32 results about "Recyclable catalyst" patented technology

The invention discloses a method for efficiently preparing a fatty acid type anti-wear agent based on biodiesel, which comprises the following steps: freezing and crystallizing the raw material biodiesel, filtering, evaporating and dealcoholizing, carrying out enzyme hydrolysis, insulating and layering, and rectifying under reduced pressure to finally obtain the fatty acid type anti-wear agent. Wherein the fatty acid composition of the crude methyl ester can be directionally regulated and controlled through freezing crystallization and filtering processes; through the synergistic effect of enzyme hydrolysis reaction and high-vacuum rectification separation coupling, efficient production of the fatty acid anti-wear agent prepared from biodiesel is achieved, the production period is greatly shortened, and the product quality is improved. According to the technology disclosed by the invention, the high-quality fatty acid type anti-wear agent can be produced economically, greenly, efficiently and stably, and the acid value of the product is stabilized between 198-203mgKOH / g oil and meets the Q / SHCG 57-2017 standard. The method has the advantages of low raw material requirement, wide application range, high production efficiency, high product quality, reproducible and reusable catalyst and the like, and is suitable for industrial production.

The invention relates to a composite catalyst as well as a preparation method and application thereof, and mainly solves the problems of high temperature, more byproducts, catalyst residues, equipment corrosion, low catalytic efficiency of a novel catalyst and the like when a traditional strong acid catalyst system is used in the prior art. The research method comprises the following steps: preparing a sulfonic acid alkyl imidazole compound catalyst by a two-step method; 1 wt% of the catalyst is used for carrying out esterification reaction on polyhydric alcohol and fatty acid; after the reaction is finished, a product is separated from the catalyst, and the ionic liquid is recycled; and carrying out weak base washing, filtering and water washing refining on the product. The catalytic efficiency of the catalyst reaches up to 99.5% or above, the product hydroxyl value is smaller than 5 mgKOH / g, the acid value is smaller than 0.5 mgKOH / g, and the esterification efficiency is still kept to be 99.0% or above after the catalyst is recycled 6 times. The method has the advantages of simple process, mild reaction conditions and recyclable catalyst, well solves the problems of high temperature, catalyst residue, many byproducts and equipment corrosion in the traditional catalytic esterification system, and can be used in the preparation process of various ester products.

The claimed invention is directed to a catalytic graphitization process to convert fuel-grade petroleum coke into battery-grade graphite using a recyclable catalyst derived from iron, nickel or cobalt.

The invention belongs to the technical field of water treatment, discloses a process and a method for removing DOM in initial rainwater, and aims to solve the problems that DOM components in runoff rainwater are complex, the removal rate of a traditional process is low, membrane pollution is easily caused, a powder catalyst is difficult to recover and the like. The method comprises the following steps: introducing rainwater into a reactor with a ceramic membrane, and directly adding free-state GAC, CuO and PS; static circulation is firstly carried out at a high shear rotating speed, and GAC and CuO are used for synergistically activating PS to generate a large number of free radicals for in-situ degradation of DOM; and then solid-liquid separation is carried out through suction of a ceramic membrane. Efficient removal of DOM in initial rainwater and membrane pollution control are realized. Under the optimal working condition operation, the total organic carbon (TOC) removal rate can reach 83% or above. The process is simple, operation is stable, the catalyst can be recycled, and the method is suitable for efficient resource utilization of rainwater and has good engineering practical application potential.

The claimed invention is directed to a catalytic graphitization process to convert fuel-grade petroleum coke into battery-grade graphite using a recyclable catalyst derived from iron, nickel or cobalt.

The invention discloses a preparation method of high-purity magnesium glycerophosphate, and belongs to the technical field of organic salt synthesis. According to the method, glycerol and phosphoric acid which are low in cost and easy to obtain are taken as starting raw materials, esterification reaction is firstly carried out under the action of a specific catalyst to generate glycerophosphate, then a magnesium source is added for salt forming reaction, and a high-purity magnesium glycerophosphate product is finally obtained by regulating and controlling the type of the catalyst, the reaction temperature, the pH value and the reaction time and combining a step-by-step purification process. The method has the advantages of easily available raw materials, recyclable catalyst, mild reaction conditions, simple process flow, high product purity, no generation of harmful impurities and the like, solves the problems of high raw material cost, complex process, difficulty in ensuring the product purity and the like in the existing magnesium glycerophosphate synthesis method, and is suitable for industrial large-scale production.

