Acrylic Acid Purification via Dynamic Melt Crystallization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for purifying acrylic acid, particularly those involving melt crystallization, face challenges such as solvent requirement, energy consumption, and equipment complexity due to the precipitation of maleic anhydride, which leads to downtime and increased costs.
Innovation Solution
A process involving dynamic and static melt crystallization stages with controlled solvent addition to maintain maleic anhydride in solution, reducing the need for extensive solvent use and energy consumption, and simplifying equipment requirements by avoiding precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If melt crystallization is used for further purification of crude acrylic acid, then purification effectiveness is improved, but maleic anhydride precipitates and accumulates in equipment causing downtime and increased operational complexity
Solution Approach 1:
The patent applies preliminary action by adding a solvent to the crude acrylic acid composition before the melt crystallization process begins. This pre-treatment step ensures that maleic anhydride remains dissolved throughout the crystallization process, preventing precipitation and accumulation in the equipment. The solvent is added in an amount sufficient to keep maleic anhydride in solution at all times during crystallization, thereby maintaining equipment functionality while achieving effective purification.
2Productivity
If solvent is added to crude acrylic acid before crystallization to prevent maleic anhydride precipitation, then equipment downtime is reduced, but solvent consumption and energy requirements increase
Solution Approach 1:
The patent applies parameter changes by carefully controlling the amount of solvent added to the crude acrylic acid composition. The solvent quantity is optimized to be the minimum sufficient to prevent maleic anhydride precipitation throughout the crystallization process. This parameter optimization balances the need to maintain equipment availability with the goal of minimizing solvent consumption and associated energy requirements for heating and cooling the larger volume.
3Reliability
If high amounts of solvent are added to keep maleic anhydride in solution, then precipitation is prevented, but crystal growth of acrylic acid is hindered resulting in smaller crystals with higher surface area
Solution Approach 1:
The patent applies parameter changes by precisely controlling the solvent-to-maleic anhydride weight ratio to fall within the range of 0.05 to 0.5. This optimized parameter range is sufficient to prevent maleic anhydride precipitation while minimizing the solvent's interfering effect on acrylic acid crystal growth. The controlled solvent addition maintains reliability by preventing precipitation while preserving manufacturing precision by allowing formation of larger, higher-quality crystals with lower surface area.
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 results in efficient purification of acrylic acid with lower operational and investment costs, minimizing solvent use and energy consumption while preventing maleic anhydride precipitation, thus maintaining equipment functionality.
Implementation Method 1
Both, distillation and melt crystallization are suitable methods therefor
Implementation Method 2
adding a solvent (26) which is capable of dissolving maleic anhydride to the first residue
Data Source
AI summary
A process and an apparatus for the purification of a crude acrylic acid composition containing maleic anhydride as an impurity comprising the following steps: (a) carrying out at least one dynamic melt crystallization stage (14, 14a, 14b, 14c, 14d) with the crude acrylic acid composition to prepare a first purified acrylic acid composition and a first residue containing at least 3.5% by weight maleic anhydride, (b) adding a solvent (26) which is capable of dissolving maleic anhydride to the first residue in an amount that the weight ratio of the solvent to the maleic anhydride is 0.3 or more to prepare a ratio-adjusted residue and (c) carrying out at least one further dynamic melt crystallization stage and/or at least one static melt crystallization stage (18, 18a, 18b) with the ratio-adjusted residue to prepare a second purified acrylic acid composition and a second residue.