from one of high-purity hydrogen or a mixed gas containing hydrogen and nitrogen.

[0062] The present disclosure provides a method for preparing a Pd-based catalyst. Using a shaped or powdered oxide or mixed oxide as a substrate, an active metal precursor and a non-noble metal MOx precursor are introduced onto the surface of the carrier by co-impregnation or mixed impregnation. After subsequent calcination and reduction steps, a Pd-based catalyst modified by non-noble metal oxide MOx clusters is obtained. By controlling the addition amount of the non-noble metal MOx precursor, the impregnation method, the calcination conditions, and the reduction conditions in the catalyst preparation process, the regulation of the electronic structure, geometric structure, and dispersion structure of Pd by MOx clusters can be achieved. If the reduction temperature is too low, the Pd element cannot be reduced to metallic Pd, while if the reduction temperature is too high, the Pd particles will agglomerate and the non-noble metal oxide MOx will be reduced to a metallic form, which will have a negative impact on the catalyst performance. However, a catalyst with excellent performance can be obtained according to the preparation conditions provided by the present disclosure.

[0063] In a specific embodiment, in step S1, the carrier is selected from one or more of transition metal oxides and inert oxides; preferably, the carrier is selected from one or more of MgO, Al2O3, TiO2, SiO2, ZnO2, ZrO2, CeO2, and Co2O3; the carrier used in the present disclosure can be one or several doped by physical or chemical methods; the oxide or mixed oxide carrier used can be a shaped carrier, such as strip-shaped, spherical (including microspherical), O-shaped, four-leaf-shaped, etc., or a powder-type carrier;

[0064] The palladium source is selected from one or more of Pd(NH3)2Cl2, Pd(NO3)2, Na2PdCl4, and C 10 H 14 O4Pd;

[0065] The non-noble metal M source is selected from one or more of nitrates, sulfates, and chlorides of non-noble metal M; non-noble metal M is preferably selected from one or more of the elements Ga, Ti, Mn, Cr, In, Co, Ni, and Zn; further preferably, the non-noble metal M source is selected from one or more of gallium nitrate, titanium tetrachloride, manganese chloride, chromium chloride, indium nitrate, cobalt chloride, nickel nitrate, and zinc sulfate.

[0066] The reaction raw materials involved in the present disclosure can be obtained through ordinary commercial purchase channels or prepared by known methods.

[0067] In one embodiment, in step S1, the addition amounts of the palladium source and the non-noble metal M source are added according to the loadings of Pd metal and non-noble metal M in the catalyst to be prepared. Among them, based on the total weight of the prepared Pd-based catalyst, the addition amount of the palladium source makes the loading of Pd metal be 0.05-5 wt%, preferably 0.25-1 wt%; the addition amount of the non-noble metal M source makes the loading of non-noble metal M be 0.005-5 wt%, preferably 0.025-0.2 wt%. Adding the palladium source and the non-noble metal M source according to the preferred loadings of Pd metal and non-noble metal M in this embodiment results in a catalyst with more excellent catalytic performance.

[0068] In a preferred embodiment, the molar ratio of Pd atoms of the palladium source to M atoms of the non-noble metal M source is 1:1-0.001, preferably 1:0.1-0.5. The molar ratio of Pd atoms to non-noble metal M atoms of the catalyst provided in this embodiment can ensure an appropriate ratio between the active metal Pd and the non-noble metal oxide existing in the form of atomic clusters in the obtained catalyst, and the catalytic performance of the catalyst is excellent.

[0069] In a specific embodiment, the palladium source is used in the form of a solution, and the concentration of the palladium source solution is 0.1 to 5 M; the non-noble metal M source is used in the form of a solution, and the concentration of the non-noble metal M source solution is 0.01 to 5 M.

[0070] In a specific embodiment, step S1 includes the following steps a1 to a3:

[0071] a1. Contact the carrier with water for soaking treatment to obtain the soaked carrier;

[0072] a2. Add the palladium source solution to the soaked carrier, and perform the first adsorption treatment and the first solid-liquid separation treatment; the obtained solid product is subjected to the second aging treatment, the second drying treatment and the second calcination treatment to obtain the palladium source loaded product;

[0073] a3. Contact the non-noble metal M source solution with the palladium source loaded product, and perform the second adsorption treatment and the second solid-liquid separation treatment to obtain the loaded product;

[0074] Alternatively, step S1 includes the following steps b1 to b2:

[0075] b1. Contact the carrier with water for soaking treatment to obtain the soaked carrier;

[0076] b2. Add the palladium source solution and the non-noble metal M source solution to the soaked carrier, and perform the third adsorption treatment and the third solid-liquid separation treatment to obtain the loaded product.

[0077] In an embodiment, in step a1 or step b1, relative to 1 g of the carrier, the amount of water used is 1:1.2 to 10, preferably 1:1.5 to 5. The conditions of the soaking treatment include: the soaking temperature is 20 to 95 °C, and the soaking time is 10 to 360 min; preferably, the soaking temperature is 25 to 80 °C, and the soaking time is 30 to 120 min; optionally, step a1 or step b1 includes: performing solid-liquid separation on the suspension obtained by soaking the carrier with water, and contacting the obtained solid with water to continue the soaking treatment, repeating multiple times, preferably repeating 3 to 10 times. By soaking the carrier multiple times, it has the effect of effectively removing the adsorbed impurity gases and ions on the carrier surface.

