Summary of the invention
Of the present inventionly be the deficiency overcoming existing acetic ester production technology, provide a kind of with acetic acid and lower aliphatic alcohols for raw material, take the vitriol oil as catalyzer, in a loop of esterifying kettle and reboiler composition, carry out esterification; By the gaseous phase materials that steams after the esterification sour trap by an inner liner polytetrafluoroethylene, in ceramic packing layer, carry out mass transfer exchange with from liquid at the bottom of the tower at the bottom of esterification column, most of acetic acid that gaseous stream is carried secretly up, most sulfuric acid are washed down; According to the difference of the azeotrope boiling point of the kind of esterification lower aliphatic alcohols used and the acetic ester generated and water, lower aliphatic alcohols, by from sour trap top different gaseous stream out to be connected the opening for feed of esterification column different heights position by the combination selection of valve, reduce the method for acidity of acetate through the further separation of esterification column and follow-up treating process.
The object of the present invention is achieved like this: a kind of method reducing acidity of acetate, be mainly with acetic acid and lower aliphatic alcohols as raw material, continue respectively to pump into acetic acid preheater and lower aliphatic alcohols preheater, esterifying kettle is passed into after preheating, mixing, take the vitriol oil as catalyzer, in the loop that esterifying kettle and reboiler form, carry out esterification, prepare acetic ester;
The acetic ester that in loop, esterification generates and water, lower aliphatic alcohols form azeotrope, boiling point is lower, be distilled out of with the form of gas phase, entered the sour trap bottom of inner liner polytetrafluoroethylene by the gaseous phase outlet at esterifying kettle top, gaseous stream carries part acetic acid and a small amount of sulfuric acid while entering sour trap;
The ceramic packing layer of described gaseous stream upwards in peracid trap, that gets off with top carries out mass transfer exchange from the bottom of esterification column, via liquid at the bottom of the tower of flow control valve, most of acetic acid that gaseous stream is carried secretly up, most sulfuric acid are washed down, the acid solution of washing deposits to the bottom of sour trap, and flowing back in esterifying kettle, the sulfuric acid in acid solution can continue the esterification occurred in esterifying kettle to play katalysis;
According to the difference of the azeotrope boiling point of the kind of esterification lower aliphatic alcohols used and the acetic ester generated and water, lower aliphatic alcohols, by from sour trap top different gaseous stream out to be connected the opening for feed of esterification column different heights position by the combination selection of valve, the gaseous stream that azeotropic point is low carries out the opening for feed of esterification column higher position, and the gaseous stream that azeotropic point is high carries out the opening for feed of esterification column lower position;
Gaseous stream just can form the low acetic ester of acidity and water, lower aliphatic alcohols azeotrope at tower top after the further separation of esterification column, again through follow-up treating process, the acetic ester obtained just can meet the requirement of corresponding product standard for product acidity.
The invention has the advantages that:
1) adopt the sulfuric acid that boiling point is higher as catalyzer, the solid acid catalysis oxidant layer caused after material can be avoided to wash away solid acid catalysis oxidant layer is cracked, efflorescence and the unfavorable factor such as knot is fast, avoid catalyst fines, particle, the block tamper that hardens circulation causes the possibility of Peril Incident after footpath, avoid frequently changing the idle cost that solid acid catalysis oxidant layer is brought, avoid the cost of solid acid catalyst regenerative process.Adopt liquid acid as catalyzer, acid can also be made to be evenly distributed in the liquid material participating in reaction, esterification is carried out smoothly.The boiling point of sulfuric acid is higher, is just not easy to be carried secretly up by gaseous stream, makes catalytic efficiency higher, and being separated also just to become of a small amount of sulfuric acid catalyst gaseous phase materials and its carried secretly is more prone to.
2) loop of esterifying kettle and reboiler composition is adopted to come to esterification transfer heat, the large feature of reboiler heat interchanging area can be made full use of to improve the efficiency of heating, the esterifying kettle of jacketed type is avoided to be not easy to be delivered to the centre of still because of the heat from outside, cause the non-uniform temperature in still, the rough sledding that by product is many, and do not need to experience again temperature variation violent when comparatively high temps and heating steam enter due to esterifying kettle, processing request for esterifying kettle also becomes simple, adopt enamel still just can solve the significant corrosion problems of acid to esterifying kettle in traditional mode of production mode.
