Acrylic Acid Crystallization Methacrolein Removal
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Solution Overview
Problem
The existing processes for producing acrylic acid are inefficient in removing methacrolein, a secondary component, which can contaminate the final product and affect polymer quality, especially in the production of water-superabsorbent polymers, due to its tendency for free-radical polymerization and adverse effects on molecular weight distribution and crosslinking.
Innovation Solution
A crystallization process is employed to separate methacrolein from acrylic acid, where the depletion coefficient is greater than 15, allowing for the efficient removal of methacrolein by accumulating it in the mother liquor while the acrylic acid crystallizes, thereby achieving high purity in a single separation step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional separation processes (absorption, condensation, distillation) are used to remove methacrolein from acrylic acid, then the separation process becomes complex and requires multiple stages, but the methacrolein removal efficiency is insufficient and polymer quality is affected
Solution Approach 1:
The patent employs crystallization (solid-liquid phase transition) to separate methacrolein from acrylic acid. By controlling the phase transition of acrylic acid into crystals while methacrolein remains in the liquid mother liquor, the process achieves efficient separation in a single step, resolving the contradiction between removal efficiency and process complexity
Solution Approach 2:
The patent utilizes the difference in solubility parameters between methacrolein and acrylic acid in the liquid phase. By adjusting temperature and concentration parameters, acrylic acid crystallizes while methacrolein remains dissolved, enabling selective removal without complex multi-stage separation processes
2Manufacturing precision
If multiple separation stages are used to achieve high purity acrylic acid, then the purity increases, but the production time and energy consumption increase
Solution Approach 1:
The crystallization process achieves high-purity acrylic acid separation in a single operation by exploiting the phase transition difference between the two compounds. This eliminates the need for multiple sequential separation stages, thereby maintaining high purity while significantly improving production efficiency and reducing energy consumption
3Quantity of substance
If crude propylene with C4 hydrocarbons is used for acrylic acid production, then the raw material cost decreases, but methacrolein content in the product increases
Solution Approach 1:
The patent converts the harmful effect of methacrolein contamination into a beneficial separation opportunity. By allowing methacrolein to remain in the liquid phase during acrylic acid crystallization, the process effectively removes this impurity that originated from using cost-effective crude propylene with C4 hydrocarbons, thus maintaining both low raw material cost and high product purity
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 removes methacrolein to undetectable levels, ensuring high-purity acrylic acid suitable for superabsorbents, reducing the need for multiple separation stages and improving polymer quality by maintaining the acrylic acid in the crystals and methacrolein in the mother liquor, with depletion coefficients up to 30 or more.
Implementation Method 1
A procedure for removing methacrolein from liquid phase P comprising acrylic acid as a main constituent and target product, and methacrolein as a secondary component, is found which comprises effecting the removal by crystallization, the acrylic acid accumulating in the crystals formed and the methacrolein in the remaining mother liquor.
Data Source
AI summary
A process for removing methacrolein from liquid phase P comprising acrylic acid as a main constituent and target product, and methacrolein as a secondary component in which the removal is effected by crystallization, the acrylic acid accumulating in the crystals formed and the methacrolein in the remaining mother liquor.