Nano-gold supported titanium-silicon molecular sieve, preparation method thereof and method for propylene gas phase epoxidation

Abstract

The present application relates to the field of propylene epoxidation, and discloses a nano gold loaded titanium-silicon molecular sieve, characterized in that the nano gold loaded titanium-silicon molecular sieve comprises a titanium-silicon molecular sieve carrier and nano gold loaded on the carrier; wherein the content of the nano gold is 0.01wt%-1wt% based on the total amount of the nano gold loaded titanium-silicon molecular sieve; wherein the micropore volume of the nano gold loaded titanium-silicon molecular sieve is 0.06-0.18cm 3 / g, the particle size is 100-250nm, and the crystallinity is greater than or equal to 50%. The present application loads nano gold particles on a titanium-silicon molecular sieve with specific physical parameters by using microwave-assisted heating, and the nano gold loaded titanium-silicon molecular sieve obtained has high nano gold dispersity. When the nano gold loaded titanium-silicon molecular sieve is applied to propylene gas phase epoxidation reaction, it has high catalytic activity, the conversion rate of propylene is increased to 8%-14%, and the selectivity of propylene oxide is increased to 90%-95%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of propylene epoxidation, in particular to a nano-gold loaded titanium-silicon molecular sieve, a preparation method thereof and a propylene gas phase epoxidation method. BACKGROUND

[0002] Propylene oxide, also known as oxirane or methyl epoxide, has the chemical formula C3H6O and is an important propylene derivative. Propylene oxide has a low boiling point and is flammable and miscible with ethanol and diethyl ether.

[0003] Currently, the industrial production of propylene oxide mainly adopts chlorohydrination method, co-oxidation method and hydrogen peroxide direct oxidation method (HPPO). The chlorohydrination method needs to use toxic chlorine gas and produces a large amount of calcium chloride waste residue in the production process; the process benefit of the co-oxidation method is deeply affected by the co-produced products. The HPPO process is relatively simple and clean and environmentally friendly. The HPPO process uses titanium-silicon molecular sieve as a catalyst and hydrogen peroxide as an oxidant. Hydrogen peroxide is one of the main reactants and is used in a large amount; however, due to the cost and transportation problems of hydrogen peroxide, the HPPO process usually needs to be matched with a hydrogen peroxide production device. In order to further optimize the process layout, the production of hydrogen peroxide is integrated into the epoxidation process, that is, under the action of the catalyst, propylene directly reacts with hydrogen and oxygen to occur epoxidation. In order to realize the in-situ synthesis of hydrogen peroxide, another metal active center needs to be loaded on the original titanium-silicon molecular sieve carrier. Research has found that Au, Ag, Pd and their alloys can be used as active centers for catalyzing the generation of hydrogen peroxide.

[0004] As a carrier for loading metal nanoparticles, TS-1 molecular sieve not only has framework Ti atoms as active centers for catalyzing epoxidation reactions, but also has ten-membered ring micropore channels. The rich pore structure in the molecular sieve promotes the diffusion of reaction molecules in its interior while fully contacting and reacting with the adjacent framework Ti atoms. For conventional TS-1 molecular sieve, micropores with a pore size of 0.55 nm account for the majority, and the internal surface area and micropore volume are limited, which leads to limited reaction effect when the reaction molecules diffuse in the TS-1 channel. When using plugged TS-1 molecular sieve as a carrier for loading metal, only the framework Ti atoms on the outer surface of the particles can play a synergistic catalytic role with the metal nanoparticles, and a large number of four-coordinated Ti species in the interior of the particles do not play a catalytic role. Therefore, it is very important to use TS-1 molecular sieve carriers with high specific surface area to improve the catalytic reaction effect.

[0005] In addition, the dispersion of metal nanoparticles also has a significant impact on the catalytic effect. Currently, there is little research on the control of the dispersion of metal nanoparticles. SUMMARY

[0006] The present application aims to overcome the problems of low internal surface area of TS-1 molecular sieve carrier and control of dispersion of metal nanoparticles loaded thereon in the prior art, and provides a nano-gold loaded titanium-silicon molecular sieve, a preparation method thereof and a method for propylene gas phase epoxidation.

[0007] To achieve the above-mentioned object, the present application provides a nano-gold loaded titanium-silicon molecular sieve, wherein the nano-gold loaded titanium-silicon molecular sieve comprises a titanium-silicon molecular sieve carrier and nano-gold loaded on the carrier; wherein the content of the nano-gold is 0.01wt%-1wt% based on the total amount of the nano-gold loaded titanium-silicon molecular sieve; wherein the micropore volume of the nano-gold loaded titanium-silicon molecular sieve is 0.06-0.18cm 3 / g, the particle size is 100-250nm, and the crystallinity is ≥50%.

[0008] The present application provides a method for preparing a nano-gold loaded titanium-silicon molecular sieve, wherein the method comprises:

[0009] (1) uniformly mixing a silicon source, an alkaline template agent, a titanium source, water and isopropyl alcohol to obtain a titanium-silicon sol;

[0010] (2) adding a compound represented by formula (I) into the titanium-silicon sol, and subjecting the obtained mixture to hydrothermal crystallization and calcination to obtain a titanium-silicon molecular sieve;

[0011]

[0012]

[0013] wherein i is an integer of 1-6; R1, R2 and R3 are each independently selected from C1-C6 alkyl;

[0014] (3) mixing the titanium-silicon molecular sieve with an aqueous solution containing a gold-containing compound, and then adding a pH adjusting agent to obtain a first suspension;

[0015] (4) subjecting the first suspension to microwave heating until the pH is 6-10 to obtain a second suspension;

[0016] (5) filtering the second suspension, and subjecting the obtained filter residue to calcination to obtain the nano-gold loaded titanium-silicon molecular sieve.

[0017] The present application provides a nano-gold loaded titanium-silicon molecular sieve prepared by the method according to the second aspect.

[0018] The fourth aspect of the present application provides a method for propylene gas phase epoxidation, which comprises: mixing hydrogen, oxygen and propylene to react under the protection of inert gas and in the presence of a catalyst to obtain propylene oxide; the catalyst is the nano-gold loaded titanium silicalite molecular sieve of the first and third aspects.