3) the sour trap of an inner liner polytetrafluoroethylene is added relative to traditional acetic ester mode of production, use the filler of the acid corrosion-resistants such as pottery, utilize, from liquid at the bottom of a part of tower at the bottom of esterification column, mass transfer exchange is carried out to the gaseous stream in sour trap, can both solve containing sour logistics sour trap, the corrosion of filler itself, and the most acetic acid that gaseous stream can be made to carry secretly up, overwhelming majority sulfuric acid is washed down, ensure that the content entering acid in the logistics of esterification column is very low, the material requirement to esterification column etc. can be reduced, the cost of reduction equipment, reduce production cost.
4) the most sulfuric acid owing to being carried secretly up by gaseous stream have been washed down, and acid solution flow back in esterifying kettle, greatly can reduce the consumption of sulfuric acid, make sulfuric acid be recovered utilization in time, reduce production cost.
5) according to the kind of esterification lower aliphatic alcohols used and the acetic ester generated and water, the difference of the azeotrope boiling point of lower aliphatic alcohols, by from sour trap top, different gaseous stream out to enter the opening for feed of esterification column different heights position by the combination selection of valve, the gaseous stream that azeotropic point is low carries out the higher position of esterification column, the gaseous stream that azeotropic point is high carries out the lower position of esterification column, not only can energy efficient, and a set of production system can be made to may be used for the production of different sorts acetic ester, greatly improve the ability of enterprise's strain market environment.
In a word, by improving traditional acetic ester mode of production, esterifying kettle and reboiler are formed a loop, after increasing the sour trap of an inner liner polytetrafluoroethylene, the position of esterification column is entered in conjunction with the gaseous stream that choose reasonable is different, the indexs such as the acidity of the acetic ester product produced not only can be made to meet the requirement of corresponding product standard, and greatly reduce production cost.
Embodiment
As shown in Figure 1, the esterification system structure taked in the present invention is: acetic acid preheater 1 is communicated with through the opening for feed of mixing tank with esterifying kettle 5 with the discharge port of lower aliphatic alcohols preheater 2, and esterifying kettle 5 and reboiler 6 form the loop connected and composed by pipeline.The top of esterifying kettle 5 has a gaseous phase outlet, the gas phase inlet communication of sour trap 3 lower sides of this gaseous phase outlet and inner liner polytetrafluoroethylene, arrange two-layer ceramic filler 4 in acid trap 3, the lower end liquid-phase outlet of sour trap 3 is communicated with esterifying kettle 5 by the pipeline of band valve; The top of acid trap 3 arranges gaseous phase outlet, and this gaseous phase outlet selects the opening for feed connecting esterification column 7 different heights position by the combined optional of valve; The bottom of esterification column 7 is communicated with the fluid inlet of sour trap 3 upper portion side wall with the pipeline of product pump by band flow control valve 8.
Embodiment 1
A kind of method reducing n-butyl acetate acidity, be mainly with acetic acid and propyl carbinol as raw material, continue respectively to pump into acetic acid preheater 1 and propyl carbinol preheater 2, esterifying kettle 5 is passed into after preheating, mixing, take the vitriol oil as catalyzer, in the loop that esterifying kettle 5 and reboiler 6 form, at the temperature of 120 ± 5 DEG C, carry out esterification, prepare n-butyl acetate;
The n-butyl acetate that in loop, esterification generates and water, propyl carbinol form azeotrope, the boiling point of this azeotrope is 90.7 DEG C, be distilled out of with the form of gas phase, entered sour trap 3 bottom of inner liner polytetrafluoroethylene by the gaseous phase outlet at esterifying kettle 5 top, gaseous stream carries part acetic acid and a small amount of sulfuric acid while entering sour trap 3.
