Boiling Oil Distillation for Polymerizable Compound Purification
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Solution Overview
Problem
Existing processes for purifying polymerizable compounds, such as acrylic and methacrylic acids, require additional desorption and distillation steps to separate the target products from solvents, leading to solvent losses and potential polymerization issues.
Innovation Solution
A distillation process using a high-boiling, inert, thermally stable 'boiling oil' in the bottom of a rectification column, where the boiling oil has a higher boiling point than the target product, preventing polymerization by reducing residence time and allowing up to 10% auxiliary discharge, with suitable substances like unbranched paraffins, aromatic compounds, or sulfolane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If countercurrent scrubbing with high-boiling inert solvent is used to obtain anhydrous acrylic acid or methacrylic acid, then the target product can be separated from reaction gases, but additional desorption and distillation steps are required to separate the target product from the solvent
Solution Approach 1:
The invention extracts only the necessary function of solvent absorption while eliminating the need for solvent recovery steps. The boiling oil is taken out of the system after performing its absorption function, allowing direct product collection without additional desorption or distillation steps.
Solution Approach 2:
The boiling oil serves multiple functions: it absorbs water from reaction gases to produce anhydrous product, and simultaneously acts as a heating medium through its high boiling point. This multi-functionality eliminates the need for separate heating steps and reduces overall process complexity.
2Manufacturing precision
If conventional distillation is used to purify polymerizable compounds, then the target product can be separated, but long residence times in the bottom of the column lead to polymerization
Solution Approach 1:
The invention changes the temperature parameter by using a boiling oil with a higher boiling point than the target product. This creates a temperature gradient where the bottom of the column remains hot enough to vaporize the target product but not hot enough to cause polymerization, as the boiling oil temperature is controlled to be below the polymerization threshold.
Solution Approach 2:
The invention rushes the target product through the dangerous zone (bottom of the column) by maintaining low residence time. The continuous vaporization and upward flow of the target product minimizes its exposure time to elevated temperatures, preventing polymerization while still achieving separation.
3Productivity
If the boiling point of the boiling oil is increased to improve separation efficiency, then distillation effectiveness increases, but thermal stress on the polymerizable compound increases
Solution Approach 1:
The invention optimizes the boiling point parameter of the boiling oil to be higher than the target product (enabling effective separation) but lower than the polymerization temperature (reducing thermal stress). This parameter optimization achieves both separation efficiency and product protection simultaneously.
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 method enables high-purity polymerizable compound recovery without further solvent purification and minimizes polymerization risks, allowing the boiling oil to be reused, with up to 99.7% purity achieved in examples like methacrylic and acrylic anhydride purification.
Implementation Method 1
the concentration of the compound susceptible to polymerization decreases sharply in the direction of the bottom and thus in the direction of increasing temperature as a result of the heat exchange with the boiling oil vapors
Implementation Method 2
the purification of the polymerizable compound by distillation is carried out in the presence of a high-boiling, inert, thermally long-term stable substance
Data Source
Figure 1
AI summary
The invention relates to a method for purifying, by distillation, polymerizable compounds, using a high-boiling, inert substance as the boiling oil, said substance having a long-term thermal stability. The invention is characterized in that the boiling oil is present in the sump of a rectification column.