[0019] Through the above technical solution, the nano-gold loaded titanium silicalite molecular sieve is obtained by loading nano-gold particles on the titanium silicalite molecular sieve with specific physical parameters in a microwave-assisted heating mode, and the nano-gold dispersion degree of the nano-gold loaded titanium silicalite molecular sieve is high. When the nano-gold loaded titanium silicalite molecular sieve is applied to propylene gas phase epoxidation reaction, it has high catalytic activity, the conversion rate of propylene is increased to 8%-14%, and the selectivity of propylene oxide is increased to 90%-95%. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a reaction path diagram of propylene gas phase epoxidation in the present application;

[0021] Figure 2 is a pore size distribution diagram of the titanium silicalite molecular sieve obtained in Preparation Example 1 of the present application;

[0022] Figure 3 is a TEM diagram of the titanium silicalite molecular sieve obtained in Preparation Example 1 of the present application;

[0023] Figure 4 is an XRD diagram of the titanium silicalite molecular sieve obtained in Preparation Example 1 of the present application;

[0024] Figure 5 is an XRD diagram of the titanium silicalite molecular sieve obtained in Preparation Example 5 of the present application;

[0025] Figure 6 is a pore size distribution diagram of the titanium silicalite molecular sieve obtained in Preparation Example 6 of the present application;

[0026] Figure 7 is a TEM diagram of the nano-gold loaded titanium silicalite molecular sieve obtained in Example 1 of the present application;

[0027] Figure 8 is a TEM diagram of the nano-gold loaded titanium silicalite molecular sieve obtained in Comparative Example 5 of the present application. DETAILED DESCRIPTION

[0028] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The ranges or values should be construed to be roughly about the ranges or values. For values comprising ranges, the endpoints between the ranges of values, between the endpoints and the individual values, and between the individual values, are not to be construed as mutually exclusive. New ranges can be created by combining the endpoints of the ranges or values with the individual values.

[0029] The first aspect of the present application provides a nano-gold loaded titanium-silicon molecular sieve, wherein the nano-gold loaded titanium-silicon molecular sieve comprises a titanium-silicon molecular sieve carrier and nano-gold loaded on the carrier; wherein the content of the nano-gold is 0.01wt%-1wt% based on the total amount of the nano-gold loaded titanium-silicon molecular sieve; wherein the micropore volume of the nano-gold loaded titanium-silicon molecular sieve is 0.06-0.18cm 3 / g, the particle size is 100-250nm, and the crystallinity is ≥50%.

[0030] According to the present application, preferably, the molar ratio of titanium to silicon in the nano-gold loaded titanium-silicon molecular sieve is 0.001-0.04:1, preferably 0.005-0.025.

[0031] In the present application, in the infrared spectrum of the nano-gold loaded titanium-silicon molecular sieve, the peak at a wave number of 960cm -1 is a characteristic peak of a framework Ti atom, the peak at a wave number of 800cm -1 is a characteristic peak of a Si-O-Si structure, and the ratio of the peak area at a wave number of 960cm -1 to the peak area at a wave number of 800cm -1 is too small, which indicates that the content of the framework Ti atom in the nano-gold loaded titanium-silicon molecular sieve is insufficient, and the catalytic performance is low, and vice versa, which indicates that part of the Ti atoms are aggregated into non-framework TiO2, which can cause the occurrence of a side reaction; preferably, in the infrared spectrum of the nano-gold loaded titanium-silicon molecular sieve, the ratio of the peak area at a wave number of 960cm -1 to the peak area at a wave number of 800cm -1 is 0.4-1.5.

[0032] According to the present application, preferably, more than 90% of the gold in the nano-gold has a valence of 0.

[0033] According to the present application, preferably, the number of Au particles in any 50nm*50nm area on the nano-gold loaded titanium-silicon molecular sieve differs by no more than 30%. In the present application, the particle size of the nano-gold particles and the number of the nano-gold particles in the 50nm*50nm area are determined by transmission electron microscopy (TEM), and the valence of the nano-gold particles is determined by XPS characterization.

[0034] In the present application, the number of Au particles in any 50nm*50nm region on the nanometer gold loaded titanium silicalite molecular sieve is not more than 30% different, which means that in the TEM photo of a single nanometer gold loaded titanium silicalite molecular sieve particle, the nanometer gold loaded titanium silicalite molecular sieve is divided into several (not less than three) 50nm*50nm regions, and the number of Au particles in each 50nm*50nm region is calculated, wherein the region with the most Au particles is A1 region, and the region with the least Au particles is A2 region, and (A1 region Au particle number-A2 region Au particle number) / A1 region Au particle number≤30%.

[0035] The second aspect of the present application provides a method for preparing a nanometer gold loaded titanium silicalite molecular sieve, wherein the method comprises:

[0036] (1) uniformly mixing a silicon source, an alkaline template agent, a titanium source, water and isopropyl alcohol to obtain a titanium silicate sol;

[0037] (2) adding a compound represented by formula (I) to the titanium silicate sol, and hydrothermally crystallizing and calcining the obtained mixture to obtain a titanium silicalite molecular sieve;

[0038]

[0039] wherein i is an integer of 1-6; R1, R2 and R3 are each independently selected from C1-C6 alkyl;

[0040] (3) mixing the titanium silicalite molecular sieve with an aqueous solution containing a gold compound, and then adding a pH adjusting agent to obtain a first suspension;

[0041] (4) microwave heating the first suspension to a pH of 6-10 to obtain a second suspension;

[0042] (5) filtering the second suspension, and calcining the obtained filter residue to obtain the nanometer gold loaded titanium silicalite molecular sieve.

[0043] In the present application, C1-C6 alkyl refers to an alkyl group with a total number of carbon atoms of 1-6, for example, it can be one of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl and n-hexyl.

[0044] In some preferred embodiments of the present application, i is an integer of 1-5, for example, it can be 1, 2, 3, 4 or 5.

[0045] In some preferred embodiments of the present application, R1, R2 and R3 are each independently selected from C1-C3 alkyl, which can be methyl, ethyl, n-propyl or isopropyl, preferably, R1, R2 and R3 are each independently selected from methyl, ethyl or n-propyl. In the present application, R1, R2 and R3 can be the same or different, preferably, R1, R2 and R3 are all the same.

