CN100491324C - Method and apparatus for continuously preparing ethyl acetate by single tower - Google Patents
Method and apparatus for continuously preparing ethyl acetate by single tower Download PDFInfo
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Abstract
The single tower ethyl acetate preparing process includes boiling the mixed liquid in certain acid/alcohol ratio and with strong acid catalyst and water carrying agent inside tower; opening condensating water for full reflux operation and stable top temperature after the vapor reaches to tower top; regulating acid/alcohol ratio to 1 and feeding strong acid catalyst from the top; regulating certain reflux ratio with the reflux ratio regulator, taking coarse ester product from the top and maintaining the top temperature unchanged; discharging gas material from the bottom, condensating in condensator, separating water in phase separator and refluxing organic phase with rich water carrying agent to the tower. The present invention has ester content in coarse ester product over 94 %, high conversion rate, low power consumption and low production cost.
Description
Technical field
The present invention relates to the preparation method and the equipment of the production process of organic chemical industry's basic raw material, particularly ethyl acetate.
Background technology
Ethyl acetate is a kind of important organic chemical industry's basic raw material, has been widely used industrial.From in the world, international clean air act regulation will be stopped using the superior air solvent slop after 2003 in most of coating, and ethyl acetate is as a kind of selectable replace solvents, and demand constantly increases.From domestic, developing rapidly of industries such as China's coating, medicine, automobile, electronics, make the consumption accelerated growth of ethyl acetate, in " production of ethyl acetate and market ", Li Tao, Cao Xiaolan " Speciality Petrochemicals progress " 2002,9 (3): 37～40 thinks that ethyl acetate is a product that is worth development of chemical industry.From production technique, at present, it is the direct esterification technology of catalyzer that the production of China's ethyl acetate is mainly adopted with the vitriol oil, and reaction is owing to limited by equilibrated, and per pass conversion is lower.In order to improve transformation efficiency, often adopt ethanol excessive in the production, washing is reclaimed.Production Flow Chart is long, the energy consumption height, and cause part material and product loss.In recent years, the new process of production to ethyl acetate has carried out big quantity research both at home and abroad, as " several industrial ethyl acetate preparation methods' economical comparision ", and Li Xiong " petrochemical technology economy " 2002,17 (1): 19～22." application of catalytic rectification process in esterification ", Liao Anping. blue equality " chemical industry progress " 2001,20 (12): 30～32; " research and development of acetic acid/ethylene esterification synthesizing ethyl acetate technology ", Zhu Jifang. Liao Shijun etc. " chemical reaction engineering and technology " 1999,15 (3); 314～340; " fluidized catalytic rectification prepares ethyl acetate research ", Liao Anping, blue flat, Li Mei, Lan Lihong " chemical engineering " 2000,06, this article have studied the catalytic distillation process of catalyzer with Flow of Goods and Materials in φ 25 packing towers.Dichlorodiphenyl Acetate and ethyl esterification reaction system have been investigated the influence of factors such as catalyst levels, acid alcohol ratio, feed entrance point, reflux ratio, backflow composition to process.Under selected experiment condition, the ester content of overhead product reaches 94.33%, and ester reaches 96.22% to the per pass conversion of alcohol; " the catalytic reaction rectification technology prepares ethyl acetate continuously ", Liao Anping, Lan Ping, Zhou Gui, Xie Tao " modern chemical industry " 1997,09, in the catalytic rectifying tower of diameter 30mm, carry out the research of synthesizing ethyl acetate, investigated the influence of factor such as acid alcohol ratio, feed rate, reflux ratio, feed entrance point to process, under this experiment optimal conditions, cat head can obtain ester content greater than 94% product.
Through retrieval, we also recognize present some researchs to the ethyl acetate preparation method:
1, reactive distillation synthesizing ethyl acetate [author] He Shoulin, Wang Hong [periodical name] 1996 04 phases of Hubei chemical industry [mechanism] Wuhan Institute of Chemical Technology, Hubei Province's chemical research designing institute [summary] provide with the vitriol oil and have made catalyzer, obtain the method for higher degree ethyl acetate in packing tower.Investigate the influence to the cat head ester content such as charge ratio, reflux ratio, feeding temperature, still temperature, found out preferable processing condition and main control parameters
2, extractive reaction rectifying synthesis of high purity ethyl acetate [author] Li Yonghong, Liu Jiaqi, Ma Peisheng [periodical name] 1996 10 phases of petrochemical complex [mechanism] University Of Tianjin chemical industry system [summary] is by the Phase Equilibrium Calculation of Dichlorodiphenyl Acetate and ethyl esterification reaction system, analyze the influence that acetic acid is formed ethanol-ethyl acetate-water azeotropic, determined to eliminate the minimum acetate concentration of ternary azeotrope.The operability that the extractive reaction distillation process is used for synthesizing ethyl acetate has been examined or check in test, has inquired into the influence rule of each operating parameters to product ester purity.The result shows that the ester purity that single tower flow process obtains can reach more than 97%, and the impurity in the product mainly is water, and alcoholic acid content is less than 0.3%.But it does not consider the processing of tower bottoms diluted acid.
