Perovskite composite oxide, method for producing the same, and method for synthesizing 2,3,6-trimethylphenol

Abstract

The application relates to the field of perovskite, and discloses a perovskite type composite oxide. 1‑ m A m Fe 1‑n A′ n O3, wherein A is selected from at least one of alkaline earth metal elements, A' is selected from at least one of Co, Ni, Cu and Zn, m ranges from 0.05 to 0.4, and n ranges from 0 to 0.4; the specific surface area of the perovskite type composite oxide is 20-60 m 2 / g; the specific surface area of the perovskite type composite oxide is large, the perovskite type composite oxide is applied to the reaction of 2,5-dimethylphenol for preparing 2,3,6-trimethylphenol, the conversion rate of 2,5-dimethylphenol is high, and the selectivity of 2,3,6-trimethylphenol is high.

Description

Technical Field

[0001] This invention relates to the field of perovskites, specifically to a perovskite-type composite oxide, its preparation method and application, and a method for synthesizing 2,3,6-trimethylphenol. Background Technology

[0002] 2,3,6-Tricresol is an important raw material for the production of vitamin E, polyphenylene ether engineering plastics, and plastic alloys. In addition, it is widely used in the production of food and feed additives, cosmetics, pesticides, and disinfectants. Currently, the commonly used large-scale industrial production method of 2,3,6-tricresol mainly achieves this through the methylation reaction of phenols. This involves using methanol as the methylating agent and m-cresol or 2,5-xylenol as the raw material, with the reaction completed under certain conditions through the action of a catalyst.

[0003] Numerous documents and patents have reported on related reactions and catalysts. CN102974354B discloses a catalyst using m-cresol as a raw material, which is composed of iron oxide, silicon dioxide, aluminum oxide, and alkali metal oxide.

[0004] CN101844968A discloses a preparation process using 2,5-xylenol as a raw material, employing iron-based composite oxides doped with elements such as Ge, Cr, and In as catalysts. Besides iron oxide-based catalysts, numerous publications have also reported on iron-containing composite oxides with spinel-type structures as catalysts for the ortho-methylation of phenols.

[0005] Perovskite ABO3 is another common type of complex oxide. Compared to single oxides, complex oxides with a perovskite structure often exhibit high stability when used as catalysts. However, there are few reports on the use of perovskite oxides in the ortho-methylation reaction of phenols. Summary of the Invention

[0006] The inventors of this invention discovered in their research that perovskite composite oxides possess good structural modulometry and stability, but due to their low specific surface area and poor catalytic performance, they are difficult to use industrially for catalyzing ortho-methylation reactions of phenols. The purpose of this invention is to overcome the problem that existing perovskite catalysts have low specific surface area and are difficult to apply to ortho-methylation reactions of phenols, such as the inability to apply them to the methylation reaction of 2,5-xylenol. This invention provides a perovskite composite oxide, its preparation method, its application, and a method for synthesizing 2,3,6-trimethylphenol.

[0007] To achieve the above objectives, a first aspect of the present invention provides a perovskite-type composite oxide having the general formula Yi. 1-m A m Fe 1-n A′ nThe composition shown in O3 includes A selected from at least one alkaline earth metal element, A′ selected from at least one of Co, Ni, Cu, and Zn, m ranging from 0.05 to 0.4, and n ranging from 0 to 0.4; the specific surface area of ​​the perovskite-type composite oxide is 20-60 m². 2 / g.

[0008] The second aspect of the present invention provides a method for preparing a composite oxide, the method comprising: contacting a solution containing a Y precursor, an A precursor, an Fe precursor and / or an A precursor with a template agent, and then drying and calcining the obtained product, wherein A is selected from at least one alkaline earth metal element, and A′ is selected from at least one of Co, Ni, Cu and Zn.

[0009] A third aspect of the present invention provides a composite oxide prepared by the method described in the second aspect of the present invention.

[0010] The fourth aspect of the present invention provides the application of the composite oxide described in the first or third aspect of the present invention as a catalyst in the ortho-methylation reaction of phenol and its derivatives.

[0011] The fifth aspect of the present invention provides a method for synthesizing 2,3,6-trimethylphenol, the method comprising: subjecting 2,5-dimethylphenol to a gas-phase catalytic reaction in the presence of methanol and a catalyst; wherein the catalyst comprises the composite oxide described in the first or third aspect of the present invention.

[0012] The perovskite-type composite oxide provided by this invention has a large specific surface area. When applied to the reaction of 2,5-xylenol to 2,3,6-trimethylphenol, the conversion rate of 2,5-xylenol is high and the selectivity of 2,3,6-trimethylphenol is high.

[0013] The perovskite-type composite oxide provided by this invention improves the activity and stability of the perovskite-type composite oxide through the combination of multiple elements. At the same time, the perovskite-type composite oxide has a high specific surface area, which increases the reactive sites and improves the reactivity. Attached Figure Description

[0014] Figure 1 This is a scanning electron microscope image of the perovskite-type composite oxide prepared in Example 1.

[0015] Figure 2 This is a scanning electron microscope image of the perovskite-type composite oxide prepared in Comparative Example 2. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] The first aspect of this invention provides a perovskite-type composite oxide having the general formula Y 1- m A m Fe 1-n A′ n The composition shown in O3 includes A selected from at least one alkaline earth metal element, A′ selected from at least one of Co, Ni, Cu, and Zn, m ranging from 0.05 to 0.4, and n ranging from 0 to 0.4; the specific surface area of ​​the perovskite-type composite oxide is 20-60 m². 2 / g. The perovskite-type composite oxide provided by this invention has a high specific surface area, and when used to synthesize 2,3,6-trimethylphenol from 2,5-xylenol, both the raw material conversion rate and product selectivity are high.

[0018] In this invention, the content of each element in the perovskite-type composite oxide is determined by ICP-AES (inductively coupled plasma atomic emission spectrometry).

[0019] The inventors of this invention have discovered that if m is greater than 0.4 and / or n is greater than 0.4, it is impossible to form a composite oxide with a perovskite structure.