[0078] In the present disclosure, the solid-liquid separation treatment can be carried out by conventional operations in the art, such as by filtration and other methods.

[0079] In one embodiment, the conditions of the first adsorption treatment in step a2, the second adsorption treatment in step a3, and the third adsorption treatment in step b2 each independently include: the adsorption temperature is 20 to 95 °C, the adsorption time is 30 to 360 min, and generally the pressure is normal pressure without pressure adjustment during adsorption; optionally, the rotation rate is 10 to 1000 r / min; preferably, the adsorption temperature is 25 to 80 °C, the adsorption time is 30 to 240 min, and the rotation rate is 50 to 200 r / min; in the present disclosure, rotary adsorption uses conventional instrument devices in the art, such as a rotary evaporator.

[0080] In one embodiment, in step a2, the conditions of the second aging treatment include: the aging temperature is 20 to 90 °C, and the aging time is 2 to 48 h; preferably, the aging temperature is 20 to 35 °C, and the aging time is 2 to 6 h;

[0081] The conditions of the second drying treatment include: the drying temperature is 90 to 180 °C, and the drying time is 6 to 48 h; preferably, the drying temperature is 100 to 120 °C, and the drying time is 10 to 18 h;

[0082] The conditions of the second calcination treatment include: the calcination temperature is 350 to 650 °C, the calcination time is 0.5 to 8 h, and the calcination atmosphere is selected from one of air, high-purity nitrogen, and high-purity oxygen; preferably, the calcination temperature is 350 to 500 °C, and the calcination time is 3 to 5 h.

[0083] In one embodiment, in step S2, the conditions of the first aging treatment include: the aging temperature is 20 to 90 °C, and the aging time is 2 to 48 h; preferably, the aging temperature is 20 to 35 °C, and the aging time is 2 to 6 h;

[0084] The conditions of the first calcination include: the calcination temperature is 350 to 450 °C, the calcination time is 0.5 to 4 h; generally, pressure calcination is not carried out, and the calcination pressure is default normal pressure; optionally, the heating rate is 0.5 to 10 °C / min, preferably 2 to 5 °C / min; preferably, the purity of the high-purity nitrogen is above 99.9 vol%, and the purity of the high-purity oxygen is above 99.9 vol%;

[0085] The conditions of the first drying treatment include: the drying temperature is 90 to 180 °C, and the drying time is 6 to 48 h; preferably, the drying temperature is 100 to 120 °C, and the drying time is 10 to 18 h.

[0086] In a preferred embodiment, in step S3, the conditions of the reduction treatment include: the reduction temperature is 100 to 150 °C, and the reduction time is 2 to 6 h;

[0087] Optionally, when a mixed gas containing hydrogen and nitrogen is used as the reducing atmosphere, the volume ratio of hydrogen to nitrogen is 1:1 to 10, preferably 1:3 to 5;

[0088] Optionally, the purity of the high-purity hydrogen is above 99.9% by volume.

[0089] By using the optimized process conditions provided by the present disclosure (such as the first calcination conditions and reduction conditions, etc.) for catalyst preparation, a catalyst with better performance can be obtained.

[0090] The third aspect of the present disclosure provides a Pd-based catalyst prepared by the method described in the second aspect of the present disclosure.

[0091] The fourth aspect of the present disclosure provides the application of the Pd-based catalyst described in the first aspect or the third aspect of the present disclosure in the reaction of selective hydrogenation of anthraquinone to prepare hydrogen peroxide.

[0092] In a preferred embodiment, the conditions for the reaction of selective hydrogenation of anthraquinone to prepare hydrogen peroxide include: the temperature of the hydrogenation reaction is 40 to 80 °C, the pressure is 0.1 to 1.2 MPa, and the molar ratio of hydrogen to the material to be hydrogenated is 4 to 200:1.

[0093] The following further illustrates the present invention through examples, but does not limit the content of the present disclosure thereby.

[0094] Unless otherwise specified, the raw materials used in the examples are all chemically pure reagents.

[0095] The instrument for testing the XPS elemental content of the catalyst is a Thermo VG ESCALAB 250 spectrometer, and the method used is the peak area integration method;

[0096] The instrument for testing the Pd 3d XPS of the catalyst is a Thermo VG ESCALAB 250 spectrometer, and the method used is the Gaussian fitting method;

[0097] The instrument for testing the XRD pattern of the catalyst is a Shimadzu XRD-6000, and the test method is: 40 kV, 30 mA, the emission source is Cu Ka (k = 0.154 nm), 5 to 70°, 10°·min -1 ;

[0098] The component content of the catalyst is obtained by testing with inductively coupled plasma atomic emission spectrometry and X-ray fluorescence spectrometry;

[0099] The average particle size of the active metal of the catalyst is obtained by the method of counting the particle size from the HRTEM photos;

[0100] The test instrument and test method for the BET specific surface area and pore volume structure characteristics of the catalyst are as follows: Weigh 2 g of the sample and place it in a sample tube. Degas it in a nitrogen atmosphere at 120 °C for 6 h, and then perform the determination of the specific surface area, pore volume, pore size distribution, and physical adsorption curve of the material in a Micromeritics ASAP 2020M + C fully automatic physical and chemical adsorption analyzer.