3, research [author] Huang Kelin of reactive distillation-extraction combined process synthesizing ethyl acetate, Huang Huansheng, Lee is former, Fan Xiaodan [periodical name] Hubei chemical industry 04 phase of nineteen ninety-five [summary] places reaction fractionating tower as Primary Catalysts and Stainless Steel Helices with-fixed rule with solid acid, place the tower still with a Lewis acid as cocatalyst, adopt the continuous synthesizing ethyl acetate of form of reactive distillation.The whole esters of cat head after water is sloughed in extraction again extension be back to the reactive distillation column overhead, constituted reactive distillation-extraction combined process.This process conversion rate of esterification height, ester facies tract outlet capacity is strong, has reduced reflux ratio, has reduced energy consumption, has improved the throughput of equipment.
4, the catalytic reaction rectification extraction prepares ethyl acetate [author] Wang Jiantian continuously, Liu Weiping [periodical name] 2004 01 phases of Zhejiang chemical industry [summary] this paper makes Primary Catalysts with solid acid, the vitriol oil is made cocatalyst, carries out the research of synthesizing ethyl acetate in the catalytic rectifying tower of diameter 200mm.The cat head ester is after the extraction dehydration, and extension is back to cat head, constitutes reactive distillation---the extraction combined process.Investigated feed entrance point, acid-alcohol ratio, the factor such as feeding temperature that refluxes when is to the influence of process, under this experiment optimal conditions, finally can obtain ester content greater than 99.5% product.
Summary of the invention
The inventor has studied homogeneous reaction distillation technology continuous production ethyl acetate technology according to the feature of acetic acid ethyl reaction system.Think that reaction process catalyzer, band aqua and consumption are key problem in technology, the water selecting suitable and suitable band aqua to make to generate with reaction in the system when catalyzer and usage quantity forms vapour mixture and draws from the certain position of tower, can overcome the shortcoming among the ethyl acetate preparation method who is reported at present.So the condition of setting is tested, has been obtained success.
Technical scheme of the present invention is as follows:
Single tower prepares the method for ethyl acetate, comprise that acid and alcohol react under the effect of catalyzer, effect by distillation or rectifying, reacted ethyl acetate is drawn from cat head, obtain the process of ethyl acetate through separation, be characterized in: in the tower still, add earlier than the acid alcohol mixed solution that is 10～2:1 in chemical reaction ratio acid alcohol, add strong acid catalyst or powdery solid acid catalyst and band aqua, solution is to boiling in heating tower's still, when steam arrives cat head, open water of condensation, keep total reflux operation, after stablizing to tower top temperature, with the charging acid alcohol than the top charging of the mixture that is adjusted to 1:1 and strong acid catalyst from tower, regulate certain reflux ratio with the reflux ratio device, the thick ester product that reaction is produced is taken overhead out, and keeps tower top temperature constant; From the bottom gas phase discharging of reaction tower, enter the water that phase splitter separating reaction system produces through condensation, the organic phase reflux that is rich in the band aqua is to the tower still; The tower bottoms circulation enters the tower internal reaction after charging mixes.
Above-described strong acid catalyst is selected the vitriol oil or powdery solid super acids for use, and consumption is 5%-25% of an acetic acid quality.
Above-described band aqua is high boiling alcohols, ester compound, benzene class and cycloalkane compound.Select butanols for use, N-BUTYL ACETATE, isobutyl acetate, the different ester etc. of defending of acetic acid, benzene, toluene, cyclohexane, perhaps wherein two kinds, two or more mixture, consumption be in the reaction system unit time water production rate 30-250%.
