Catalyst, preparation method thereof and method for preparing hydrogen peroxide through anthraquinone hydrogenation

Abstract

The invention relates to the technical field of catalysts, and discloses a catalyst, a preparation method thereof and a method for preparing hydrogen peroxide through anthraquinone hydrogenation. The catalyst comprises a modified carrier and an active component loaded on the modified carrier; the modified carrier comprises an inorganic heat-resistant oxide and a modified component, and is characterized in that the modified component comprises rare earth metal, and the atom dispersity of the rare earth metal in the catalyst is not less than 92%. The rare earth metal in the catalyst provided by the invention is highly dispersed, so that the catalyst has excellent catalytic performance; according to the method for preparing the catalyst provided by the invention, the rare earth metal can be highly dispersed on the carrier in a short time, and the agglomeration phenomenon in the roasting process is avoided, so that the catalyst has excellent catalytic performance, hydrogenation efficiency, hydrogen peroxide selectivity and relatively high production capacity.

Description

Technical Field

[0001] The invention relates to the field of nano catalysts, and in particular to a catalyst with hydrogenation activity and a preparation method thereof, and a method for preparing hydrogen peroxide by hydrogenating anthraquinone. Background Art

[0002] In the hydrogenation reaction, the activation of hydrogen usually occurs on the surface of active metals such as Pd and Pt, but the activated H * It will compete with another reactant for adsorption on the active metal surface, occupying part of the active metal surface, resulting in a decrease in the number of active sites. 2 、CeO 2 Hydrogen overflow is a common phenomenon in catalysts (such as Al2O3, etc.). This phenomenon can be used to improve the hydrogenation capacity of the catalyst. However, non-reducible carriers (such as Al 2 O 3 ), so it is very challenging to enhance the hydrogenation performance of non-reducible carrier catalysts. Generally, doping rare earth elements in the carrier can inhibit the sintering and phase change of the carrier, which is an excellent means to improve the stability and performance of the carrier. The latest research shows that the presence of rare earth elements such as Ce, La, Sm, and Gd on the surface of non-reducible carriers makes the Al 2 O 3 The hydrogen overflow phenomenon on the surface of irreducible carriers is possible, and the introduced rare earth elements can be 2 O 3 By constructing (O)-Ln hydrogen transfer and hydrogen storage sites on the surface of the carrier, the catalytic performance of the hydrogenation reaction can be improved by increasing the active hydrogen concentration on the catalyst surface.

[0003] The prior art generally uses an impregnation method to introduce rare earth elements into the surface of a carrier. For example, "Alicia Carrero, Arturo J. Vizcaíno, José A, et al. Hydrogen production through glycerol steam reforming using Co catalysts supported on SBA-15 doped with Zr, Ce and La. Journal of Energy Chemistry, 2017, 26 (1): 42-48" discloses the use of an impregnation method to introduce Ce elements into an SBA-15 carrier.

[0004] Anthraquinone method is the main industrial production method for preparing hydrogen peroxide, accounting for about 98% of the production share. Hydrogenation is the key step in the anthraquinone hydrogenation process. In theory, by doping with rare earth elements, the traditional Pd / Al 2 O3 Constructing new active centers on the basis of a catalyst and regulating the active centers can improve hydrogen activation and the residence time of activated hydrogen. However, experiments have shown that the introduction of rare earth elements has a limited effect on improving the activity of the anthraquinone hydrogenation reaction.

[0005] CN113600157A discloses a rare earth-doped spherical alumina Pd-based catalyst, its preparation method and application. The method includes: (1) preparing a rare earth-doped aluminum sol: adding a rare earth source and aluminum powder with a particle size of 1-200 μm to a dilute hydrochloric acid solution and mixing to prepare a rare earth-doped aluminum sol; the rare earth source is one or more of hydroxides or soluble salts of yttrium, lanthanum, and europium. (2) preparing a rare earth-doped spherical alumina support: mixing the rare earth-doped aluminum sol prepared in step (1) with an organic amine, dropping it into a forming oil with a disperser to form small balls, aging, and calcining to obtain a rare earth-doped spherical alumina, denoted as X-Al 2 O 3 。(3) Loading Pd: Immerse the X-Al 2 O 3 support in a palladium impregnation solution and mix well, impregnate for 2-5 hours to obtain a Pd / X-Al 2 O 3 catalyst; the support size is 20-200 μm. Compared with the ordinary impregnation method, the advantage of this method is that rare earth elements can be highly dispersed in alumina and do not agglomerate even after high-temperature calcination. Rare earth elements not only do not block the pores of spherical alumina, but also increase the pore diameter and pore volume, providing a good mass transfer space for reactant macromolecules.