[0101] Example 1

[0102] The specific preparation steps of the Co oxide cluster modified Pd-based catalyst are as follows:

[0103] A. Take 30 g of spherical alumina and add it to 60 mL of deionized water. The amount of water used is 2 mL relative to 1 g of the carrier. After soaking at 50 °C for 30 min, remove the deionized water, and then take another 60 mL of deionized water for soaking. Repeat this step 3 times;

[0104] B. According to the Pd metal loading of 0.3 wt%, take a certain volume of 0.1 M Na2PdCl4 solution, dilute it to 60 ml with deionized water, and then add it to the soaked alumina carrier. Rotate and adsorb at room temperature (25 °C) for 2 h, and the rotation rate is 200 r / min;

[0105] C. After filtering the above material that has fully adsorbed the active metal precursor to remove the filtrate, let it stand and age at room temperature (25 °C) for 12 h;

[0106] D. Dry the above-aged material at 120 °C for 12 h, and then calcine it in an air atmosphere at 450 °C for 4 h;

[0107] E. Prepare 60 mL of cobalt nitrate solution according to the Pd:Co atomic molar ratio of 1:0.25. The concentration of cobalt nitrate is 0.1 M. Based on the dry weight of the carrier, the addition amount of the Co source is 0.13 wt% of the carrier weight. Quickly add the oxide obtained in step D to the cobalt nitrate solution, and rotate and adsorb at room temperature (25 °C) for 2 h. The rotation rate is 200 r / min;

[0108] F. After filtering the above material that has fully adsorbed the active metal precursor (the loaded product) to remove the filtrate, let it stand and age at room temperature (25 °C) for 6 h;

[0109] G. Dry the above-aged material at 120 °C for 12 h, and then calcine it in an air atmosphere at 450 °C for 4 h to obtain the precursor of the required catalyst.

[0110] H. The above catalyst precursor can be reduced in a mixed atmosphere of H2 / N2 (the volume ratio of hydrogen to nitrogen is 1:5) at 120 °C for 4 h to obtain a Pd-based catalyst modified with CoOx clusters.

[0111] Comparative Example 1

[0112] The catalyst in this comparative example is a commercially available ordinary anthraquinone hydrogenation catalyst. This catalyst is a single Pd catalyst supported on spherical alumina, with a Pd loading of 0.3 wt%, and the specific surface area of the catalyst is 160.2 m 2 / g.

[0113] Comparative Example 2

[0114] This comparative example refers to the preparation method in Example 1. The difference from Example 1 is that:

[0115] The calcination conditions in step D are: calcination at 300 °C for 10 h in an air atmosphere;

[0116] The calcination conditions in step G are: calcination at 800 °C for 0.2 h in a hydrogen atmosphere;

[0117] The remaining processes are the same as those in Example 1 to prepare a Pd-based catalyst.

[0118] Comparative Example 3

[0119] This comparative example refers to the preparation method in Example 1. The difference from Example 1 is that:

[0120] The reduction conditions in step H are: the catalyst precursor is reduced in a mixed atmosphere of H2 / N2 (the mixed volume ratio of hydrogen to nitrogen is 1:5) at 50 °C for 1 h; the remaining processes are the same as those in Example 1 to prepare a Pd-based catalyst.

[0121] Comparative Example 4

[0122] A PdM alloy catalyst was prepared by referring to the method disclosed in the existing literature (Yuan, Enxian, et al. "Synergistic effects of second metals on performance of (Co, Ag, Cu)-doped Pd / Al2O3 catalysts for 2-ethyl-anthraquinone hydrogenation." Journal of Catalysis 347 (2017): 79-88), which specifically includes the following steps:

[0123] The PdCo / Al2O3 catalyst was prepared by co-impregnation of the corresponding metal precursor solution and γ-Al2O3 support. Among them, according to the Pd metal loading of 0.3 wt%, the M oxide loading of 0.053 wt%, PdCl2 and Co metal precursor (cobalt nitrate) were added to the NH3-H2O aqueous solution with pH = 11. Then, 5.00 g of Al2O3 was added to the above solution. After impregnation for 1 hour, the solid was dried at 110 °C for 12 hours and calcined in air at 350 °C for 4 hours, and the heating rate was 1 °C / min. The obtained catalyst was designated as PdCo / Al2O3.

[0124] Example 2

[0125] The specific preparation steps of the Co oxide cluster modified Pd-based catalyst are as follows:

[0126] A. Take 30 g of spherical alumina and add it to 100 mL of deionized water. The amount of water used is 3.33 mL relative to 1 g of the support. After soaking at 80 °C for 30 min, the deionized water was removed, and then another 100 mL of deionized water was taken for soaking. This step was repeated 3 times;

[0127] B. According to the Pd metal loading of 0.3 wt% and the Pd:Co atomic molar ratio of 1:0.25, a certain volume of 0.1 M Na2PdCl4 solution and cobalt chloride salt were taken. Among them, based on the dry weight of the support, the addition amount of the palladium source was 0.59 wt% of the support weight, and the addition amount of the Co source was 0.73 wt% of the support weight. After adding 30 ml of deionized water to dissolve and mix evenly, it was diluted to 80 ml with deionized water and then added to the soaked alumina support, and rotated and adsorbed at room temperature for 4 h, and the rotation rate was 120 r / min;

[0128] C. After filtering and removing the filtrate from the material fully adsorbed with the active metal precursor above, it was left to age at room temperature for 8 h;

[0129] D. After drying the above-aged material at 180 °C for 24 h, it was calcined in an air atmosphere at 450 °C for 4 h to obtain the precursor of the required catalyst;

[0130] E. After reducing the above catalyst precursor in a H2 atmosphere at 100 °C for 6 h, the CoOx cluster modified Pd-based catalyst can be obtained.