Single tower of the present invention prepares the method for ethyl acetate, from the bottom gas phase discharging of reaction tower, enters the water that phase splitter separating reaction system produces through condensation, and the organic phase reflux that is rich in the band aqua is to the tower still; The tower bottoms circulation enters the tower internal reaction after charging mixes.
The principle that the single tower of the present invention prepares ethyl acetate is:
Following esterification takes place and generates ester and water under the condition that strong acid (as the vitriol oil) catalyzer exists in acetic acid and ethanol.
This reaction is reversible reaction, and under the situation of not separating product, the balance rate of rotationization is about 66%
[2]Change in the reaction system at this, binary that can form between reactant and product or ternary azeotrope see Table 1.
Table 1 reaction system component, azeotrope are formed and boiling point (normal pressure)
[6]
Wherein the constant boiling point of the ternary azeotrope of Xing Chenging is minimum, and two yuan of azeotropes of its boiling point and ethyl acetate-water are approaching.In reactive distillation processes, what overhead product obtained in theory is ethyl acetate-ethanol-water tertiary mixture.For the ease of follow-up purification operations, require to reduce alcoholic acid content in the overhead product as far as possible, therefore in reaction, adopt acetic acid excessive, make ethanol synthesis complete as far as possible.From reaction formula as can be known, the ethyl ester that reaction generates and the mass ratio of water are about 4.9:1, even do not consider the water in the industrial alcohol raw material, the water that reaction itself generates can not all be taken out of from cat head by the ethyl ester-ethanol-water tertiary mixture that forms, and promptly not adding the band aqua in addition is all to take the water that reaction generates out of reaction system.Unnecessary water will enter the tower still, thereby influence entire reaction course.Therefore add the band aqua in reaction process, the certain position of the water in the reaction system (water that water that reaction generates and raw material are brought into) from reaction tower taken out, to guarantee the concentration of acetic acid in the tower still, the excessive acetic acid of tower still recycles.
Form at the bottom of the still and can measure acetic acid content, use the gas chromatograph for determination water-content with neutralization titration.Cat head organic phase composition is used gas chromatograph for determination, measures wherein acetic acid content with neutralization titration simultaneously.
The equipment that the single tower of the present invention prepares the method employing of ethyl acetate comprises reaction fractionating tower, water cooler, recycle pump, and be characterized in: reaction fractionating tower is divided into three parts, and the tower opening for feed is above to be to be conversion zone and reboiler below rectification and purification section, the opening for feed.Raw material mixes at mixing tank with circulation fluid, and the mixer outlet pipe is equipped with spinner-type flowmeter, and receives the reaction fractionating tower middle and upper part; The reaction fractionating tower top is provided with Steam Pipe, condenser, backflow controller and phase splitter, and backflow controller bottom has the pipe circulation to get back to the reactive distillation top of tower; Phase splitter top has pipe to draw rent ester product.The reaction fractionating tower middle and lower part also is connected to Steam Pipe, condenser, phase splitter, and the reboiler of reactive distillation tower bottom is received in the outlet of phase splitter top.The reboiler bottom also has water cooler to be attached thereto, and water cooler has pipe to be connected with pump inlet, and the circulating-pump outlet pipe is connected with spinner-type flowmeter and leads in the mixing tank.
Also equidistant several thief holes that is provided with of the body of the tower of reaction and rectification device, interior dress porcelain ring filler, the packing layer coca is according to the needs decision, and number of theoretical plate is about the 10-20 piece, adds heat at the bottom of the still and regulates by voltate regulator.
The present invention compared with prior art, its outstanding substantive distinguishing features and obvious improvement is:
1, select suitable band aqua that the water in the reaction process is all taken out of from the highest zone of water content, bottom, and by of the influence of the various processing parameters of research to process, the tertiary mixture that the thick ester product that the reactive distillation cat head is obtained is ester, alcohol, water, mainly contain ester and water, a spot of alcohol does not contain acid.The thick ester of cat head can obtain to meet the ethyl acetate product of GB3728-91 salable product index through saline solution one step dehydration.The work simplification of research Production Flow Chart, improved simultaneously the per pass conversion of reaction greatly, reduced production energy consumption.
2. in reactive distillation processes, add high boiling point band aqua, realized that three process bonded of water that the separating reaction process produces prepare the ethyl acetate process continuously in Dan Tazhong reaction, rectification and purification.Simplified Production Flow Chart, improved the yield of utilization ratio of raw materials and product, reduced the energy consumption that product is purified, and significantly reduced the discharging of factory effluent and the pollution of environment.
