137 results about "Reactive distillation" patented technology

The invention relates to a process for producing polyethylene glycol by coupling a reactive distillation separation ternary water-containing azeotropic system. According to the process, excessive ethylene oxide is introduced into a ternary water-containing azeotropic system, water in the system is completely converted into polyethylene glycol to be extracted as a by-product, and the excessive ethylene oxide and residual organic components of the system are separated through a common rectification technology. According to the invention, chemical reaction and rectification separation are coupled to be carried out in one tower, reaction and separation are realized at the same time, and heat released by the reaction can reduce the thermal load of the reboiler.

This application relates to a UV-3 ultraviolet absorber and its preparation method, belonging to the field of chemical synthesis technology. The preparation method employs a one-pot process, in which benzocaine reacts with triethyl orthoformate in xylene solvent. This step utilizes reactive distillation coupling control, continuously removing the generated alcohol distillate through a distillation separation device to promote reaction equilibrium shift, obtaining a xylene solution of the intermediate NET. Subsequently, the solution is heated to a reaction temperature of 135–145°C, and benzyl chloride is added dropwise for N-alkylation, while a tail gas absorption device absorbs byproduct gases. The reaction slurry is then cooled for crystallization, solid-liquid separation, and drying to obtain the UV-3 product. This invention simplifies the production process through a one-pot process, avoids the use of toxic DMF solvent, and solves the technical problem of raw material residues leading to subsequent side reactions in the one-pot process through reactive distillation coupling control, resulting in a final product with high purity and high yield.

The invention discloses a method for preparing 6N and above high-purity Nb2O5 by using a niobium oxalate precursor, belongs to the technical field of niobium pentoxide preparation, and solves the problems of low purity and high impurity content of Nb2O5 prepared by the existing method. The method comprises the following steps: mixing niobium oxalate with high-purity water to obtain a mixed solution; performing cold crystallization purification; separating niobium oxalate crystals from the mother liquor, washing and drying; the method comprises the following steps: putting niobium oxalate crystals into a crucible, putting the crucible into a vacuum reaction distillation furnace, sealing a system, vacuumizing to below 1Pa, carrying out inert gas replacement, and then carrying out stage heating and heat preservation; cooling to 800-900 DEG C, introducing high-purity oxygen into the system, and carrying out oxidation stabilization treatment at a constant temperature; after treatment, continuously cooling to 200 DEG C or below, and then naturally cooling to room temperature to obtain a high-purity Nb2O5 product. The Nb2O5 product prepared by the method disclosed by the invention is high in purity and low in impurity content.

The invention relates to the technical field of isopropanol preparation, in particular to a device and a process for preparing isopropanol through reactive distillation. Comprising refining equipment, a preheater, a hydrogen filter, a hydrogen compressor, a buffer tank, a hydrogen heat exchanger, a hydrogenation reactor, a gas-liquid separator and a recovery tower, the hydrogenation reactor comprises a tower body; the tower body comprises an upper tower body and a lower tower body; a gas inlet is formed in the upper end of the upper tower body; by arranging the material changing box, the catalytic plate can be pre-filled in the material changing box, specifically, before the reactor is shut down, an operator pre-loads a new catalytic plate into the material changing box and completes nitrogen replacement so as to thoroughly eliminate oxygen in the material changing box, and therefore during replacement, the replacement efficiency is greatly improved. Compared with the prior art, an operator can directly push the pre-filled catalytic plate into the tower body for replacement without replacing hydrogen in the tower body after shutdown, so that the hydrogen replacement steps are reduced, the shutdown time of equipment is remarkably shortened, and the production efficiency of isopropanol is improved.