[0131] The HRTEM photo of the catalyst prepared in this example is as Figure 1 shown, and it can be seen from Figure 1 that in the catalyst prepared by the method provided in the present disclosure, the active metal did not form a PdCo alloy, but existed in the form of elemental Pd metal particles modified by CoOx nanoparticles.

[0132] Example 3

[0133] The specific preparation steps of the Pd-based catalyst modified with Ni oxide clusters are as follows:

[0134] A. Take 10 g of alumina powder and add it to 30 mL of deionized water. The amount of water used is 3 mL relative to 1 g of the carrier. After stirring and soaking at 25 °C for 25 min, remove the deionized water, and then take another 30 mL of deionized water for soaking. Repeat this step 5 times;

[0135] B. According to the proportion of Pd metal loading of 0.3 wt% and Pd:Ni atomic molar ratio of 1:0.5, take a certain volume of 0.1 M Pd(NH3)2Cl2 solution and nickel nitrate salt. Based on the dry weight of the carrier, the addition amount of the palladium source is 0.59 wt% of the carrier weight, and the addition amount of the Ni source is 0.515 wt% of the carrier weight. After adding 10 ml of deionized water to dissolve and mix evenly, dilute it to 30 ml with deionized water, and then add it to the soaked alumina carrier. Rotate and adsorb at room temperature for 4 h, and the rotation rate is 760 r / min;

[0136] C. After filtering and removing the filtrate from the material fully adsorbed with the active metal precursor above, let it stand and age at room temperature for 12 h;

[0137] D. After drying the aged material above at 95 °C for 48 h, calcine it in an air atmosphere at 550 °C for 3 h to obtain the precursor of the required catalyst;

[0138] E. After reducing the above catalyst precursor in a H2 / N2 mixed atmosphere (the volume ratio of hydrogen to nitrogen is 1:4) at 80 °C for 6 h, the Pd-based catalyst modified with NiOx clusters can be obtained.

[0139] The Pd 3d XPS spectrum of the catalyst prepared in this example is as Figure 2 shown, and from Figure 2 it can be seen that the Pd catalyst prepared by the method provided in the present disclosure has spectral peaks at around 337 eV and around 343 eV, indicating that the reduced Pd in the catalyst obtained in this example does not exist in the form of PdNi alloy, but in the form of higher-valent Pd δ+ (Pd-O-Ni) exists on the catalyst surface, that is, Pd particles are modified by NiOx.

[0140] Example 4

[0141] The specific preparation steps of the Pd-based catalyst modified with Ni oxide clusters are as follows:

[0142] A. Take 10 g of alumina powder and add it to 30 mL of deionized water. The amount of water used is 3 mL relative to 1 g of the carrier. Stir and soak at 25 °C for 25 min, then remove the deionized water. Then take another 30 mL of deionized water for soaking, and repeat this step 5 times;

[0143] B. According to a Pd metal loading of 0.3 wt%, take a certain volume of 0.1 M Pd(NO3)2 solution (based on the dry weight of the carrier, the addition amount of the palladium source is 0.65 wt% of the carrier weight). After diluting it to 30 ml with deionized water, add it to the soaked alumina carrier, and rotate and adsorb at room temperature for 4 h, with a rotation rate of 200 r / min;

[0144] C. After filtering the material that has fully adsorbed the active metal precursor to remove the filtrate, let it stand and age at room temperature for 6 h;

[0145] D. Dry the material after aging above at 100 °C for 10 h, and then calcine it in an air atmosphere at 500 °C for 4 h;

[0146] E. Prepare 30 mL of nickel nitrate solution according to a Pd:Ni atomic molar ratio of 1:0.5 (based on the dry weight of the carrier, the addition amount of the nickel source is 0.26 wt% of the carrier weight). Quickly add the oxide obtained in step D to the nickel nitrate solution, and rotate and adsorb at room temperature for 2 h;

[0147] F. After filtering the material that has fully adsorbed the active metal precursor to remove the filtrate, let it stand and age at room temperature for 6 h;

[0148] G. Dry the material after aging above at 100 °C for 10 h, and then calcine it in an air atmosphere at 500 °C for 4 h;

[0149] H. Reduce the above catalyst precursor in a H2 / N2 mixed atmosphere (the volume ratio of hydrogen to nitrogen is 1:3) at 120 °C for 4 h, and then a NiOx cluster-modified Pd-based catalyst can be obtained.

[0150] The XRD pattern of the catalyst prepared in this example is as Figure 3 shown. It can be seen from the figure that this pattern is the characteristic peak of typical γ-alumina, and there are no other impurity peaks. This indicates that the active metal in the catalyst prepared in this example is highly dispersed on the catalyst surface.

