Alkyl Acrylate Purification via Thermal Cracking of Residues
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Solution Overview
Problem
The manufacturing of C4-C10 alkyl (meth)acrylates by direct esterification of (meth)acrylic acid faces challenges in achieving high purity and productivity due to the formation of heavy by-products like Michael adducts, which accumulate and are difficult to eliminate, leading to losses and impurities that do not meet strict purity standards required for applications such as pressure-sensitive adhesives.
Innovation Solution
A process involving thermal cracking of residues from the purification column, followed by recycling the cracked products, which includes acidic impurities and olefins, to minimize equipment size and energy costs while achieving high purity and productivity of C4-C10 acrylic esters like 2-ethylhexyl acrylate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct esterification of (meth)acrylic acid is used to manufacture C4-C10 alkyl (meth)acrylates, then the reaction can proceed with conventional catalysts, but heavy by-products like Michael adducts form and accumulate, making purification complex and reducing productivity
Solution Approach 1:
The patent applies the 'Blessing in disguise' principle by converting the harmful heavy by-products (Michael adducts) into valuable resources through thermal cracking. Instead of simply eliminating these impurities, the process cracks them into useful components that are recycled back into the esterification reaction, transforming a purification burden into a productivity advantage.
Solution Approach 2:
The patent implements 'Discarding and recovering' by recovering the heavy by-products through thermal cracking and returning the cracked products to the reaction system. The cracked material is not discarded but rather reused as a feedstock, thereby eliminating the need for complex purification steps while maintaining high productivity.
2Productivity
If excess alcohol is used to drive the esterification reaction, then the reaction equilibrium shifts toward the desired ester, but the concentration of acidic impurities and by-products increases, requiring complex purification
Solution Approach 1:
The patent converts the harmful acidic impurities and by-products generated during excess alcohol esterification into useful resources through thermal cracking. The cracked products are then recycled to the reaction system, transforming the purification problem into an advantage that maintains both high productivity and high purity.
Solution Approach 2:
The patent implements feedback by continuously recycling the thermal cracking products back into the esterification reaction system. This closed-loop approach allows the system to self-correct by using the cracked material to maintain reaction equilibrium while preventing impurity accumulation, thereby achieving both high productivity and high purity.
3Productivity
If thermal cracking of bottom residues is implemented, then heavy by-products are valorized and productivity increases, but energy consumption increases
Solution Approach 1:
The patent recovers valuable materials from the thermal cracking process and returns them to the esterification reaction system. By recovering and reusing the cracked products rather than simply consuming energy to destroy the by-products, the process achieves high productivity while minimizing net energy consumption through material recycling.
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 effectively recycles and valorizes heavy by-products, achieving a C4-C10 acrylic ester with purity greater than 99.7% and reduced acidic impurity content, thereby increasing productivity and meeting stringent purity standards for applications in adhesives and coatings.
Implementation Method 1
a step of thermal cracking of the bottom residues of the purification column, leading to the production of cracking products which are recycled in the process
Implementation Method 2
a stream rich in acid impurities such as β-hydroxypropionic acid and β-acryloxypropionic acid is withdrawn via a side outlet during the distillation of the crude reaction mixture
Data Source
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AI summary
The invention relates to the manufacturing of alkyl acrylates by direct esterification of acrylic acid with the corresponding alcohol. In particular, the invention relates to the use of a cracker in combination with a topping column equipped with a side stream for drawing off a stream rich in acid impurities such as β-hydroxypropionic acid and β-acryloxypropionic acid during the distillation of the crude reaction mixture, in order to produce an acrylic ester corresponding to purity standards that are compatible with its use for preparing acrylic polymers.