[0006] However, experiments have shown that when the above catalyst is used in the reaction of anthraquinone hydrogenation to hydrogen peroxide, there is a problem that a large amount of catalyst is needed to improve the hydrogenation efficiency, that is, the production capacity is low. Summary of the Invention

[0007] The object of the present invention is to overcome the problem of low production capacity of the catalyst existing in the prior art, and provide a new catalyst, its preparation method and a method for preparing hydrogen peroxide by anthraquinone hydrogenation. The preparation method of this catalyst is efficient, simple and fast, and can obtain a high production capacity in the preparation of hydrogen peroxide by anthraquinone hydrogenation.

[0008] To achieve the above object, in the first aspect of the present invention, a catalyst is provided. The catalyst includes a modified support and an active component supported on the modified support; the modified support includes an inorganic heat-resistant oxide and a modifying component, wherein the modifying component includes a rare earth metal, and the atomic dispersion degree of the rare earth metal in the catalyst is not less than 92%.

[0009] In the second aspect of the present invention, a preparation method of a catalyst is provided, wherein the method includes the following steps:

[0010] (1) In the presence of a solvent, a support, a heteropolyacid and a rare earth salt are contacted in a rotating liquid film reactor, and then the solid product obtained from the contact is subjected to a first drying and a first calcination to obtain a rare earth-doped support.

[0011] (2) A metal salt solution of the active component is mixed with the rare earth-doped support and subjected to a reduction treatment, and then the solid product obtained from the contact is subjected to a second drying and a second calcination.

[0012] The third aspect of the present invention provides a method for preparing hydrogen peroxide by anthraquinone hydrogenation, which includes reacting a 2-ethylanthraquinone solution with hydrogen in the presence of a catalyst, wherein the catalyst is the catalyst described in the first aspect or the catalyst prepared by the preparation method described in the second aspect.

[0013] For the catalyst provided by the present invention, since the atomic dispersion of the rare earth metal in the catalyst is not less than 92%, the rare earth metal is highly dispersed, so that the catalyst has excellent catalytic performance, high hydrogenation efficiency, hydrogen peroxide selectivity and production capacity.

[0014] In the method for preparing the catalyst provided by the present invention, a rotating liquid film reactor and a heteropolyacid are used for preparing the catalyst and combined with liquid-phase reduction and gas-phase calcination technologies, which can highly disperse the rare earth metal on the support in a short time and avoid agglomeration during the calcination process, so that the catalyst has excellent catalytic performance, high hydrogenation efficiency, hydrogen peroxide selectivity and production capacity. Description of the Drawings

[0015] Figure 1 It is a spherical aberration electron microscope schematic diagram of the catalysts prepared in Example 1 and Comparative Example 4. Detailed Embodiments

[0016] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0017] The first aspect of the present invention provides a catalyst, which includes a modified support and an active component supported on the modified support; the modified support includes an inorganic heat-resistant oxide and a modifying component, wherein the modifying component includes a rare earth metal, and the atomic dispersion of the rare earth metal in the catalyst is not less than 92%.

[0018] According to a preferred embodiment of the present invention, the atomic dispersion of the rare earth metal is preferably 92-97%, more preferably 94-96.8%.

[0019] In the present invention, the test methods for the dispersion degree of the active component and the atomic dispersion of the rare earth metal are as follows:

[0020] 1. The dispersion degree of the active component is measured using an AutoChem II 2920 chemisorption instrument. Specifically, 0.1 g of the sample is first treated in a 10% H 2 / Ar gas stream at 300 °C for 30 min, then cooled to 50 °C. After purging with H 2 clean, CO is pulsed and introduced multiple times, and the dispersion degree of the active component is calculated based on the CO adsorption amount.

[0021] Dispersion degree D of the active component:

[0022]

[0023] Among them, V CO is the CO adsorption amount, in mL; Vm is the gas molar volume constant, 22414 mL / mol; m cat is the mass of the catalyst sample, in g; ω is the loading amount of the active component in the catalyst, wt%, measured using an inductively coupled plasma mass spectrometer (ICP-MS) of model Aglient 7800; M is the molar mass of the active component in the catalyst, in g / mol.