The application provides a method for preparing vinylene carbonate without solvent. The method comprises the following steps: mixing chlorovinyl carbonate with a catalyst, heating to a reaction temperature, introducing a protective gas, and carrying out a dechlorination reaction; after the reaction is completed, filtering the reaction solution, and subjecting the filtrate to rectification, crystallization and melting to obtain vinylene carbonate; the catalyst is a supported Schiff base metal complex catalyst, which comprises an A12O3 carrier and an active component supported on the carrier, and the active component is one or more of Cu(II) Schiff base complex, Mn(II) Schiff base complex and Co(II) Schiff base complex. The method has the characteristics of high selectivity, high product conversion rate, low energy consumption and low discharge amount of three wastes; the reaction condition is mild, and the method has the characteristics of high activity, high selectivity, few side reactions, high yield, simple post-treatment, recyclable catalyst and green production process.

This invention discloses a continuous production process for ethyl methyl carbonate (EMC), belonging to the field of organic carbonate synthesis technology. It aims to solve the problems of low conversion rate, poor selectivity, difficulty in catalyst separation and recovery, high energy consumption, and difficulty in stably preparing electronic-grade products in traditional batch processes. This invention uses dimethyl carbonate and ethanol as raw materials, employing a continuous reactive distillation coupled with a multi-stage distillation integrated process. Under the action of a solid base catalyst, a continuous transesterification reaction is achieved, simultaneously completing the discharge of the target product, online catalyst circulation, continuous separation of light and heavy components, and product purification. By precisely controlling the raw material ratio, reaction temperature, pressure, reflux ratio, and residence time, the entire process can operate continuously and stably. This invention features strong process continuity, high ethanol conversion rate, high EMC selectivity and yield, recyclable catalyst, low energy and material consumption, and the obtained product purity can reach electronic grade. It is suitable for the production of lithium-ion battery electrolyte solvents and is easy to scale up industrially and manage continuously.

The application provides a chloramphenicol-containing organic porous polymer catalyst and a synthesis method and application thereof, and belongs to the technical field of organic synthesis. The polymer catalyst comprises intermediates A, B and C, the intermediates A and B are styrene and divinylbenzene isomer mixtures respectively, and the intermediates A, B and C are synthesized through a polymerization reaction under the action of a free radical initiator. The polymer catalyst is a heterogeneous catalyst with a chloramphenicol chiral skeleton structure, can be synthesized by taking industrial waste chloramphenicol as a starting material, has the advantages of low cost, good catalytic efficiency, high enantioselectivity and multiple recycling, etc. The asymmetric catalytic synthesis using the catalyst can separate and recycle the catalyst from the reaction system through a simple filtration operation, has the technical advantages of simple experimental operation steps, recyclable catalyst, etc. The chloramphenicol polymer catalyst has good industrial application prospect when applied to the asymmetric alcoholysis ring-opening of a cyclic anhydride.

The application discloses a 6-aminoquinoxaline compound and a preparation method and application thereof. The structural formula of the 6-aminoquinoxaline compound is shown in the following formula: wherein R 1 is one of hydrogen, methyl, benzyl, 1H-indolyl, 2-methyl-1H-indolyl, 1H-quinolinyl and benzomorpholinyl, R 2 is one of phenyl, ester-substituted hydrocarbon, 2-methylphenyl, 2-hydroxymethylphenyl and 2-amino-4,5-dimethylphenyl, and R 3 is one of hydrogen, bromine, diphenyl, difuryl and cyclohexyl. The 6-aminoquinoxaline compound is novel in structure, can be used for preparing bioactive molecules, photoelectric materials, organic pigments / dyes and the like, and the preparation method has the advantages of simple synthesis steps, safe operation, low cost and wide applicability of raw materials, high atom economy, recyclable catalyst and the like, and is suitable for large-scale industrial application.