[0046] In the present application, by using the compound shown in formula (I) as a silylating agent, a titanium silicalite molecular sieve with a full microporous structure can be formed through the weak intermolecular interaction force between the alkyl chains of the silylating agent during the hydrothermal crystallization reaction, and the titanium silicalite molecular sieve has a high specific surface area and pore volume, which is beneficial to the intracrystalline and intercrystalline mass transfer diffusion of reactant molecules and product molecules when the nanometer gold is loaded thereon to catalyze the propylene gas phase epoxidation reaction.

[0047] According to the present application, if the amount of the silylating agent (the compound shown in formula (I)) is too high, the crystallization performance of the titanium silicate sol will be poor, and the molecular sieve cannot be obtained; and if the amount of the silylating agent (the compound shown in formula (I)) is too low, the specific surface area of the obtained titanium silicalite molecular sieve will be reduced, which affects the mass transfer and further affects the catalytic activity of the nanometer gold loaded titanium silicalite molecular sieve on the propylene gas phase epoxidation reaction; preferably, in step (1), the molar ratio of the silicon source (calculated as SiO2) to the compound shown in formula (I) is 1:(0.01-0.3), preferably 1:(0.01-0.2), and more preferably 1:(0.05-0.2).

[0048] In some preferred embodiments of the present application, the molar ratio of the silicon source (calculated as SiO2), the basic template agent (calculated as N when the basic template agent contains nitrogen element, and calculated as OH when the basic template agent does not contain nitrogen element) and water is 1:(0.05-0.4):(5-40), preferably 1:(0.1-0.3):(5-25). -

[0049] According to the present application, preferably, the silicon source is selected from at least one of tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, tetrabutyl silicate, silica gel, white carbon black and silica sol.

[0050] According to the present application, preferably, the basic template agent is selected from at least one of quaternary ammonium base, aliphatic amine and aliphatic alcohol amine, preferably at least one of tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide and tetrabutyl ammonium hydroxide.

[0051] ​In some preferred embodiments of the present invention, the silicon source is calculated as SiO2, the titanium source is calculated as TiO2, and the molar ratio of the silicon source, the titanium source and isopropanol is 1:(0.001-0.04):(0.1-10), preferably 1:(0.005-0.025):(0.1-5).

[0052] According to the present invention, under preferred conditions, the titanium source is selected from an organic titanium source and / or an inorganic titanium source; further preferably, the titanium source is selected from at least one of titanium tetrachloride, titanium sulfate, titanium nitrate, tetraethyl titanate, tetrapropyl titanate and tetrabutyl titanate.

[0053] According to the present invention, under preferred conditions, step (1) further comprises: first stirring and mixing the silicon source, the alkaline template, and water to obtain a mixed system; and then dropwise adding a mixture of the titanium source and isopropanol to the mixed system for second stirring to obtain a mixed solution.

[0054] In the present invention, the droplet acceleration rate of the mixed solution is preferably 0.01-0.5 mL / min; more preferably 0.1-0.5 mL / min.

[0055] In the present invention, preferably, the first stirring time is 0.1-2h.

[0056] In the present invention, preferably, the second stirring time is 0.5-6 h, preferably 0.5-3 h.

[0057] In the present invention, preferably, step (1) further comprises: driving out the alcohol from the mixed solution; driving out the alcohol can remove the alcohol generated by hydrolysis of the silicon source and the titanium source. In the present invention, the alcohol generated in the system is preferably removed by azeotropic distillation, and the water lost by azeotropic distillation is replenished during the driving out of the alcohol to ensure that the ratio of each substance in the titanium silicalite meets the above requirements; preferably, the conditions for driving out the alcohol include: temperature of 30-100°C and time of 2-10h; preferably temperature of 40-90°C and time of 4-10h.

[0058] According to the present invention, in order to enable the silanization agent to be uniformly dispersed in the titanium silica sol, under preferred conditions, step (1) further comprises: adding the compound represented by formula (I) to the titanium silica sol and performing a third stirring for 0.1-24 hours, preferably the third stirring time is 0.5-10 hours, more preferably 1-3 hours.

[0059] In the present application, by fast heating, the nucleation and growth rate of the molecular sieve under low temperature state can be controlled, so that smaller molecular sieve particles are obtained, and when the gold nanoparticles are loaded, the internal diffusion path of product molecules can be shortened, and the selectivity can be improved; according to the present application, preferably, in step (2), the hydrothermal crystallization conditions include: heating the mixture to 50-200℃ within 0.1-1h, and then hydrothermal crystallization at 50-200℃ for 10-100h; preferably, hydrothermal crystallization is carried out at 100-200℃ for 20-80h; further preferably, the heating time is 0.1-0.5h; more preferably, the hydrothermal crystallization conditions include: temperature of 120-180℃, and time of 20-80h; under the above preferred conditions, the crystallinity, specific surface area and pore volume of the molecular sieve can be balanced; and the molecular sieve with specific crystallinity, specific surface area and pore volume is prepared.

[0060] The pressure of the hydrothermal crystallization in the present application is not particularly limited, and can be the autogenous pressure of the crystallization system.

[0061] According to the present application, preferably, the method further comprises: washing, filtering and drying the product obtained by hydrothermal crystallization; wherein the washing, filtering and drying processes can be known by those skilled in the art. Exemplarily, the temperature of the washing can be 20-50℃, the washing solvent can be water, and the amount of the washing solvent is 1-20 times the mass of the crystallization product; the drying conditions can be: temperature of 40-150℃, and time of 0.5-24h.

[0062] The titanium-silicon molecular sieve support prepared in the present application has abundant micropore volume and internal surface area, which is beneficial to improve the intracrystalline diffusion rate of the reaction molecules and improve the reaction effect; on the other hand, it is beneficial to deposit the Au nanoparticles into the molecular sieve crystals, and play a synergistic catalytic effect with the intracrystalline Ti active center; preferably, the pore size of the titanium-silicon molecular sieve is 0.1-2nm, the specific surface area is 440-580m 2 / g, the total pore volume is 0.4-0.6cm 3 / g, the external surface area is 50-200m 2 / g, the micropore volume is 0.13-0.20cm 3 / g, the particle size is 100-250nm, and the crystallinity is ≥50%; in the present application, the external surface area of the titanium-silicon molecular sieve refers to the surface area of the external surface of the titanium-silicon molecular sieve, which can be obtained by BET method; the specific surface area of the titanium-silicon molecular sieve refers to the BET specific surface area.

