Process for the preparation of vicinal diols by oxidation of olefins

Abstract

The present application discloses a method for preparing vicinal diols by olefin oxidation, which comprises contacting an olefin, an oxidant, an acid and a solvent with a composite catalyst to obtain a product containing vicinal diols, wherein the composite catalyst comprises a titanium silicalite and a tungsten-containing compound. The method has the characteristics of mild reaction conditions, simple operation process, high raw material conversion rate, high vicinal diol selectivity and high utilization rate of hydrogen peroxide.

Description

Technical Field

[0001] This invention relates to a method for preparing vicinal diols by olefin oxidation, and more specifically, to a method for preparing vicinal diols by co-catalyzing olefin oxidation with titanium silicate molecular sieves and tungsten-containing compounds. Background Technology

[0002] vicinal glycols are hydrocarbon organic compounds in which hydroxyl groups are present on two adjacent carbon atoms. Common vicinal glycols include 1,2-ethylene glycol (hereinafter referred to as ethylene glycol), 1,2-propanediol (hereinafter referred to as propylene glycol), 1,2-butanediol (hereinafter referred to as butanediol), and 1,2-hexanediol (hereinafter referred to as hexanediol). Vicinal glycols have important applications. For example, ethylene glycol can be used as a solvent, antifreeze, and in the synthesis of polyester; propylene glycol can be used to synthesize unsaturated polyester resins and as an antifreeze and moisturizer; and hexanediol can be used in the production of high-end cosmetics. Vicinal glycols have broad market applications and large production volumes. For example, in 2018, the global production capacity of propylene glycol reached 1.8 million tons per year.

[0003] The main production method for vicinal glycols involves the hydrolysis of upstream epoxides under specific conditions. For example, ethylene oxide hydrolyzes to yield ethylene glycol, propylene oxide hydrolyzes to yield propylene glycol, and hexane oxide hydrolyzes to yield hexanediol. Additionally, propylene glycol can also be obtained through a dimethyl carbonate / propylene glycol co-production method. The epoxide hydrolysis method requires the prior preparation of the epoxide compound, increasing process complexity, reducing raw material utilization, and causing waste emissions, directly leading to increased costs. The co-production method also requires the prior production of the epoxide compound; furthermore, the price of co-produced products is always subject to market fluctuations.

[0004] US10214471 and US20180354878A1 disclose a method for reacting propylene and hydrogen peroxide in a reactor to obtain propylene glycol under the action of a heteropolyacid and a phase transfer catalyst. In this method, the heteropolyacid reacts with hydrogen peroxide in an aqueous phase to form a peroxide heteropolyacid salt, which is then reacted with the peroxide heteropolyacid salt to form a soluble salt in the organic phase via a phase transfer catalyst. In this method, an alkylated aromatic organic solvent with 8-12 carbon atoms increases the proportion of the heteropolyacid salt in the organic phase to complete the oxidation of propylene to propylene oxide. The heteropolyacid dissolves in water and continues to react with hydrogen peroxide; the resulting propylene oxide can enter the aqueous phase. Since the pH of the aqueous phase is maintained in the range of 1-3.5, the propylene oxide is hydrolyzed under the action of the acid in the aqueous phase to obtain propylene glycol. This method essentially only involves the two-step reaction of propylene epoxidation to propylene oxide and the hydrolysis of propylene oxide under acid to obtain propylene glycol, all carried out in a single reactor. The reaction requires a large amount of solvent and has a complex catalyst system, making the operation difficult.

[0005] EP1527057A1 discloses a method for the continuous preparation of propylene glycol. This method involves reacting propylene with hydrogen peroxide to produce propylene oxide, simultaneously generating propylene glycol as a byproduct. The generated propylene oxide is then reacted at 180-220°C and 15-25 bar to produce propylene glycol, which is then separated. This method is a physical integration of two steps: epoxidation and hydrolysis, and therefore cannot avoid the problems of low reaction efficiency and harsh hydrolysis conditions.

[0006] WO2019029808A1 discloses a method for preparing terminal 1,2-alkanediols with 5-12 carbon atoms. The method involves reacting the corresponding terminal olefin with formic acid and hydrogen peroxide to obtain a monoformate or diformate, followed by decomposition under the action of a decarbonization catalyst to yield the corresponding diol and carbon monoxide. This method has low selectivity and poses significant safety risks associated with organic peroxides.

[0007] CN103570493A discloses a method for synthesizing 1,2-vicinal diol via phase transfer catalytic oxidation using a supported heteropolyacid. The method involves mixing and reacting an acid, a terminal alkene, hydrogen peroxide, and a heteropolyacid phase transfer catalyst, followed by separation to obtain an epoxidized mixture. An alkaline solution is then added to maintain the pH at 10-12, and the mixture is further extracted by esterification and subjected to vacuum distillation to obtain the vicinal diol. This method has a long operational process and low product yield.

[0008] CN107879893A discloses a method for preparing vicinal diols via catalytic oxidation. The method involves preparing vicinal diols through the action of an olefin, an oxidant, and a bifunctional catalyst. The bifunctional catalyst contains silica-alumina molecular sieves, alumina, and titanium-silicon molecular sieves. This method uses an aluminum-containing catalyst, resulting in low utilization of hydrogen peroxide.