This invention discloses a 2,5-dimethyl- N The preparation method of 2,5-arylpyrrole involves reacting 2,5-hexanedione and nitroaromatic hydrocarbons in a hydrogen atmosphere and a reaction solvent under the action of a supported bimetallic bifunctional catalyst to obtain 2,5-dimethyl- N -Arylpyrrole. The supported bimetallic bifunctional catalyst includes a support and an active component supported on the support. The support is one of silica (SiO2), titanium dioxide (TiO2), and activated carbon (AC). The active component includes oxides of nickel and manganese. The method of this invention synthesizes 2,5-dimethyl- N The yield of arylpyrrole is over 90%. This invention features a simple process, recyclable catalyst, high reaction selectivity, and high product yield, offering significant advantages for industrial production.

This invention discloses a combined process for the pretreatment of polyester waste and the preparation of dioctyl terephthalate in the field of polymer chemical recycling and resource recycling. The process utilizes specially formulated layered molybdenum-titanium bimetallic phosphate nanosheets with intercalation catalysis as a catalyst. The crushed polyester waste is mixed with isooctanol and pretreated at a lower temperature, followed by a catalytic alcoholysis and transesterification reaction. Ethylene glycol is continuously removed by fractional distillation to drive the reaction to completion. After the reaction, the mixture is cooled and filtered to separate the regenerable solid catalyst. The filtrate is then neutralized, washed with water, and subjected to two-step vacuum distillation. This process achieves a high degree of synergy between the catalyst and the reaction steps, simplifying the traditional multi-step complex process into four core steps. It has the advantages of mild reaction conditions, simple and efficient process, recyclable catalyst, and high product purity, providing a novel and practical technical solution for the high-value resource utilization of polyester waste.

The application belongs to the technical field of organic synthesis and relates to a method for preparing dimethyl carbonate. The method uses a deep eutectic solvent (DES) as a catalyst to catalyze the reaction of CO2 and methanol to prepare dimethyl carbonate in the presence of an organic solvent and a dehydrating agent, and the reaction conditions are as follows: the initial pressure of CO2 is 1-6 MPa, the temperature is 100-120 DEG C, and the time is 4-10 h. After the reaction, the layers are separated by standing, the lower layer DES is separated from the dehydrating agent by centrifugation, and then can be directly recycled, and the upper layer product phase is removed from the organic solvent by rectification to obtain the product dimethyl carbonate, and the organic solvent can be recycled. The characteristics of the application are that the DES-dehydrating agent system can realize the high-yield and high-purity synthesis of dimethyl carbonate, solves the problems of difficult recovery of the catalyst, many by-products and low yield in the traditional method, has the advantages of recyclable catalyst and solvent, low cost and simple operation, and is suitable for industrial production.

The application provides a kind of catalyst recyclable carboxin synthesis method, belong to organic synthesis technical field, comprising: the condensation reaction of alpha-chloroacetyl acetanilide and 2-mercaptoethanol under alkaline conditions, intermediate is obtained by separation;With toluene as solvent, the obtained intermediate is mixed with ionic liquid catalyst to form a reaction system, heating reaction, after the reaction is completed, the temperature of the reaction system is reduced to 5-25 DEG C, the reaction system is layered, then separation treatment is carried out, carboxin product and separated ionic liquid catalyst are obtained, then the separated ionic liquid catalyst is regenerated by dehydration and recycled;Wherein, the ionic liquid catalyst is 1-(polyethylene glycol monomethyl ether group)-3-(3-sulfopropyl) imidazole hydrogen sulfate salt.The reaction system has homogeneous high-efficiency conversion at high temperature and automatic separation at low temperature, which realizes the green upgrading of carboxin synthesis process.

This invention discloses a method for preparing cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol. The method comprises the following steps: S1: Under a hydrogen atmosphere, using 2,2,4,4-tetramethyl-1,3-cyclobutanedione as a raw material, a reaction is carried out in the presence of a modified transition metal catalyst and an auxiliary agent to obtain a cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol reaction solution; S2: The auxiliary agent is separated to obtain crude cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol; S3: After washing and drying, cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol product with a purity of over 99.9% is obtained. This method features mild reaction conditions, a simple process, recyclable catalyst, and the ability to obtain pure cis-structured CBDO product, providing high-quality monomers for downstream polyester production.