[0063] In a preferred embodiment of the present application, the molar ratio of titanium to silicon in the titanium-silicon molecular sieve is 0.001-0.04:1, preferably 0.005-0.025.

[0064] In a preferred embodiment of the present application, in the infrared spectrum of the titanium silicalite molecular sieve, the ratio of the peak area at wave number of 960 cm-1 to the peak area at wave number of 800 cm-1 is 0.4-1.5. -1 -1 In a preferred embodiment of the present application, in the infrared spectrum of the titanium silicalite molecular sieve, the ratio of the peak area at wave number of 960 cm-1 to the peak area at wave number of 800 cm-1 is 0.4-1.5.

[0065] In a preferred embodiment of the present application, in step (2), the calcination conditions include: temperature of 400-800℃, time of 1-15h; preferably, temperature of 500-600℃, time of 4-10h.

[0066] In the present application, too high amount of chloroauric acid will cause aggregation of the nano-gold particles, and induce side reactions in the propylene gas phase epoxidation reaction, thereby reducing the selectivity of propylene oxide; too low amount of chloroauric acid will reduce the catalytic activity of the nano-gold loaded titanium silicalite molecular sieve prepared; under preferred conditions, the amount of the chloroauric acid aqueous solution is 0.01wt%-5wt% of the titanium silicalite molecular sieve, calculated as gold.

[0067] In order to further optimize the catalytic performance of the nano-gold loaded titanium silicalite molecular sieve in the propylene gas phase epoxidation reaction, under preferred conditions, the concentration of the chloroauric acid aqueous solution is 0.0001-0.1M.

[0068] The present application does not have particular limitation on the type of the pH regulator, as long as it can adjust the pH of the mixed system within a specific range; preferably, the pH regulator is urea.

[0069] In a preferred embodiment of the present application, the molar ratio of the urea to the chloroauric acid aqueous solution is (5-10):1, calculated as gold.

[0070] In the present application, the basic reagent can be more uniformly dispersed in the chloroauric acid aqueous solution by the microwave heating method, and the hydroxyl ions can be uniformly released and combined with gold, thereby promoting the uniform deposition of Au on the titanium silicalite molecular sieve. Under preferred conditions, in step (4), the microwave heating temperature is 80-100℃.

[0071] In a preferred embodiment of the present application, in step (4), the microwave heating time is 0.5-5h.

[0072] In order to improve the loading efficiency of nano-gold, it is further preferred that, in step (4), the first suspension is continuously stirred under the microwave heating condition until the pH is 7-9.

[0073] ​In some preferred embodiments of the present application, in order to improve the catalytic activity of the composite titanium silicalite molecular sieve, in step (5), the calcination conditions include: temperature of 150-300℃, time of 1-4h.

[0074] The third aspect of the present application provides a nano-gold loaded titanium silicalite molecular sieve prepared by the method according to the preceding second aspect.

[0075] In a preferred embodiment of the present application, the nano-gold loaded titanium silicalite molecular sieve comprises a titanium silicalite molecular sieve carrier and nano-gold loaded on the carrier; wherein the content of the nano-gold is 0.01wt%-1wt% based on the total amount of the nano-gold loaded titanium silicalite molecular sieve.

[0076] In a preferred embodiment of the present application, the nano-gold loaded titanium silicalite molecular sieve has a micropore volume of 0.06-0.18cm 3 / g, a particle size of 100-250nm, and a crystallinity of ≥50%.

[0077] In a preferred embodiment of the present application, the nano-gold loaded titanium silicalite molecular sieve has a molar ratio of titanium to silicon of 0.001-0.04:1, preferably 0.005-0.025.

[0078] In a preferred embodiment of the present application, in the infrared spectrum of the nano-gold loaded titanium silicalite molecular sieve, the ratio of the peak area at a wave number of 960cm -1 to the peak area at a wave number of 800cm -1 is 0.4-1.5.

[0079] In the present application, the more the content of 0-valence gold is, the higher the catalytic activity of the nano-gold loaded titanium silicalite molecular sieve is; preferably, more than 90% of the gold in the nano-gold has a valence of 0.

[0080] In a preferred embodiment of the present application, the number of Au particles in any 50nm*50nm area on the nano-gold loaded titanium silicalite molecular sieve differs by no more than 30%.

[0081] Further preferably, the nano-gold loaded titanium silicalite molecular sieve has high catalytic activity for propylene gas phase epoxidation reaction, the conversion rate of propylene is increased to 8%-14%, and the selectivity of propylene oxide is increased to 90%-95%.

[0082] The fourth aspect of the present application provides a method for propylene gas phase epoxidation, which comprises: mixing hydrogen, oxygen and propylene to react under the protection of inert gas and in the presence of a catalyst to obtain propylene oxide; the catalyst is the nano-gold loaded titanium silicalite molecular sieve according to the preceding first and third aspects.

[0083] According to the present application, preferably, the reaction conditions include that the volume flow ratio of the hydrogen, oxygen and propylene is 0.5-2:0.5-2:1; further preferably, the volume flow ratio of the propylene and inert gas is 1:1-10.

[0084] In some preferred embodiments of the present application, the reaction conditions further include that the temperature is 100-250℃, the time is 1-1000h, and the pressure is 0.1-6MPa; further preferably, the temperature is 120-200℃, the time is 1-500h, and the pressure is 0.1-3MPa.

[0085] In the present application, the reaction path of the propylene gas phase epoxidation is as shown in Figure 1 As can be seen from Figure 1 Au catalyzes the generation of H2O2 from H2 and O2, and then H2O2 and TS-1 form Ti-OOH active sites, which catalyze the generation of propylene oxide from propylene.

[0086] In the present application, the method of the propylene gas phase epoxidation can adopt a continuous operation mode, specifically, after the catalyst is loaded in the reactor, the mixed gas of hydrogen, oxygen, propylene and inert gas is continuously added for reaction.

[0087] The present application does not have special requirements for the form of the catalyst, and the catalyst can be nano gold loaded titanium silicalite molecular sieve powder, or can be further loaded on a carrier for use, and those skilled in the art can select according to the type of the reactor.