[0009] CN102452899A discloses a method for producing propylene glycol from propylene, which involves an epoxidation ring-opening hydration reaction of a titanium-silicon molecular sieve composite catalyst, propylene, and hydrogen peroxide to prepare propylene glycol. The titanium-silicon molecular sieve composite catalyst includes a titanium-silicon molecular sieve, an acidic molecular sieve, and a resin. However, this method has low hydrogen peroxide utilization.

[0010] CN104447204A discloses a method for preparing diols, which uses titanium-silicon molecular sieves supported on rare earth oxides as catalysts to promote the reaction of olefins and oxidants to produce diols. However, this method has low hydrogen peroxide utilization. Summary of the Invention

[0011] The purpose of this invention is to provide a method for preparing vicinal diols by olefin oxidation. This method has the advantages of mild reaction conditions, simple operation process, high raw material conversion rate, high selectivity of vicinal diols, and high effective utilization rate of hydrogen peroxide.

[0012] To achieve the above objectives, the present invention provides a method for preparing vicinal diols by olefin oxidation, characterized in that the method includes contacting an olefin with an oxidant in the presence of an acid, a solvent, and a composite catalyst to obtain a product containing vicinal diols, wherein the composite catalyst contains a titanium silicate molecular sieve and a tungsten-containing compound.

[0013] In the method described, the olefin is a C2-C30 monoolefin or polyolefin. The olefin may also contain one or more functional groups selected from alkyl, aryl, ester, nitro, hydroxyl, carboxyl, aldehyde, ketone, cyano, ether, amino, imino, and halogen substituents, or further contain oxygen, nitrogen, sulfur, phosphorus, or halogen heteroatom groups. Preferably, the olefin is one or more selected from ethylene, vinyl chloride, propylene, allyl chloride, bromopropylene, acrylonitrile, acrylic acid, acrolein, allyl alcohol, vinyl acetate, butenoic acid, isobutene, 1-butene, 2-butene, butadiene, 1-pentene, cyclopentene, methylcyclopentene, 1,4-pentadiene, cyclopentadiene, isoprene, 1-hexene, cyclohexene, hexadiene, 1-heptene, cycloheptene, 1-octene, cyclooctene, 1-decene, cyclododecene, styrene, styrene, oleic acid, methyl oleate, castor oil acid, and methyl ricinoleate. More preferably, the olefin is one or more selected from propylene, 1-butene, 1-hexene, cyclohexene, and allyl chloride.

[0014] In the method, the oxidant is selected from at least one of inorganic peroxides, organic peroxides, and ozone; the inorganic peroxide is selected from at least one of hydrogen peroxide, urea peroxide, potassium persulfate, potassium persulfate, sodium percarbonate, percarbonamide, and sodium perborate; the organic peroxide is selected from at least one of tert-butyl hydroperoxide, cyclohexyl hydroperoxide, cumene peroxide, ethylbenzene hydroperoxide, benzoic acid peroxide, methyl ethyl ketone peroxide, tert-butyl perpentyl peroxide, isopropyl hydroperoxide, tert-amyl hydroperoxide, and di-tert-butyl peroxide; preferably, the oxidant is hydrogen peroxide.

[0015] In the method described, the acid is one or more of organic carboxylic acids, substituted benzenesulfonic acids, phosphoric acid, nitric acid, and sulfuric acid; preferably, the acid is selected from one or more of phosphoric acid, nitric acid, and sulfuric acid.

[0016] In the method described, the solvent is one or more of water, C2-C20 ethers, C2-C20 acids, C2-C30 esters and their derivatives; preferably, the solvent is water.

[0017] In the method described, the titanium-silicon molecular sieve is at least one of MFI-type titanium-silicon molecular sieve, MEL-type titanium-silicon molecular sieve, BEA-type titanium-silicon molecular sieve, MWW-type titanium-silicon molecular sieve, MOR-type titanium-silicon molecular sieve, TON-type titanium-silicon molecular sieve, TUN-type titanium-silicon molecular sieve, and hexagonal titanium-silicon molecular sieve; preferably, the titanium-silicon molecular sieve is an MFI-type titanium-silicon molecular sieve; more preferably, the MFI-type titanium-silicon molecular sieve has a hierarchical porous structure or an intracrystalline hollow structure.

[0018] In the method, the tungsten-containing compound is selected from tungsten-containing oxides, oxyacids, and salts; preferably, the tungsten-containing compound is selected from one or more of tungsten trioxide, blue tungsten, yellow tungsten, flaked tungsten acid, scheelic acid, metatungstenic acid, silicotungstenic acid, ammonium tungstate, ammonium metatungstate, and sodium tungstate; more preferably, the tungsten-containing compound is tungsten trioxide and / or metatungstenic acid.

[0019] In the method, the weight ratio of the titanium-silicon molecular sieve to the oxidant is (0.01-10):1. The weight ratio of the tungsten-containing compound to the titanium-silicon molecular sieve is (0.01-0.5):1, preferably (0.03-0.3):1, more preferably (0.07-0.2):1. The acid makes the pH of the reaction solution system 1-4, preferably 1.5-3. The molar ratio of the oxidant to the olefin is (0.1-20):1, preferably (0.5-10):1, more preferably (0.8-5):1. The molar ratio of the oxidant to the solvent is 1:(3-200), preferably 1:(5-80), more preferably 1:(10-40). The contact conditions are a temperature of 5℃-100℃ and a pressure of atmospheric pressure to 5MPa.