The application relates to the field of chemical substance preparation and purification, and particularly discloses a highly purified brominated triazine and a preparation method thereof. The preparation method of the highly purified brominated triazine comprises the following steps: (1) a bromination reaction: phenol, bromine and hydrogen peroxide are reacted in a mixed solvent of water and dichloromethane at 5-40 DEG C to obtain a bromination reaction liquid; (2) washing treatment: after the bromination reaction liquid is reacted with a sodium sulfite solution, washing is performed to obtain tribromophenol; (3) a condensation reaction: tribromophenol, liquid alkali, a recyclable catalyst and cyanuric chloride are subjected to a condensation reaction in a synthesis kettle; (4) crystallization and post-treatment: process water is added into the condensation reaction liquid in an amount equal to that of the condensation reaction liquid, crystallization is performed, and the final product is obtained through filtration and drying; in addition, the preparation method has the advantages of improving the product purity of a brominated triazine synthesis process.

The invention belongs to the technical field of green synthetic chemistry, and particularly relates to a method for synthesizing 4-methylbenzyl iodide by iodinating p-tolualdehyde through photocatalysis. The method comprises the following steps: mixing an M-MAPbI3 photocatalyst, p-tolualdehyde, an MAPbI3 saturated HI aqueous solution and a non-water-soluble organic solvent in an irradiation type closed reaction container, and carrying out a photocatalytic reaction in an inert atmosphere under the condition of violent stirring to prepare the 4-methylbenzyl iodide, the cocatalyst is selected from any one of Pt, Pd, Au and Ru; the molar concentration of p-tolualdehyde in a mixed solvent formed by the MAPbI3 saturated HI aqueous solution and the water-insoluble organic solvent is less than or equal to 5 mmol / L; according to the method, cheap p-tolualdehyde is directly used as a reactant, the 4-methylbenzyl iodide is obtained through the catalytic reaction under the conditions of room temperature and illumination, the method has the advantages that operation is easy, the reaction condition is mild, the whole process is free of pollution, and the catalyst can be recycled, and green development of the aromatic aldehyde halogenation reaction is promoted.

This invention discloses a method for catalytically depolymerizing waste poly(p-dioxanone) to recover monomers, belonging to the field of heterocyclic compound technology. The method includes: mixing an oxide and / or hydroxide of an alkali metal or alkaline earth metal with a polyol, stirring and reacting under atmospheric pressure (100-180℃) or reduced pressure (10-120℃) while removing moisture to obtain a catalyst; mixing the obtained catalyst with waste poly(p-dioxanone), and carrying out a depolymerization reaction under an absolute pressure of 0.1-30 kPa and a temperature of 120-180℃, the generated poly(p-dioxanone) monomer being continuously distilled off by reduced pressure distillation and collected by condensation; the collected crude distillate being purified by reduced pressure distillation to obtain polymerization-grade poly(p-dioxanone) monomer. Experiments show that the purified monomer yield can reach 99%, with a purity of not less than 99.5%, and the recovered monomer can be used for ring-opening polymerization to synthesize poly(p-dioxanone) with an intrinsic viscosity ≥1.8 dL / g. This invention features a low-cost catalyst raw material, mild depolymerization conditions, good reaction system fluidity, recyclable catalyst, low purification loss, and is easy to implement industrially.

The application discloses a method for degrading organic pollutants containing carbonyl and carboxyl by using cryptomelane oxygen vacancies, and adds cryptomelane into wastewater containing organic pollutants containing carbonyl and carboxyl, mixes sufficiently to generate hydrogen peroxide, and further degrades the organic pollutants by the hydrogen peroxide; the cryptomelane is an octahedral molecular sieve of manganese oxide mineral, and the crystal form is alpha-MnO2. The application utilizes the catalytic ability, oxidation ability and adsorption ability of the cryptomelane itself to degrade pollutants, and simultaneously utilizes the catalytic ability of the cryptomelane oxygen vacancies to generate hydrogen peroxide from pollutants containing carbonyl and carboxyl to remove the pollutants deeply, and the whole reaction process simultaneously utilizes the oxidation, adsorption and catalytic properties of the cryptomelane. Therefore, the application has the advantages of cheap and easily available required catalyst, wide pH application range, small required catalyst amount, no need of additional other oxidants, low reaction activation energy, completion under normal temperature and pressure air conditions, simple operation, high catalytic efficiency, recyclable catalyst and the like.