3. the catalyzer of reaction process use can be and reaction system formation homogeneous concentrated sulfuric acid catalyst, also powdery solid acid catalyst, all raw materials can be the higher raw materials of purity, also can be the higher raw materials of water content, enlarge the subject range of raw material, reduced production cost.
4. under selected processing condition, the vapour mixture of cat head is after dividing water naturally, the content of ester can be stabilized in about 94% in the thick ester that obtains, and does not contain acid substantially, and thick ester can directly obtain meeting the ethyl acetate product of 6B3728-91 salable product requirement after the saline solution extraction.
5. the reaction fractionating tower in this technology can utilize existing production of ethyl equipment, is applicable to the transformation of traditional processing technology, also can be used for the foundation of new production device, has better industrial application prospects.
Description of drawings
Fig. 1 is a reaction and rectification device synoptic diagram of the present invention.
Reaction fractionating tower 7 is divided into three parts, and charging aperture is above to be to be below rectifying section, the charging aperture to mix conversion zone and reboiler 1 Device 3 outlets are equipped with spinner flowmeter 2, and receive epimere rectifying column middle and upper part; The reaction fractionating tower top be provided with Steam Pipe, Condenser 4, counter flow controller 5 and phase-splitter 6. Counter flow controller 5 bottoms have the pipe circulation to get back to the rectifying column top; Phase-splitting Device 6 bottoms are connected to pipe and take out rent ester product. The rectifying column middle and lower part also is connected to Steam Pipe and condenser 8, phase-splitter 9, divides The reboiler 1 of rectifier bottoms is received in 9 outlets of phase device. Reboiler 1 also has cooler 10 to be attached thereto, and cooler has pipe Be connected with circulating pump 11 imports, circulating-pump outlet 11 pipes lead in the blender 3.
The body of the tower of reaction and rectification device is also equidistant to be provided with five sample taps, in-built porcelain ring filler, and the packing layer coca determines according to needs, Number of theoretical plate is about the 10-20 piece, adds heat at the bottom of the still and regulates by pressure regulator.
Embodiment
Embodiment 1
(1). in the tower still, add acid alcohol earlier than acid alcohol mixed solution, add acetic acid quality 5% vitriol oil and 10-50ml butanols band aqua for 5:1 (mol ratio).
(2). solution when steam arrives cat head, is opened water of condensation to boiling in heating tower's still, keeps total reflux operation.To tower top temperature stable after, the adjusting reflux ratio is 1:1 (mol ratio) simultaneously with the acid alcohol ratio and contain the top charging of the mixture of the vitriol oil from tower, regulates certain reflux ratio with the reflux ratio device, the thick ester product that reaction is produced is taken overhead out, and keeps tower top temperature constant.From the bottom gas phase discharging of tower, enter phase splitter through condensation and divide water simultaneously, organic phase reflux is to the tower still.Get the thick ester sample of cat head at regular intervals and analyze its composition, the tower bottoms circulation.
(3). according to selected experiment condition operation, regulate inlet amount, tower bottoms internal circulating load and thick product taking-up amount, keep process stabilization.
Under selected processing condition, prepare the ethyl acetate experiment continuously.The band aqua once adds, and after the vapour mixture that the water in band aqua and the tower forms was drawn tower, through the condensation phase-splitting, water sepn went out system, is with the aqua tower still that refluxes back; The mixed solution of acid and catalyzer circulation at the bottom of the still.Operation is 48 hours continuously, gets the thick ester sample of cat head every 2 hours and analyzes its composition.The thick ester of cat head is after dividing water naturally, and thick ester product content all is stabilized in about 94%, and the acid content in the thick product directly reaches the requirement of GB3728-91 salable product, and experimental result sees Table.
Table is preparation ethyl acetate experimental result continuously
Embodiment 2
((1). add acid alcohol earlier than the acid alcohol mixed solution for 10:1 (mol ratio) in the tower still, adding quality is acetic acid 10% vitriol oil and 15-45ml N-BUTYL ACETATE band aqua.
(2). solution when steam arrives cat head, is opened water of condensation to boiling in heating tower's still, keeps total reflux operation.To tower top temperature stable after, acid alcohol than for 1:1 (mol than) with contain the top charging of the mixture of the vitriol oil from tower, is regulated certain reflux ratio with the reflux ratio device, the thick ester product that reaction is produced is taken overhead out, and the maintenance tower top temperature is constant.From the bottom gas phase discharging of tower, enter phase splitter through condensation and divide water simultaneously, organic phase reflux is to the tower still.Get the thick ester sample of cat head at regular intervals and analyze its composition, the tower bottoms circulation.