[0020] The method for preparing vicinal diols by olefin oxidation provided by this invention involves reacting olefins, oxidants, acids, and solvents in a single reactor under the action of a composite catalyst containing titanium-silicon molecular sieves and tungsten compounds to generate a product containing vicinal diols in one step. Compared with existing methods, this invention eliminates the need for a prior preparation of epoxide compounds, simplifies the operation, provides milder reaction conditions, achieves higher raw material conversion rates, exhibits higher selectivity for vicinal diols, and is safer and more efficient, making it suitable for large-scale industrial production applications. Detailed Implementation

[0021] The present invention provides a method characterized by contacting an olefin with an oxidant in the presence of an acid, a solvent, and a composite catalyst to obtain a product containing a vicinal diol, wherein the composite catalyst contains a titanium silicate molecular sieve and a tungsten-containing compound.

[0022] This invention does not limit the type of olefin used as a raw material; it can be a monoolefin or a polyolefin. The olefin can be an aliphatic hydrocarbon, an alicyclic hydrocarbon, or an aromatic hydrocarbon, and may contain substituents such as alkyl, aryl, ester, nitro, hydroxyl, carboxyl, aldehyde, ketone, cyano, ether, amino, imino, or halogen substituents. It may also contain oxygen, nitrogen, sulfur, phosphorus, or halogen heteroatoms. Preferably, the olefin is a C2-C30 monoolefin or polyolefin; more preferably, the olefin is C2-C18; and even more preferably, the olefin is C3-C8. For example, the olefins may be ethylene, vinyl chloride, propylene, chloropropylene, acrylonitrile, acrylic acid, acrolein, allyl alcohol, butenoic acid, isobutene, 1-butene, 2-butene, butadiene, 1-pentene, cyclopentene, 1,4-pentadiene, cyclopentadiene, isoprene, 1-hexene, cyclohexene, 1-heptene, 1-octene, cyclooctene, 1-decene, cyclododecene, styrene, styrene, oleic acid, methyl oleate, castor oil acid, methyl ricinoleate, etc.

[0023] According to the present invention, the olefin can be a single-component olefin, a mixed-component olefin, or a mixed olefin feedstock of olefin and inert components, such as nitrogen, argon, helium, neon, air, oxygen, hydrogen, methane, ethane, propane, and butane. In the mixed olefin feedstock, the molar content of the olefin is preferably greater than 20%, more preferably greater than 50%, further preferably greater than 70%, and most preferably greater than 90%. For safety reasons, the oxygen and hydrogen content in the mixed olefin feedstock is controlled; preferably, the molar content of oxygen and the molar content of hydrogen are each less than 5%, preferably less than 2%, and more preferably less than 1%.

[0024] According to the present invention, the oxidant may be at least one of inorganic peroxides, organic peroxides, and ozone; the inorganic peroxide is selected from at least one of hydrogen peroxide, urea peroxide, potassium persulfate, potassium persulfate, sodium percarbonate, percarbonamide, and sodium perborate; the organic peroxide is selected from at least one of tert-butyl hydroperoxide, cyclohexyl hydroperoxide, cumene peroxide, ethylbenzene hydroperoxide, benzoic acid peroxide, methyl ethyl ketone peroxide, tert-butyl perpentyl peroxide, isopropyl hydroperoxide, tert-amyl hydroperoxide, and di-tert-butyl peroxide; the preferred oxidant is hydrogen peroxide. Hydrogen peroxide is usually prepared as an aqueous solution, i.e., hydrogen peroxide solution. The present invention does not have special requirements on the mass concentration of the hydrogen peroxide solution. Preferably, the hydrogen peroxide solution is a solution with a hydrogen peroxide mass concentration of 2%-70%, more preferably 10%-50%, and even more preferably 20%-45%.

[0025] According to the present invention, the acid includes organic acids and / or inorganic acids. For example, it may be one or more of organic carboxylic acids, substituted benzenesulfonic acids, phosphoric acid, nitric acid, and sulfuric acid. The organic acid may be a carboxylic acid, such as formic acid, acetic acid, trifluoroacetic acid, difluoroacetic acid, monofluoroacetic acid, propionic acid, butyric acid, succinic acid, cyclohexyl acid, benzoic acid, and their derivatives, etc., and may be a benzenesulfonic acid, such as benzenesulfonic acid, methylbenzenesulfonic acid, dimethylbenzenesulfonic acid, ethylbenzenesulfonic acid, diethylbenzenesulfonic acid, isopropylphenylbenzenesulfonic acid, pentylbenzenesulfonic acid, cyclohexylbenzenesulfonic acid, decylbenzenesulfonic acid, dodecylbenzenesulfonic acid, tetradecylbenzenesulfonic acid, hexadecylbenzenesulfonic acid, octadecylbenzenesulfonic acid, phenylbenzenesulfonic acid, and p-chlorobenzenesulfonic acid. The inorganic acid may be one or more of phosphoric acid, nitric acid, and sulfuric acid. Preferably, the acid is one or more of phosphoric acid, nitric acid, and sulfuric acid. In the method provided by the present invention, the acid ionizes in the solvent to generate hydrogen protons, preferably such that the pH value of the solution system is 1-4, and more preferably the pH value is 1.5-3.