[0151] Example 5

[0152] The specific preparation steps of the Ti oxide cluster-modified Pd-based catalyst are as follows:

[0153] A. Take 10 g of Al2O3-SiO2 powder (element molar ratio Al:Si = 2:1) of magnesium-aluminum mixed oxide powder and add it to 30 mL of deionized water. The amount of water used is 3 mL relative to 1 g of the carrier. After stirring and soaking at 60 °C for 30 min, remove the deionized water, then take another 30 mL of deionized water for soaking, and repeat this step 4 times;

[0154] B. According to the Pd metal loading of 1 wt%, take a certain volume of 0.1 M Na2PdCl4 solution, dilute it to 30 ml with deionized water, and then add it to the soaked Al2O3-SiO2 carrier. Rotate and adsorb at room temperature for 4 h, and the rotation rate is 600 r / min;

[0155] C. After filtering the above material that has fully adsorbed the active metal precursor to remove the filtrate, let it stand and age at room temperature for 24 h;

[0156] D. After drying the above-aged material at 150 °C for 10 h, calcine it in an air atmosphere at 450 °C for 4 h;

[0157] E. Prepare 30 mL of titanium tetrachloride according to the ratio of Pd:Ti atomic ratio of 1:1, quickly add the oxide obtained in step D to the titanium-containing solution, rotate and adsorb at room temperature for 4 h, and the rotation rate is 300 r / min;

[0158] F. After filtering the above material that has fully adsorbed the active metal precursor to remove the filtrate, let it stand and age at room temperature for 4 h;

[0159] G. After drying the above-aged material at 150 °C for 10 h, calcine it in an air atmosphere at 450 °C for 4 h;

[0160] H. After reducing the above catalyst precursor in a H2 / N2 mixed atmosphere (the volume ratio of hydrogen to nitrogen is 1:3) at 150 °C for 6 h, the Pd-based catalyst modified by TiOx clusters can be obtained.

[0161] The XRD pattern of the catalyst prepared in this example is as Figure 3 shown. It can be seen from the figure that this pattern is the characteristic peak of typical γ-alumina, and there are no other impurity peaks. This indicates that the active metal prepared in this example is highly dispersed on the catalyst surface.

[0162] Example 6

[0163] The specific preparation steps of the Pd-based catalyst modified by Ga oxide clusters are as follows:

[0164] A. Take 10 g of Al2O3-SiO2 powder (element molar ratio Al:Si = 2:1), add it to 80 mL of deionized water. The amount of water used is 8 mL relative to 1 g of the carrier. Stir and soak at 60 °C for 30 min, then remove the deionized water. Then take another 80 mL of deionized water for soaking, and repeat this step 8 times;

[0165] B. According to the proportion of Pd metal loading of 1.5 wt% and Pd:Ga atomic ratio of 1:0.75, take a certain volume of 0.1 M Pd(NH3)2Cl2 solution and gallium nitrate salt, add 10 ml of deionized water to dissolve and mix evenly, then dilute to 80 ml with deionized water. After that, add the soaked magnesium-aluminum mixed oxide carrier into it, and rotate and adsorb at room temperature for 4 h, with a rotation rate of 450 r / min;

[0166] C. After filtering and removing the filtrate from the material that has fully adsorbed the active metal precursor, let it stand and age at room temperature for 12 h;

[0167] D. Dry the aged material at 120 °C for 48 h, and then calcine it in an air atmosphere at 600 °C for 6 h to obtain the precursor of the required catalyst;

[0168] E. Reduce the above catalyst precursor in a H2 / N2 mixed atmosphere (volume ratio of hydrogen to nitrogen is 1:4) at 120 °C for 6 h to obtain the Pd-based catalyst modified by GaOx clusters.

[0169] Example 7

[0170] The specific preparation steps of the Pd-based catalyst modified by zinc oxide clusters are as follows:

[0171] A. Take 10 g of alumina powder, add it to 50 mL of deionized water. The amount of water used is 5 mL relative to 1 g of the carrier. Stir and soak at 25 °C for 25 min, then remove the deionized water. Then take another 50 mL of deionized water for soaking, and repeat this step 5 times;

[0172] B. According to the Pd metal loading of 0.2 wt%, take a certain volume of 0.1 M Pd(NO3)2 solution, dilute it to 50 ml with deionized water, then add the soaked alumina carrier into it, and rotate and adsorb at room temperature for 6 h, with a rotation rate of 800 r / min;

[0173] C. After filtering and removing the filtrate from the material that has fully adsorbed the active metal precursor, let it stand and age at room temperature for 48 h;

[0174] D. Dry the aged material at 170 °C for 10 h, and then calcine it in an air atmosphere at 350 °C for 4 h;

[0175] E. Prepare 30 mL of zinc sulfate solution with a zinc sulfate concentration of 0.5 M according to the ratio of Pd:Zn atomic ratio of 1:0.5. Rapidly add the oxide obtained in step D to the zinc sulfate solution, and perform rotary adsorption at room temperature for 6 h with a rotation rate of 250 r / min;

[0176] F. After filtering the material after fully adsorbing the active metal precursor to remove the filtrate, let it stand and age at room temperature for 48 h;

[0177] G. Dry the aged material at 170 °C for 36 h, and then calcine it in an air atmosphere at 350 °C for 4 h;

[0178] H. After reducing the above catalyst precursor in an H2 atmosphere at 150 °C for 8 h, a Pd-based catalyst modified with ZnOx clusters can be obtained.