The application relates to a synthesis method of N-vinyl carboxylic acid amide. The method comprises the steps of preparing a catalytic loading system, a condensation reaction, membrane separation, a dealcoholization reaction and crystal precipitation purification. A Fe3O4@SiO2@ZSM-5-SO3H solid acid catalyst and a composite stabilizer mixed system are combined with a tubular ZSM-5 molecular sieve membrane separation technology to avoid the problems of many by-reactions, complicated purification and the like in traditional processes. The method has the advantages of high reaction efficiency, few by-products, low energy consumption, recyclable catalyst, high product purity and suitability for polymerization reactions and the like, and solves the defects of the existing method.

This invention discloses a method for indirectly preparing cyclohexanol from cyclohexene. The method involves etherifying cyclohexene with ethanol under a nitrogen atmosphere in the presence of molecular sieve catalyst I to obtain cyclohexylethyl ether. Then, in the presence of molecular sieve catalyst II, the cyclohexylethyl ether undergoes hydrolysis with water. The oil phase is extracted and distilled to obtain cyclohexanol. This invention, which uses etherification of cyclohexene with ethanol followed by hydrolysis to prepare cyclohexanol, is suitable for continuous industrial production and has advantages such as high safety, environmental friendliness, low production cost, high selectivity for cyclohexanol, and environmentally friendly and recyclable catalysts. It is an effective route for preparing cyclohexanol.

The application discloses a synthesis method of antioxidant 1330, and aims to provide a synthesis method of antioxidant 1330 with high yield, high purity and recyclable catalyst. 2‑ The application relates to a synthesis method of antioxidant 1330, which is characterized by the following steps: taking SO4 2‑ / ZrO2-MWCNT solid acid as a catalyst, and taking 3,5-di-tert-butyl-4-hydroxybenzyl methyl ether and mesitylene as raw materials to synthesize antioxidant 1330, and belongs to the technical field of synthesis.

This invention discloses a method for synthesizing 4-bromo-3-cyanopyridine, comprising the following steps: (1) under alkaline conditions, oxidizing the hydroxyl group by phosphorus oxychloride to prepare the intermediate product 2-chloro-3-cyano-4-methoxypyridine; (2) placing the product obtained in step (1) in ethanol, adding palladium on carbon, and slowly introducing hydrogen gas into it to prepare the intermediate product 3-cyano-4-methoxypyridine; (3) adding phosphorus oxychloride to the acetonitrile solution of the product obtained in step (2) to prepare the target product 4-bromo-3-cyanopyridine. The synthesis method adopted in this invention has advantages such as readily available raw materials, mild reaction conditions, recyclable catalyst, no heavy metal pollution, and simple product post-processing, making it suitable for industrial production.

The application discloses a method for synthesizing ethylene glycol diacetate by using a solid superacid catalyst. 2‑ The application discloses a method for synthesizing ethylene glycol diacetate by using a solid superacid catalyst of SO4 2‑ / TiO2-SiO2 type. The catalyst is prepared by co-precipitation of a titanium source and a silicon source, impregnation with dilute sulfuric acid and calcination, and has high specific surface area and rich strong acid sites. The catalyst can be used to catalyze esterification of ethylene glycol and acetic anhydride (or acetic acid) at 140-150 DEG C to efficiently generate ethylene glycol diacetate, the yield of which can be more than 90%, and the by-product is very little. The catalyst can be easily separated from the reaction system and has good recycling performance. The application has the advantages of high catalytic activity, good selectivity, no corrosion, recyclable catalyst and the like, and can be used for industrial production of ethylene glycol diacetate.

This invention discloses a method for preparing phenylbis(2-oxazoline) compounds. Under the first reaction temperature and first feed ratio conditions, isophthalonitrile and isopropanolamine are reacted as raw materials to form a phenyl-2-oxazoline intermediate containing a mononitrile. At a second reaction temperature, isopropanolamine and a supported metal oxide catalyst are added to the intermediate, and the reaction continues until the nitrile group is completely converted, yielding a crude phenylbis(2-oxazoline) product. The crude product is filtered under positive pressure to remove the catalyst, and the excess isopropanolamine is removed by evaporation of the filtrate. A crystallization solvent is added, and the mixture is stirred and crystallized. The crystal slurry is filtered and dried to obtain the phenylbis(2-oxazoline) compounds. This invention provides a simple preparation method with high product yield, recyclable catalyst, a raw material conversion rate of over 99%, a synthetic selectivity of over 95%, and a maximum process yield of over 85%.