[0020] In this invention, m can be 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, or any range of any two of the above values ​​and any value within that range.

[0021] In this invention, n can be 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, or any range of any two of the above values, and any value within that range. To further improve the catalytic activity of perovskite-type composite oxides in the methylation reaction of 2,5-xylenol, preferably, the range of m is 0.05-0.3, more preferably 0.1-0.3; in some particularly preferred embodiments, the range of m is 0.15-0.25.

[0022] In this invention, in order to further improve the catalytic activity of perovskite-type composite oxides in the methylation reaction of 2,5-xylenol, preferably, the range of n is 0-0.2, more preferably 0.05-0.2; in some particularly preferred embodiments, the range of n is 0.05-0.15.

[0023] In this invention, in order to further improve the catalytic activity of perovskite-type composite oxides in the methylation reaction of 2,5-xylenol, preferably, the range of m is 0.05-0.3 and the range of n is 0-0.2; more preferably, the range of m is 0.1-0.3 and the range of n is 0.05-0.2; in some particularly preferred embodiments, the range of m is 0.15-0.25 and the range of n is 0.05-0.15.

[0024] In the perovskite-type composite oxide provided by this invention, the composition and structure of the perovskite metal oxide are adjusted by introducing A and A′ ions. On the one hand, the introduction of A and A′ ions can generate lattice defects and increase the specific surface area of ​​the perovskite metal oxide. On the other hand, the addition of A and A′ ions is beneficial to the interconversion between ferric and ferrous iron, thereby improving the catalytic activity of the perovskite metal oxide in the synthesis of 2,5-xylenol from 2,3,6-trimethylphenol.

[0025] In this invention, there is no particular limitation on the types of A and A′ ions, as long as they can cause lattice defects in the perovskite metal oxide. In order to achieve high raw material conversion rate and product selectivity and reduce cost when the obtained perovskite-type composite oxide catalyzes the synthesis of 2,5-xylenol from 2,3,6-trimethylphenol, the A is preferably selected from at least one of Mg, Ca, Sr, and Ba, and more preferably Mg and / or Ba.

[0026] In this invention, in order to further improve the specific surface area of ​​the perovskite-type composite oxide and its catalytic activity in the methylation reaction of 2,5-xylenol, preferably, A′ is selected from Co and / or Cu.

[0027] In this invention, the specific surface area of ​​the perovskite-type composite oxide can be 20-60 m². 2 / g, for example 20m 2 / g、21m 2 / g、22m 2 / g、23m 2 / g、24m 2 / g、25m 2 / g、26m 2 / g、27m 2 / g、28m 2 / g、29m 2 / g、30m2 / g、31m 2 / g、32m 2 / g、33m 2 / g、34m 2 / g、35m 2 / g、36m 2 / g、37m 2 / g、38m 2 / g、39m 2 / g、40m 2 / g、41m 2 / g、42m 2 / g、43m 2 / g、44m 2 / g、45m 2 / g、46m 2 / g、47m 2 / g、48m 2 / g、49m 2 / g, 50m 2 / g、51m 2 / g、52m 2 / g、53m 2 / g、54m 2 / g、55m 2 / g、56m 2 / g、57m 2 / g、58m 2 / g、59m 2 / g、60m 2 / g, and any range and any value within any range of any two of the above values. To further improve the catalytic activity of the perovskite-type composite oxide in the methylation reaction of 2,5-xylenol, preferably, the specific surface area of ​​the perovskite-type composite oxide is 30-60 m². 2 / g, more preferably 38-55m 2 / g.

[0028] In this invention, to further improve the catalytic activity of the perovskite-type composite oxide in the methylation reaction of 2,5-xylenol, preferably, the pore volume of the perovskite-type composite oxide is 0.05-0.3 cm³. 3 / g, for example, can be 0.05cm 3 / g, 0.1cm 3 / g, 0.15cm 3 / g, 0.2cm 3 / g, 0.25cm 3 / g, 0.3cm 3 / g, and any range of any two of the above values, and any value within that range; more preferably, the pore volume is 0.05-0.2cm. 3 / g, more preferably 0.05-0.15cm 3 / g.

[0029] In this invention, in order to further improve the catalytic activity of perovskite-type composite oxides in the methylation reaction of 2,5-xylenol, preferably, the average pore size is 5-60 nm, for example, it can be 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, and any range of any two of the above values ​​and any value within the range; more preferably, the average pore size is 5-20 nm, and even more preferably 8-15 nm.

[0030] In this invention, Example 1 is provided as an exemplary illustration of the pore volume and average pore size of a perovskite-type composite oxide obtained according to a preferred embodiment of the invention, but does not limit the scope of the invention.

[0031] Catalysts possessing the aforementioned characteristics of this invention can all be used in this invention, and there are no special requirements for their preparation methods. In view of this invention, a second aspect provides a method for preparing a composite oxide, the method comprising: contacting a solution containing a Y precursor, an A precursor, an Fe precursor and / or an A′ precursor with a template agent, and then drying and calcining the obtained product, wherein A is selected from at least one alkaline earth metal element, and A′ is selected from at least one of Co, Ni, Cu and Zn.

[0032] In this invention, preferably, the A precursor is selected from oxygen-containing salts and / or oxygen-containing salt hydrates containing A; more preferably, the A precursor is selected from at least one of the chloride, nitrate or acetate of A.

[0033] In this invention, preferably, the Y precursor is selected from oxy-containing salts and / or oxy-containing salt hydrates containing Y; more preferably, the Y precursor is selected from at least one of yttrium nitrate, yttrium acetate, or yttrium chloride.

[0034] In this invention, preferably, the Fe precursor is selected from Fe-containing oxygen salts and / or oxygen-containing salt hydrates; more preferably, the Fe precursor is selected from at least one of ferric acetate, ferric nitrate, or ferric chloride.