[0179] Example 8

[0180] This example refers to the preparation method in Example 5. The difference from Example 5 is as follows:

[0181] In step E: Prepare 30 mL of titanium tetrachloride according to the ratio of Pd:Ti atomic ratio of 1:0.5. Rapidly add the oxide obtained in step D to the titanium-containing solution, and then perform rotary adsorption; the remaining processes are the same as in Example 5, and a Pd-based catalyst modified with TiOx clusters is obtained.

[0182] Example 9

[0183] This example refers to the preparation method in Example 6. The difference from Example 6 is as follows:

[0184] In step B: According to a Pd metal loading of 1 wt%, and a Pd:Ga atomic ratio of 1:0.25, take a certain volume of 0.1 M Pd(NH3)2Cl2 solution and gallium nitrate salt, add 10 ml of deionized water to dissolve and mix evenly, then dilute it to 80 ml with deionized water. After adding the soaked magnesium-aluminum mixed oxide support, perform rotary adsorption. The remaining processes are the same as in Example 6, and a Pd-based catalyst modified with GaOx clusters is obtained.

[0185] Example 10

[0186] Refer to the preparation method in Example 7. The difference from Example 7 is as follows:

[0187] In step B, a certain volume of 0.1 M Pd(NO3)2 solution was taken according to a Pd metal loading of 1 wt%, diluted to 50 ml with deionized water, and then the soaked alumina support was added thereto for rotary adsorption. The remaining process was the same as that of Example 7 to obtain a Pd-based catalyst modified with ZnOx clusters.

[0188] Example 11

[0189] This example refers to the preparation method in Example 1. The difference from Example 1 is as follows:

[0190] In step D: After drying the aged material at 120 °C for 12 h, it was calcined at 550 °C for 8 h in an air atmosphere;

[0191] In step G: After drying the aged material at 120 °C for 12 h, it was calcined at 600 °C for 7 h in an air atmosphere to obtain the precursor of the required catalyst;

[0192] In step H: The catalyst precursor was reduced at 220 °C for 6 h in a H2 / N2 mixed atmosphere (the volume ratio of hydrogen to nitrogen was 1:9); the remaining process was the same as that of Example 1 to obtain a Pd-based catalyst modified with CoOx clusters.

[0193] The component contents and structural characteristic parameters of the catalysts obtained in the above examples, comparative examples, and comparative cases are listed in Table 1 below.

[0194] Table 1

[0195]

[0196] Test Example

[0197] This test example is used to illustrate the catalytic effect of the Pd-based catalysts prepared in the above examples and comparative examples in the reaction of selective hydrogenation of anthraquinone to prepare hydrogen peroxide.

[0198] For the selective hydrogenation of anthraquinone to prepare hydrogen peroxide, a fixed-bed reactor or a stirred reaction kettle can be used as the reactor in the reaction. The working fluid solvent used is a 1:1 (volume ratio) mixed solution of 1,3,5-trimethylbenzene and trioctyl phosphate. The concentration of anthraquinone molecules in the working fluid used is 80 g / L. In a single reaction, a certain amount of catalyst was loaded into the reactor. After checking the airtightness of the device, a certain amount of working fluid was loaded into the reactor, and the volume of 1,3,5-trimethylbenzene was 3 mL relative to 1 g of the catalyst. After replacing the reactor with nitrogen three times, the reactor was heated to the specified reaction temperature (50 - 60 °C), and then hydrogen was introduced at a certain flow rate for the reaction. The volume space velocity of hydrogen was 150 h -1React for 0.5 h. After the reaction is completed, take a certain volume of the working solution after the reaction and put it into a separatory funnel. At the same time, add an equal volume of deionized water, and oxidize it with high-purity oxygen at room temperature for 20 min. The volume space velocity of oxygen is 100 h -1 After the oxidation is completed, extract the oxidized working solution. The hydrogen peroxide content in the obtained extract is determined by the potassium permanganate titration method, and the effective anthraquinone content in the obtained raffinate is determined by high-performance liquid chromatography analysis.

[0199] Among them, the hydrogen peroxide hydrogenation efficiency (g / L) = (5 × potassium permanganate solution concentration × volume of potassium permanganate solution used for titration × molar mass of hydrogen peroxide) / (2 × volume of hydrogen peroxide solution used for titration);

[0200] The selectivity of effective anthraquinone (%) = the molar amount of effective anthraquinone / the total molar amount of anthraquinone × 100%;

[0201] The space-time yield of hydrogen peroxide (g H2O2 / g Pd / h / L) = hydrogen peroxide hydrogenation efficiency / (catalyst mass × active metal) / reaction time.

[0202] List the test results in Table 2 below.

[0203] Table 2

[0204]

[0205]

[0206] *In the evaluation of the catalyst of Comparative Example 4, first, the obtained catalyst was pretreated by reducing it in a H2 / N2 mixed atmosphere (the volume ratio of hydrogen to nitrogen is 1:5) at 50 °C for 1 h.

[0207] It can be seen from the data in Table 2 above that the Pd-based catalysts prepared in Examples 1 to 11 of the present disclosure can obtain high hydrogenation efficiency and effective anthraquinone selectivity in the reaction of selective hydrogenation of anthraquinone to prepare hydrogen peroxide.