[0088] In the present application, the separation of the propylene gas phase epoxidation product and the catalyst can be adjusted according to the form of the catalyst and the actual demand; for example, when the catalyst is nano gold loaded titanium silicalite molecular sieve powder, the separation of the product and the recycling of the catalyst can be realized by sedimentation, filtration, centrifugation, evaporation, membrane separation and the like; when the catalyst is nano gold loaded titanium silicalite molecular sieve loaded on a carrier (shaped catalyst), the shaped catalyst can be loaded in a fixed bed reactor, and the catalyst is recovered after the reaction is completed.

[0089] The present application will be described in detail by way of examples below. In the following examples, room temperature refers to 25±5℃.

[0090] The raw materials used in the following examples are all chemical pure reagents, except for special instructions.

[0091] In each of the following examples and comparative examples, the X-ray diffraction (XRD) crystal phase pattern of the sample is determined on a Siemens D5005 type X-ray diffractometer, the ray source is a Cu Kα tube voltage of 40kV, a tube current of 40mA, a scanning speed of 0.5° / min, and a scanning range of 2θ=5°-35°.

[0092] According to the XRD spectrum, the crystallinity is obtained by fitting with the software eva of BRUKER;

[0093] Both the external surface area and the specific surface area are obtained by BET fitting of the adsorption curve after static N2 adsorption-desorption curve of the sample is measured at liquid nitrogen temperature (77.4 K) using the ASAP2405J static nitrogen adsorption instrument of Micromeritics Company;

[0094] The pore volume is determined according to the method described in RIPP151-90 in Petroleum Chemical Industry Analysis Method (Scientific Press, September 1990, First Edition) compiled by Yang Cuiding et al;

[0095] The pore size distribution is calculated according to the BJH formula;

[0096] The particle size and the number of Au particles in a 50nm*50nm area on the titanium silicalite molecular sieve are determined by JEOL JEM-2100 transmission electron microscope (TEM);

[0097] The valence of the nano gold is determined by XPS characterization.

[0098] In the following preparation examples, the chemical structural formula of the silylating agent used is shown in Table 1; wherein, compound 1, compound 2 and compound 3 are all obtained by commercial purchase.

[0099] Table 1

[0100]

[0101] Preparation Example 1-6 is used to illustrate the preparation of the titanium silicalite molecular sieve.

[0102] Preparation Example 1

[0103] (1) The tetraethyl silicate, tetrapropyl ammonium hydroxide and water were first stirred and mixed at room temperature to obtain a mixed system, and during the stirring process, the mixed solution of tetrabutyl titanate and isopropanol was added dropwise into the mixed system at a rate of 0.2 mL / min, and then second stirring was carried out for 0.5 h to obtain a mixed solution; the tetraethyl silicate was calculated based on SiO2, the tetrapropyl ammonium hydroxide was calculated based on N, and the tetrabutyl titanate was calculated based on TiO2, and the molar ratio of tetraethyl silicate, tetrapropyl ammonium hydroxide and water was 1:0.1:15; the molar ratio of tetraethyl silicate, tetrabutyl titanate and isopropanol was 1:0.005:3;

[0104] Then the mixed solution was subjected to alcohol removal at 80℃ for 6 h to obtain a titanium silicalite sol;

[0105] (2) adding compound (1) into the titanium silicate sol, and stirring for 1.5 h at room temperature to obtain a mixture, wherein the molar ratio of compound (1) to tetraethyl orthosilicate is 0.1:1;

[0106] (3) heating the mixture to 170°C for 0.5 h, and hydrothermally crystallizing at 170°C for 24 h to obtain a crystallized product; and sequentially washing the crystallized product with water, filtering, and drying at 120°C for 2 h;

[0107] calcining the dried product at 550°C for 6 h to obtain the titanium silicate molecular sieve;

[0108] The pore size distribution of the titanium silicate molecular sieve obtained in the present preparation example is shown in Figure 2 It can be seen from Figure 2 that the titanium silicate molecular sieve obtained in the present preparation example contains only micropores with a pore size of about 0.55 nm;

[0109] The TEM image of the titanium silicate molecular sieve obtained in the present preparation example is shown in Figure 3 It can be seen from Figure 3 that the particle size of the titanium silicate molecular sieve obtained in the present preparation example is about 100-150 nm;

[0110] The XRD spectrum of the titanium silicate molecular sieve obtained in the present preparation example is shown in Figure 4 It can be seen from Figure 4 that the titanium silicate molecular sieve obtained in the present preparation example has MFI structure and good crystallization properties;

[0111] The physical property parameters of the titanium silicate molecular sieve obtained in the present preparation example are shown in Table 3.

[0112] Preparation Example 2-4

[0113] The titanium silicate molecular sieve was prepared according to the method of Preparation Example 1, and the ratio and synthesis conditions are shown in Table 2. The physical property parameters of the prepared molecular sieve are shown in Table 3.

[0114] Table 2

[0115]

[0116]

[0117] Note: 1-molar ratio; 2-molar ratio; 3-molar ratio

[0118] Preparation Example 5

[0119] A solution of tetrapropylammonium hydroxide (TPAOH, 20 wt% concentration, purchased from Aldrich, USA) was added to a solution of tetraethyl orthosilicate (TEOS), and then a solution of n-butyl titanate [Ti(OBu)4] in anhydrous isopropyl alcohol was added dropwise to the obtained liquid mixture under vigorous stirring, and a clear liquid was obtained after stirring for 15 min; the clear liquid was subjected to alcohol removal at 75°C for 3h to obtain a sol; the molar ratio of tetraethyl orthosilicate (calculated as SiO2) : n-butyl titanate (calculated as TiO2) : tetrapropylammonium hydroxide (calculated as N) : deionized water was 1 : 0.03 : 0.36 : 35;

[0120] The sol was crystallized at 170°C for 3 days, the obtained solid was filtered, washed with distilled water, dried at 100°C for 5h, and then calcined at 550°C for 10h to obtain titanium silicalite TS-1-5; the physical property parameters of the titanium silicalite TS-1-5 are shown in Table 3, and the XRD characterization results of the titanium silicalite TS-1-5 are shown in Figure 5 From Figure 5 it can be seen that the titanium silicalite obtained in this preparation example has the MFI structure characteristic peaks, and is crystallized into TS-1 molecular sieve.