(3). according to selected experiment condition operation, regulate inlet amount, tower bottoms internal circulating load and thick product taking-up amount, keep process stabilization.
(4). under selected processing condition, prepare the ethyl acetate experiment continuously.The band aqua once adds, and after the vapour mixture that the water in band aqua and the tower forms was drawn tower, through the condensation phase-splitting, water sepn went out system, is with the aqua tower still that refluxes back; The mixed solution of acid and catalyzer circulation at the bottom of the still.Operation is 72 hours continuously, gets the thick ester sample of cat head every 2 hours and analyzes its composition.The thick ester content of cat head all is stabilized in about 94%, and acid content directly reaches the requirement of GB3728-91 salable product, and experimental result sees Table.
Table is preparation ethyl acetate experimental result continuously
Embodiment 3
(1). be to be raw material with about 80% aqueous acid in the first present embodiment, following acid alcohol ratio of components is the value that is converted into pure acetic acid.
(2). add acid alcohol than the acid alcohol mixed solution for 2:1 (mol ratio) in the tower still, adding quality is powdery strong acid type amberlite ester catalyst and 10-40ml N-BUTYL ACETATE band aqua of acetic acid 12%.
(3). solution when steam arrives cat head, is opened water of condensation to boiling in heating tower's still, keeps total reflux operation.To tower top temperature stable after, acid alcohol than for 1:1 (mol than) with contain the top charging of the mixture of the vitriol oil from tower, is regulated certain reflux ratio with the reflux ratio device, the thick ester product that reaction is produced is taken overhead out, and the maintenance tower top temperature is constant.From the bottom gas phase discharging of tower, enter phase splitter through condensation and divide water simultaneously, organic phase reflux is to the tower still.Get the thick ester sample of cat head at regular intervals and analyze its composition, the tower bottoms circulation.
(4). according to selected experiment condition operation, regulate inlet amount, tower bottoms internal circulating load and thick product taking-up amount, keep process stabilization.
(5). under selected processing condition, prepare the ethyl acetate experiment continuously.The band aqua once adds, and after the vapour mixture that the water in band aqua and the tower forms was drawn tower, through the condensation phase-splitting, water sepn went out system, is with the aqua tower still that refluxes back; The mixed solution of acid and catalyzer circulation at the bottom of the still.Operation is 116 hours continuously, gets the thick ester sample of cat head every 2 hours and analyzes its composition.The thick ester content of cat head all is stabilized in about 94%, and acid content directly reaches the requirement of GB3728-91 salable product, and experimental result sees Table.
Table is preparation ethyl acetate experimental result continuously
Embodiment 4
(1). in the tower still, add earlier acid alcohol than acid alcohol mixed solution, add quality and be acetic acid 10% vitriol oil and 15-80ml butanols, N-BUTYL ACETATE, isobutyl acetate mixed zone aqua for 5:1 (mol than).
(2). solution when steam arrives cat head, is opened water of condensation to boiling in heating tower's still, keeps total reflux operation.To tower top temperature stable after, acid alcohol than for 1:1 (mol than) with contain the top charging of the mixture of the vitriol oil from tower, is regulated certain reflux ratio with the reflux ratio device, the thick ester product that reaction is produced is taken overhead out, and the maintenance tower top temperature is constant.From the bottom gas phase discharging of tower, enter phase splitter through condensation and divide water simultaneously, organic phase reflux is to the tower still.Get the thick ester sample of cat head at regular intervals and analyze its composition, the tower bottoms circulation.
(3). according to selected experiment condition operation, regulate inlet amount, tower bottoms internal circulating load and thick product taking-up amount, keep process stabilization.
(4). under selected processing condition, prepare the ethyl acetate experiment continuously.The band aqua once adds, and after the vapour mixture that the water in band aqua and the tower forms was drawn tower, through the condensation phase-splitting, water sepn went out system, is with the aqua tower still that refluxes back; The mixed solution of acid and catalyzer circulation at the bottom of the still.Operation is 72 hours continuously, gets the thick ester sample of cat head every 2 hours and analyzes its composition.The thick ester content of cat head all is stabilized in about 94%, and acid content directly reaches the requirement of GB3728-91 salable product, and experimental result sees Table.