[0035] In this invention, preferably, the A′ precursor is selected from oxygen-containing salts and / or oxygen-containing salt hydrates containing A; more preferably, the A′ is selected from at least one of the chloride, nitrate or acetate of A;

[0036] In this invention, the Y precursor, A precursor, Fe precursor, and / or A′ precursor are converted into the general formula Y during subsequent calcination. 1-m A m Fe 1-n A′ n O3 perovskite-type composite oxide, wherein the stoichiometry of each precursor is relative to the general formula Y 1-m A m Fe 1-n A′ n In the perovskite-type composite oxide of O3, the stoichiometric ratios of Y, A, Fe, and A′ elements are consistent.

[0037] In this invention, to further improve the specific surface area of ​​the perovskite-type composite oxide and its catalytic activity in the methylation reaction of 2,5-xylenol, preferably, in the solution, the sum of the ion concentrations of the Y precursor, A precursor, Fe precursor and / or A′ precursor, calculated by metal element, is 0.1-3 mol / L. For example, it can be 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.4 mol / L, 2.6 mol / L, 2.8 mol / L, 3 mol / L, and any range of any two of the above values, more preferably 0.2-2 mol / L, and even more preferably 1-2 mol / L.

[0038] In this invention, in order to further improve the specific surface area of ​​the perovskite-type composite oxide and its catalytic activity in the methylation reaction of 2,5-xylenol, preferably, the molar ratio of the total amount of Y precursor, A precursor, Fe precursor and A′ precursor, based on metal elements, is 1:(0.04-1):(0.5-2):(0-1), more preferably 1:(0.04-0.5):(0.5-1.5):(0-0.3), more preferably 1:(0.1-0.5):(0.8-1.5):(0.05-0.3); in some particularly preferred embodiments, the molar ratio of Y precursor to A precursor, based on metal elements, is 1:(0.1-0.4):(1-1.3):(0.05-0.2).

[0039] In this invention, in order to further improve the specific surface area of ​​the perovskite-type composite oxide and its catalytic activity in the methylation reaction of 2,5-xylenol, preferably, the molar ratio of the Y precursor to the A precursor, based on metal elements, is 1:(0.04-1), more preferably 1:(0.04-0.5), even more preferably 1:(0.1-0.5), and in some particularly preferred embodiments, it is 1:(0.1-0.4).

[0040] In this invention, in order to further improve the specific surface area of ​​the perovskite-type composite oxide and its catalytic activity in the methylation reaction of 2,5-xylenol, preferably, the molar ratio of the Fe precursor to the A′ precursor is 1:(0-1), more preferably 1:(0-0.3), even more preferably 1:(0.05-0.3), and in some particularly preferred embodiments, it is 1:(0.05-0.2).

[0041] In this invention, in order to further improve the specific surface area of ​​the perovskite-type composite oxide and its catalytic activity in the methylation reaction of 2,5-xylenol, preferably, the molar ratio of the Y precursor to the Fe precursor, based on metal elements, is 1:(0.5-2), more preferably 1:(0.5-1.5), even more preferably 1:(0.8-1.5), and in some particularly preferred embodiments, it is 1:(1-1.3).

[0042] In this invention, in order to further improve the specific surface area of ​​the perovskite-type composite oxide and its catalytic activity in the methylation reaction of 2,5-xylenol, preferably, the template agent is amorphous carbon, which is commercially available.

[0043] In this invention, preferably, the contact includes impregnation. In order to further improve the specific surface area of ​​the perovskite-type composite oxide and its catalytic activity in the methylation reaction of 2,5-xylenol, the contact is an equal-volume impregnation method or an excess impregnation method. The equal-volume impregnation method or the excess impregnation method is not particularly limited and can be implemented in a conventional manner.

[0044] In this invention, to further improve the specific surface area of ​​the perovskite-type composite oxide and its catalytic activity in the methylation reaction of 2,5-xylenol, preferably, the specific surface area of ​​the template agent is 300 m². 2 / g or more, preferably 300-1500m 2 / g, for example, can be 300m 2 / g、400m 2 / g、500m 2 / g、600m 2 / g、700m 2 / g、800m2 / g、900m 2 / g, 1000m 2 / g、1100m 2 / g、1200m 2 / g、1300m 2 / g, 1400m 2 / g, 1500m 2 / g and any range of any two of the above values, and any value within that range, more preferably 300-800m 2 / g.

[0045] In this invention, in order to further improve the specific surface area of ​​the perovskite-type composite oxide and its catalytic activity in the methylation reaction of 2,5-xylenol, preferably, the mass ratio of the solution to the template agent is (0.2-1.5):1, for example, it can be 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, and any range and any value within any range of any two of the above values, more preferably (0.2-1.2):1, and even more preferably (0.5-1):1.

[0046] In this invention, the drying temperature is sufficient to remove the solvent and is not particularly limited. In order to improve the specific surface area of ​​the perovskite-type composite oxide and its catalytic activity in the methylation reaction of 2,5-xylenol, the drying temperature is preferably 50-80°C, for example, it can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, or any range of any two of the above values ​​and any value within the range.

[0047] In this invention, the drying time is sufficient to remove the solvent. To further improve the specific surface area of ​​the perovskite-type composite oxide and its catalytic activity in the methylation reaction of 2,5-xylenol, the drying time is preferably 2-36 hours, for example, 2 hours, 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, 36 hours, and any two of the above values, or any value within the range, and more preferably 12-36 hours.

[0048] In this invention, the calcination temperature is sufficient to remove the template agent and reduce the sintering effect of high temperature on the perovskite composite oxide. In order to further improve the specific surface area of ​​the perovskite composite oxide and its catalytic activity in the methylation reaction of 2,5-xylenol, the calcination temperature is preferably 500-900℃, more preferably 600-900℃.

[0049] In this invention, the calcination time is sufficient to remove the template agent and reduce the sintering effect of high temperature on the perovskite composite oxide. In order to further improve the specific surface area of ​​the perovskite composite oxide and its catalytic activity in the methylation reaction of 2,5-xylenol, preferably, the calcination time is 2-10h, for example, it can be 2h, 4h, 6h, 8h, 10h, or any two of the above values ​​and any value within the range, more preferably 2-6h.

[0050] A third aspect of the present invention provides a composite oxide prepared by the method described in the second aspect of the present invention.