[0121] Preparation Example 6

[0122] The titanium silicalite was prepared according to the method of CN106145151B Example 1, and the specific method was as follows:

[0123] Tetraethyl orthosilicate, tetrapropylammonium hydroxide, tetrabutyl titanate and deionized water were mixed to obtain a mixture with a molar ratio of SiO2: structure directing agent: TiO2: H2O = 1: 0.2: 0.025: 50. Then, according to the molar ratio of SiO2 to silanization reagent of 1:0.1 and the weight ratio of SiO2 to natural polymer compound of 1:0.1, the quaternary aminated cellulose and N-phenyl-3-aminopropyl trimethoxysilane were added into the titanium silicalite precursor gel mixture, and after stirring uniformly, the obtained silanization reagent and modified natural polymer compound treated titanium silicalite precursor was transferred to a pressure-resistant stainless steel reaction kettle; under stirring, it was heated to 170°C and crystallized under autogenous pressure for 24h. After the stainless steel pressure-resistant reaction kettle was cooled to room temperature, the obtained uncalcined titanium silicalite was recovered, dried at 110°C for 6h, and then calcined at 550°C for 4h to obtain titanium silicalite TS-1-6. The pore size distribution thereof is shown in Figure 6 From Figure 6 it can be seen that the titanium silicalite obtained in this preparation example has a mesoporous structure with a pore size of 3nm.

[0124] Table 3

[0125] Preparation Example 1 Preparation Example 2 Preparation Example 3 Preparation Example 4 Preparation Example 5 Preparation Example 6 Titanium Silicalite Molecular Sieve TS-1-1 TS-1-2 TS-1-3 TS-1-4 TS-1-5 TS-1-6 Total pore volume (cm 3 / g) 0.532 0.530 0.493 0.530 0.480 0.670 <![CDATA[Micropore volume (cm 3 / g)]]> 0.176 0.174 0.165 0.177 0.391 0.270 Specific surface area (m 2 / g) 472 474 486 474 448 712 External surface area (m 2 / g) 157 162 191 159 211 341 Particle Size (nm) 180 183 210 181 380 300 I 960 / I 800 *]]> 0.52 0.48 0.71 0.55 2.32 2.12 Crystallinity (%) 76 73 71 75 45 53 Silicon: Titanium Molar Ratio 1：0.005 1：0.005 1：0.005 1：0.005 1：0.030 1：0.025

[0126] Note: *-In the infrared spectrum of titanium silicate molecular sieve, the wave number is 960cm -1 The peak area and wave number are 800cm -1 The ratio of the peak area

[0127] Example 1

[0128] 5g of titanium silicate molecular sieve TS-1-1 was added to 50mL of an aqueous solution (0.0005M) of chloroauric acid (HAuCl4) under stirring. 0.01g of urea was added as an alkaline pH regulator to obtain a first suspension, which was placed in a microwave heating device and stirred at 90°C until the pH value of the mixed system reached 7.5 to obtain a second suspension. The residue obtained by filtering the second suspension was calcined at 200°C for 2h in an air atmosphere to obtain a nano-gold-loaded molecular sieve catalyst Au / TS-1-1. The reaction conditions and raw materials are shown in Table 4. The physical properties of the obtained nano-gold-loaded molecular sieve catalyst Au / TS-1-1 are shown in Table 5. Compared with the data in Table 3, it can be seen that the particle size, I 960 / I 800 The parameter values ​​of , crystallinity and silicon: titanium molar ratio remain unchanged. The TEM image of the nano-gold loaded titanium silicon molecular sieve prepared in this embodiment is as follows: Figure 7 As shown, from Figure 7 It can be seen that the Au nanoparticles are evenly dispersed.

[0129] Examples 2-9 and Comparative Examples 1-6

[0130] According to the method of Example 1, the difference is that the reaction conditions and raw materials are as shown in Table 4, and the physical properties of the obtained nano-scale loaded multi-level porous titanium silicon molecular sieve are shown in Table 5. Among them, the TEM image of the nano-gold loaded titanium silicon molecular sieve obtained in Comparative Example 5 is as shown in Figure 8 As shown, from Figure 8 It can be seen from the figure that the Au nanoparticles are unevenly distributed and there is aggregation.

[0131] Table 4

[0132]

[0133]

[0134] Table 5

[0135]

[0136] Note: 1 - In the TEM photo of the single gold nanoparticles loaded titanium silicalite molecular sieve particles, the gold nanoparticles loaded titanium silicalite molecular sieve is divided into several (not less than three) 50nm*50nm adjacent regions, and the number of Au particles in each 50nm*50nm region is calculated, wherein the region with the largest number of Au particles is the A1 region, the region with the smallest number of Au particles is the A2 region, and the difference in the number of Au particles is (A1 region Au particle number-A2 region Au particle number) / A1 region Au particle number

[0137] 2 - In the infrared spectrum of the gold nanoparticles loaded titanium silicalite molecular sieve, the ratio of the peak area at a wave number of 960cm -1 to the peak area at a wave number of 800cm -1

[0138] Test Example

[0139] The gold nanoparticles loaded titanium silicalite molecular sieves prepared in Examples 1-9 and Comparative Examples 1-6 were used as catalysts, the catalysts were loaded into a tubular reactor with an inner diameter of 8mm, then heated to 180℃ in a N2 atmosphere, and hydrogen, oxygen and propylene were introduced to start the reaction, after 1h of reaction, the product was analyzed online; wherein the amount of catalyst was 0.4g, the flow rates of the gases, the reaction temperature and the pressure are shown in Table 6, and the catalytic reaction results are shown in Table 7.

[0140] In the present application, gas chromatography was used to analyze the reactants and products in the evaluation system. The analysis conditions of the gas chromatography were as follows: Agilent-6890 chromatograph, molecular sieve 5A and PoraBONDU chromatographic column, FID and TCD detectors.

[0141] Propylene conversion % = (mole number of propylene in raw material-mole number of propylene in product) / mole number of propylene in raw material x 100%

[0142] Propylene conversion % = (mole number of propylene in raw material-mole number of propylene in product) / mole number of propylene in raw material x 100%

[0143] Table 6

[0144]

[0145]

[0146] Table 7

[0147]

[0148]

[0149] ​As can be seen from the results of Test 1-12 and Test 19-23 in Table 7, the nano-gold loaded titanium silicalite of the embodiment of the present application has high catalytic activity for propylene gas phase epoxidation reaction, so that the conversion rate of propylene is increased to 10.1% or more, and the selectivity of the product propylene oxide is increased to 90.3% or more.