[0026] According to the present invention, the solvent can be selected from one or more of water, C2-C20 ethers, C2-C20 acids, C2-C30 esters, and their derivatives. For example, the solvent can be organic solvents such as dimethyl ether, diethyl ether, methyl tert-butyl ether, methyl cyclohexyl ether, anisole, acetic acid, propionic acid, butyric acid, malonic acid, octanoic acid, nonanoic acid, methyl formate, ethyl acetate, ethyl formate, butyl acetate, isopropyl acetate, cyclohexyl acetate, methyl oleate, ethyl oleate, and methyl castor oil. Considering that adding organic solvents requires additional solvent separation, purification, and recovery units, resulting in increased process complexity and energy consumption, from the perspective of optimizing the reaction process, reducing energy consumption, reducing waste emissions, and improving the economic efficiency of the equipment, it is preferable to use only water as the solvent for the contact reaction without adding the aforementioned organic solvents.

[0027] It is understandable that the heterogeneous mass transfer resistance present during the reaction process can be overcome by existing technologies such as selecting a suitable reactor, adding internal components, and adjusting process parameters, which will not be elaborated here. The method provided by this invention is carried out in the presence of a composite catalyst containing titanium-silicon molecular sieves and tungsten-containing compounds. The titanium species in the framework of the titanium-silicon molecular sieve have excellent properties for activating hydrogen peroxide and catalyzing the oxidation of organic molecules. According to the present invention, the titanium-silicon molecular sieve is a common titanium-silicon molecular sieve. For example, the titanium-silicon molecular sieve can be an MFI-type titanium-silicon molecular sieve (such as TS-1 molecular sieve), a MEL-type titanium-silicon molecular sieve (such as TS-2 molecular sieve), a BEA-type titanium-silicon molecular sieve (such as Ti-β molecular sieve), a MWW-type titanium-silicon molecular sieve (such as Ti-MCM-22 molecular sieve), a MOR-type titanium-silicon molecular sieve (such as Ti-MOR molecular sieve), a TUN-type titanium-silicon molecular sieve (such as Ti-TUN molecular sieve), a hexagonal titanium-silicon molecular sieve (such as Ti-MCM-41 molecular sieve, Ti-SBA-15 molecular sieve), and other structural titanium-silicon molecular sieves (such as Ti-ZSM-48 molecular sieve). Preferably, the titanium-silicon molecular sieve is selected from at least one of the MFI-type, MEL-type, and BEA-type titanium-silicon molecular sieves. More preferably, the titanium-silicon molecular sieve is an MFI-type titanium-silicon molecular sieve.

[0028] According to the present invention, the MFI-type titanium-silicon molecular sieve can be a TS-1 molecular sieve prepared by conventional methods such as hydrothermal synthesis and post-processing synthesis; it can be a titanium-silicon molecular sieve with a hierarchical porous structure (i.e., a pore distribution within the molecular sieve crystal in the range of 2-50 nm is obtained by BJH fitting the molecular sieve pore distribution curve according to the N2 adsorption-desorption curve); it can be a hollow titanium-silicon molecular sieve HTS with a hollow internal structure (i.e., TEM characterization shows that there is one or more internal cavities within the molecular sieve crystal); or it can be a titanium-silicon molecular sieve with a plate-like, spherical, hexagonal prism shape and an open surface. The present invention does not impose specific limitations on this. To achieve better technical effects, the more preferred MFI-type titanium-silicon molecular sieve of the present invention is a titanium-silicon molecular sieve with a hierarchical porous structure as described above and / or a hollow titanium-silicon molecular sieve HTS with a hollow internal structure.

[0029] The framework titanium in the titanium-silicon molecular sieve is the catalytic active center of the sieve. This invention does not have specific requirements for its titanium content; however, without violating objective laws, the higher the framework titanium content, the higher its catalytic activity. According to this invention, the titanium-silicon molar ratio of the titanium-silicon molecular sieve can be (0.001-0.05):1, preferably (0.01-0.03):1.

[0030] According to the present invention, the titanium-silicon molecular sieve can be used directly as a catalyst from raw molecular sieve powder, or it can be shaped, for example, by pressing into tablets, by rolling to prepare microspheres or small spheres, by extrusion to prepare strip catalysts, by spray drying to prepare spherical catalysts, etc., before use; or it can be used directly without shaping, by adding the titanium-silicon molecular sieve and other catalysts, co-catalysts, and inert matrix supports simultaneously or sequentially to the reaction of the present invention, and the present invention does not impose any limitations on this. The catalyst containing titanium-silicon molecular sieve preferably has a titanium-silicon molecular sieve weight content of 20%-100%, more preferably 50%-100%, and even more preferably 80%-100%. In addition to titanium-silicon molecular sieve as the main catalyst, it may also contain binders, co-catalysts, pore expanders, inert matrix supports, etc.

[0031] The inventors unexpectedly discovered that when titanium-silicon molecular sieves and tungsten-containing compounds are used as a composite catalyst in the oxidation of olefins to prepare vicinal diols, they exhibit a significant promoting effect. The tungsten-containing compounds include tungsten oxides, oxyacids, and salts. Preferred tungsten-containing compounds are selected from one or more of tungsten trioxide, blue tungsten, yellow tungsten, flaking tungstic acid, scheelic acid, metatungstic acid, silicotungstic acid, ammonium tungstate, ammonium metatungstate, and sodium tungstate. More preferably, the tungsten-containing compounds are one or more of tungsten trioxide and metatungstic acid. The weight ratio of the tungsten-containing compound to the titanium-silicon molecular sieve is (0.01-0.5):1, preferably (0.03-0.3):1, and more preferably (0.07-0.2):1. In the composite catalyst containing titanium-silicon molecular sieves and tungsten-containing compounds, the titanium-silicon molecular sieve can be mechanically mixed with the tungsten-containing compound before use, or the titanium-silicon molecular sieve and tungsten-containing compound can be shaped and used as a catalyst; this invention does not impose any limitations.