[0024] 2. CO-D 2 Co-adsorption

[0025] Weigh 30 mg of the sample for infrared tablet pressing measurement. Heat it to 150 °C at a heating rate of 10 °C / min in an argon gas stream of 30 mL / min and keep it at this temperature for 30 min. After cooling to room temperature, introduce CO gas at 20 mL / min and measure the infrared spectrum of the sample once every minute until the sample is saturated with adsorption. Then, blow off the physical adsorption of CO with argon at 30 mL / min, and then introduce D 2 for adsorption. Calculate the infrared adsorption peak area ratio of the active component to the rare earth metal based on the infrared adsorption peak area of CO and the infrared adsorption peak area of O-D.

[0026] Infrared adsorption peak area ratio A of the active component to the rare earth metal:

[0027]

[0028] Among them, Area CO is the area of the CO infrared adsorption peak (1900-2100 cm -1 ), AreaO-D is the area of the O-D infrared adsorption peak (at 2100-2800 cm -1 ), and the peak area is calculated by Origin software.

[0029] 3. Calculate the dispersion degree D of the rare earth metal according to the dispersion degree D of the active component and the ratio A of the infrared adsorption peak area of the active component to the rare earth metal through the following formula R .

[0030] The dispersion degree D of the rare earth metal R :

[0031]

[0032] where D is the dispersion degree of the active component, with the unit of %, and A is the ratio of the infrared adsorption peak area of the active component to the rare earth metal.

[0033] As can be seen from the above method, the rare earth dispersion degree of the present invention is atomic dispersion degree. A dispersion degree of more than 92% indicates that the rare earth elements are highly dispersed on the carrier, reaching the atomic dispersion level.

[0034] According to a preferred embodiment of the present invention, based on the total weight of the catalyst, calculated as oxides, the content of the rare earth metal is preferably 1-20 wt%, more preferably 6.5-10 wt%.

[0035] According to a preferred embodiment of the present invention, the rare earth metal is preferably selected from at least one of Ce, Sm, Pr, and Gd.

[0036] According to a preferred embodiment of the present invention, the modifying component may further include WO 3 , P 2 O 5 , MoO 3 and SiO 2 in at least one. Preferably, based on the total weight of the catalyst, the contents of WO 3 , P 2 O 5 , MoO 3 and SiO 2 are preferably 0.5-15 wt%, more preferably 8.5-12 wt%.

[0037] According to a preferred embodiment of the present invention, based on the total weight of the catalyst, the content of the active component is preferably 0.05-5 wt%, more preferably 1.2-1.6 wt%.

[0038] According to a preferred embodiment of the present invention, the active component is preferably selected from at least one of Pd, Pt, Ru, Ni, and Cu.

[0039] In the present invention, the contents of the components in the catalyst are determined by an inductively coupled plasma mass spectrometer (ICP-MS) of model Aglient 7800.

[0040] According to a preferred embodiment of the present invention, the inorganic heat-resistant oxide is preferably selected from at least one of alumina, titanium dioxide and zirconium dioxide, and is preferably alumina and / or titanium dioxide. Based on the total weight of the catalyst, the content of the inorganic heat-resistant oxide is preferably 60-98.45 wt%, more preferably 78-85 wt%.

[0041] According to a preferred embodiment of the present invention, the average particle size of the catalyst is preferably 2-5 nm, the pore volume is preferably 0.65-0.75 cm 3 / g, and the specific surface area is preferably 90-150 m 2 / g; more preferably, the specific surface area is 95-110 m 2 / g.

[0042] In the present invention, when the average particle size, pore volume and specific surface area of the catalyst are within the above ranges, the catalytic performance of the catalyst can be higher.

[0043] In the present invention, the pore volume and specific surface area of the catalyst can be measured by a specific surface area-pore size analyzer of model Micrometric Gemini VII2390; the average particle size of the catalyst is measured by an instrument of model JEOLJEM-2100F.

[0044] The second aspect of the present invention provides a method for preparing a catalyst, wherein the method comprises the following steps:

[0045] (1) In the presence of a solvent, a carrier, a heteropolyacid and a rare earth salt are contacted in a rotating liquid film apparatus, and then the solid product obtained by the contact is subjected to a first drying and a first calcination to obtain a rare earth-doped carrier;

[0046] (2) A metal salt solution of the active component is mixed with the rare earth-doped carrier and subjected to a reduction treatment, and then the obtained solid product is subjected to a second drying and a second calcination.