[0051] The fourth aspect of the present invention provides the application of the composite oxide described in the first or third aspect of the present invention as a catalyst in the ortho-methylation reaction of phenol and its derivatives, for example, in the preparation of 2,3,6-trimethylphenol from phenol and / or phenol containing methyl groups.

[0052] In this invention, preferably, the application is in the preparation of 2,3,6-trimethylphenol from 2,5-xylenol.

[0053] The fifth aspect of the present invention provides a method for synthesizing 2,3,6-trimethylphenol, the method comprising: subjecting 2,5-dimethylphenol to a gas-phase catalytic reaction in the presence of methanol and a catalyst; wherein the catalyst comprises the composite oxide described in the first or third aspect of the present invention.

[0054] According to a preferred embodiment of the present invention, the reactor for the catalytic reaction is not particularly limited, and a conventional reactor in the art is acceptable. In order to further improve the selectivity and conversion rate of the catalytic reaction, the reaction is preferably carried out in a fixed-bed reactor.

[0055] According to a preferred embodiment of the present invention, preferably, the methanol and 2,5-xylenol are vaporized before the reaction.

[0056] In this invention, preferably, the perovskite-type composite oxide can be made into particles, for example, into 60-80 mesh particles.

[0057] In this invention, the reaction conditions and reaction time for synthesizing 2,3,6-trimethylphenol can be adjusted according to actual needs, as long as 2,3,6-trimethylphenol can be obtained.

[0058] In this invention, the amount of perovskite-type composite oxide used is not particularly limited and can be adjusted according to actual needs. In the examples, the amount of perovskite-type composite oxide loaded in the fixed-bed reactor is 30 ml as an example to illustrate the advantages of this invention, but this does not limit the scope of this invention.

[0059] In this invention, in order to further improve the selectivity and conversion rate of the catalytic reaction, preferably, the reaction conditions include: the reactants are 2,5-xylenol, methanol and water, and the molar ratio of 2,5-xylenol, methanol and water is 1:(0.05-8):(0.01-2); in the examples, the molar ratio of 2,5-xylenol, methanol and water is 1:(1.5):(0.2) as an example to illustrate the advantages of the invention, but does not limit the scope of the invention.

[0060] Preferably, the reaction temperature is 200-500℃, for example, it can be 200℃, 220℃, 240℃, 260℃, 280℃, 300℃, 320℃, 340℃, 360℃, 380℃, 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, and any two of the above values, or any value within the range; in the embodiments, a reaction temperature of 320℃ is used as an example to illustrate the advantages of the present invention, but this does not limit the scope of the present invention.

[0061] Preferably, the reaction pressure is 0-1 MPa, for example, it can be 0 MPa, 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, and any two of the above values, or any value within the range; in the embodiments, a reaction pressure of 0.1 MPa is used as an example to illustrate the advantages of the present invention, but this does not limit the scope of the present invention.

[0062] Preferably, the volume hourly space velocity (VHSV) of the reactant feed is 0.2-3 h⁻¹. -1 For example, it can be 0.2h -1 0.3h -1 0.4h -1 0.5h -1 0.6h -1 0.7h -1 0.8h -1 0.9h -1 1h -1 1.1h -1 1.2h -1 1.3h -1 1.4h -1 1.5h -1 1.6h -1 1.7h -1 1.8h -1 1.9h -1 2h -1 2.1h -1 2.2h -12.3h -1 2.4h -1 2.5h -1 2.6h -1 2.7h -1 2.8h -1 2.9h -1 3h -1 And the range formed by any two of the above values, and any value within the range; in the example, the volume hourly space velocity of the reactant feed is 0.5 h⁻¹. -1 The advantages of the invention are illustrated by way of example, but are not intended to limit the scope of the invention.

[0063] The present invention will be described in detail below through embodiments. It should be understood that the embodiments and examples described herein are for illustration and explanation only and are not intended to limit the present invention.

[0064] Unless otherwise specified, all reagents or instruments used in the examples are commercially available conventional products.

[0065] ICP-AES analysis revealed that the composition of each metal element in the perovskite-type composite oxide was close to the amount of feed.

[0066] Determination of specific surface area, pore volume and average pore size of perovskite-type composite oxides: The specific surface area was calculated by the Brunauer-Emmett-Teller (BET) method. The pore volume and average pore size were determined from the desorption branch of the N2 adsorption isotherm using this method. The measuring instrument was a Micromeritics ASAP 2460 from the United States.

[0067] Example 1

[0068] Preparation of Y 0.8 Mg 0.2 Fe 0.9 Co 0.1 O3 (m = 0.2, n = 0.1):

[0069] 29.20 g of Y(NO3)3·6H2O, 2.97 g of Mg(NO3)2, 36.36 g of Fe(NO3)3·9H2O, and 2.91 g of Co(NO3)2·6H2O were weighed and dissolved in 120 g of H2O to obtain a solution. This solution was then impregnated onto 200 g of amorphous carbon using an equal-volume impregnation method. The specific surface area of ​​the amorphous carbon was 782 m². 2 / g.

[0070] The impregnated powder was dried in an oven at 60°C for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 800°C for 4 hours.

[0071] Example 2

[0072] The method is the same as in Example 1, except that A is Ca.

[0073] Preparation of Y 0.8 Ca 0.2 Fe 0.9 Co 0.1 O3 (m = 0.2, n = 0.1): Weigh 29.20g Y(NO3)3·6H2O, 3.28g Ca(NO3)2, 36.36g Fe(NO3)3·9H2O, and 2.91g Co(NO3)2·6H2O, and dissolve them in 120g H2O to obtain a solution. Impregnate 200g of amorphous carbon with this solution using an equal-volume impregnation method. The specific surface area of ​​the amorphous carbon is 782 m². 2 / g.

[0074] The impregnated powder was dried in an oven at 60°C for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 800°C for 4 hours.

[0075] Example 3

[0076] The method is the same as in Example 1, except that A is Sr.