[0032] According to the present invention, the weight ratio of the titanium-silicon molecular sieve (based on SiO2) to the oxidant is (0.01-10):1, preferably (0.05-5):1, and more preferably (0.1-2):1. The molar ratio of the oxidant to the solvent is 1:(3-200), preferably 1:(5-80), and more preferably 1:(10-40). The molar ratio of the oxidant to the olefin is (0.1-20):1, preferably (0.5-10):1, and more preferably (0.8-5):1.

[0033] Without violating objective laws, the method for preparing vicinal diols by olefin oxidation provided by the present invention is preferably implemented as follows: the method includes premixing the oxidant with the composite catalyst and contacting them sufficiently for a period of time as a pre-activation of the catalyst, resulting in a mixture of the oxidant and the composite catalyst. The contact time is preferably 1-30 minutes. After this, the olefin, acid, and solvent are contacted with the mixture of the oxidant and the composite catalyst to obtain a product containing vicinal diol.

[0034] In this invention, the preferred conditions for contact are: a temperature of 5-100℃, preferably 20-80℃, and a pressure of atmospheric pressure to 5 MPa (gauge pressure). Within the preferred pressure range of the contact, the reaction system of this invention can be a liquid-liquid-solid three-phase reaction, a gas-liquid-solid three-phase reaction, a liquid-solid two-phase reaction, or a gas-liquid-liquid-solid four-phase reaction.

[0035] In this invention, the pressure can be the self-generated pressure formed by the reactants under reaction conditions, or it can be maintained by introducing gaseous components that are inert to the reaction, such as, but not limited to, nitrogen, argon, helium, neon, air, oxygen, methane, ethane, propane, and butane, to carry out the contact reaction process of this invention under conditions that do not violate objective laws. For safety reasons, the oxygen and hydrogen content is controlled, preferably with each molar content of oxygen and hydrogen being less than 5%, more preferably less than 2%, and even more preferably less than 1%.

[0036] This invention can be carried out under intermittent or continuous conditions. From the perspective of reducing labor intensity, improving product quality, and considering the feasibility and safety of the technology, this invention is preferably carried out under continuous conditions. The contact time, i.e., the reaction time, is preferably 1 min to 24 h, or the feed mass hourly space velocity (WHSV) based on oxides is preferably 0.1 to 5 h. -1 .

[0037] The method provided by this invention can achieve batch or continuous reactions in various types of reactors, such as batch reactors, fixed-bed reactors, tubular reactors, fluidized-bed reactors, suspended-bed reactors, and microchannel reactors. Different reactor types are chosen simply to meet specific needs and achieve better results in the one-step direct preparation of vicinal diols from olefins. This invention preferably uses appropriate catalysts in conjunction with the reactor; for example, fixed-bed reactors and tubular reactors use molded catalysts, batch reactors use molecular sieve powder, and microchannel reactors use molecular sieve powder or have the catalyst immobilized within microchannels to achieve relatively better reaction results. All of these should be considered part of this invention.

[0038] The reaction process of the method of the present invention mainly generates vicinal diols, mono-vicinal diols (i.e., condensation etherification products of 2 vicinal diol molecules), di-vicinal diols (i.e., condensation etherification products of 3 vicinal diol molecules), aldehydes generated from the double bond cleavage of the starting olefin, and acids obtained from further oxidation of the aldehydes. The method provided by the present invention further includes a step of separating the reaction products, for example, but not limited to, separating unreacted olefins and generated aldehydes by distillation, and separating the generated vicinal diols, mono-vicinal diols, and di-vicinal diols under reduced pressure or by extraction. The product separation steps described above have low energy consumption.

[0039] In the method of this invention, the separation of the catalyst from the reaction system can be achieved in various ways. For example, but not limited to, when using raw powdered titanium silicate molecular sieve as the catalyst, the product separation and catalyst recovery and reuse can be achieved through sedimentation, filtration, centrifugation, evaporation, membrane separation, etc. Alternatively, the catalyst can be shaped and loaded into a fixed-bed reactor, and the catalyst can be recovered after the reaction is completed. Various methods for the separation and recovery of catalysts are widely discussed in existing literature and will not be elaborated here.

[0040] The present invention will be further illustrated by the following examples, but these examples do not limit the scope of the invention.