[0047] According to a preferred embodiment of the present invention, in step (1), the heteropolyacid is preferably selected from at least one of phosphotungstic acid, phosphomolybdic acid, silicotungstic acid and silicomolybdic acid. The mass ratio of the heteropolyacid to the rare earth salt is preferably (0.1-5):(0.03-0.68), and further preferably (1-2):(0.24-0.4).

[0048] According to a preferred embodiment of the present invention, in step (1), the solvent is preferably selected from ethanol, H 2At least one of O and methanol, preferably ethanol.

[0049] According to a preferred embodiment of the present invention, in step (1), the mass-volume ratio of the carrier, heteropolyacid, rare earth salt to the solvent is preferably 1 g:(0.1 - 5) g:(0.03 - 0.68) g:(150 - 250) mL, and more preferably 1 g:(1 - 2) g:(0.24 - 0.4) g:(160 - 200) mL.

[0050] According to a preferred embodiment of the present invention, in step (1), the rare earth salt is preferably selected from nitrates and / or sulfates of rare earth metals, more preferably Ce(NO 3 ) 3 , Sm(NO 3 ) 3 , Gd(NO 3 ) 3 and Pr(NO 3 ) 3 and at least one of their hydrates.

[0051] According to a preferred embodiment of the present invention, in step (1), the conditions for contacting include: temperature is 10 - 50 °C, time is 5 - 30 min.

[0052] According to a preferred embodiment of the present invention, in step (1), the conditions for contacting further include: adjusting the pH = 9 - 10 by adding an alkali solution during contact; the alkali solution can be a NaOH solution with a concentration of 0.5 - 1.5 mol / L.

[0053] According to a preferred embodiment of the present invention, in step (1), preferably, the conditions of the rotating liquid film device include: rotational speed is 1500 - 3500 r / min, slit gap is 0.1 - 0.3 mm.

[0054] According to a preferred embodiment of the present invention, in step (1), preferably, the conditions for the first drying include: temperature is 80 - 120 °C, time is 5 - 10 h.

[0055] According to a preferred embodiment of the present invention, in step (1), preferably, the conditions for the first calcination include: temperature is 600 - 1200 °C, time is 2 - 5 h.

[0056] In the present invention, step (2) is a liquid-phase reduction - gas-phase calcination process. Using this process can greatly improve the catalytic activity and stability of the catalyst.

[0057] According to a preferred embodiment of the present invention, in step (2), the metal salt solution is preferably selected from K 2 PdCl4 , Na 2 PdCl 4 , H 2 PtCl 6 , RuCl 3 , Cu(NO 3 ) 2 and Ni(NO 3 ) 2 at least one in the aqueous solution.

[0058] According to a preferred embodiment of the present invention, in step (2), the concentration of the metal salt solution is preferably 0.025 - 0.05 mol / L.

[0059] According to a preferred embodiment of the present invention, in step (2), the mass - volume ratio of the rare - earth - doped carrier to the metal salt solution is preferably 1 g:(0.0005 - 0.005) L.

[0060] According to a preferred embodiment of the present invention, in step (2), preferably, the reducing agent is selected from at least one of C 2 H 5 OH, CH 3 OH, HCHO, NaBH 4 , LiAlH 4 and LiBH 4 . The reduction conditions include: the reduction temperature is 40 - 90 °C, and the reduction time is 2 - 5 h. The reduction can be carried out under stirring conditions.

[0061] According to a preferred embodiment of the present invention, in step (2), preferably, the conditions for the second drying include: the temperature is 80 - 120 °C, and the time is 5 - 10 h.

[0062] According to a preferred embodiment of the present invention, in step (2), preferably, the conditions for the second calcination include: the temperature is 250 - 500 °C, and the time is 2 - 5 h.

[0063] In the present invention, the temperature of the second calcination is lower than that of the first calcination, which is more conducive to obtaining a higher rare - earth dispersion. Preferably, the second calcination temperature is 350 - 700 °C lower than the first calcination temperature.