[0077] Preparation of Y 0.8 Sr 0.2 Fe 0.9 Co 0.1 O3 (m = 0.2, n = 0.1): 29.20 g Y(NO3)3·6H2O, 4.23 g Sr(NO3)2, 36.36 g Fe(NO3)3·9H2O, and 2.91 g Co(NO3)2·6H2O were weighed and dissolved in 120 g H2O to obtain a solution. This solution was then impregnated onto 200 g of amorphous carbon using an equal-volume impregnation method. The specific surface area of ​​the amorphous carbon was 782 m². 2 / g.

[0078] The impregnated powder was dried in an oven at 60°C for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 800°C for 4 hours.

[0079] Example 4

[0080] The method is the same as in Example 1, except that A is Ba.

[0081] Preparation of Y 0.8 Ba 0.2 Fe 0.9 Co 0.1O3 (m = 0.2, n = 0.1): Weigh 29.20g Y(NO3)3·6H2O, 5.23g Ba(NO3)2, 36.36g Fe(NO3)3·9H2O, and 2.91g Co(NO3)2·6H2O, and dissolve them in 120g H2O to obtain a solution. Impregnate 200g of amorphous carbon with this solution using an equal-volume impregnation method. The specific surface area of ​​the amorphous carbon is 782 m². 2 / g.

[0082] The impregnated powder was dried in an oven at 60°C for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 800°C for 4 hours.

[0083] Example 5

[0084] The method is the same as in Example 1, except that A′ is Ni.

[0085] Preparation of Y 0.8 Mg 0.2 Fe 0.9 Ni 0.1 O3 (m = 0.2, n = 0.1): 29.20 g Y(NO3)3·6H2O, 2.97 g Mg(NO3)2, 36.36 g Fe(NO3)3·9H2O, and 2.91 g Ni(NO3)2·6H2O were weighed and dissolved in 120 g H2O to obtain a solution. This solution was then impregnated onto 200 g of amorphous carbon using an equal-volume impregnation method. The specific surface area of ​​the amorphous carbon was 782 m². 2 / g.

[0086] The impregnated powder was dried in an oven at 60°C for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 800°C for 4 hours.

[0087] Example 6

[0088] The method is the same as in Example 1, except that A′ is Cu.

[0089] Preparation of Y 0.8 Mg 0.2 Fe 0.9 Cu 0.1 O3 (m=0.2, n=0.1): Weigh 29.20g Y(NO3)3·6H2O, 2.97g Mg(NO3)2, 36.36g Fe(NO3)3·9H2O, and 2.42g Cu(NO3)2·3H2O and dissolve them in 120g H2O to obtain a solution. Impregnate 200g of amorphous carbon with the above solution using an equal-volume impregnation method.

[0090] The specific surface area of ​​the aforementioned amorphous carbon is 782 m². 2 / g. The impregnated powder was placed in an oven at 60℃ and dried for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 800℃ for 4 hours.

[0091] Example 7

[0092] The method is the same as in Example 1, except that A′ is Zn.

[0093] Preparation of Y 0.8 Mg 0.2 Fe 0.9 Zn 0.1 O3 (m = 0.2, n = 0.1): Weigh 29.20g Y(NO3)3·6H2O, 2.97g Mg(NO3)2, 36.36g Fe(NO3)3·9H2O, and 2.97g Zn(NO3)2·6H2O, and dissolve them in 120g H2O to obtain a solution. Impregnate 200g of amorphous carbon with this solution using an equal-volume impregnation method. The specific surface area of ​​the amorphous carbon is 782 m². 2 / g. The impregnated powder was placed in an oven at 60℃ and dried for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 800℃ for 4 hours.

[0094] Example 8

[0095] The method is the same as in Example 1, except that the A′ element is missing (n = 0).

[0096] Preparation of Y 0.8 Mg 0.2 FeO3 (m=0.2, n=0): 29.20g Y(NO3)3·6H2O, 2.97g Mg(NO3)2, and 40.40g Fe(NO3)3·9H2O were weighed and dissolved in 120g H2O to obtain a solution. This solution was then impregnated onto 200g of amorphous carbon using an equal-volume impregnation method. The specific surface area of ​​the amorphous carbon was 782m². 2 / g. The impregnated powder was placed in an oven at 60℃ and dried for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 800℃ for 4 hours.

[0097] Example 9

[0098] The method is the same as in Example 1, except that m = 0.2 and n = 0.4.

[0099] Preparation of Y 0.8 Mg 0.2 Fe 0.6 Co 0.4O3 (m=0.2, n=0.4): 29.20g Y(NO3)3·6H2O, 2.97g Mg(NO3)2, 24.24g Fe(NO3)3·9H2O, and 11.64g Co(NO3)2·6H2O were weighed and dissolved in 120g H2O to obtain a solution. This solution was then impregnated onto 200g of amorphous carbon using an equal-volume impregnation method. The specific surface area of ​​the amorphous carbon was 782m². 2 / g. The impregnated powder was placed in an oven at 60℃ and dried for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 800℃ for 4 hours.

[0100] Example 10

[0101] The method is the same as in Example 1, except that m = 0.05 and n = 0.1.

[0102] Preparation of Y 0.95 Mg 0.05 Fe 0.9 Co 0.1 O3 (m = 0.05, n = 0.1): 34.67 g Y(NO3)3·6H2O, 0.74 g Mg(NO3)2, 36.36 g Fe(NO3)3·9H2O, and 2.91 g Co(NO3)2·6H2O were weighed and dissolved in 120 g H2O to obtain a solution. This solution was then impregnated onto 200 g of amorphous carbon using an equal-volume impregnation method. The specific surface area of ​​the amorphous carbon was 782 m². 2 / g. The impregnated powder was placed in an oven at 60℃ and dried for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 800℃ for 4 hours.

[0103] Example 11

[0104] The method is the same as in Example 1, except that m = 0.4 and n = 0.1.