[0041] The preparation method of the MFI type titanium-silicon molecular sieve TS-1 used in the examples is as follows (refer to the method in Zeolites, 1992, 12(8), 943-50): about 3 / 4 of the tetrapropylammonium hydroxide (TPAOH, 20%, purchased from Aldrich, USA) solution was added to the tetraethyl orthosilicate (TEOS) solution to obtain a liquid mixture with a pH of about 13. Then, under vigorous stirring, the required amount of anhydrous tetrabutyl titanate [Ti(OBu)4] was added dropwise to the obtained liquid mixture. An isopropanol solution was stirred for 15 minutes to obtain a clear liquid. Finally, the remaining TPAOH was slowly added to the clear liquid, and the mixture was stirred at 348-353 K for approximately 3 hours to obtain a sol with a chemical composition of 0.03TiO2:SiO2:0.36TPA:35H2O. This sol was then crystallized at 443 K for 3 days. The resulting solid was filtered, washed with distilled water, dried at 373 K for 5 hours, and then calcined at 823 K for 10 hours to obtain the TS-1 molecular sieve sample. The composition included 42 g of TEOS, 73 g of TPAOH, 2 g of Ti(OBu)4, 10 g of anhydrous isopropanol, and 68 g of water. The Ti:Si molar ratio in the TS-1 molecular sieve sample was 0.03:1.

[0042] The preparation of the MFI type titanium-silicon molecular sieve hierarchical TS-1 used in the examples (refer to CN112898237A, Comparative Example 2): (1) Tetraethyl orthosilicate, tetrabutyl titanate, tetrapropylammonium hydroxide, and water were mixed and treated at 30°C for 12 h to obtain a product with a molar composition of SiO2:TiO2:tetrapropylammonium hydroxide:water = 1:0.03:0.13:50; (2) The product from step (1) was subjected to... (2) The product from step (2) (based on SiO2) and the silanizing agent were added to N-phenyl-3-aminopropyltrimethoxysilanizing agent at a molar ratio of 1:0.1 and treated at 170℃ for 48 hours; (3) The product obtained in step (3) was filtered and washed, and the filter cake was dried at 90℃ for 12 hours and calcined at 550℃ for 6 hours to obtain the MFI type titanium-silicon molecular sieve hierarchical TS-1 with silanizing agent pore expansion. In the hierarchical TS-1, the Ti:Si molar ratio was 0.03:1. After N2 adsorption-desorption characterization and BJH pore distribution fitting, it was found that there were obvious mesopores in the range of 5-30 nm, and the mesopore volume was greater than 0.7 cm. 3 / g.

[0043] The MFI-type hollow titanium-silicon molecular sieve HTS used in the examples was prepared according to the method described in Example 1 of Chinese Patent CN1301599A. In the HTS molecular sieve, the Ti:Si molar ratio is 0.03:1. TEM characterization shows that there is an obvious hollow structure inside the molecular sieve crystal.

[0044] Unless otherwise specified, all raw materials used in the examples are chemically pure reagents.

[0045] The reaction products were analyzed by gas chromatography, and the results were quantified using the external standard method. The chromatographic conditions were as follows: Agilent-6890 chromatograph, HP-5 capillary column, injection volume 0.5 μL, injection port temperature 280℃. Column temperature was maintained at 100℃ for 2 min, then increased to 250℃ at a rate of 15℃ / min and held for 15 min. An FID detector was used, with a detector temperature of 280℃.

[0046] The hydrogen peroxide content was measured using the indirect titration method with sodium thiosulfate.

[0047] The following indicators were mainly examined in each embodiment and comparative example:

[0048] Olefin conversion rate = (Number of moles of olefins consumed in the formation of each substance in the product) / (Number of moles of olefins in the feedstock) × 100%

[0049] Selectivity for vicinal diols = (Number of moles of vicinal diols in the product) / (Number of moles of olefins consumed in the formation of main and by-products) × 100%

[0050] Effective utilization rate of hydrogen peroxide = (moles of hydrogen peroxide consumed in the formation of organic matter in the product) / (moles of hydrogen peroxide in the raw materials before the reaction - moles of hydrogen peroxide in the product after the reaction) × 100%

[0051] Example 1

[0052] HTS molecular sieve, tungsten trioxide, propylene, 30% (w / w) hydrogen peroxide solution, phosphoric acid, and the required amount of water were added to a reaction vessel. The weight ratio of tungsten trioxide to titanium silicate molecular sieve was 0.1:1, the molar ratio of titanium silicate molecular sieve to hydrogen peroxide was 0.2:1, the pH of the reaction solution was 2.0, the molar ratio of hydrogen peroxide (calculated as hydrogen peroxide) to propylene was 2:1, and the molar ratio of hydrogen peroxide (calculated as hydrogen peroxide) to water was 1:20. The mixture in the reaction vessel was then reacted at 60℃ and 2MPa for 3 hours. After the reaction was completed, samples were taken for analysis, and the results are shown in Table 1.

[0053] Example 2

[0054] HTS molecular sieve, tungsten trioxide, 1-butene, 40% (w / w) hydrogen peroxide solution, phosphoric acid, and the required amount of water were added to a reactor. The weight ratio of tungsten trioxide to titanium silicate molecular sieve was 0.1:1, the molar ratio of titanium silicate molecular sieve to hydrogen peroxide was 0.2:1, the pH of the reaction solution was 2.5, the molar ratio of hydrogen peroxide to 1-butene was 2:1, and the molar ratio of hydrogen peroxide to water was 1:15. The mixture in the reactor was then reacted at 40℃ and 1 MPa for 4 hours. After the reaction was completed, samples were taken for analysis, and the results are shown in Table 1.