[0150] As can be seen from the comparison between Test 1 and Test 13-16, the conditions of propylene gas phase epoxidation also affect the conversion rate of propylene and the selectivity of propylene oxide.

[0151] As can be seen from the comparison between Test 1 and Test 17-18, when the pore volume of the titanium silicalite does not meet the requirements, the catalytic activity of the nano-gold loaded titanium silicalite for propylene gas phase epoxidation reaction is also obviously reduced, and it is difficult to simultaneously meet the requirements of high conversion rate of propylene and high selectivity of propylene oxide.

[0152] As can be seen from the comparison between Test 1 and Test 24-25, during the preparation of the nano-gold loaded titanium silicalite, too high or too low calcination temperature will reduce the catalytic activity of the nano-gold loaded titanium silicalite for propylene gas phase epoxidation reaction.

[0153] As can be seen from the comparison between Test 1 and Test 26-27, during the preparation of the nano-gold loaded titanium silicalite, too low microwave heating time will reduce the dispersion degree of the gold nano-particles loaded on the molecular sieve, and further reduce the catalytic activity of the nano-gold loaded titanium silicalite for propylene gas phase epoxidation reaction.

[0154] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application, and all fall within the protection scope of the present application.

Claims

1. A nano-gold loaded titanium-silicon molecular sieve, characterized in that, The nano gold loaded titanium silicalite molecular sieve comprises a titanium silicalite molecular sieve carrier and nano gold loaded on the carrier; wherein the content of the nano gold is 0.01wt%-1wt% based on the total amount of the nano gold loaded titanium silicalite molecular sieve; wherein the micropore volume of the nano gold loaded titanium silicalite molecular sieve is 0.06-0.18cm 3 / g, the particle size is 100-250nm, and the crystallinity is ≥50%. The preparation method of the nano gold loaded titanium silicon molecular sieve comprises the following steps: (1) uniformly mixing a silicon source, an alkaline template agent, a titanium source, water and isopropyl alcohol to obtain a titanium silicon sol; (2) adding a compound shown in formula (I) into the titanium silicon sol, and performing hydrothermal crystallization and calcination on the obtained mixture to obtain a titanium silicon molecular sieve; Formula (I) wherein i is an integer of 1-6; R1, R2 and R3 are each independently selected from C1-C6 alkyl; (3) mixing the titanium silicon molecular sieve with an aqueous solution containing a gold compound, and then adding a pH adjusting agent to obtain a first suspension; (4) microwave heating the first suspension to a pH of 6-10 to obtain a second suspension; (5) filtering the second suspension, and calcining the obtained filter residue to obtain the nano gold loaded titanium silicon molecular sieve; The molar ratio of the silicon source to the compound shown in formula (I) is 1:(0.01-0.3) in terms of SiO2; said silicon source in terms of SiO2, said alkaline templating agent in terms of N when said alkaline templating agent contains nitrogen, said alkaline templating agent in terms of OH when said alkaline templating agent does not contain nitrogen, said titanium source in terms of TiO2, - said silicon source in terms of SiO2, said alkaline templating agent in terms of N when said alkaline templating agent contains nitrogen, said alkaline templating agent in terms of OH when said alkaline templating agent does not contain nitrogen, said titanium source in terms of TiO2, The molar ratio of the silicon source, the alkaline template agent and water is 1:(0.05-0.4):(5-40); The molar ratio of the silicon source, the titanium source and isopropyl alcohol is 1:(0.001-0.04):(0.1-10); In step (2), the conditions of the hydrothermal crystallization include: increasing the temperature of the mixture to 50-200 DEG C within 0.1-1 h, and then performing crystallization at 50-200 DEG C for 10-100 h; In step (5), the conditions of the calcination include: a temperature of 150-300 DEG C, and a time of 1-4 h.

2. The nanogold supported titanium silicalite of claim 1, wherein, The molar ratio of titanium to silicon in the nano gold loaded titanium silicon molecular sieve is 0.001-0.04:

1.

3. The nanogold supported titanium silicalite of claim 2 wherein, The molar ratio of titanium to silicon in the nano gold loaded titanium silicon molecular sieve is 0.005-0.025:

1.

4. The nano gold loaded titanium silicon molecular sieve according to any one of claims 1-3, wherein, In the infrared spectrum of the nanogold loaded titanium-silicon molecular sieve, the ratio of the peak area of the peak with wave number of 960 cm -1 to the peak area of the peak with wave number of 800 cm -1 is 0.4-1.

5.

5. The nano gold loaded titanium silicon molecular sieve according to any one of claims 1-3, wherein, More than 90% of the gold in the nano gold has a valence of 0.

6. The nano gold loaded titanium silicon molecular sieve according to any one of claims 1-3, wherein, The number of Au particles in any 50nm*50nm area on the nano gold loaded titanium silicon molecular sieve differs by no more than 30%.

7. A method for preparing a nano-gold supported titanium-silicon molecular sieve, characterized in that, The method comprises: (1) uniformly mixing a silicon source, an alkaline template agent, a titanium source, water and isopropyl alcohol to obtain a titanium silicon sol; (2) adding a compound shown in formula (I) into the titanium silicon sol, and performing hydrothermal crystallization and calcination on the obtained mixture to obtain a titanium silicon molecular sieve; Formula (I) wherein i is an integer of 1-6; R1, R2 and R3 are each independently selected from C1-C6 alkyl; (3) mixing the titanium silicon molecular sieve with an aqueous solution containing a gold compound, and then adding a pH adjusting agent to obtain a first suspension; (4) microwave heating the first suspension to a pH of 6-10 to obtain a second suspension; (5) filtering the second suspension, and calcining the obtained filter residue to obtain the nano gold loaded titanium silicon molecular sieve; The molar ratio of the silicon source to the compound shown in formula (I) is 1:(0.01-0.3) in terms of SiO2. said silicon source in terms of SiO2, said alkaline templating agent in terms of N when said alkaline templating agent contains nitrogen, said alkaline templating agent in terms of OH when said alkaline templating agent does not contain nitrogen, said titanium source in terms of TiO2, - said silicon source in terms of SiO2, said alkaline templating agent in terms of N when said alkaline templating agent contains nitrogen, said alkaline templating agent in terms of OH when said alkaline templating agent does not contain nitrogen, said titanium source in terms of TiO2, The molar ratio of the silicon source, the alkaline template agent and water is 1:(0.05-0.4):(5-40). The molar ratio of the silicon source, the titanium source and isopropyl alcohol is 1:(0.001-0.04):(0.1-10). In step (2), the hydrothermal crystallization conditions include: heating the mixture to 50-200 ℃ within 0.1-1 h, and then crystallizing at 50-200 ℃ for 10-100 h. In step (5), the calcination conditions include: temperature of 150-300 ℃, and time of 1-4 h.