The diphenyl carbonate reactive distillation system comprises a reactive distillation tower, a reflux pipeline, a tower top reflux tank, a first condenser, a methanol recovery system, a reflux pump, a side extraction pipeline, a side extraction pump, a buffer tank, a discharge pipeline, a tower bottom pump and a flash tank, a tower top liquid material of the reactive distillation tower enters a tower top reflux tank through a reflux pipeline, and a gas material enters a methanol recovery system after being condensed by a first condenser; controlling the reflux ratio, and refluxing the material in the tower top reflux tank; the reactive distillation column is provided with a height-adjustable side line extraction opening for extracting by-products such as anisole; and separating the reaction organisms through a flash tank to obtain diphenyl carbonate. The device integrates chemical reaction and rectification separation, methanol is separated from a material refluxed at the top of the tower, by-products such as anisole are extracted from a side line, the thermodynamic equilibrium of the reaction is broken, and the reaction is pushed to proceed in the positive direction, so that the conversion rate is increased, and meanwhile, a plurality of by-products are obtained; and the side line extraction position is adjustable, safe and convenient.

This invention discloses a method for producing 4-methyl-2-pentanone, which is implemented using a 4-methyl-2-pentanone production apparatus. The apparatus includes a reactive distillation column, a condenser connected to the top of the reactive distillation column, and a reboiler connected to the bottom of the column. The reactive distillation column has a rectification section, a reaction section, and a stripping section arranged sequentially from top to bottom. During operation, a catalyst is placed in the reaction section, and 4-methyl-2-pentanol is introduced into the reaction section. The temperature of the reaction section is controlled at 180–280°C. The gas phase produced by the reaction is condensed by the condenser to produce 4-methyl-2-pentanone. This production method features high conversion rate, stable product quality, and low energy consumption.

A process for treating a crude oil feedstock includes: introducing a crude oil stream into a reactive distillation unit to remove Conrason carbon residues and metals from the crude oil stream and produce a distillate stream having an average boiling point distribution that is less than the average boiling point distribution of the crude oil stream; and feeding the distillate stream in gaseous form, in a continuous manner and without further treatment, to a catalytic cracking reactor operating at a temperature of 300 DEG C to 800 DEG C, the catalytic cracking reactor having a cracking catalyst arranged therein, the cracking catalyst cracking the distillate stream, to form a petrochemical product stream comprising light olefins and BTX.

The invention provides a preparation method of N, N-diisopropylethylamine based on a liquid-phase compression synthesis process, which comprises the following steps: mixing ethanol with hydrobromic acid with specified concentration, and carrying out reactive distillation treatment in the presence of a phase transfer catalyst to generate bromoethane; p-bromoethane and diisopropylamine are subjected to a liquid phase addition and compression combination reaction, and a reaction mixture is obtained; and sequentially neutralizing, distilling, condensing and filtering the reaction mixture to obtain the N, N-diisopropylethylamine, so as to solve the problems that the existing preparation method of the N, N-diisopropylethylamine is high in energy consumption, high in operation risk, large in pollutant discharge amount, low in by-product resource utilization rate, low in cost and the like. The safety is poor; the energy efficiency is low; and by-products cannot be recycled.

The invention provides an ethyl tert-butyl ether preparation method, which comprises: carrying out at least two-stage etherification reaction on a C4 raw material and ethanol to obtain a pre-product; carrying out reactive distillation on the pre-product, wherein the reactive distillation comprises stripping treatment and reactive distillation treatment; the pre-product is subjected to stripping treatment, an ethyl tert-butyl ether product is extracted, and a C4 and ethanol mixture obtained through separation is subjected to reactive distillation treatment; ethyl tert-butyl ether obtained through reactive distillation treatment is returned for stripping treatment, and C4 and ethanol obtained through reactive distillation separation are subjected to ethanol recovery treatment. According to the preparation method, stripping of reactive distillation and reactive distillation are carried out separately, and ethyl tert-butyl ether in a pre-product and unreacted C4 and ethanol are separated before reactive distillation, so that the raw material conversion rate of the reactive distillation step is greatly improved, and the overall conversion rate of isobutene is further improved; and meanwhile, the purity of the ethyl tert-butyl ether product extracted by reaction distillation is improved.