[0055] Example 3

[0056] HTS molecular sieve, metatungstic acid, propylene, 27% (w / w) hydrogen peroxide solution, sulfuric acid, and the required amount of water were added to a reaction vessel. The weight ratio of metatungstic acid to titanium-silicon molecular sieve was 0.15:1, the molar ratio of titanium-silicon molecular sieve to hydrogen peroxide was 0.5:1, the pH of the reaction solution was 1.5, the molar ratio of hydrogen peroxide to propylene was 3:1, and the molar ratio of hydrogen peroxide to water was 1:30. The mixture in the reaction vessel was then reacted at 80℃ and 4MPa for 2 hours. After the reaction was completed, samples were taken for analysis, and the results are shown in Table 1.

[0057] Example 4

[0058] HTS molecular sieve, tungsten trioxide, and 27% (w / w) hydrogen peroxide solution were mixed and activated at 60°C for 10 min. Then, propylene, phosphoric acid, and the required amount of water were added to the reactor. The weight ratio of tungsten trioxide to titanium silicate molecular sieve was 0.2:1, the molar ratio of titanium silicate molecular sieve to hydrogen peroxide was 0.2:1, the pH of the reaction solution was 2.0, the molar ratio of hydrogen peroxide to propylene was 2:1, and the molar ratio of hydrogen peroxide to water was 1:20. The mixture in the reactor was reacted at 60°C and 2 MPa for 3 h. After the reaction was completed, samples were taken for analysis, and the results are shown in Table 1.

[0059] Example 5

[0060] HTS molecular sieve, tungsten trioxide, and 30% (w / w) hydrogen peroxide solution were mixed and activated at 50°C for 20 min. Then, 1-hexene, sulfuric acid, and the required amount of water were added to the reactor. The weight ratio of tungsten trioxide to titanium silicate molecular sieve was 0.07:1, the molar ratio of titanium silicate molecular sieve to hydrogen peroxide was 1:1, the pH of the reaction solution was 1.5, the molar ratio of hydrogen peroxide to 1-hexene was 1.2:1, and the molar ratio of hydrogen peroxide to water was 1:20. The mixture in the reactor was reacted at 50°C and 0.5 MPa for 3 h. After the reaction was completed, samples were taken for analysis, and the results are shown in Table 1.

[0061] Example 6

[0062] HTS molecular sieve, metatungstic acid, and 30% (w / w) hydrogen peroxide solution were mixed and activated at 30°C for 30 min. Then, this mixture was introduced into a microchannel reactor with allyl chloride, phosphoric acid, and the required amount of water for reaction. The weight ratio of metatungstic acid to titanium silicate molecular sieve was 0.2:1, the molar ratio of titanium silicate molecular sieve to hydrogen peroxide was 0.3:1, the pH of the reaction solution was 2.0, the molar ratio of hydrogen peroxide to allyl chloride was 1.5:1, and the molar ratio of hydrogen peroxide to water was 1:15. The mixture in the reactor was reacted at 30°C and 0.2 MPa for 5 min. After the reaction was completed, samples were taken for analysis, and the results are shown in Table 1.

[0063] Example 7

[0064] HTS molecular sieve, metatungstic acid, and 30% (w / w) hydrogen peroxide solution were mixed and activated at 80°C for 10 min. Then, propylene, phosphoric acid, and the required amount of water were added to the reactor. The weight ratio of metatungstic acid to titanium silicate molecular sieve was 0.15:1, the molar ratio of titanium silicate molecular sieve to hydrogen peroxide was 0.3:1, the pH of the reaction solution was 2.5, the molar ratio of hydrogen peroxide to propylene was 2:1, and the molar ratio of hydrogen peroxide to water was 1:30. The mixture in the reactor was reacted at 80°C and 3 MPa for 2 h. After the reaction was completed, samples were taken for analysis, and the results are shown in Table 1.

[0065] Example 8

[0066] HTS molecular sieve, metatungstic acid, and 30% (w / w) hydrogen peroxide solution were mixed and activated at 60°C for 10 min. Then, propylene, sulfuric acid, and the required amount of water were added to the reactor. The weight ratio of metatungstic acid to titanium-silicon molecular sieve was 0.15:1, the molar ratio of titanium-silicon molecular sieve to hydrogen peroxide was 0.2:1, the pH of the reaction solution was 2.5, the molar ratio of hydrogen peroxide to propylene was 3:1, and the molar ratio of hydrogen peroxide to water was 1:20. The mixture in the reactor was reacted at 60°C and 2 MPa for 3 h. After the reaction was completed, samples were taken for analysis, and the results are shown in Table 1.

[0067] Example 9

[0068] HTS molecular sieve, tungsten trioxide, and 30% (w / w) hydrogen peroxide solution were mixed and activated at 60°C for 5 min. Then, propylene, nitric acid, and the required amount of water were added to the reactor. The weight ratio of tungsten trioxide to titanium silicate molecular sieve was 0.2:1, the molar ratio of titanium silicate molecular sieve to hydrogen peroxide was 0.2:1, the pH of the reaction solution was 2.0, the molar ratio of hydrogen peroxide to propylene was 1.5:1, and the molar ratio of hydrogen peroxide to water was 1:15. The mixture in the reactor was reacted at 60°C and 2 MPa for 4 h. After the reaction was completed, samples were taken for analysis, and the results are shown in Table 1.