Table is preparation ethyl acetate experimental result continuously
Embodiment 5
(1). add acid alcohol earlier than the acid alcohol mixed solution for 5:1 (mol ratio) in the tower still, adding quality is acetic acid 25% vitriol oil and 10-45ml benzene class mixed zone aqua.
(2). solution when steam arrives cat head, is opened water of condensation to boiling in heating tower's still, keeps total reflux operation.To tower top temperature stable after, acid alcohol than for 1:1 (mol than) with contain the top charging of the mixture of the vitriol oil from tower, is regulated certain reflux ratio with the reflux ratio device, the thick ester product that reaction is produced is taken overhead out, and the maintenance tower top temperature is constant.From the bottom gas phase discharging of tower, enter phase splitter through condensation and divide water simultaneously, organic phase reflux is to the tower still.Get the thick ester sample of cat head at regular intervals and analyze its composition, the tower bottoms circulation.
(3). according to selected experiment condition operation, regulate inlet amount, tower bottoms internal circulating load and thick product taking-up amount, keep process stabilization.
(4). under selected processing condition, prepare the ethyl acetate experiment continuously.The band aqua once adds, and after the vapour mixture that the water in band aqua and the tower forms was drawn tower, through the condensation phase-splitting, water sepn went out system, is with the aqua tower still that refluxes back; The mixed solution of acid and catalyzer circulation at the bottom of the still.Operation is 72 hours continuously, gets the thick ester sample of cat head every 2 hours and analyzes its composition.The thick ester content of cat head all is stabilized in about 94%, and acid content directly reaches the requirement of GB3728-91 salable product, and experimental result sees Table.
Table is preparation ethyl acetate experimental result continuously
Embodiment 6
(1). add acid alcohol earlier than the acid alcohol mixed solution for 5:1 (mol ratio) in the tower still, adding quality is acetic acid 10% vitriol oil and 10-65ml cyclohexane band aqua.
(2). solution when steam arrives cat head, is opened water of condensation to boiling in heating tower's still, keeps total reflux operation.To tower top temperature stable after, acid alcohol than for 1:1 (mol than) with contain the top charging of the mixture of the vitriol oil from tower, is regulated certain reflux ratio with the reflux ratio device, the thick ester product that reaction is produced is taken overhead out, and the maintenance tower top temperature is constant.From the bottom gas phase discharging of tower, enter phase splitter through condensation and divide water simultaneously, organic phase reflux is to the tower still.Get the thick ester sample of cat head at regular intervals and analyze its composition, the tower bottoms circulation.
(3). according to selected experiment condition operation, regulate inlet amount, tower bottoms internal circulating load and thick product taking-up amount, keep process stabilization.
(4). under selected processing condition, prepare the ethyl acetate experiment continuously.The band aqua once adds, and after the vapour mixture that the water in band aqua and the tower forms was drawn tower, through the condensation phase-splitting, water sepn went out system, is with the aqua tower still that refluxes back; The mixed solution of acid and catalyzer circulation at the bottom of the still.Operation is 72 hours continuously, gets the thick ester sample of cat head every 2 hours and analyzes its composition.The thick ester content of cat head all is stabilized in about 94%, and acid content directly reaches the requirement of GB3728-91 salable product, and experimental result sees Table.
Table is preparation ethyl acetate experimental result continuously
The experimental example of differential responses condition:
1. catalyst levels is to the influence of overhead product composition
Fixedly add under the heat at the bottom of feed entrance point and the still, charge raw material acid-alcohol ratio 2:1 (mol ratio), reflux ratio 2.5:1, band aqua consumption is 40% (mass fraction) that reaction system produces the water yield, when inlet amount (with alcohol meter) is 1.0mol/h, changes catalyst levels in the charging, from result of experiment as can be seen, ethyl ester content increases along with the increase of catalyzer add-on in the thick ester of cat head, increases catalyst levels, helps reaction and carries out fully.When catalyst levels 15% when above, the content of ethyl ester increases not quite in the thick ester of cat head, but partially carbonized phenomenon occurs in the tower still, so the amount of selecting catalyst is the 5%-25% of acetic acid quality.
2. inlet amount is to the influence of overhead product
Add under the certain situation of heat at the tower still, reaction and fractional dose in the tower are certain.Inlet amount has considerable influence to vapour-liquid two phase flow in the tower, influences the residence time of material in tower simultaneously, thereby influences tower internal reaction and isolating effect.