The utility model provides a tetramethyl ammonium bicarbonate preparation device with low energy consumption, which comprises a reactive distillation tower, a static mixer, a methanol removal tower and a methanol recovery tower, a gas phase discharge port of the methanol removal tower is connected with an inlet of a steam compressor, a first branch connected with an outlet of the steam compressor is connected with a gas inlet of the methanol recovery tower, and a second branch connected with an outlet of the steam compressor is connected with a gas outlet of the methanol recovery tower. A second branch connected with an outlet of the steam compressor is connected with the first return tank through a heating medium channel of the steam generator; a third branch connected with an outlet of the first reflux tank is connected with a feed port of the methanol recovery tower, and a fourth branch connected with the outlet of the first reflux tank is connected with a tower kettle of the methanol removal tower; after pure water exchanges heat through a refrigerant channel of the steam generator, steam is output, and the steam is input into a tower kettle of the methanol removal tower through a pipeline; and the methanol recovery tower is provided with a side extraction opening for extracting high-purity methanol. The device disclosed by the utility model is low in operation energy consumption, low in equipment investment and high in raw material utilization rate, and can be used for continuously preparing high-purity TMAB and recovering to obtain a high-purity methanol product.

The present invention relates to a process for preparing at least one alkali metal methoxide by reactive distillation in at least one reaction column. At the lower end of the reaction column(s), the respective alkali metal methoxide dissolved in methanol is withdrawn. The methanol / water mixture obtained at the top of the reaction column(s) is separated by distillation in a rectification column.The vapours obtained at the upper end of the rectification column are compressed in at least two stages and the energy of the vapours compressed in each case is advantageously transferred to bottoms and side streams of the rectification column. This allows particularly efficient use of the energy of the compressed vapours in the process according to the invention. In addition, the energy in the product stream of alkali metal methoxide which is obtained at the lower end of the reaction column(s) is advantageously transferred to the vapour streams from the rectification column, especially before these vapours are subjected to compression.The energy from the compressed vapour may additionally be used for operation of the reaction column(s) or for operation of a reaction column in which a process for transalcoholization of alkali metal alkoxides is performed.

This invention discloses a catalytic reactive distillation unit, apparatus, and method. The catalytic reactive distillation unit includes: a reaction mass transfer channel, the upper end of which receives low-temperature liquid-phase reactants flowing downwards, and the lower end of which receives high-temperature gas phase flowing upwards; the reaction mass transfer channel contains a catalyst layer and a packing layer, with the catalyst layer positioned above the packing layer, and a first space between them; and a rising gas bypass, located outside the reaction mass transfer channel and connected to the first space. The liquid-phase products after the catalytic reaction merge with the high-temperature gas phase in the packing layer and undergo gas-liquid mass transfer. The rising gas phase after mass transfer carries the light components from the liquid-phase products into the rising gas bypass, completing mass transfer separation. This invention, through the setting of the rising gas bypass, not only increases the gas phase flow rate and effectively reduces the pressure drop within the reaction mass transfer channel, but also effectively solves the space occupation problem of the equipment. This invention can clean the blockage of the catalyst filter without additional power and can realize online replacement of the catalyst and / or packing.

This invention provides an intelligent control system and method for the production of tert-butane without catalytic reduction, belonging to the field of tert-butane production control. The intelligent control system includes a host computer and sensing and execution mechanisms electrically connected to the host computer. The sensing mechanisms include a TDLAS analyzer installed at the top outlet of the reactive distillation column, NIR analyzers installed at the tert-butanol inlet of the mixing preheater and the side outlet of the reactive distillation column, temperature sensors installed at the top, bottom, and side outlet of the reactive distillation column, flow meters installed at the feed inlet, top outlet, and reflux inlet of the reactive distillation column, and multiple pressure sensors spaced at equal intervals along the height of the reaction section. The execution mechanisms include electrically operated regulating valves installed at the feed inlet and reflux inlet of the reactive distillation column. The control system integrates multiple sensors and execution mechanisms, enabling closed-loop intelligent control of the entire process.