[0064] The third aspect of the present invention provides a method for preparing hydrogen peroxide by anthraquinone hydrogenation, which includes reacting a 2 - ethylanthraquinone solution with hydrogen in the presence of a catalyst, wherein the catalyst is the catalyst described in the first aspect or the catalyst prepared by the preparation method described in the second aspect.

[0065] Preferably, the mass-volume ratio of the catalyst to the 2-ethylanthraquinone solution is (3-10) mg: 12 mL, preferably (4-8) mg: 12 mL; the concentration of the 2-ethylanthraquinone solution is 90-150 g / L, preferably 100-120 g / L; the reaction conditions include: the pressure is 0.1-0.5 MPa, preferably 0.2-0.4 MPa; the temperature is 30-70 °C, preferably 40-50 °C; the time is 0.5-3 h, preferably 1-2 h.

[0066] The present invention will be described in detail below through examples. In the following examples, the raw materials and equipment used in the examples and comparative examples, such as the rotating liquid film device, are all commercially available products.

[0067] Example 1

[0068] (1) In the presence of an ethanol solvent, an alumina support, a 1 mol / L NaOH solution, phosphotungstic acid, and Ce(NO 3 ) 3 were added to a rotating liquid film device and contacted at 30 °C for 10 min. The pH of the system was 9, and then centrifugal separation was carried out. The obtained solid product was first dried at 100 °C for 7.5 h and first calcined at 900 °C for 3.5 h to obtain a rare earth-doped alumina support. Among them, the mass-volume ratio of the support, heteropolyacid, rare earth salt, and solvent was 1 g: 1.43 g: 0.34 g: 170 mL. The rotation speed of the rotating liquid film device was 2500 r / min, and the slit gap was 0.2 mm;

[0069] (2) A 0.035 mol / L K 2 PdCl 4 solution was added to the rare earth-doped alumina support, and then C 2 H 5 OH was added and reduced at 65 °C for 3.5 h. Then centrifugal separation was carried out. The obtained solid product was secondarily dried at 100 °C for 7.5 h and secondarily calcined at 400 °C for 3.5 h to obtain the target catalyst product. Among them, the mass-volume ratio of the rare earth-doped alumina support to the K 2 PdCl 4 solution was 1 g: 0.0025 L.

[0070] The schematic spherical aberration electron microscope diagram of the obtained catalyst is as shown in Figure 1 (2) below, where the white bright spots are the rare earth element Ce. It can be seen that the rare earth element Ce is more evenly dispersed and shows a highly dispersed state at the atomic level; Figure 1The white bright spots in (1) are rare earth element Eu. It can be seen that the rare earth element Eu shows an agglomeration phenomenon. Although it presents a relatively high degree of dispersion, it does not reach the highly efficient atomic-level dispersion. And what is known in the art and proven by the inventors of the present invention through practice is that Ce is more likely to agglomerate compared to other rare earth metal elements.

[0071] Example 2

[0072] (1) In the presence of H 2 O, a titanium dioxide support, 1 mol / L NaOH solution, phosphomolybdic acid, and Sm(NO 3 ) 3 are added to a rotating liquid film apparatus and contacted at 20 °C for 7.5 min. The pH of the system is 10. Then, centrifugal separation is carried out. The obtained solid product is first dried at 90 °C for 6 h and first calcined at 700 °C for 3 h to obtain a rare earth-doped titanium dioxide support. Among them, the mass-volume ratio of the titanium dioxide support, phosphomolybdic acid, Sm(NO 3 ) 3 to H 2 O is 1 g:1 g:0.24 g:200 mL. The rotation speed of the rotating liquid film apparatus is 2000 r / min, and the slit gap is 0.1 mm;

[0073] (2) 0.03 mol / L Na 2 PdCl 4 solution is added to the rare earth-doped titanium dioxide support, and then CH 3 OH is added and reduction is carried out at 75 °C for 3 h. Then, centrifugal separation is carried out. The obtained solid product is secondarily dried at 90 °C for 6 h and secondarily calcined at 350 °C for 3 h to obtain the target catalyst product. Among them, the mass-volume ratio of the rare earth-doped alumina support to the K 2 PdCl 4 solution is 1 g:0.004 L.

