Methyl Methacrylate Purification via Entrainer Distillation
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Solution Overview
Problem
Current processes for purifying methyl methacrylate (MMA) reaction products from oxidative esterification reactors are inefficient in separating components, particularly when dealing with MMA salts, and do not effectively break the methanol/MMA azeotrope.
Innovation Solution
A multi-step distillation process involving a series of columns with specific tray configurations and entrainers, including a C6-C7 hydrocarbon like n-hexane, to separate and purify MMA, methanol, and alkali metal methacrylates, where the reaction product mixture is fed above the middle of the first distillation column, and subsequent streams are processed through water separators and drying columns to achieve high-purity MMA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a methanol recovery column using hexane as an entrainer is used, then methanol can be recovered, but the process is not suitable for reaction products containing MMA salts
Solution Approach 1:
The purification process is divided into multiple distillation columns, each performing a specific separation function. The first column removes light components and breaks the methanol/MMA azeotrope using C6-C7 hydrocarbon entrainer. The second column separates MMA from alkali metal methacrylates. This segmentation allows the process to handle MMA salts effectively while maintaining high methanol recovery efficiency.
Solution Approach 2:
C6-C7 hydrocarbon entrainer (such as n-hexane or heptane) is introduced as an intermediary substance to break the methanol/MMA azeotrope. The entrainer forms a ternary azeotrope with methanol and water that has a lower boiling point, allowing methanol to be removed more efficiently. This intermediary enables the process to work effectively with reaction products containing MMA salts.
2Manufacturing precision
If conventional distillation processes are used, then separation of components can be achieved, but the methanol/MMA azeotrope cannot be effectively broken
Solution Approach 1:
C6-C7 hydrocarbon entrainer is used as an intermediary to break the methanol/MMA azeotrope. The entrainer forms a new azeotropic system that allows methanol to be separated at lower temperatures and with higher efficiency. This resolves the contradiction by enabling both precise separation and effective azeotrope breaking.
Solution Approach 2:
The process changes the physical parameters of the distillation system by introducing an entrainer that alters the vapor-liquid equilibrium relationships. The C6-C7 hydrocarbon changes the relative volatility between methanol and MMA, allowing the azeotrope to be broken. This parameter change enables simultaneous achievement of high separation efficiency and azeotrope breaking capability.
3Device complexity
If a single distillation column is used, then the process is simpler, but the separation of multiple components including MMA salts is inefficient
Solution Approach 1:
The system uses two distillation columns with specific functions: the first column removes light components and breaks the methanol/MMA azeotrope, while the second column separates MMA from alkali metal methacrylates. This segmentation achieves efficient multi-component separation including MMA salts, while keeping each column's design relatively simple and focused on a specific separation task.
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
The process effectively separates and recovers MMA, methanol, and alkali metal methacrylates, preventing salt precipitation and achieving high-purity MMA product with minimal operational issues.
Implementation Method 1
a multi-step distillation process involving a series of columns with specific tray configurations
Implementation Method 2
do not effectively break the methanol/MMA azeotrope
Implementation Method 3
feeding the first overhead stream to a first water separator to produce (i) a first organic phase and (ii) a first aqueous phase
Data Source
Figure 1
AI summary
A process for purifying methyl methacrylate by (a) feeding a mixture comprising methyl methacrylate and its alkali salt into a distillation column above the middle along with a hydrocarbon; (b) removing a first overhead stream; (c) removing a first bottoms stream; (d) feeding the first overhead stream to a first water separator to produce (i) a first organic phase and (ii) a first aqueous phase which enters a methanol drying column which produces a second overhead stream and a second bottoms stream; (e) feeding the first bottoms stream to a second water separator to produce (i) a second aqueous phase which is fed to an MMA stripper column which produces a third overhead stream and a third bottoms stream, and (ii) a second organic phase; (f) combining the second organic phase and the second bottoms stream into a third water separator which produces a third organic phase which enters an MMA drying column which produces a fourth bottoms stream, and (g) feeding the fourth bottoms stream to an MMA product column.