The invention discloses a reactive distillation tower and maintenance equipment thereof, and belongs to the technical field of reactive distillation equipment. The device comprises a tower body, a flow dividing assembly is arranged on one side of the tower body and in the middle of the tower body, the flow dividing assembly comprises a flow dividing pipe, the bottom of the flow dividing pipe is fixedly connected with a flow dividing disc, the middle of the bottom of the flow dividing disc is fixedly connected with a lower flow dividing spray head, and the edge of the bottom of the flow dividing disc is fixedly connected with a plurality of side flow dividing spray heads. The side shunting nozzles are obliquely arranged towards the middle part of the shunting plate; according to the reactive distillation tower disclosed by the invention, the side shunting nozzles positioned on the outer side edges of the shunting assemblies are obliquely arranged towards the inner side, so that liquid flow sprayed by the side shunting nozzles can mutually impact liquid flow sprayed by the lower shunting nozzles in the side shunting nozzles, and the liquid flow cannot directly impact the inner wall of the tower body; therefore, the erosion loss speed of the anti-corrosion coating on the inner wall of the tower body is reduced, the service life of the reactive distillation tower is effectively prolonged, and the maintenance frequency is reduced.

A method for controlling a reactive distillation column for effecting a transalcoholisation reaction, comprising feeding a metal methoxide into the reactive distillation column via a side feed; feeding a reactant alcohol into a lower part of the reactive distillation column; withdrawing methanol from the top of the reactive distillation column; and withdrawing a solution of a product metal alkoxide in the reactant alcohol from the bottom of the reactive distillation column; wherein the method comprises a process control scheme selected from: Scheme A: establishing a signal S1 which is responsive to a temperature in the rectifying section disposed above the feed of the metal methoxide; and manipulating in response to the signal S1 the feed amount of the reactant alcohol; Scheme B: establishing a signal S1 which is responsive to a temperature in the rectifying section disposed above the feed of the metal methoxide; and manipulating in response to the signal S1 the heat supplied to the bottom of the reactive distillation column. The invention also relates to a method for controlling a reactive distillation column for effecting a transalcoholisation reaction, comprising feeding a metal methoxide into the reactive distillation column via a side feed; feeding a reactant alcohol into a lower part of the reactive distillation column; causing an auxiliary alcohol to be present in the reactive distillation column; and optionally replenishing the auxiliary alcohol via a side feed located above the feed of the reactant alcohol and below the top of the column; withdrawing methanol from the top of the reactive distillation column; and withdrawing a solution of a product metal alkoxide in the reactant alcohol from the bottom of the reactive distillation column; wherein the method comprises a process control scheme selected from: Scheme C: establishing a signal S2 which is responsive to a temperature at a point located between the feed of the metal methoxide and the bottom of the reactive distillation column; and manipulating in response to the signal S2 the feed amount of the reactant alcohol; Scheme D: establishing a signal S2 which is responsive to a temperature at a point located between the feed of the metal methoxide and the bottom of the reactive distillation column; and manipulating in response to the signal S2 the heat supplied to the bottom of the reactive distillation column. The methods of the invention allow for improved controlling of a reactive distillation column for effecting a transalcoholisation reaction.

The invention relates to an electronic-grade acetic ether production method and device based on reactive distillation-dividing wall tower distillation reinforcement. The device is composed of a reactive distillation system, an alcohol ester recovery tower system, an acetic ether concentration system and an acetic ether refining dividing wall tower system. An esterification reactor of the reactive distillation system adopts strong acid ion exchange resin as a catalyst; the contents of acetic acid and ethanol in the acetic ether reaction liquid are controlled by feeding fresh ethanol and acetic acid in a reactive distillation system; and crude ethyl acetate from which water and ethanol are removed by the ethyl acetate concentration tower is subjected to light component removal and heavy component removal by an ethyl acetate refining dividing wall tower to obtain an electronic-grade ethyl acetate product. The product purity is extremely high and stable, the whole set of process is designed for obtaining electronic-grade products, the final product purity stably reaches 99.99% or above, and the requirements of the high-end electronic chemical market are met. A dividing wall tower technology is adopted, light component removal and heavy component removal processes are integrated in a single tower, the number of devices and the occupied area are reduced, and energy is saved by 20%-30% compared with a traditional process.