[0105] Preparation of Y 0.6 Mg 0.4 Fe 0.9 Co 0.1 O3 (m = 0.4, n = 0.1): Weigh 21.90 g Y(NO3)3·6H2O, 5.93 g Mg(NO3)2, 36.36 g Fe(NO3)3·9H2O, and 2.91 g Co(NO3)2·6H2O, and dissolve them in 120 g H2O to obtain a solution. Impregnate 200 g of amorphous carbon with this solution using an equal-volume impregnation method. The specific surface area of ​​the amorphous carbon is 782 m². 2 / g. The impregnated powder was placed in an oven at 60℃ and dried for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 800℃ for 4 hours.

[0106] Example 12

[0107] The method is the same as in Example 1, except for the amount of each precursor, the specific surface area of ​​the template agent, and the calcination time.

[0108] Preparation of Y 0.8 Mg 0.2 Fe 0.9 Co 0.1 O3 (m=0.2,n=0.1): Weigh 3.48g Y(NO3)3·6H2O, 0.35g Mg(NO3)2, 4.33g Fe(NO3)3·9H2O, and 0.35g Co(NO3)2·6H2O and dissolve them in 120g H2O to obtain a solution.

[0109] The above solution was impregnated onto 200g of amorphous carbon using an equal-volume impregnation method. The specific surface area of ​​the amorphous carbon was 400m². 2 / g. The impregnated powder was placed in an oven at 60℃ and dried for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 600℃ for 4 hours.

[0110] Example 13

[0111] The method is the same as in Example 1, except that the amount of each precursor and the specific surface area of ​​the template agent are different.

[0112] Preparation of Y 0.8 Mg 0.2 Fe 0.9 Co 0.1 O3 (m=0.2, n=0.1): Weigh 43.80g Y(NO3)3·6H2O, 4.46g Mg(NO3)2, 54.54g Fe(NO3)3·9H2O, and 4.37g Co(NO3)2·6H2O, and dissolve them in 120g H2O to obtain a solution. The total molar concentration of metal ions in the precursor aqueous solution is greater than 2mol / L.

[0113] The above solution was impregnated onto 200g of amorphous carbon using an equal-volume impregnation method. The specific surface area of ​​the amorphous carbon was 1500m². 2 / g. The impregnated powder was placed in an oven at 60℃ and dried for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 800℃ for 4 hours.

[0114] Example 14

[0115] The method is the same as in Example 1, except that the amount of amorphous carbon used is 230g, and the specific surface area is 259m². 2 / g. The specific preparation method is as follows:

[0116] Preparation of Y0.8 Mg 0.2 Fe 0.9 Co 0.1 O3 (m=0.2,n=0.1): Weigh 29.20g Y(NO3)3·6H2O, 2.97g Mg(NO3)2, 36.36g Fe(NO3)3·9H2O, and 2.91g Co(NO3)2·6H2O and dissolve them in 120g H2O to obtain a solution.

[0117] The above solution was impregnated onto 230g of amorphous carbon using an equal-volume impregnation method. The specific surface area of ​​the amorphous carbon was 259m². 2 / g. The impregnated powder was placed in an oven at 60℃ and dried for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 800℃ for 4 hours.

[0118] Example 15

[0119] The method is the same as in Example 1, except that m = 0.4, n = 0.4, and the general formula of the perovskite-type composite oxide is Y. 0.6 Mg 0.4 Fe 0.6 Co 0.4 O3.

[0120] Preparation of precursor aqueous solution: Weigh 21.90g Y(NO3)3·6H2O, 5.93g Mg(NO3)2, 24.24g Fe(NO3)3·9H2O, and 11.64g Co(NO3)2·6H2O and dissolve them in 120g H2O to obtain a solution.

[0121] Comparative Example 1

[0122] The method is the same as in Example 1, except that m = 0 and n = 0.

[0123] YFeO3 (m=0, n=0): Weigh 36.50g Y(NO3)3·6H2O and 40.40g Fe(NO3)3·9H2O

[0124] A solution was obtained by dissolving the amorphous carbon in 120g of H2O. This solution was then impregnated onto 200g of amorphous carbon using an equal-volume impregnation method. The specific surface area of ​​the amorphous carbon was 782 m². 2 / g. The impregnated powder was placed in an oven at 60℃ and dried for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 800℃ for 4 hours.

[0125] Comparative Example 2

[0126] Solvent-gel method for preparing Y 0.8 Mg 0.2 Fe 0.9Co 0.1 O3 (m=0.2, n=0.1): Weigh 29.20g Y(NO3)3·6H2O, 2.97g Mg(NO3)2, 36.36g Fe(NO3)3·9H2O, 2.91g Co(NO3)2·6H2O, and 46.11g citric acid, and dissolve them in 150g H2O to obtain a solution. Heat the above solution to 80℃ and stir continuously at this temperature until a gel-like substance is formed. Place the gel-like substance in an oven at 110℃ and dry it for 12 hours. Crush the dried sponge-like substance and place it in a muffle furnace, then calcine it at 800℃ for 4 hours.

[0127] The resulting perovskite-type composite oxide has a pore volume of 0.006 cm³. 3 / g, with an average pore size of 56.3nm.

[0128] Comparative Example 3

[0129] The purchased iron oxide catalyst (Sigma-Aldrich) was placed in a muffle furnace and calcined at 800°C for 4 hours.

[0130] Comparative Example 4

[0131] The method is the same as in Example 1, except that the element of A′ is Cr.

[0132] Y 0.8 Mg 0.2 Fe 0.9 Cr 0.1 O3 (m=0.2, n=0.1): Weigh 29.20g Y(NO3)3·6H2O, 2.97g

[0133] Mg(NO3)2, 36.36g Fe(NO3)3·9H2O, and 4.00g Cr(NO3)3·9H2O were dissolved in 120g H2O. The above solution was then impregnated onto 200g of amorphous carbon using an equal-volume impregnation method. The specific surface area of ​​the amorphous carbon was 782 m². 2 / g. The impregnated powder was placed in an oven at 60℃ and dried for 24 hours. The dried powder was then placed in a muffle furnace and calcined at 800℃ for 4 hours.

[0134] Test case

[0135] (1) Determination of specific surface area, pore volume and average pore size of perovskite composite oxides: The determination method was N2 isothermal adsorption method, and the instrument was a Micromeritics ASAP 2460 from the United States.