[0208] Among them, comparing Examples 1 to 2 and 11 with Comparative Examples 1 to 2 and 4, under the conditions of the same type of supported metal and the same loading amount, the catalyst prepared in Example 1 has higher hydrogenation efficiency, effective anthraquinone selectivity, and space-time yield of hydrogen peroxide in the reaction of selective hydrogenation of anthraquinone to prepare hydrogen peroxide; among them, Comparative Example 4 is a PdM alloy catalyst prepared by the prior art. Through data comparison, it can be seen that the catalyst prepared in Example 1 of the present disclosure (the oxide of the non-precious metal M as the active metal promoter in the catalyst has a cluster structure, avoiding the existence in the form of PdM alloy) has more excellent catalytic performance;

[0209] Comparing Example 1 with Comparative Example 3, it can be seen that in Example 1, the catalyst was prepared according to the preferred reduction conditions "the reduction temperature is 100 - 150 °C, and the reduction time is 2 - 6 h". The catalyst obtained in Example 1 can achieve higher hydrogenation efficiency, effective anthraquinone selectivity, and hydrogen peroxide space-time yield compared to the catalyst obtained in Comparative Example 3.

[0210] Comparing Example 5 with Example 8, Example 6 with Example 9, and Example 7 with Example 10, under the condition of the same metal type loaded, the Pd content, M oxide content, and carrier content in Examples 8 - 10 are within the optimized content ranges provided by the present disclosure. Compared with Examples 5 - 7, the catalysts prepared in Examples 8 - 10 can achieve higher hydrogenation efficiency, effective anthraquinone selectivity, and hydrogen peroxide space-time yield in the reaction of selective hydrogenation of anthraquinone to prepare hydrogen peroxide.

[0211] Comparing Example 1 with Examples 2 and 11, it can be seen that in Example 1, the catalyst was prepared according to the preferred conditions provided by the present disclosure. The catalyst obtained in Example 1 can achieve higher hydrogenation efficiency, effective anthraquinone selectivity, and hydrogen peroxide space-time yield in the reaction of selective hydrogenation of anthraquinone to prepare hydrogen peroxide compared to the catalysts prepared in Examples 2 and 11.

[0212] The preferred embodiments of the present disclosure have been described in detail above. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0213] In addition, it should be noted that in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination methods.

[0214] Furthermore, any combination can be made between various different embodiments of the present disclosure as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.

Claims

1. A Pd-based catalyst, characterized in that, The catalyst comprises a support and an active metal Pd and an oxide of a non-noble metal M supported on the support; the non-noble metal M is selected from one or more of non-noble metal elements in Groups IIB to VIIB, Group IIIA and Group VIII.

2. The Pd-based catalyst according to claim 1, characterized in that, Based on the total weight of the Pd-based catalyst, the content of the active metal Pd is 0.05 to 5% by weight, the content of the oxide of the non-noble metal M is 0.005 to 5% by weight, and the content of the support is 90 to 99.945% by weight; Preferably, the content of the active metal Pd is 0.25 to 1% by weight, the content of the oxide of the non-noble metal M is 0.025 to 0.5% by weight, and the content of the support is 98.5 to 99.725% by weight.

3. The Pd-based catalyst according to claim 1, wherein The non-noble metal M is selected from one or more of Ga, Ti, Mn, Cr, In, Co, Ni and Zn; The support is selected from one or more of transition metal oxides and inert oxides; preferably, the support is selected from one or more of MgO, Al2O3, TiO2, SiO2, ZnO2, ZrO2, CeO2 and Co2O; Preferably, the oxide of the non-noble metal exists in the form of atomic clusters; preferably, there is no PdM alloy in the Pd-based catalyst; More preferably, the average particle size of the active metal in the Pd-based catalyst is 0.1 to 4.5 nm, preferably 0.1 to 1.5 nm; Optionally, the BET specific surface area of the Pd-based catalyst is 100 to 300 m 2 / g, preferably 150 to 220 m 2 / g.

4. A method for preparing a Pd-based catalyst, characterized in that, Comprising the following steps: S1. Contact the support, a palladium source, a non-noble metal M source and water, and carry out an adsorption treatment to obtain a supported product, wherein the non-noble metal M is selected from one or more of non-noble metal elements in Groups IIB to VIIB, Group IIIA and Group VIII; S2. Carry out a first aging treatment, a first drying treatment and a first calcination treatment on the supported product to obtain a catalyst precursor; wherein, the conditions of the first calcination treatment include: the calcination temperature is 350 to 650 °C, the calcination time is 0.5 to 8 h, and the calcination atmosphere is selected from one of air, nitrogen and oxygen; S3. Carry out a reduction treatment on the catalyst precursor; the conditions of the reduction treatment include: the reduction temperature is 50 to 250 °C, the reduction time is 0.5 to 8 h, and the reduction atmosphere is selected from hydrogen or a mixed gas containing hydrogen and nitrogen.