The utility model relates to a sodium carbonate removal device for distilling propylene glycol crude products. According to the technical scheme, one side of a reactive distillation tower is connected with a feeding pipeline, the bottom of the reactive distillation tower is connected to a top inlet of a first falling-film evaporator through a carbonized crude propylene glycol feeding line and a crude propylene glycol feeding pump, and a bottom outlet of the first falling-film evaporator is connected with a buffer tank through a pipeline; the top of the buffer tank is connected to the middle lower side of the propylene glycol light component removal tower through a light component removal line, the bottom of the buffer tank is connected to the plate-and-frame filter press through a pipeline and a feeding pump, and an outlet of the plate-and-frame filter press is connected to the upper side of the propylene glycol light component removal tower through a propylene glycol feeding line. The device has the beneficial effects that water in the system is removed through the falling film evaporator, so that sodium carbonate salt is separated out before entering the light component removal tower, the carrying quantity of the sodium carbonate salt in the system is reduced, the problem of equipment blockage is solved, and meanwhile, the product quality of propylene glycol is improved.

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 system and method for photocatalytic production of tetrahydrocycloheptane based on reactive distillation, and relates to the technical field of catalytic chemistry. The system comprises a backpack reactive distillation device, a solvent recovery and product purification column, and multiple heat exchangers. The backpack reactive distillation device comprises a distillation column and N photo reactors connected with the distillation column. The raw material norbornadiene, the side sampling stream of the distillation column, and the circulating stream taken from the bottom of the solvent recovery and product purification column are respectively introduced into each photo reactor from three paths. The reflux stream of the distillation column and the outlet streams of the N photo reactors are introduced into the distillation column. The crude product taken from the bottom of the distillation column is introduced into the solvent recovery and product purification column, the solvent recovery and product purification column separates and purifies tetrahydrocycloheptane and recovers the solvent, and high-efficiency and high-purity preparation of tetrahydrocycloheptane is realized.

The embodiment of the invention provides a separation method and a separation device for ethylene glycol and 1, 2-butanediol. The method comprises the following steps: carrying out reactive distillation treatment on a to-be-separated system containing ethylene glycol and 1, 2-butanediol and isobutene to obtain an ethylene glycol mono-tert-butyl ether crude product light component and a 1, 2-butanediol crude product heavy component; carrying out first rectification treatment on the ethylene glycol mono-tert-butyl ether crude product light component to obtain a refined ethylene glycol mono-tert-butyl ether light component and an alcohol-containing mixture heavy component; carrying out second rectification treatment on the 1, 2-butanediol crude product heavy component to obtain an alcohol-containing mixture light component and a refined 1, 2-butanediol heavy component; and returning the alcohol-containing heavy component and the alcohol-containing mixture light component to participate in the reactive distillation treatment. According to the method, efficient separation of ethylene glycol and 1, 2-butanediol is realized, and high-valued resource utilization of by-products of a system to be separated is realized at the same time.

A method for producing a carbonate having an aryl group, said method comprising: a reaction distillation step in which a starting material containing a dialkyl carbonate and a hydroxyaryl compound is continuously supplied into a reaction distillation column (A) in which a transesterification reaction catalyst is present; reaction and distillation are simultaneously performed in the tower A, a fraction AU containing an alkyl alcohol and a dialkyl carbonate is continuously extracted from the upper part of the tower A, and a fraction AL containing a hydroxyaryl compound, an alkyl carbonate aryl ester and a diaryl carbonate is continuously extracted in a liquid form from the lower part of the tower A; an extraction distillation step in which an extraction agent having a hydroxyaryl compound as the main component is supplied from the upper part of an extraction distillation column (B), a mixture containing an alkyl alcohol and a dialkyl carbonate is supplied from the lower part of the column (B), extraction distillation is performed, a fraction (BU) having an alkyl alcohol as the main component is extracted from the upper part of the column (B), and the fraction (BU) is extracted from the lower part of the column (B). And withdrawing a fraction BL containing dialkyl carbonate and a hydroxyaryl compound from the lower part of the column B; and a supply step in which the fraction (BL) is continuously supplied to the tower (A).