[0074] Example 3

[0075] (1) In the presence of an ethanol solvent, a zirconia support, 1 mol / L NaOH solution, silicotungstic acid, and Gd(NO 3 ) 3 are added to a rotating liquid film apparatus and contacted at 40 °C for 13 min. The pH of the system is 9. Then, centrifugal separation is carried out. The obtained solid product is first dried at 110 °C for 9 h and first calcined at 1100 °C for 4 h to obtain a rare earth-doped zirconia support. Among them, the mass-volume ratio of the zirconia support, silicotungstic acid, Gd(NO 3 ) 3The mass-volume ratio with ethanol is 1 g: 0.84 g: 0.2 g: 250 mL, the rotation speed of the rotating liquid film device is 3000 r / min, and the slit gap is 0.3 mm;

[0076] (2) Add the 0.04 mol / L H 2 PtCl 6 solution to the rare earth-doped zirconia support, then add NaBH 4 Reduce at 55 °C for 4 h, then perform centrifugal separation. Dry the obtained solid product at 110 °C for 9 h for the second time and calcine at 400 °C for 4 h for the second time to obtain the target catalyst product, where the mass-volume ratio of the rare earth-doped zirconia support to the H 2 PtCl 6 solution is 1 g: 0.0015 L.

[0077] Example 4

[0078] (1) In the presence of an ethanol solvent, add the titanium dioxide support, 1 mol / L NaOH solution, silicomolybdic acid, and Pr(NO 3 ) 3 to the rotating liquid film device and contact at 10 °C for 20 min. The system pH = 10, then perform centrifugal separation. Dry the obtained solid product at 80 °C for 5 h for the first time and calcine at 600 °C for 2 h for the first time to obtain the rare earth-doped titanium dioxide support, where the mass-volume ratio of the titanium dioxide support, silicomolybdic acid, Pr(NO 3 ) 3 to ethanol is 1 g: 1.13 g: 0.27 g: 150 mL, the rotation speed of the rotating liquid film device is 1500 r / min, and the slit gap is 0.1 mm;

[0079] (2) Add the 0.025 mol / L RuCl 3 solution to the rare earth-doped titanium dioxide support, then add LiAlH 4 Reduce at 90 °C for 2 h, then perform centrifugal separation. Dry the obtained solid product at 80 °C for 5 h for the second time and calcine at 250 °C for 2 h for the second time to obtain the target catalyst product, where the mass-volume ratio of the rare earth-doped titanium dioxide support to the RuCl 3 solution is 1 g: 0.005 L.

[0080] Example 5

[0081] (1) In the presence of an ethanol solvent, add the alumina support, 1 mol / L NaOH solution, phosphotungstic acid, and Ce(NO 3 ) 3Add it to a rotating liquid film device and contact it at 50 °C for 5 min. The pH of the system is 10. Then, perform centrifugal separation. Dry the obtained solid product for the first time at 120 °C for 10 h and calcine it for the first time at 1200 °C for 5 h to obtain a rare earth-doped alumina support. Among them, the mass-volume ratio of the alumina support, phosphotungstic acid, Ce(NO 3 ) 3 to ethanol is 1 g: 0.29 g: 0.068 g: 150 mL. The rotation speed of the rotating liquid film device is 3500 r / min, and the slit gap is 0.3 mm;

[0082] (2) Add a 0.05 mol / L Cu(NO 3 ) 2 solution to the rare earth-doped alumina support, and then add LiBH 4 Reduce it at 40 °C for 5 h, then perform centrifugal separation. Dry the obtained solid product for the second time at 120 °C for 10 h and calcine it for the second time at 500 °C for 5 h to obtain the target catalyst product. Among them, the mass-volume ratio of the rare earth-doped alumina support to the Cu(NO 3 ) 2 solution is 1 g: 0.0005 L.

[0083] Comparative Example 1

[0084] Prepare the catalyst according to the method of Example 1, except that phosphotungstic acid is not added.

[0085] Comparative Example 2

[0086] Prepare the catalyst according to the method of Example 1, except that a rotating liquid film reactor is not used.

[0087] Comparative Example 3

[0088] Prepare the catalyst according to the method of Example 1, except that phosphotungstic acid is replaced with phosphoric acid.

[0089] Comparative Example 4

[0090] According to the preparation method of Example 1 in CN113600157A, catalyst D4 is obtained. The schematic aberration-corrected electron microscopy image of the obtained catalyst is as shown in Figure 1 (1). The white bright spots therein are rare earth element Eu. It can be seen that the rare earth element Eu shows agglomeration and does not achieve highly efficient atomic-level dispersion.