8. The method of claim 7, wherein, i is an integer of 1-5.

9. The method of claim 7, wherein, R1, R2 and R3 are each independently selected from methyl, ethyl or propyl.

10. The method of claim 7, wherein, The molar ratio of the silicon source to the compound shown in formula (I) is 1:(0.01-0.2) in terms of SiO2.

11. The method of claim 7, wherein, said silicon source in terms of SiO2, said alkaline templating agent in terms of N when said alkaline templating agent contains nitrogen, said alkaline templating agent in terms of OH when said alkaline templating agent does not contain nitrogen, said titanium source in terms of TiO2, - said silicon source in terms of SiO2, said alkaline templating agent in terms of N when said alkaline templating agent contains nitrogen, said alkaline templating agent in terms of OH when said alkaline templating agent does not contain nitrogen, said titanium source in terms of TiO2, The molar ratio of the silicon source, the alkaline template agent and water is 1:(0.1-0.3):(5-25). The molar ratio of the silicon source, the titanium source and isopropyl alcohol is 1:(0.005-0.025):(0.1-5).

12. The method of any of claims 7-11, wherein, The silicon source is at least one selected from tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, tetrabutyl silicate, white carbon black and silica sol.

13. The method of any one of claims 7-11, wherein, The alkaline template agent is at least one selected from quaternary ammonium base, aliphatic amine and aliphatic alcohol amine.

14. The method of claim 13, wherein, The alkaline template agent is at least one selected from tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide and tetrabutyl ammonium hydroxide.

15. The method of any one of claims 7-11, wherein, The titanium source is selected from organic titanium source and / or inorganic titanium source.

16. The method of claim 15, wherein, The titanium source is at least one selected from titanium tetrachloride, titanium sulfate, titanium nitrate, tetraethyl titanate, tetrapropyl titanate and tetrabutyl titanate.

17. The method of any of claims 7-11, wherein, In step (1), further comprising: stirring and mixing the silicon source, the alkaline template agent and water to obtain a mixed system; and then adding a mixed solution of the titanium source and isopropyl alcohol dropwise into the mixed system to obtain a mixed solution.

18. The method of claim 17, wherein, The dropwise adding speed of the mixed solution is 0.01-0.5 mL / min.

19. The method of claim 17, wherein, In step (1), further comprising: alcohol removal of the mixed solution. The alcohol removal conditions include: temperature of 30-100 ℃, and time of 2-10 h.

20. The method of claim 19, wherein, The alcohol removal conditions include: temperature of 40-90 ℃, and time of 4-10 h.

21. The method of any one of claims 7-11, wherein, In step (2), the hydrothermal crystallization conditions include: heating the mixture to 100-200 ℃ within 0.1-1 h, and then crystallizing at 100-200 ℃ for 20-80 h.

22. The method according to any one of claims 7-11, wherein, In step (2), the calcination conditions include: temperature of 400-800°C, time of 1-15 h.

23. The method according to any one of claims 7-11, wherein, The pore size of the titanium silicalite is 0.1-2 nm, the specific surface area is 440-580 m 2 / g, the total pore volume is 0.4-0.6 cm 3 / g, the external surface area is 50-200 m 2 / g, the micropore volume is 0.13-0.20 cm 3 / g, the particle size is 100-250 nm, and the crystallinity is ≥50%.

24. The method according to any one of claims 7-11, wherein, The molar ratio of titanium to silicon in the titanium silicalite molecular sieve is 0.001-0.04:

1.

25. The method according to claim 24, wherein, The molar ratio of titanium to silicon in the titanium silicalite molecular sieve is 0.005-0.025:

1.

26. The method according to any one of claims 7-11, wherein, In the infrared spectrum of the titanium silicalite, the ratio of the peak area at a wave number of 960 cm -1 to the peak area at a wave number of 800 cm -1 is 0.4 to 1.

5.

27. The method of any one of claims 7-11, wherein, The aqueous solution of gold-containing compound is selected from the group consisting of aqueous chloroauric acid; the concentration of the aqueous chloroauric acid is 0.0001-0.1 M.

28. The method according to claim 27, wherein, The aqueous chloroauric acid is used in an amount of 0.01wt%-5wt% of the titanium silicalite molecular sieve, calculated as gold.

29. The method of claim 27, wherein, In step (3), the pH regulator is urea; The molar ratio of urea to aqueous chloroauric acid, calculated as gold, is (5-10):

1.

30. The method of any one of claims 7-11, wherein, In step (4), the microwave heating temperature is 80-100°C.

31. The method according to any one of claims 7-11, wherein, The microwave heating time is 0.5-5 h.

32. The method according to any one of claims 7-11, wherein, The first suspension is continuously stirred under microwave heating until the pH is 7-9.

33. The method of any one of claims 7-11, wherein, In step (5), the calcination conditions include: temperature of 150-300°C, time of 1-4 h.

34. A nano-gold supported titanium silicalite molecular sieve prepared by the method according to any one of claims 7-33.

35. A process for the gas phase epoxidation of propene, said process comprising: Hydrogen, oxygen and propylene are mixed and reacted in the presence of a catalyst to obtain propylene oxide; The catalyst is the nano-gold supported titanium silicalite molecular sieve according to any one of claims 1-6, 34.

36. The method of claim 35, wherein, The reaction conditions include: the volume flow ratio of hydrogen, oxygen and propylene is 0.5-2:0.5-2:

1.

37. The method according to claim 35, wherein, The volume flow ratio of propylene to inert gas is 1:1-10.

38. The method of any one of claims 35-37, wherein, The reaction conditions include: temperature of 100-250°C, time of 1-1000 h, pressure of 0.1-6 MPa.

39. The method according to claim 38, wherein, The reaction conditions include: temperature of 120-220°C, time of 1-500 h, pressure of 0.1-3 MPa.

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