Systems and methods for processing mixed plastic waste can include one or more reactive extruders for initially dechlorinating and depolymerizing the mixed plastic waste and a catalytic reactive distillation column for further processing the dechlorinated, depolymerized mixed plastic waste. Depolymerization of the mixed plastic waste by one or more of the disclosed systems and methods produces at least a naphtha mixed feedstock and increases its yield.

This invention provides a method and system for preparing ethylene glycol mono-tert-butyl ether, relating to the field of chemical synthesis technology. The method for preparing ethylene glycol mono-tert-butyl ether includes: in a plug flow reactor, ethylene glycol and isobutylene undergo an etherification reaction in the presence of a liquid acid catalyst to obtain a mixture one; the mixture one is subjected to azeotropic separation to obtain a mixture two containing ethylene glycol mono-tert-butyl ether and ethylene glycol di-tert-butyl ether; the mixture two is purified and separated to obtain ethylene glycol mono-tert-butyl ether and ethylene glycol di-tert-butyl ether respectively; the separated ethylene glycol di-tert-butyl ether is returned to the plug flow reactor so that the subsequent etherification reaction can be carried out in the presence of ethylene glycol di-tert-butyl ether. This invention utilizes a plug flow reactor reaction and reactive distillation technology, and employs a liquid acid catalyst to provide a high concentration of protons, reducing the activation energy of the reaction, thereby efficiently activating the reactant molecules and achieving the goal of efficiently producing ethylene glycol mono-tert-butyl ether.

The invention provides a system and a method for preparing oxalic acid by hydrolyzing dimethyl oxalate. The system comprises a pre-reaction kettle, a methanol tower, a hydrolysis tower, a methanol tower condenser, a mother liquor heat exchanger and a crystallization unit which are connected with one another through pipelines. The method comprises the following steps: feeding a mixed solution of fresh dimethyl oxalate and desalted water and a thermally coupled circulating mother solution into a pre-reaction kettle for primary hydrolysis reaction, then feeding into a methanol tower for reactive distillation, returning a tower bottom solution to a hydrolysis tower material for reactive distillation, and returning a gas phase at the top of the hydrolysis tower to the bottom of the methanol tower material for feeding, refined methanol is extracted from the top of the methanol tower, one stream of oxalic acid hydrolysate in the kettle of the hydrolysis tower is mixed with the mother liquor and enters the pre-reaction kettle, and the other stream of oxalic acid hydrolysate is thermally coupled with the mother liquor and then enters the crystallization unit to obtain refined oxalic acid. The dimethyl oxalate conversion rate is high, the methanol purity is high, the monomethyl oxalate content in the oxalic acid hydrolysate is low, oxalic acid crystallization and thermal coupling of the mother liquor and the hydrolysate are facilitated, and the overall energy consumption is reduced.

A process for preparing trioxane from methanol includes: step 1: subjecting a mixture of methanol and methylal to a reaction to obtain formaldehyde, and absorbing the formaldehyde with water to obtain a concentrated formaldehyde aqueous solution; step 2: subjecting the concentrated formaldehyde aqueous solution to cyclization to obtain a mixture containing trioxane, and passing the mixture through a trioxane concentration tower to obtain a crude trioxane product; step 3: converting a by-product and unreacted formaldehyde in the crude trioxane product into methanol, conducting dehydration through a membrane dehydration process, and subjecting a retentate to dealcoholization to obtain purified trioxane; and step 4: subjecting the remaining streams to reactive distillation to obtain a mixture of methanol and methylal at a top- and water at a bottom of the reactive distillation tower; returning the mixture of methanol and methylal to step 1; and returning or discharging the water.

