263 results about "Reactive distillation" patented technology

The invention discloses a system for purifying trimethylsilane containing dichlorosilane impurities, which comprises a reactive distillation column and a purification distillation column, and also discloses a method for purifying trimethylsilane containing dichlorosilane impurities, which comprises the following steps of: feeding trimethylsilane gas containing dichlorosilane impurities into the reactive distillation column; trimethylsilane gas containing dichlorosilane impurities enters the reaction section to react, the dichlorosilane impurities react to generate silane gas and a material containing tetrachlorosilane impurities, the silane gas is discharged from an exhaust port in the top of the reactive distillation tower, and the material containing tetrachlorosilane impurities enters the purification distillation tower from a discharge port in the bottom of the reactive distillation tower; according to the method disclosed by the invention, dichlorosilane is taken as a raw material, the dichlorosilane is taken as a raw material, the dichlorosilane is rectified in a purification rectifying tower and is collected at a tower top collecting port to obtain the high-purity trimethylsilane, the dichlorosilane impurity in the trimethylsilane can be effectively removed through the method disclosed by the invention, the high-purity trimethylsilane with the purity of 99.99% or above is obtained, the yield is greater than 85%, the process is simple, and the cost is low.

A synthesis method for phosphorus pentafluoride and a synthesis device therefor. The synthesis method comprises: continuously feeding hydrogen fluoride, liquid chlorine and liquid yellow phosphorus into a reactive distillation tower to perform a reaction, so as to obtain phosphorus pentafluoride gas, wherein the molar ratio of hydrogen fluoride, liquid chlorine and liquid yellow phosphorus is 8-12:4-6:1-3. By using hydrogen fluoride, liquid chlorine and liquid yellow phosphorus as raw materials, liquid yellow phosphorus reacts with liquid chlorine in advance in a reactive distillation tower and the resulting product then reacts with hydrogen fluoride, thereby synthesizing phosphorus pentafluoride gas by means of a one-step method. The preparation process is simple, and the synthesis device has a stable and reliable structure and is very suitable for large-scale production, implementation and use.

The invention relates to the technical field of chemical engineering, and discloses a catalyst, a preparation method and application of the catalyst in preparation of isopentenal. According to the catalyst for catalyzing isomerization rearrangement of 2-methyl-3-butyne-2-alcohol to prepare isopentenal, provided by the invention, the lanthanide metal oxide is utilized to modify the supported vanadium catalyst, so that the selectivity of the catalyst can be improved, and the yield of isopentenal is increased. According to the synthesis process of the isopentenal, 2-methyl-3-butene-2-alcohol can be isomerized and rearranged into the isopentenal by adopting a reactive distillation mode without using a toxic solvent, efficient and continuous production of the isopentenal is realized, meanwhile, under the catalytic action of the catalyst, the raw material can be converted into the isopentenal with high selectivity, the yield of the isopentenal is increased, and the yield of the isopentenal is increased. And under proper process conditions, hydrogen ions can be provided in the presence of a proper amount of water, so that the raw materials are promoted to be subjected to isomerization rearrangement reaction quickly, the surface temperature of the catalyst is reduced, and the carbon deposition phenomenon of the catalyst is relieved to a certain extent.

The invention provides a low-energy-consumption preparation process of tetramethylammonium bicarbonate, and relates to the technical field of chemical synthesis. The preparation process comprises the following steps: inputting trimethylamine, dimethyl carbonate and a solvent methanol into a reactive distillation tower, carrying out a quaternization reaction to generate methyl carbonate tetramethylammonium, and carrying out a hydrolysis reaction on a first liquid phase obtained by rectification and water vapor to generate TMAB; the reacted material is input into a methanol removal tower for rectification, an obtained second gas phase is heated and pressurized, one part of the second gas phase is input into a subsequent methanol recovery tower, the other part of the second gas phase exchanges heat with water to generate steam, the steam is input into a tower kettle of the methanol removal tower, and high-purity methanol is extracted from the side of the methanol recovery tower. The number of reaction equipment is reduced, and the energy utilization rate is increased; the steam grade is improved by utilizing a heat pump technology, and steam latent heat is integrated between the methanol removal tower and the methanol recovery tower through thermal coupling, so that the overall process energy consumption is remarkably reduced while the product quality is ensured.

