Azeotropic Distillation with Lateral Withdrawal for Acrylate Purification
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Solution Overview
Problem
The production of light (meth)acrylic esters, such as methyl or ethyl acrylate, faces challenges due to the formation of by-products like methyl methoxy propionate, which interferes with purification and leads to material losses and energy inefficiencies in the purification process, particularly due to its azeotropic behavior with water.
Innovation Solution
A process involving azeotropic distillation in a distillation column with lateral withdrawal of a fraction rich in alkyl alkoxy propionate by-product, allowing for effective elimination of methyl methoxy propionate and promoting equilibrium shift to improve yield and simplify the purification process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional distillation and extraction processes are used to purify light acrylic esters, then impurities can be removed, but the process becomes complex and energy-intensive
Solution Approach 1:
The patent combines multiple purification operations (distillation, extraction, decantation) into a single integrated distillation column with lateral withdrawal. The column simultaneously performs separation of acrylic acid, removal of methyl methoxy propionate through side draw, and purification of the ester product, eliminating the need for separate extraction and decantation units.
Solution Approach 2:
The distillation column is divided into functional zones with lateral withdrawal ports at specific heights. The column segments the purification process by extracting different fractions at different locations: overhead for light impurities, lateral withdrawal for methyl methoxy propionate at mid-height, and bottom for heavy impurities and acrylic acid, allowing simultaneous multi-purpose operation.
2Manufacturing precision
If multiple distillation and extraction steps are implemented, then purification effectiveness is improved, but energy consumption increases
Solution Approach 1:
The patent merges multiple energy-intensive separation steps into a single distillation column operating under unified conditions. By performing separation, extraction, and decantation functions simultaneously in one column, the total energy input is reduced compared to sequential operation of multiple independent units.
Solution Approach 2:
The patent employs lateral withdrawal at specific column heights where the concentration of methyl methoxy propionate is maximized. By changing the spatial parameter (withdrawal location) and operating under reduced pressure, the process achieves efficient separation with lower energy input than conventional atmospheric distillation followed by extraction.
3Object-generated harmful factors
If acrylic acid is purged from the recycling loop to remove methyl methoxy propionate, then by-product accumulation is reduced, but significant acrylic acid is lost
Solution Approach 1:
The patent extracts methyl methoxy propionate from the recycling loop through lateral withdrawal at a specific column height where this by-product concentrates. This selective removal allows acrylic acid to remain in the recycling stream without significant purging, separating the harmful by-product removal from the valuable acid recovery.
Solution Approach 2:
The distillation column acts as an intermediary device between the reactor and recycling loop. It provides a controlled environment where methyl methoxy propionate can be selectively removed through lateral withdrawal while acrylic acid is purified and returned to the reactor, mediating the separation without requiring aggressive purging.
4Quantity of substance
If methyl methoxy propionate accumulates in the recycling loop, then material balance is disrupted, but purification becomes more difficult
Solution Approach 1:
The patent performs preliminary removal of methyl methoxy propionate through lateral withdrawal before the by-product can accumulate and disrupt the material balance in the recycling loop. This proactive extraction prevents the formation of problematic concentrations that would complicate subsequent purification steps.
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 approach effectively eliminates alkyl alkoxy propionate, reduces material losses, and optimizes the material balance, leading to a simplified and energy-efficient production of high-purity methyl or ethyl acrylate.
Implementation Method 1
the azeotropic distillation of the reaction mixture carried out in a single distillation column equipped with a side-drawing
Implementation Method 2
lateral withdrawal of a fraction rich in alkyl alkoxy propionate by-product
Data Source
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AI summary
The present invention concerns the production of light (meth)acrylic esters by direct esterification of acrylic acid by methanol or ethanol. The invention relates more particularly to a method for recovering/purifying C1-C2 alkyl acrylate, comprising azeotropic distillation of the crude reaction mixture using a distillation column comprising a lateral withdrawal of a fraction rich in alkyl alkoxy propionate by-product, the boiling point of which is close to that of acrylic acid and therefore problematic in the purification method.