[0136] The results of the specific surface area measurement are shown in Table 1.

[0137] The perovskite-type composite oxide obtained in Example 1 has a pore volume of 0.11 cm³. 3 / g, with an average pore size of 10.2nm.

[0138] The perovskite-type composite oxide obtained in Comparative Example 2 has a pore volume of 0.006 cm³. 3 / g, with an average pore size of 56.3nm.

[0139] It can be seen that the perovskite-type composite oxide obtained in Example 1 of the present invention has a larger pore volume and an average pore size than Comparative Example 2.

[0140] (2) Morphology and Structure Testing: The crystal forms of the perovskite-type composite oxides in Example 1 and Comparative Example 2 were determined by scanning electron microscopy (SEM) as follows: Figure 1 , Figure 2 As shown, it was observed that the perovskite-type composite oxide prepared in Example 1 had a more porous structure, while Comparative Example 2 had a more dense lamellar morphology.

[0141] Based on the measurements of specific surface area, pore volume, and average pore size, it can be seen that the perovskite-type composite oxide obtained by the specific preparation method of this invention has a high specific surface area and a large number of pore structures.

[0142] (3) The perovskite-type composite oxides obtained in each example and comparative example are compressed into tablets, crushed and sieved to obtain 60-80 mesh particles for the reaction of 2,5-xylenol to prepare 2,3,6-trimethylphenol.

[0143] The specific steps are as follows: 30 mL of perovskite-type composite oxide is placed in a fixed bed; the molar ratio of 2,5-xylenol, methanol, and water is 1:(1.5):(0.2), and after mixing, it is vaporized through a vaporizer, and then discharged at a volume hourly space velocity of 0.5 h⁻¹. -1 The reaction was carried out in a fixed-bed reactor at a temperature of 320℃ and a pressure of 0.1MPa. The reacted material was collected in a condenser and analyzed by gas chromatography to obtain the conversion rate and selectivity. The results are shown in Table 1.

[0144] The catalytic products were analyzed by external standard method in gas chromatography.

[0145] The gas chromatograph is manufactured by Shimadzu Corporation, model GC-2014C.

[0146] 2,5-xylenol conversion rate (%) = (molar amount of 2,5-xylenol consumed in the reaction / molar amount of 2,5-xylenol added to the reaction) × 100%.

[0147] 2,3,6-Trimethylphenol selectivity (%) = (molar amount of 2,3,6-trimethylphenol produced in the reaction / theoretically produced molar amount of 2,3,6-trimethylphenol) × 100%.

[0148] Table 1

[0149]

[0150]

[0151] As can be seen from the results in Table 1, the perovskite-type composite oxide prepared using the technical solution described in this invention has a large specific surface area. Furthermore, when applied to the reaction of 2,5-xylenol to 2,3,6-trimethylphenol, it exhibits high conversion rate and high selectivity for 2,5-xylenol. This demonstrates that the perovskite-type composite oxide with the structure described in Examples 1-15, combined with a specific preparation method, can further enhance the catalytic activity of the perovskite-type composite oxide in the reaction of 2,5-xylenol to 2,3,6-trimethylphenol.

[0152] Examples 1-8, 10 and 12 have better overall performance (conversion rate and selectivity) than the other examples, with examples 1, 5, 6, 8 and 12 having the best overall performance.

[0153] In Example 13, the total molar concentration of metal ions in the precursor aqueous solution was outside the preferred range, and the specific surface area was smaller compared to Example 1; in Example 14, compared to Example 1, the amount of template agent was increased, and the specific surface area of ​​the template agent was less than 300 m². 2 / g indicates that when the specific surface area of ​​the template agent and the total molar concentration of metal ions in the precursor aqueous solution are within the preferred range, it is beneficial to increase the specific surface area of ​​the obtained perovskite oxide.

[0154] The perovskite-type composite oxide obtained in Comparative Example 1 lacks A-site and A′-site substitution. Although the specific surface area of ​​the perovskite-type composite oxide in Comparative Example 1 is larger than that in Examples 1-7 and 9-11, its catalytic activity is poor. Compared with Example 8, Comparative Example 1 lacks A-site substitution, and the conversion rate of 2,5-xylenol and the selectivity of 2,3,6-trimethylphenol are significantly lower than those in Example 8. This indicates that A-site substitution in perovskite has a significant promoting effect on improving the catalytic activity of perovskite-type composite oxide in the reaction of 2,5-xylenol to 2,3,6-trimethylphenol.

[0155] Comparative Example 2 is a perovskite-type composite oxide prepared by solvent-gel method, which has low specific surface area, small pore volume and average pore size, and poor catalytic activity.

[0156] Comparative Example 3 uses commercially available iron oxide, a commonly used catalyst in the preparation of 2,3,6-trimethylphenol from 2,5-xylenol. Its catalytic activity is lower than that of the examples, indicating that perovskite oxides have better catalytic activity.

[0157] The element A′ in Comparative Example 4 is Cr. Compared with Examples 5-7, although Comparative Example 4 has a larger specific surface area, its catalytic activity is lower than that of Examples 5-7. It can be seen that the perovskite oxide with specific composition, structure and specific surface area provided by the present invention can improve its catalytic activity in the reaction of 2,5-xylenol to 2,3,6-trimethylphenol.

[0158] 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 inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A perovskite-type composite oxide, characterized in that, The composite oxide has the general formula Y. 1-m A m Fe 1-n A′ n The composition shown in O3 includes A selected from at least one alkaline earth metal element, A′ selected from at least one of Co, Ni, Cu, and Zn, m ranging from 0.05 to 0.4, and n ranging from 0.05 to 0.4; the specific surface area of ​​the perovskite-type composite oxide is 20-60 m². 2 / g; The method for preparing the composite oxide includes: contacting a solution containing Y precursor, A precursor, Fe precursor and A′ precursor with a template agent, and then drying and calcining the resulting product; The template agent is amorphous carbon; The specific surface area of ​​the template agent is 300-1500 m². 2 / g; In the solution, the sum of the ion concentrations of the Y precursor, A precursor, Fe precursor, and A′ precursor, calculated as metal elements, is 0.1-2 mol / L.