The invention provides a system and method for preparing carbonic ester, and the system comprises a pre-reactor which is used for the pre-reaction of carbonic ester and alcohol; the suspension type reaction rectifying tower comprises a rectifying section, a reaction section and a stripping section and is used for continuously reacting the pre-reacted material in the reaction section after rectifying the pre-reacted material through the rectifying section, and the heterogeneous solid catalyst reacts in the reaction section in a suspension manner; the suspended reactive distillation tower is provided with a gas ascending pipeline, and the gas ascending pipeline is communicated with a gas outlet in the top of the stripping section and a gas phase space in the top of the reaction section and is used for separating gas phase ascending of the stripping section. The system disclosed by the invention is simple in structure, effectively solves the problems of complex loading and unloading of a catalyst, damage of the catalyst and large discharge amount of three wastes in existing heterogeneous reactive distillation, and can be applied to industrial production; the method is especially suitable for production of chain carbonate or linear carbonate generated by esterification reaction of cyclic carbonate and alcohol.

The invention discloses a composite catalyst for synthesizing polyester as well as a preparation method and application thereof, and relates to the technical field of catalysts. According to the technical scheme, the method comprises the following steps: in a nitrogen atmosphere, mixing a first metal catalyst, a slow release agent and an organic solvent, reacting at 130-150 DEG C for 1-3 hours, and distilling to separate by-products to obtain a reaction product; and adding a second metal catalyst and an activity regulator into the reaction product, reacting at 130-150 DEG C for 1-3 hours, and distilling to separate by-products, thereby obtaining the composite catalyst for synthesizing polyester. The composite catalyst for synthesizing polyester has good compatibility with water, ethylene glycol or PET oligomer, and has the characteristic of controllable catalytic activity compared with a traditional titanium catalyst. When the composite catalyst is applied to synthesis of polyester, the composite catalyst has the characteristics of few side reactions and fast ester exchange reaction, and the obtained polyester product has the advantages of high intrinsic viscosity and good product hue.

The invention provides a method for preparing tetracyclododecene in a reactive distillation device by taking C9 fraction and norbornene as raw materials. The method comprises the following steps: mixing the C9 fraction and the norbornene in a mixer and reacting in the reactive distillation device; the reacted material is directly rectified in a reaction rectification device, residual C9 fraction and norbornene in the reaction are obtained at the tower top, and a crude tetracyclododecene product is obtained in the reaction kettle; and separating high-boiling-point components from the crude tetracyclododecene product in the reaction kettle section of the rectifying tower in the reactive distillation device in a third rectifying tower to obtain the high-purity tetracyclododecene product. According to the invention, the reaction rectification device is used, and the reactor is combined with the rectification tower, so that the reaction product can be directly and preliminarily separated to obtain a light component mainly containing norbornene and a heavy component containing tetracyclododecene, the equipment cost can be saved, the energy consumption can be reduced, and the rectification effect can be improved; meanwhile, the C9 fraction is used as a raw material, and downstream application of the C9 fraction is expanded.

A reactive distillation system for decomposition of hydriodic acid into hydrogen gas and iodine, with optional secondary purification unit(s) is described. Methods for using the reactive distillation system with optional secondary purification unit(s) for the decomposition of hydriodic acid into hydrogen gas and iodine is also described. When the purification unit is present, the system and methods of the disclosure can be used for the production and purification of hydrogen from hydriodic acid.

The invention relates to a method for efficiently preparing hydroxylamine hydrochloride. The method comprises the following steps: mixing a diacetylmonoxime solution and a hydrochloric acid solution, pretreating through a pressurized nano-bubble fluidized bed, and carrying out reaction distillation under heating and pressurizing; after the reaction is finished, cooling reaction liquid, performing primary filtration and suction filtration through cross-flow filtration equipment, and collecting hydroxylamine hydrochloride crystals; and washing the crystal with absolute ethyl alcohol, recovering ethyl alcohol through cross-flow filtration equipment, and finally freeze-drying to obtain the high-purity hydroxylamine hydrochloride. The preparation method comprises the following steps: stirring quinoline-8-yl acrylate, tributyltin acrylate, 4-vinyl benzocyclobutene, ethanol and benzoyl peroxide to obtain a mixed solution; immersing the PTFE membrane subjected to low-temperature plasma pretreatment into the mixed solution, and then carrying out ultrasonic cleaning and vacuum drying to obtain a polymer modified PTFE membrane; the hydroxylamine hydrochloride prepared by the method disclosed by the invention has relatively high purity and yield, and meanwhile, the content of heavy metal ions and the content of water are effectively reduced.