The ceramic packing layer 4 of gaseous stream upwards in the sour trap 3 of inner liner polytetrafluoroethylene, with top get off from esterification column 7 end, carry out mass transfer exchange via liquid at the bottom of the tower of flow control valve 8, most of acetic acid that gaseous stream is carried secretly up, most sulfuric acid are washed down, the acid solution of washing deposits to the bottom of sour trap, and flowing back in esterifying kettle, the sulfuric acid in acid solution can continue the esterification occurred in esterifying kettle to play katalysis.
According to esterification be propyl carbinol and the n-butyl acetate generated and water, propyl carbinol azeotrope boiling point the practical situation of 90.7 DEG C, by from sour trap top, this gaseous stream out to enter the opening for feed of esterification column middle and lower part by the combination selection of valve.
Gaseous stream just can form the azeotrope of the n-butyl acetate of acidity≤0.010% and water, propyl carbinol after the further separation of esterification column at tower top, again through follow-up treating process, the n-butyl acetate obtained with the acidity of acetometer for 0.003%, meet " industrial n-butyl acetate " national standard require acidity should≤0.010% index.
Comparative example 1
A kind of method of producing n-butyl acetate, be mainly with acetic acid and propyl carbinol as raw material, continue respectively to pump into acetic acid preheater and propyl carbinol preheater, esterifying kettle is passed into after preheating, mixing, take the vitriol oil as catalyzer, without reboiler heating, directly carry out esterification with esterifying kettle, generate n-butyl acetate.Reaction needed is carried out at the temperature of 125 ± 5 DEG C.
In the present embodiment, according to enamel still as esterifying kettle, under temperature of reaction high like this, the flow of the gaseous stream steamed in still still only have esterifying kettle and reboiler are formed the gas evaporation amount after a loop half below; According to 316L material as esterifying kettle, then namely corresponding esterifying kettle is corroded perforation after one week of use.
Esterifying kettle gaseous stream out is directly accessed the middle and lower part of esterification column, also there is the situation of boring a hole that is corroded in two months in use in the esterification column of 316L material later.Gaseous stream after the further separation of esterification column can tower top formed acidity be 0.018% n-butyl acetate and water, propyl carbinol azeotrope, again through follow-up treating process, the n-butyl acetate obtained with the acidity of acetometer for 0.009%, n-butyl acetate content is 99.1%, the content of propyl carbinol is 0.55%, separately have the unknown impuritie of accumulative 0.3%, by product when esterification is described becomes many.Although reach the requirement of " industrial n-butyl acetate " national standard salable product reluctantly, do not reach the requirement of acceptable end product.
Embodiment 2
A kind of method reducing ethyl acetate acidity, be mainly with acetic acid and alcohol (main component is for ethanol) as raw material, continue respectively to pump into acetic acid preheater 1 and ethanol preheater 2, esterifying kettle 5 is passed into after preheating, mixing, take the vitriol oil as catalyzer, esterification is carried out, preparation ethyl acetate in the loop that esterifying kettle 5 and reboiler 6 form;
The ethyl acetate that in loop, esterification generates and water, ethanol form azeotrope, the boiling point of this azeotrope is 70.2 DEG C, be distilled out of with the form of gas phase, entered sour trap 3 bottom of inner liner polytetrafluoroethylene by the gaseous phase outlet at esterifying kettle 5 top, gaseous stream carries part acetic acid and a small amount of sulfuric acid while entering sour trap 3.
The ceramic packing layer 4 of gaseous stream upwards in the sour trap 3 of inner liner polytetrafluoroethylene, that gets off with top carries out mass transfer exchange from the bottom of esterification column, via liquid at the bottom of the tower of flow control valve 8, most of acetic acid that gaseous stream is carried secretly up, most sulfuric acid are washed down, the acid solution of washing deposits to the bottom of sour trap, and flowing back in esterifying kettle, the sulfuric acid in acid solution can continue the esterification occurred in esterifying kettle to play katalysis.
According to esterification be alcohol and the ethyl acetate generated and water, ethanol azeotrope boiling point the practical situation of 70.2 DEG C, by from sour trap top, this gaseous stream out to enter the opening for feed of esterification column middle and upper part by the combination selection of valve.