It is certain to add heat, and other conditions are identical with 1 part; When inlet amount hour, find in the experiment that whole tower temperature raises.May be in inlet amount hour, water and ester total amount that reaction generates be less, owing to adopt excessive acid in the reaction, so acetate concentration increases in the tower, causes the acid of cat head band serious, and acid content is higher in the thick ester of cat head.Inlet amount increases, and acid content descends in the thick ester product of cat head, and ethyl ester content increases.But when inlet amount surpassed 2.0mol (ethanol)/h, pure content increased greatly in the thick ester of cat head; May be relative inlet amount, add heat when certain, inlet amount increases, and fractional dose descends and causes reacting weight to descend; Unreacted alcohol enters cat head, causes in the overhead product pure content to swash to increase severely to add.In selected adding under the heat, inlet amount is defined as 1-2.0mol (ethanol)/h.
3. band aqua extraction location is to the influence of overhead product
The band aqua that adds is drawn from the tower certain position with the water formation vapour mixture that reaction generates, the condensation phase-splitting goes out water sepn answering system, and the organic phase that is rich in the band aqua loops back the tower still, inlet amount is 1-2.0mol (ethanol)/h, and other conditions are with top identical.Change band aqua extraction location, will influence reaction and sepn process effect in the tower.Under certain operational condition, each component concentrations distribution is certain on interior certain cross section of tower; And during with different band aqua, in the tower on certain cross section each component concentrations to distribute be different.So different band aqua extraction locations, the water yield of taking out of is different; Because band aqua extraction location will be considered the acid amount of taking out of simultaneously generally in the bottom of tower.Under the identical operations condition, the water yield of telling is many more, and the acid amount of taking out of is few more, and is all favourable to reaction and sepn process in the tower.Know that from experimental result when making the band aqua with butanols, slave unit Y4 divides the position water effect better; When making the band aqua with N-BUTYL ACETATE, slave unit Y5 divides the position water effect better.During with butanols, N-BUTYL ACETATE, isobutyl acetate mixed zone aqua, slave unit Y5 divides the position water effect better.During with benzene class mixed zone aqua, slave unit Y5 divides the position water effect better.During with cyclohexane band aqua, slave unit Y5 divides the position water effect better.
4. reflux ratio is to the influence of overhead product
The fixed position charging, than being 2:1 (mol), inlet amount is 1-2.0mol (ethanol)/h, changes reflux ratio at the charging acid alcohol, other conditions are identical with above-mentioned experiment.In reactive distillation, the influence of backflow comparison process is different with general rectifying, and is comparatively complicated.Reflux ratio is too little, and is all unfavorable to reaction and sepn process, and the thick ester band acid of cat head band alcohol is more.When reflux ratio increased, the liquid holdup in the tower increased, and the residence time of material in tower increases relatively, helped reaction and sepn process, and the acid amount reduces in the thick ester of cat head.But when reflux ratio was too big, liquid holdup increased in the tower, and the product amount also will increase in the liquid phase, on the contrary the carrying out of inhibited reaction process.On the other hand, in the homogeneous reaction rectifying, only there is sepn process more than the feed entrance point.Know that from table 1 pure content is higher in the azeotrope that ethyl ester and ethanol form, boiling point is lower; Reflux ratio increases, and light constituent alcohol content will increase in the overhead product, and pure content increases in the thick ester of cat head thereby cause, and is unfavorable for the purification that thick ester is follow-up.Under experiment condition, when making the band aqua with butanols, reflux ratio is that 3:1 is better; When making the band aqua with N-BUTYL ACETATE, reflux ratio is that 2.5:1 is better.During with the mixed zone aqua, reflux ratio is that 2.5:1 is better.
5. band aqua consumption is to the influence of overhead product
In the esterification system, the water that generates in time if can be isolated system, will strengthen reaction process greatly.Select reflux ratio according to band aqua type for use by described in 4, other conditions are with top identical.Change band aqua consumption, the present invention is because the band aqua that adopts is high boiling alcohols, ester compound, benzene class and cycloalkane compound, band aqua consumption not only influences water amount, also may influence the relative volatility of each component in the system simultaneously, plays the effect of strengthening separating effect.Under experiment condition, consider the actually operating situation, select tape aqua consumption be in the reaction system unit time water production rate 30-250%.