This invention discloses a recyclable catalyst for purifying CO-rich waste gas and its preparation method, belonging to the field of catalyst preparation technology. It addresses the technical problem that the mechanical and regeneration performance of existing CO waste gas purification catalysts needs further improvement. This invention involves preparing a rare-earth manganese-zirconium composite oxygen storage body, a phosphorus-boron-aluminum-silicon composite, and a manganese-iron-titanium-phosphorus composite oxide, and then combining them to construct a recyclable catalyst. The rare-earth manganese-zirconium composite oxygen storage body provides an oxygen storage and release framework, the phosphorus-boron-aluminum-silicon composite constructs an inorganic connection network, and the manganese-iron-titanium-phosphorus composite oxide plays a role in interface transition and structural coordination. The three components work synergistically to improve the catalyst's structural integrity, interfacial bonding stability, and operational stability during the recycling process.

The application belongs to the technical field of organic synthesis and relates to a method for preparing diphenyl carbonate. The method uses a deep eutectic solvent (DES) as a catalyst to catalyze the one-pot reaction of CO2, carbon tetrachloride and phenol in the presence of an organic solvent, and the reaction conditions are as follows: the initial pressure of CO2 is 1-6 MPa, the temperature is 100-160 DEG C, and the time is 6-12 h. After the reaction, the layers are separated by standing, the lower layer DES can be directly recycled, the upper layer product phase is subjected to rectification to remove the organic solvent to obtain diphenyl carbonate, and the organic solvent can be recycled. The application solves the problems of difficult recovery of the catalyst, many by-products and low yield in the traditional method, has the advantages of high product purity, recyclable catalyst and solvent and simple operation, and is suitable for industrial production.

The application discloses a preparation method of a heterojunction bifunctional photocatalytic material Cu-BTC-TiO2 and application of the material in photocatalytic oxidation of phenylethylene, and relates to the following steps: under mild conditions, a MOF material Cu-BTC is compounded with a semiconductor TiO2 to obtain a bifunctional catalyst, and the catalyst successfully realizes the oxidation of aryl ethylene under the condition that oxygen is used as an oxygen source, and a series of aromatic aldehydes are synthesized by the method. The method has the advantages of recyclable catalyst, mild conditions, large-scale synthesis and the like. The application provides a new path of high efficiency, mildness and greenness for the preparation of aromatic aldehydes through the oxidation of aryl ethylene.

The invention discloses a method for synthesizing methyl benzoate, monosubstituted methyl benzoate and dimethyl furan-2, 5-dicarboxylate through a photocatalytic oxidation esterification one-pot method. According to the method, cobalt phthalocyanine / B / P co-doped g-C3N4 Z-type heterojunction is taken as a visible light active photocatalyst, air is taken as a molecular oxygen source, a 300W xenon lamp is taken as a light source, and methyl benzoate, series monosubstituted methyl benzoate and 2, 5-dihydroxymethylfurfural are synthesized from benzyl alcohol or series monosubstituted benzyl alcohol or 5-hydroxymethylfurfural and methanol through a one-step photocatalytic oxidation esterification one-pot method under the conditions of room temperature and normal pressure. The invention discloses a novel green and low-carbon synthesis process of dimethyl furandicarboxylate. The synthesis method has the characteristics of atom economy of a synthesis route, cheap and wide sources of raw materials, direct use of air as an O2 source, high activity of a catalytic system, good selectivity, recyclability of the catalyst and the like.

The application belongs to the technical field of catalytic organic synthesis, and relates to a method for catalyzing aldol condensation reaction. Under the catalysis of a functionalized metal organic framework material catalyst, substrates 1 and 2 undergo aldol condensation reaction in a reaction solvent and under certain reaction conditions to generate an aldol condensation product. Through catalyst structure design and reaction condition optimization, the aldol condensation reaction yield and selectivity of the target product are significantly improved. The preparation method of the application realizes efficient aldol condensation reaction of biomass platform compounds and ketone or carboxylic acid substrates by using a functionalized metal organic framework material as a catalyst, and has the advantages of mild reaction conditions, recyclable catalyst and high product selectivity.