Gaseous stream just can form the azeotrope of the ethyl acetate of acidity≤0.005% and water, ethanol after the further separation of esterification column at tower top, again through follow-up treating process, the ethyl acetate obtained with the acidity of acetometer for 0.001%, meet acidity that " industrial ethyl acetate " national standard requires ethyl acetate premium grads should≤0.004% index.
Comparative example 2
A kind of method of producing ethyl acetate, be mainly with acetic acid and alcohol (main component is for ethanol) as raw material, continue respectively to pump into acetic acid preheater and ethanol preheater, esterifying kettle is passed into after preheating, mixing, take the vitriol oil as catalyzer, esterification is carried out, preparation ethyl acetate in the loop that esterifying kettle and reboiler form;
Esterifying kettle gaseous stream out is directly accessed the middle and upper part of esterification column; Gaseous stream after the further separation of esterification column tower top formed acidity be 0.012% ethyl acetate and water, ethanol azeotrope, again through follow-up treating process, the ethyl acetate obtained with the acidity of acetometer for 0.006%, do not meet acidity that " industrial ethyl acetate " national standard requires ethyl acetate salable product should≤0.005% index.
Comparative example 3
A kind of method of producing ethyl acetate, be mainly with acetic acid and alcohol (main component is for ethanol) as raw material, continue respectively to pump into acetic acid preheater and ethanol preheater, esterifying kettle is passed into after preheating, mixing, take the vitriol oil as catalyzer, esterification is carried out, preparation ethyl acetate in the loop that esterifying kettle and reboiler form;
Esterifying kettle gaseous stream out is directly accessed the middle and lower part of esterification column, corresponding steam consumption is 1.2 times of steam consumption when esterifying kettle gaseous stream out directly being accessed the middle and upper part of esterification column.
Gaseous stream after the further separation of esterification column tower top formed acidity be 0.008% ethyl acetate and water, ethanol azeotrope, again through follow-up treating process, the ethyl acetate obtained with the acidity of acetometer for 0.004%, meet reluctantly acidity that " industrial ethyl acetate " national standard requires ethyl acetate premium grads should≤0.004% index.
Embodiment 3
A kind of method reducing n-propyl acetate acidity, be mainly with acetic acid and n-propyl alcohol as raw material, continue respectively to pump into acetic acid preheater 1 and n-propyl alcohol preheater 2, esterifying kettle 5 is passed into after preheating, mixing, take the vitriol oil as catalyzer, in the loop that esterifying kettle 5 and reboiler 6 form, carry out esterification, prepare n-propyl acetate;
The n-propyl acetate that in loop, esterification generates and water, n-propyl alcohol form azeotrope, the boiling point of this azeotrope is 82.2 DEG C, be distilled out of with the form of gas phase, entered sour trap 3 bottom of inner liner polytetrafluoroethylene by the gaseous phase outlet at esterifying kettle 5 top, gaseous stream carries part acetic acid and a small amount of sulfuric acid while entering sour trap 3.
The ceramic packing layer 4 of gaseous stream upwards in the sour trap 3 of inner liner polytetrafluoroethylene, that gets off with top carries out mass transfer exchange from the bottom of esterification column, via liquid at the bottom of the tower of flow control valve 8, most of acetic acid that gaseous stream is carried secretly up, most sulfuric acid are washed down, the acid solution of washing deposits to the bottom of sour trap, and flowing back in esterifying kettle, the sulfuric acid in acid solution can continue the esterification occurred in esterifying kettle to play katalysis.
According to esterification be n-propyl alcohol and the n-propyl acetate generated and water, n-propyl alcohol azeotrope boiling point the practical situation of 82.2 DEG C, by from sour trap top, this gaseous stream out enters opening for feed in the middle part of esterification column by the combination selection of valve.
Gaseous stream after the further separation of esterification column just can tower top formed acidity be≤0.010% n-propyl acetate and water, n-propyl alcohol azeotrope, again through follow-up treating process, the n-propyl acetate obtained with the acidity of acetometer for 0.004%, meet " industrial n-propyl acetate " company standard require acidity should≤0.010% index.