2. The composite oxide according to claim 1, wherein, The A is selected from at least one of Mg, Ca, Sr, and Ba; And / or, the specific surface area of ​​the composite oxide is 30-60 m². 2 / g.

3. The composite oxide according to claim 2, wherein, The range of m is 0.05-0.3; And / or, the range of n is 0.05-0.2; And / or, the specific surface area of ​​the composite oxide is 38-55 m². 2 / g.

4. The composite oxide according to claim 3, wherein, The range of m is 0.1-0.

3.

5. A method for preparing the composite oxide according to any one of claims 1-4, the method comprising: A solution containing Y precursor, A precursor, Fe precursor and A′ precursor is contacted with a template agent, and the resulting product is then dried and calcined, wherein A is selected from at least one alkaline earth metal element, and A′ is selected from at least one of Co, Ni, Cu and Zn; In this context, the molar ratio of the total amount of Y precursor, A precursor, Fe precursor and A′ precursor, calculated by metal elements, is 1:(0.04-1):(0.5-2):(0-1). The template agent is amorphous carbon.

6. The method according to claim 5, wherein, The A is selected from at least one of Mg, Ca, Sr, and Ba.

7. The method according to claim 6, wherein, The A precursor is selected from oxygen-containing salts and / or oxygen-containing salt hydrates containing A; And / or, the Y precursor is selected from Y-containing oxygenated salts and / or oxygenated salt hydrates; And / or, the Fe precursor is selected from Fe-containing oxygen salts and / or oxygen-containing salt hydrates; And / or, the A′ precursor is selected from oxygenated salts and / or oxygenated salt hydrates containing A′.

8. The method according to claim 7, wherein, The A precursor is selected from at least one of the chloride, nitrate or acetate of A; And / or, the Y precursor is selected from at least one of yttrium nitrate, yttrium acetate, or yttrium chloride; And / or, the Fe precursor is selected from at least one of ferric acetate, ferric nitrate or ferric chloride; And / or, the A′ precursor is selected from at least one of the chloride, nitrate or acetate of A′.

9. The method according to any one of claims 5-8, wherein, Based on metallic elements, the molar ratio of the total amount of Y precursor, A precursor, Fe precursor and A′ precursor is 1:(0.04-0.5):(0.5-1.5):(0-0.3).

10. The method according to claim 9, wherein, Based on metallic elements, the molar ratio of the total amount of Y precursor, A precursor, Fe precursor and A′ precursor is 1:(0.1-0.5):(0.8-1.5):(0.05-0.3). And / or, based on metal elements, the sum of the ion concentrations of the Y precursor, A precursor, Fe precursor and A′ precursor is 0.2-2 mol / L.

11. The method according to claim 10, wherein, In the solution, the sum of the ion concentrations of the Y precursor, A precursor, Fe precursor, and A′ precursor, calculated as metal elements, is 1-2 mol / L.

12. The method according to any one of claims 5-8 and 10-11, wherein, The mass ratio of the solution to the template agent is (0.2-1.5):

1.

13. The method according to claim 12, wherein, The mass ratio of the solution to the template agent is (0.2-1.2):

1.

14. The method according to claim 13, wherein, The specific surface area of ​​the template agent is 300-800 m². 2 / g; And / or, the mass ratio of the solution to the template agent is (0.5-1):

1.

15. The method according to claim 9, wherein, The mass ratio of the solution to the template agent is (0.2-1.5):

1.

16. The method according to claim 15, wherein, The mass ratio of the solution to the template agent is (0.2-1.2):

1.

17. The method according to claim 16, wherein, The specific surface area of ​​the template agent is 300-800 m². 2 / g; And / or, the mass ratio of the solution to the template agent is (0.5-1):

1.

18. The method according to any one of claims 5-8, 10-11, and 13-17, wherein, The drying temperature is 50-80°C.

19. The method according to claim 18, wherein, The drying time is 2-36 hours; And / or, the calcination temperature is 500-900°C; And / or, the calcination time is 2-10 hours.

20. The method according to claim 19, wherein, The drying time is 12-36 hours; And / or, the calcination temperature is 600-900°C; And / or, the calcination time is 2-6 hours.

21. The method according to claim 9, wherein, The drying temperature is 50-80°C.

22. The method according to claim 21, wherein, The drying time is 2-36 hours; And / or, the calcination temperature is 500-900°C; And / or, the calcination time is 2-10 hours.

23. The method according to claim 22, wherein, The drying time is 12-36 hours; And / or, the calcination temperature is 600-900°C; And / or, the calcination time is 2-6 hours.

24. The method according to claim 12, wherein, The drying temperature is 50-80°C.

25. The method according to claim 24, wherein, The drying time is 2-36 hours; And / or, the calcination temperature is 500-900°C; And / or, the calcination time is 2-10 hours.

26. The method of claim 25, wherein, The drying time is 12-36 hours; And / or, the calcination temperature is 600-900°C; And / or, the calcination time is 2-6 hours.

27. A composite oxide prepared by the method of any one of claims 5-26.

28. The use of the composite oxide according to any one of claims 1-4 and 27 as a catalyst in the ortho-methylation reaction of phenol and its derivatives; in, The application is in the preparation of 2,3,6-trimethylphenol from 2,5-xylenol.

29. A method for synthesizing 2,3,6-trimethylphenol, characterized in that, The method comprises: subjecting 2,5-xylenol to a gas-phase catalytic reaction in the presence of methanol and a catalyst; wherein the catalyst comprises the composite oxide according to any one of claims 1-4 and 27.

30. The method according to claim 29, wherein, The conditions for the reaction include: The reactants are 2,5-xylenol, methanol, and water.

31. The method according to claim 30, wherein, The molar ratio of 2,5-xylenol, methanol, and water is 1:(0.05-8):(0.01-2). And / or, the reaction temperature is 200-500℃; And / or, the reaction pressure is 0-1 MPa; And / or, the feed volume hourly space velocity of the reactants is 0.2-3 h⁻¹. -1 .

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