6. prepare the ethyl acetate experiment continuously
Under selected processing condition, carried out continuous preparation ethyl acetate experiment.The band aqua once adds, and after the vapour mixture that the water in band aqua and the tower forms was drawn tower from the tower bottom, through the condensation phase-splitting, water sepn went out system, is with the aqua tower still that refluxes back; The mixed solution of acid and catalyzer circulation at the bottom of the still.Operation is 48-116 hours continuously, gets the thick ester sample of cat head every 2 hours and analyzes its composition.The thick ester content of cat head all is stabilized in more than 94%, and acid content directly reaches the requirement of GB3728-91 salable product.
7. the thick ester of saline solution purification by liquid extraction
With the salt of selecting, be made into certain density salts solution, directly extract the thick ester product of cat head, extract the back ethyl acetate product that obtains by analysis, every index meets the requirement of G B3728-91 ethyl acetate salable product.Salts solution after the extraction recycles after simple heating concentrates, cools off after its salt concn is reduced to finite concentration.
Claims (2)
1, a kind of single tower prepares the method for ethyl acetate, comprise that acid and alcohol react under the effect of catalyzer, effect by rectifying, reacted ethyl acetate is drawn from cat head, obtain the process of ethyl acetate through separation, it is characterized in that: in the tower still, add earlier and press the chemical reaction mol ratio, acid alcohol is than the acid alcohol mixed solution that is 10～2:1, add the vitriol oil or powdery solid super acidic catalyst and band aqua, the consumption of the vitriol oil or powdery solid super acidic catalyst is 5%～25% of a quality of acetic acid, solution is to boiling in heating tower's still, when steam arrives cat head, open water of condensation, keep total reflux operation, to tower top temperature stable after, the acid alcohol ratio is adjusted to 1:1, and with its be selected from of the top charging of the mixture of the vitriol oil or powdery solid super acidic catalyst from tower, regulate certain reflux ratio with the reflux ratio device, the thick ester product that reaction is produced is taken overhead out, and keeps tower top temperature constant; From the bottom gas phase discharging of reaction tower, enter the water that phase splitter separating reaction system produces through condensation, the organic phase reflux that is rich in the band aqua is to the tower still; The tower bottoms circulation enters the tower internal reaction after charging mixes;
Described band aqua is a butanols, N-BUTYL ACETATE, isobutyl acetate, different ester, the toluene defended of acetic acid, two kinds of hexanaphthene or they, two or more mixture, consumption be in the reaction system unit time water production rate 30-250%.
2, a kind of single tower as claimed in claim 1 prepares the equipment of the method employing of ethyl acetate, it is characterized in that: reaction fractionating tower is divided into three parts, opening for feed is that rectifying section, opening for feed are conversion zone and reboiler with the hypomere with the epimere, and raw material mixes at mixing tank with circulation fluid; The entry mixers outlet pipe is equipped with under meter, and receives the rectifying tower middle and upper part; The rectifying tower top is provided with Steam Pipe, condenser, backflow controller and phase splitter; The logical reactive distillation cat head of getting back to of pipe is arranged at backflow controller bottom; Phase splitter top has pipe to draw the thick ester of acquisition; The rectifying tower middle and lower part has Steam Pipe to connect condenser, after connect phase splitter, the reboiler of reactive distillation tower bottom is received in phase splitter top outlet; The reboiler bottom also has water cooler to be attached thereto, and water cooler has pipe to be connected with pump inlet, and the circulating-pump outlet pipe is connected with spinner-type flowmeter and leads in the mixing tank.
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| CN101830799B (en) * | 2010-05-25 | 2013-05-08 | 临沂市金沂蒙生物科技有限公司 | Single-tower rectifying method for synthetizing ethyl acetate by esterification method |
| CN102249913B (en) * | 2011-05-17 | 2013-11-06 | 上海华谊丙烯酸有限公司 | Preparation method of butyl acrylate |
| CN104402717A (en) * | 2014-10-31 | 2015-03-11 | 江苏索普（集团）有限公司 | Technology and device for water diversion in middle of esterification column in ethyl acetate production |
| CN105773767B (en) * | 2016-04-20 | 2018-02-13 | 江苏金聚合金材料有限公司 | A kind of method of wood acetylation and coproduction by acetic acid ester |
| CN107790078B (en) * | 2017-12-08 | 2024-03-19 | 南京大学 | Device and process for producing acetaminophen |
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