The invention provides an ethylene glycol purification method and an ethylene glycol purification device. The method comprises the following steps: carrying out reactive distillation treatment on a to-be-purified system containing ethylene glycol and 1, 2-butanediol and ethylene carbonate to obtain an ethylene glycol crude product light component and a carbonate heavy component; carrying out ethylene glycol rectification treatment on the ethylene glycol crude product light component to obtain a refined ethylene glycol heavy component and an unreacted to-be-purified system; returning the unreacted to-be-purified system to carry out the reactive distillation treatment; carrying out carbonate rectification treatment on the carbonate heavy component to obtain a refined butylene carbonate light component and an ethylene carbonate crude product heavy component; performing crystallization treatment on the heavy component of the ethylene carbonate crude product to obtain refined ethylene carbonate and mother liquor rich in butylene carbonate; wherein part of the refined ethylene carbonate is returned to participate in the reactive distillation treatment. According to the method, efficient purification of ethylene glycol is realized, internal circulation of ethylene carbonate is formed, and a high-purity carbonate product is obtained.

The application relates to the technical field of oil field development, in particular to a preparation method and application of a composite catalyst for in-situ catalytic pyrolysis of oil shale. The preparation method of the composite catalyst for in-situ catalytic pyrolysis of oil shale comprises the following steps: step one, a certain amount of 3-mercapto propyl trimethoxysilane and ZMS-5 are weighed and placed in toluene, refluxed at 110 DEG C for 12 hours, cooled, filtered, oxidized at normal temperature for 12 hours by using a certain amount of 30% H2O2, reacted at normal temperature for 12 hours by using a certain amount of 0.5 mol / L H2SO4, cleaned by using distilled water, filtered, placed in a drying box, dried at 110 DEG C for 6 hours, and sulfonated modified ZSM-5 is obtained; step two, active ingredients, 0.1wt%-25wt% Mo salt and 0.1wt%-25wt% W salt, are dissolved in deionized water according to a proportion, stirred and dissolved to form a solution; and step three, the composite catalyst is prepared by using an impregnation and calcination method.

The invention relates to a process for the continuous production of optically pure lactide from aqueous lactic acid by performing two reactive distillations followed by a main distillation column with a side draw wash column. The first reactive distillation is used to produce lactic acid oligomers and the second reactive distillation is used to depolymerize the lactic acid oligomers thus obtained into lactide. The crude lactide resulting from the second reactive distillation is further purified in the main distillation column with a side draw wash column.

This invention provides a method for synthesizing carboxylic acid esters, belonging to the field of organic synthesis. The synthesis method of this invention includes the following steps: mixing a fatty alcohol and / or alcohol ether, a fatty acid, and p-toluenesulfonate for an esterification pre-reaction to obtain a pre-reaction system containing dissolved p-toluenesulfonate; the pre-reaction system contains a portion of the carboxylic acid ester, unreacted fatty alcohol and / or alcohol ether, fatty acid, and a portion of byproduct water; mixing the pre-reaction system with an azeotropic dehydrating agent for a reactive distillation esterification reaction, separating the byproduct water, and obtaining the carboxylic acid ester. This invention uses p-toluenesulfonate as a catalyst for the esterification pre-reaction to obtain a pre-reaction system containing dissolved p-toluenesulfonate. During the reactive distillation esterification reaction, the reaction system is homogeneous. After the reaction, it can be separated, recovered, and recycled, exhibiting good selectivity and minimal corrosion to the reactor. Through the esterification pre-reaction and reactive distillation esterification reaction, the reaction time can be shortened and energy consumption reduced.

Disclosed herein are various embodiments pertaining to continuous processes for making ethylene glycol diacetate, also known as 1,2-diacetoxyethane, by esterification of monoethylene glycol to 2-hydroxyethyl acetate and the esterification of 2-hydroxyethyl acetate to ethylene glycol diacetate. Various embodiments herein use reactive distillation in processes promising enhanced economic viability in the production of high-quality ethylene glycol diacetate.