The utility model provides a production system for producing silane gas by combining a fixed bed reactor and a reactive distillation tower, and relates to the technical field of silane gas production. The production system for producing the silane gas by combining the fixed bed reactor and the reactive distillation column comprises the fixed bed reactor which is provided with a DCS (Distributed Control System) feed port and can be used for performing DCS disproportionation reaction to prepare a one-step disproportionated product; the primary separation tower is communicated with the fixed bed reactor and can be used for rectifying and separating a one-step disproportionated product, crude SiH4 is extracted from the tower top of the primary separation tower, and a chlorosilane mixture is extracted from the tower kettle of the primary separation tower; the second-stage separation tower is communicated with the first-stage separation tower and can be used for rectifying and separating the chlorosilane mixture, and a TCS mixture is extracted from a tower kettle of the second-stage separation tower; and the reactive distillation tower is communicated with the second-stage separation tower, is provided with a TCS feed port, can perform a TCS disproportionation reaction and rectify and separate a product, and crude SiH4 is extracted from the tower top of the reactive distillation tower. According to the utility model, not only can the conversion rate of the DCS total reaction process be improved, but also the silane gas productivity can be improved, and the operation energy consumption can be reduced.

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.

The invention relates to the field of rectifying towers, and discloses a reaction rectifying tower for ethylene glycol preparation, which comprises a rectifying tower body, a wave tower plate, a discharge shell, a turnover piece, a scraping mechanism, a rolling suction mechanism, an ejection mechanism, a guide return piece, a draw-off pump and a communication shell, the wave tower plate is mounted in the rectifying tower body, the middle part of the wave tower plate is divided into two sub-wave tower plates by the discharging shell, and the two sub-wave tower plates are connected through the communicating shell so as to guide an ethylene glycol solution; the overturning piece is arranged on the discharging shell, and the guiding return piece is connected with the scraping mechanism. The scraping mechanism is connected with the driving part, and when the driving part drives the scraping mechanism to scrape the wave tower plate, steam extraction and drainage are synchronously carried out. The driving piece and the scraping mechanism work cooperatively, non-stop cleaning is achieved, the sleeve plate one-way air inlet valve is matched with the scraping plate exhaust hole to purge impurities and strengthen mass transfer, the magnetic block rotates to attract the ejection mechanism to eject the pipe to clear blockage, and it is guaranteed that steam passes through.

The invention discloses a resource utilization method of 1, 1, 2-trichloroethane waste liquid, which comprises the following steps: 1) feeding the 1, 1, 2-trichloroethane waste liquid into a scraper device to remove heavy components, and extracting gas-phase light components from the top; (2) condensing the gas-phase light component, feeding into a chlorination reactor, and carrying out chlorination reaction; and 3) carrying out reactive distillation on the material at the outlet of the chlorination reactor to remove light components and heavy components to obtain 1, 1, 2-trichloroethane. According to the method, on one hand, impurities which influence the purity of 1, 1, 2-trichloroethane and are difficult to separate react with chlorine under specific conditions to generate heavier components, and on the other hand, it is ensured that light components cannot be chlorinated into the impurities which are difficult to separate, and 1, 1, 2-trichloroethane with the purity being 99% or above can be recycled; on the other hand, 5-20 wt% of 1, 1, 2-trichloroethane is additionally generated in the reactive distillation process, waste liquid recycling is achieved, and the method has the advantages of being simple in technological process, low in energy consumption and high in product yield.

The invention belongs to the technical field of chemical synthesis, and particularly relates to a method for preparing peroxy acid. The method comprises the following steps: S1, carrying out reaction on organic acid, hydrogen peroxide, a catalyst and a solvent in a first pre-reactor, and introducing a product obtained by the reaction into a first reactive distillation tower for reaction; s2, reacting the product obtained in the step S1 in a second pre-reactor, and introducing the product into a second reactive distillation tower for reaction after the reaction is finished; s3, the product obtained in the step S2 and a stabilizer are subjected to a reaction in a mixer, the stabilizer is a nitrogen-containing alkaline compound, lone pair electrons exist on N atoms, and the catalyst is selected from one or two or more of sulfuric acid, nitric acid, isopolyacid and heteropolyacid. By adopting the method to prepare the peroxy acid solution, the selectivity and yield of peroxy acid can be improved, and the total conversion rate of hydrogen peroxide is gt; the selectivity of peroxy acid is gt; meanwhile, caprolactone is prepared by using the peroxy acid to dissolve cyclohexanone oxide liquid, and the conversion rate of cyclohexanone is gt; the selectivity of the obtained caprolactone is gt; 85%.