5. The method according to claim 4, wherein In step S1, the support is selected from one or more of transition metal oxides and inert oxides; preferably, the support is selected from one or more of MgO, Al2O3, TiO2, SiO2, ZnO2, ZrO2, CeO2 and Co2O3; The palladium source is selected from one or more of Pd(NH3)2Cl2, Pd(NO3)2, Na2PdCl4 and C 10 H 14 O4Pd; The non-noble metal M source is selected from one or more of nitrates, sulfates and chlorides of the non-noble metal M; preferably, the non-noble metal M is selected from one or more of Ga, Ti, Mn, Cr, In, Co, Ni and Zn; more preferably, the non-noble metal M source is selected from one or more of gallium nitrate, titanium tetrachloride, manganese chloride, chromium chloride, indium nitrate, cobalt chloride, nickel nitrate and zinc sulfate.

6. The method according to claim 4, wherein In step S1, based on the total weight of the prepared Pd-based catalyst, the addition amount of the palladium source is such that the loading amount of Pd metal is 0.05 to 5 wt%, preferably 0.25 to 1 wt%; the addition amount of the non-noble metal M source is such that the loading amount of the non-noble metal M is 0.005 to 5 wt%, preferably 0.025 to 0.5 wt%. Preferably, the molar ratio of Pd atoms of the palladium source to M atoms of the non-noble metal M source is 1:0.01 to 1, preferably 1:0.1 to 0.5; Optionally, the palladium source is used in the form of a solution, and the concentration of the solution of the palladium source is 0.1 to 5 M; the non-noble metal M source is used in the form of a solution, and the concentration of the solution of the non-noble metal M source is 0.01 to 5 M.

7. The method according to claim 4, characterized in that, Step S1 includes the following steps a1 to a3: a1. Contact the carrier with water for soaking treatment to obtain the soaked carrier; a2. Add the solution of the palladium source to the soaked carrier, and perform the first adsorption treatment and the first solid-liquid separation treatment; The obtained solid product is subjected to a second aging treatment, a second drying treatment and a second calcination treatment to obtain a palladium source-loaded product; a3. Contact the solution of the non-noble metal M source with the palladium source-loaded product, and perform a second adsorption treatment and a second solid-liquid separation treatment to obtain the loaded product; Alternatively, step S1 includes the following steps b1 to b2: b1. Contact the carrier with water for soaking treatment to obtain the soaked carrier; b2. Add the solution of the palladium source and the solution of the non-noble metal M source to the soaked carrier, and perform a third adsorption treatment and a third solid-liquid separation treatment to obtain the loaded product.

8. The method according to claim 7, wherein In step a1 or step b1, with respect to 1 g of the carrier, the amount of water used is 1.2 to 10 mL, preferably 1.5 to 5 mL. The conditions of the soaking treatment include: the soaking temperature is 20 to 95 °C, and the soaking time is 10 to 360 min; preferably, the soaking temperature is 25 to 80 °C, and the soaking time is 30 to 120 min; optionally, step a1 or step b1 includes: performing solid-liquid separation on the suspension obtained by soaking the carrier in water, and contacting the obtained solid with water to continue the soaking treatment, repeating multiple times, preferably repeating 3 to 10 times; The conditions of the first adsorption treatment in step a2, the second adsorption treatment in step a3 and the third adsorption treatment in step b2 each independently include: the adsorption temperature is 20 to 95 °C, the adsorption time is 30 to 360 min, and the rotation rate is 10 to 1000 r / min; preferably, the adsorption temperature is 25 to 80 °C, the adsorption time is 30 to 240 min, and the rotation rate is 50 to 200 r / min; Optionally, in step a2, the conditions of the second aging treatment include: the aging temperature is 20 to 90 °C, and the aging time is 2 to 48 h; preferably, the aging temperature is 20 to 35 °C, and the aging time is 2 to 6 h; The conditions of the second drying treatment include: the drying temperature is 90 to 180 °C, and the drying time is 6 to 48 h; preferably, the drying temperature is 100 to 120 °C, and the drying time is 10 to 18 h; The conditions for the second calcination treatment include: the calcination temperature is 350 - 650 °C, the calcination time is 0.5 - 8 h, and the calcination atmosphere is selected from one of air, nitrogen, and oxygen; preferably, the calcination temperature is 350 - 500 °C, and the calcination time is 3 - 5 h.

9. The method according to claim 4, characterized in that In step S2, the conditions for the first aging treatment include: the aging temperature is 20 - 90 °C, and the aging time is 2 - 48 h; preferably, the aging temperature is 20 - 35 °C, and the aging time is 2 - 6 h; The conditions for the first calcination include: the calcination temperature is 350 - 450 °C, and the calcination time is 0.5 - 4 h; preferably, the purity of the nitrogen is above 99.9 vol%, and the purity of the oxygen is above 99.9 vol%; The conditions for the first drying treatment include: the drying temperature is 9 - 180 °C, and the drying time is 12 - 48 h; preferably, the drying temperature is 100 - 120 °C, and the drying time is 10 - 18 h.

10. The method according to claim 4, wherein In step S3, the conditions for the reduction treatment include: the reduction temperature is 100 - 150 °C, and the reduction time is 2 - 6 h; Preferably, when using a mixed gas containing hydrogen and nitrogen as the reduction atmosphere, the volume ratio of hydrogen to nitrogen is 1:1 - 10, preferably 1:3 - 5.

11. A Pd-based catalyst prepared by the method according to any one of claims 4 - 10.

12. Use of the Pd-based catalyst according to any one of claims 1 - 3 and 11 in the reaction of selective hydrogenation of anthraquinone to prepare hydrogen peroxide.

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