[0091] Perform the following performance tests on the catalysts prepared in the above examples and comparative examples, and the results are shown in Table 1.

[0092] Table 1

[0093]

[0094]

[0095] Test example

[0096] Apply the catalysts prepared in the examples and comparative examples to the hydrogenation of anthraquinone to prepare hydrogen peroxide.

[0097] The specific test method is as follows:

[0098] Add 25 mg of the prepared catalyst and 60 mL of a 120 g / L 2-ethylanthraquinone working solution (the solvent is 1,3,5-trimethylbenzene and tetrabutylurea with a volume ratio of 6:4) to a high-pressure reactor, introduce hydrogen to 0.3 MPa, react for 2 h, take 3 mL, filter with an organic filter head to remove the catalyst, then use a pipette to transfer 2 mL and put it into 20 mL of deionized water. At room temperature, place the mixture in a separatory funnel and use high-purity O 2 Oxidize. After the working solution returns to bright yellow, the oxidation ends. After the oxidation reaction, let the solution stand still sufficiently to separate layers. The upper layer is the reaction solution, and the lower layer is H 2 O 2 aqueous solution. Drain the lower aqueous solution from the separatory funnel and place it in a conical flask. Wash and extract the working solution in the separatory funnel with deionized water 4 times repeatedly to obtain the final H 2 O 2 aqueous solution. Titrate and analyze the content of H 4 with a 0.02 mol / L KMnO 2 solution 2 The yield of H 2 O 2 is calculated according to the following formula:

[0099]

[0100] Among them, η is the yield of H 2 O 2 (g / L), that is, the hydrogen efficiency in Table 2 below; C is the concentration of the KMnO 4 solution (0.02 mol / L); V is the volume of the consumed KMnO 4 solution, in mL; V 0 is the volume of the oxidized working solution (2 mL), and M is the relative molecular mass of H 2 O 2 .

[0101] The specific formula for selectivity is as follows:

[0102]

[0103] Among them, n(EAQ) and n(H4EAQ) are the number of moles of 2-ethylanthraquinone and tetrahydro-2-ethylanthraquinone in the working solution after the reaction, respectively, and n 0 (EAQ) is the number of moles of 2-ethylanthraquinone in the original working solution; the number of moles of 2-ethylanthraquinone and tetrahydro-2-ethylanthraquinone is measured by W1100 high performance liquid chromatography.

[0104] The calculation formula of the production capacity is as follows:

[0105]

[0106] Among them, η is the hydrogen efficiency, that is, the H 2 O 2 yield, in g / L; V is the volume of the working solution used in the reaction, in mL; m is the mass of the catalyst, in mg; L is the loading of the active component, in wt%; T is the reaction time (d).

[0107] The results are shown in Table 2.

[0108] Table 2

[0109]

[0110] Note: Since the catalyst obtained in Comparative Example 4 is a millimeter-sized catalyst and is suitable for tubular fixed-bed reaction, the data of Comparative Example 4 are the results in a tubular fixed-bed reactor.

[0111] As can be seen from Table 1 and Table 2, when the catalyst prepared in the examples of the present invention is used in the reaction of anthraquinone hydrogenation to prepare hydrogen peroxide, the rare earth metals in the catalyst are highly dispersed (atomic dispersion degree is 92.5-96.3%), making the catalyst have excellent catalytic performance. The hydrogen efficiency at 40 °C is 11.3-12.3 g / L, the hydrogen efficiency at 50 °C is 12.9-14.2 g / L, the selectivity is 97-99% and the production capacity at 40 °C is 19696-23616 kgH 2 O 2 / (kg active component·d) and the production capacity at 50 °C is 20268-27264 kgH 2 O 2 / (kg active component·d), and both the hydrogenation efficiency and the hydrogen peroxide selectivity are relatively high.

[0112] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A catalyst comprising a modified carrier and an active component supported on the modified carrier; the modified carrier comprises an inorganic heat-resistant oxide and a modified component, characterized in that: The modified component includes rare earth metal, and the atomic dispersion of the rare earth metal in the catalyst is not less than 92%.

2. The catalyst according to claim 1, wherein The atomic dispersion of the rare earth metal is 92-97%.

3. The catalyst according to claim 1, wherein Based on the total weight of the catalyst, the rare earth metal content is 1-20wt% in terms of oxide; Preferably, the rare earth metal is selected from at least one of Ce, Sm, Pr and Gd.