The invention discloses a battery grade methyl ethyl carbonate / diethyl carbonate synthesis process, which adopts a transesterification method, and dimethyl carbonate (DMC) and ethanol react under the catalysis of sodium methoxide to generate methyl ethyl carbonate (EMC), diethyl carbonate (DEC) and byproduct methanol. High-purity battery-grade EMC and DEC products are obtained through the steps of reactive distillation, azeotrope separation, methanol refining, catalyst carbonization removal, crude EMC / DEC separation, EMC light component removal, industrial-grade EMC refining, battery-grade EMC refining, industrial-grade DEC refining, battery-grade DEC refining and the like. The method has the advantages of simple process flow, low energy consumption, easiness in product separation, high product purity and the like, and is suitable for large-scale production of battery-grade carbonate products.

The invention discloses a method for separating an azeotropic mixture of dimethyl carbonate and methanol, which comprises a reactive distillation tower, a second distillation tower and a third distillation tower, the reactive distillation tower is respectively provided with a dimethyl carbonate-methanol azeotrope feed port and an epoxypropane feed port below the dimethyl carbonate-methanol azeotrope feed port; a rectifying section of the reactive distillation tower is positioned between the dimethyl carbonate-methanol azeotrope feeding hole and the tower top, a reaction section of the reactive distillation tower is positioned between the dimethyl carbonate-methanol azeotrope feeding hole and the epoxypropane feeding hole, and a stripping section of the reactive distillation tower is positioned between the epoxypropane feeding hole and the tower bottom; the reaction section is filled with a quaternary ammonium salt catalyst; a dimethyl carbonate-methanol azeotrope with azeotropic concentration under high pressure is output from a tower top discharge end of the reactive distillation tower and is used as a feed of a second distillation tower; a mixture of dimethyl carbonate and propylene glycol monomethyl ether is output from a discharge end of the tower kettle and is used as a feed of a third rectifying tower; according to the method, the high-purity dimethyl carbonate product can be stably and continuously obtained, the consumption of heating steam is effectively reduced, particularly the energy consumption of the high-pressure tower is reduced, and the process cost is low.

The invention relates to a reactive distillation device and method for automatically separating phases and refluxing to a reaction section, and belongs to the technical field of chemical reaction and separation coupling. The reactive distillation tower (1) sequentially comprises a distillation section (11), a reaction section (12) and a stripping section (13) from top to bottom, the tower bottom of the reactive distillation tower (1) is connected with a heater (2), the tower top of the reactive distillation tower (1) is sequentially connected with a tower top condenser (3) and an automatic phase splitter (4) through pipelines, materials are condensed by the tower top condenser (3) to form a water phase and an oil phase which are not completely mutually soluble, and the water phase and the oil phase are separated from each other. After automatic phase splitting in the automatic phase splitter (4), the water phase automatically and continuously flows into a water phase collecting tank (5) from the upper part of the automatic phase splitter (4), the oil phase automatically and continuously flows out from the lower part of the automatic phase splitter (4), one part of the oil phase returns to the rectifying section (11) through the reflux ratio controller (6), and the other part of the oil phase returns to the rectifying section (11) through the reflux ratio controller (6); one part of the gas automatically flows back into the reaction section (12) by virtue of the liquid level to continuously react, so that a high-purity product is obtained in the tower kettle. The device is simple in structure and control method and convenient to operate, unreacted raw materials are rectified and then automatically flow back into the reaction section in a split-phase mode to participate in the reaction again, the raw material utilization rate is increased, the reaction conversion rate is high, and a water phase and an oil phase can be automatically extracted in a split-phase mode and flow back.

The present invention relates to a method of preparing pyrolysis oil from waste plastics, the method including: (A) preparing a waste plastic raw material; (B) supplying the waste plastic raw material through a lower portion of a reaction distillation tower and performing pyrolysis to produce pyrolysis gas; (C) supplying a hydrogen donor stream through an upper portion of the reaction distillation tower and reacting the hydrogen donor stream with the pyrolysis gas; and (D) discharging the pyrolysis gas reacted with the hydrogen donor stream through the upper portion and condensing the discharged pyrolysis gas to obtain liquid oil.

