Tert-butyl ester distillation to prevent polymerization
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Solution Overview
Problem
The challenge lies in the continuous production of tert-butyl esters of ethylenically unsaturated carboxylic acids, where the separation of tert-butyl ester from unreacted carboxylic acid is hindered by significant polymerization, leading to equipment contamination, clogging, and safety risks during distillation, especially due to high boiling points and thermal stress.
Innovation Solution
A continuous process involving the reaction of ethylenically unsaturated carboxylic acid with isobutene in the presence of an acidic catalyst, followed by separation of the catalyst, low-boiling components, and distillation of the tert-butyl ester-containing liquid, where the ester is partially condensed and refluxed, and the carboxylic acid-containing liquid is recycled, with thermal insulation and heating of the distillation device walls to prevent polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If distillation is used to separate tert-butyl ester from unreacted carboxylic acid, then separation efficiency is improved, but polymerization increases due to elevated temperatures
Solution Approach 1:
The patent applies parameter changes by operating the distillation column at reduced pressure (vacuum conditions), which lowers the boiling point of the tert-butyl ester and allows separation to proceed at lower temperatures that do not trigger polymerization. This changes the pressure parameter of the distillation process to resolve the contradiction between achieving separation efficiency and avoiding thermal polymerization
Solution Approach 2:
The patent introduces polymerization inhibitors as intermediary substances that prevent polymerization during distillation. These inhibitors act as mediators between the thermal stress of distillation and the polymerization tendency of the ethylenically unsaturated compounds, allowing the distillation to proceed without harmful polymerization side effects
2Productivity
If distillation temperature is increased to improve separation, then separation speed is improved, but equipment contamination increases due to polymerization
Solution Approach 1:
The patent changes the pressure parameter to reduced pressure operation, which enables faster separation at lower temperatures. This resolves the contradiction by allowing high productivity through efficient mass transfer at vacuum conditions while avoiding the high temperatures that cause polymerization and equipment contamination
Solution Approach 2:
Polymerization inhibitors are used as intermediary substances that prevent the formation of polymeric contaminants during the distillation process. These inhibitors protect the equipment from contamination while maintaining high separation speed, resolving the contradiction between productivity and equipment contamination
3Manufacturing precision
If conventional distillation is used, then separation is achieved, but cleaning frequency increases due to polymerization deposits
Solution Approach 1:
By changing to vacuum distillation operation, the process achieves separation at lower temperatures that prevent polymerization deposits. This eliminates the need for frequent cleaning while maintaining separation efficiency, resolving the contradiction between manufacturing precision and loss of time to cleaning operations
Solution Approach 2:
The patent uses polymerization inhibitors as intermediary substances that prevent deposit formation during distillation. This allows continuous operation without frequent cleaning interruptions, resolving the contradiction between achieving separation and the time lost to cleaning maintenance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This process minimizes polymerization during separation, reduces equipment contamination, and enhances the efficiency and safety of the distillation process by maintaining the tert-butyl ester in a gaseous state, preventing condensation and subsequent polymerization on equipment surfaces.
Implementation Method 1
separating a tert-butyl ester-containing liquid in a distillation device into a tert-butyl ester-containing gaseous top product and a carboxylic acid-containing liquid bottom product
Implementation Method 2
the tert-butyl ester-containing gaseous top product is at least partially condensed
Implementation Method 3
the condensate is partially returned as reflux to the distillation device
Implementation Method 4
the walls of the distillation device which are in contact with the vapor are heated and/or thermally insulated, at least in partial regions
Implementation Method 5
the walls of the distillation device which are in contact with the vapor are heated and/or thermally insulated
Implementation Method 6
reacting the carboxylic acid with isobutene in the presence of an acidic catalyst to form an esterification mixture
Data Source
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AI summary
A process for continuously producing the tert-butyl ester of an ethylenically unsaturated carboxylic acid where a) an ethylenically unsaturated carboxylic acid is reacted with isobutene in the presence of an acidic catalyst to give an esterification mixture; b) the acidic catalyst is removed; c) low-boiling-point constituents are removed; and d) a liquid containing tert-butyl ester is introduced into a distillation device and the product is purified by distillation in the distillation device, where d1) the liquid containing tert-butyl ester is separated in the distillation device to give a gaseous overhead product containing tert-butyl ester and a liquid bottom product containing carboxylic acid; d2) the gaseous overhead product containing tert-butyl ester is at least to some extent condensed and some of the condensate is returned to the distillation device; d3) the liquid bottom product containing carboxylic acid is at least to some extent returned to step a); d4) liquid bottom product containing carboxylic acid is drawn off and conducted to a heater, a superheated liquid return stream is taken from the heater and the superheated return stream is depressurized into the distillation device; and d5) at least in the overhead region of the distillation device those walls of the distillation device that are in contact with the vapours are thermally insulated and/or heated at least in some regions. The separation of the tert-butyl ester from unreacted carboxylic acid in the process proceeds with a particularly small extent of polymerization both of the tert-butyl ester and of the carboxylic acid.