[0069] Example 10

[0070] HTS molecular sieve, tungsten trioxide, propylene, 30% (w / w) hydrogen peroxide solution, phosphoric acid, and the required amount of methyl tert-butyl ether were added to a reaction vessel. The weight ratio of tungsten trioxide to titanium silicate molecular sieve was 0.3:1, the molar ratio of titanium silicate molecular sieve to hydrogen peroxide was 0.4:1, the pH of the reaction solution was 1.0, the molar ratio of hydrogen peroxide to propylene was 1.5:1, and the molar ratio of hydrogen peroxide to methyl tert-butyl ether was 1:10. The mixture in the reaction vessel was then reacted at 50℃ and 1.5 MPa for 2 hours. After the reaction was completed, samples were taken for analysis, and the results are shown in Table 1.

[0071] Example 11

[0072] The difference from Example 1 is that TS-1 molecular sieve was used, and the analysis results are shown in Table 1.

[0073] Example 12

[0074] The difference from Example 1 is that a multi-level porous TS-1 molecular sieve was used, and the analysis results are shown in Table 1.

[0075] Comparative Example 1

[0076] Unlike Example 11, tungsten trioxide was not added. The analysis results are shown in Table 1.

[0077] Comparative Example 2

[0078] Unlike Example 12, tungsten trioxide was not added. The analysis results are shown in Table 1.

[0079] Comparative Example 3

[0080] Unlike Example 1, tungsten trioxide was not added. The analytical results are shown in Table 1.

[0081] Comparative Example 4

[0082] Unlike Example 1, HTS molecular sieve was not added. The analytical results are shown in Table 1.

[0083] Comparative Example 5

[0084] TS-1 molecular sieves loaded with cerium dioxide were prepared according to the method of Example 1 of Chinese Patent CN104447204A, and the reaction was evaluated according to the method of Example 1. In this case, the reaction process did not involve the addition of phosphoric acid and tungsten trioxide, and CeO2 / TS-1 was used as the catalyst. The analytical results after the reaction were completed are shown in Table 1.

[0085] Table 1

[0086]

[0087] As can be seen from the results of Examples 1-12 and Comparative Examples 1-5 shown in Table 1, the method of the present invention for preparing vicinal diols is simple to operate, has mild reaction conditions, high olefin conversion rate, high vicinal diol selectivity, high hydrogen peroxide utilization rate, and is safe and controllable, making it suitable for large-scale industrial production applications.

Claims

1. A method for preparing vicinal diols by olefin oxidation, characterized in that, The method involves contacting an olefin with an oxidant in the presence of an acid, water as the solvent only, and a composite catalyst to obtain a product containing a vicinal diol. The olefin is one or more of the following: ethylene, vinyl chloride, propylene, allyl chloride, bromopropylene, acrylonitrile, acrylic acid, acrolein, allyl alcohol, vinyl acetate, butenoic acid, isobutene, 1-butene, 2-butene, butadiene, 1-pentene, cyclopentene, methylcyclopentene, 1,4-pentadiene, cyclopentadiene, isoprene, 1-hexene, cyclohexene, hexadiene, 1-heptene, cycloheptene, 1-octene, cyclooctene, 1-decene, cyclododecene, styrene, styrene, oleic acid, methyl oleate, ricinoleic acid, and methyl ricinoleate. The oxidant is hydrogen peroxide. The acid is selected from one or more of phosphoric acid, nitric acid, and sulfuric acid. The composite catalyst is obtained by mechanically mixing a titanium-silicon molecular sieve and a tungsten-containing compound, or by molding the titanium-silicon molecular sieve and the tungsten-containing compound. The titanium-silicon molecular sieve is an MFI-type titanium-silicon molecular sieve with a hierarchical porous structure or a hollow crystal structure; the tungsten-containing compound is tungsten trioxide and / or metatungstic acid.

2. The method according to claim 1, characterized in that, The olefin is one or more of propylene, 1-butene, 1-hexene, cyclohexene, and allyl chloride.

3. The method according to claim 1, characterized in that, The weight ratio of the titanium-silicon molecular sieve to the oxidant is (0.01-10):

1.

4. The method according to claim 1, characterized in that, The weight ratio of the tungsten-containing compound to the titanium-silicon molecular sieve is (0.01-0.5):

1.

5. The method according to claim 4, characterized in that, The weight ratio of the tungsten-containing compound to the titanium-silicon molecular sieve is (0.03-0.3):

1.

6. The method according to claim 5, characterized in that, The weight ratio of the tungsten-containing compound to the titanium-silicon molecular sieve is (0.07-0.2):

1.

7. The method according to claim 1, characterized in that, The acid causes the pH of the reaction solution system to be between 1 and 4.

8. The method according to claim 7, characterized in that, The acid causes the pH of the reaction solution system to be 1.5-3.

9. The method according to claim 1, characterized in that, The molar ratio of the oxidant to the olefin is (0.1-20):

1.

10. The method according to claim 9, characterized in that, The molar ratio of the oxidant to the olefin is (0.5-10):

1.

11. The method according to claim 10, characterized in that, The molar ratio of the oxidant to the olefin is (0.8-5):

1.

12. The method according to claim 1, characterized in that, The molar ratio of the oxidant to the solvent is 1:(3-200).

13. The method according to claim 12, characterized in that, The molar ratio of the oxidant to the solvent is 1:(5-80).

14. The method according to claim 13, characterized in that, The molar ratio of the oxidant to the solvent is 1:(10-40).

15. The method according to claim 1, characterized in that, The contact conditions are a temperature of 5°C to 100°C and a pressure of atmospheric pressure to 5 MPa.

Images