4. The catalyst according to any one of claims 1 to 3, wherein The modified component further comprises at least one of WO3, P2O5, MoO3 and SiO2, and the content of WO3, P2O5, MoO3 and SiO2 is 0.5-15wt% based on the total weight of the catalyst; Preferably, based on the total weight of the catalyst, the content of the active component is 0.05-5wt% and the content of the inorganic heat-resistant oxide is 60-98.45wt% in terms of oxide; Preferably, the active component is selected from at least one of Pd, Pt, Ru, Ni and Cu.

5. The catalyst according to claim 1, wherein The inorganic heat-resistant oxide is selected from at least one of alumina, titania and zirconium dioxide, preferably alumina and / or titania.

6. The catalyst according to claim 1, wherein The average particle size of the catalyst is 2-5 nm and the pore volume is 0.65-0.75 cm 3 / g, specific surface area is 90-150m 2 / g.

7. A method for preparing a catalyst, characterized in that: The method comprises the following steps: (1) contacting a carrier, a heteropoly acid and a rare earth salt in a rotary liquid film apparatus in the presence of a solvent, and then subjecting the solid product obtained by the contact to a first drying and a first calcination to obtain a rare earth doped carrier; (2) The metal salt solution of the active component is mixed with the rare earth doped carrier and subjected to reduction treatment, and then the obtained solid product is subjected to a second drying and a second calcination.

8. The preparation method according to claim 7, wherein: In step (1), the carrier is selected from inorganic heat-resistant oxides, preferably at least one selected from alumina, titania and zirconium dioxide, more preferably alumina and / or titania; Preferably, the heteropoly acid is selected from at least one of phosphotungstic acid, phosphomolybdic acid, silicotungstic acid and silicomolybdic acid; Preferably, the solvent is selected from at least one of ethanol, H2O and methanol, preferably ethanol; Preferably, the mass volume ratio of the carrier, heteropoly acid, rare earth salt and solvent is 1g: (0.1-5)g: (0.03-0.68)g: (150-250)mL; Preferably, the rare earth salt is selected from nitrates and / or sulfates of rare earth metals, more preferably at least one of Ce(NO3)3, Sm(NO3)3, Gd(NO3)3 and Pr(NO3)3 and their hydrates; Preferably, the contact conditions include: temperature of 10-50°C, time of 5-30 min, rotation speed of the rotary liquid film device of 1500-3500 r / min, and slit gap of 0.1-0.3 mm; Preferably, the conditions for the first drying include: a temperature of 80-120° C. and a time of 5-10 h; Preferably, the conditions for the first calcination include: a temperature of 600-1200° C. and a time of 2-5 hours.

9. The preparation method according to claim 7, wherein: In step (2), the metal salt solution is selected from at least one of aqueous solutions of K2PdCl4, Na2PdCl4, H2PtCl6, RuCl3, Cu(NO3)2 and Ni(NO3)2; Preferably, the concentration of the metal salt solution is 0.025-0.05 mol / L; Preferably, the mass volume ratio of the rare earth doped carrier to the metal salt solution is 1g: (0.0005-0.005)L； Preferably, the reduction conditions include: the reducing agent is selected from at least one of C2H5OH, CH3OH, HCHO, NaBH4, LiAlH4 and LiBH4, and the reduction time is 2-5h; Preferably, the conditions for the second drying include: a temperature of 80-120° C. and a time of 5-10 h; Preferably, the conditions for the second calcination include: a temperature of 250-500° C. and a time of 2-5 h.

10. A method for preparing hydrogen peroxide by hydrogenating anthraquinone, the method comprising contacting a 2-ethylanthraquinone solution with hydrogen in the presence of a catalyst for reaction, characterized in that: The catalyst is the catalyst described in any one of claims 1 to 6 or the catalyst prepared by the preparation method described in any one of claims 8 to 9; Preferably, the mass volume ratio of the catalyst to the 2-ethylanthraquinone solution is (3-10) mg:12 mL, preferably (4-8) mg:12 mL; the concentration of the 2-ethylanthraquinone solution is 90-150 g / L, preferably 100-120 g / L; the reaction conditions include: pressure of 0.1-0.5 MPa, preferably 0.2-0.4 MPa; temperature of 30-70°C, preferably 40-50°C; time of 0.5-3 h, preferably 1-2 h.

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