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 liquid phase method methanol synthesis system based on reactive distillation, which comprises the following steps: mixing hydrogen and carbon dioxide into a raw material gas stream, passing through a multi-stage compressor and then passing through a first heat exchanger to obtain a pretreated raw material gas stream; the solvent stream passes through a booster pump and then passes through a second heat exchanger to obtain a pretreated solvent stream; a pretreated raw material gas stream enters the reactive distillation tower from the bottom of the reactive distillation tower, a pretreated solvent stream enters the reactive distillation tower from the top of the reactive distillation tower to obtain a top stream and a bottom stream, the top stream passes through a condenser and then enters a flash tank, a crude methanol stream and an unreacted gas stream are separated, the crude methanol stream enters the distillation tower, and the unreacted gas stream enters the bottom of the distillation tower; a refined methanol product stream and a purge stream are obtained at the top of the rectifying tower, and a solvent and water mixture stream flows out from the bottom of the rectifying tower and is recycled. According to the method, methanol is synthesized through carbon dioxide hydrogenation in the solvent, the reaction conditions are mild, the process is simple, and the high carbon dioxide conversion per pass is achieved.

The utility model discloses a device for one-way preparation of electronic grade silane gas in a particle silicon process, the device comprises a preheater, a light component removal unit, a silane reaction unit, a condensation unit, a separation unit and a gasification purification unit which are connected in sequence, and the silane reaction unit comprises more than two silane reaction towers which are arranged in parallel. According to the utility model, more than two silane reaction towers are arranged in the silane reaction unit in parallel, so that trichlorosilane is converted into silane at one time after being sequentially subjected to the steps of preheating, light component removal, reactive distillation, condensation heat exchange, separation and gasification purification; the conversion per pass can be improved, the material condensation and reboiling processes are reduced, the energy consumption is reduced, and the production process cost is reduced.

The invention discloses a continuous production system for diethyl maleate. The continuous production system comprises a reactive distillation tower, a benzene-water separation tank, a vacuum distillation tower, a benzene removal tower and an ethanol distillation tower. The device comprises the vacuum rectifying tower, the debenzolization tower and the ethanol rectifying tower, and the vacuum rectifying tower is used for purifying tower kettle materials in the reaction rectifying tower, so that the product purity is improved; the debenzolization tower is used for removing a reboiling agent benzene in a water-phase material in the benzene-water separation tank, then the reboiling agent benzene is circulated to the benzene-water separation tank for reuse, the ethanol rectifying tower is used for separating ethanol and water from a material in a tower kettle of the debenzolization tower, and the ethanol is recycled, so that the utilization rate of raw materials is effectively improved. The invention further discloses a continuous production method of the diethyl maleate, a vacuum rectification technology and a normal-pressure double-tower rectification technology are adopted, the purity of the obtained diethyl maleate product can reach 99.9 wt% or above, the product purity is high, reboiling agents benzene and ethyl alcohol can be effectively recycled, and the utilization rate of raw materials is effectively increased.

The invention relates to a process for the preparation of dimethyl ether, comprising the following steps:-introducing a methanol-containing stream (Sfeed-RD) into a reactive distillation apparatus (RD), in which-in at least one reaction zone (RZ) of the reactive distillation apparatus (RD), methanol is reacted in the presence of an acid catalyst to form dimethyl ether and water, and separating the stream by distillation into a fraction containing dimethyl ether and leaving the reactive distillation unit (RD) as an overhead stream (Soverhead-RD) and a fraction containing water and leaving the reactive distillation unit (RD) as a bottom stream (Sbottom-RD), withdrawing a methanol-containing side stream (Sside-RD) from the reactive distillation unit (RD), introducing the methanol-containing side stream (Sside-RD) into a side reactor (SR), and reacting the methanol in the presence of an acid catalyst to form dimethyl ether and water to obtain a product stream (Sproduct-SR) containing dimethyl ether, water and methanol and withdrawn from the side reactor (SR).

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 relates to a method for depolymerizing polyethylene terephthalate (= "PET"), wherein PET is reacted in a mixture containing ethylene glycol and MAOR to form bis (2-hydroxyethyl) terephthalate (= "BHET"; cAS No.: 959-26-2) in which MA is an alkali metal selected from the group consisting of sodium, potassium, lithium, and in which R is an alkyl group having 1 to 6 carbon atoms. The MAOR is obtained by reactive distillation. The method according to the invention is characterized in that the proportion of unwanted cleavage products mono (2-hydroxyethyl) terephthalate (= "MHET") and terephthalate (= "TS") is particularly low relative to the proportion of BHET. Thus, the process according to the invention provides a high yield of BHET, which can be directly used in regenerative PET production. The invention also relates to a process for recovering PET in which BHET obtained in the PET depolymerization process is re-polymerized to form PET, optionally after further cleaning.