In Situ Water Removal in Oxidative Esterification via Coupled Reactor-Distillation
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Solution Overview
Problem
The existing methods for producing methyl methacrylate (MMA) through oxidative esterification are hindered by the detrimental effects of water on conversion and selectivity due to its interaction with Pd-containing catalysts, and the impracticality of continuous water removal using membranes for commercial-scale production.
Innovation Solution
A process involving multiple reactors and distillation columns is used to continuously remove water in situ, where a crude product stream is processed through distillation to generate overheads and bottoms streams, with the overheads stream containing less than 1 wt% water being recycled to subsequent reactors, thereby controlling water concentration and improving conversion and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If membranes are used to continuously remove water from the oxidative esterification reaction, then water removal is achieved, but the membrane area required becomes extremely large and the separation flux becomes very low
Solution Approach 1:
The patent uses distillation, which relies on phase transitions (vaporization and condensation), to separate water from the reaction mixture. The overheads stream containing water is vaporized and then condensed, achieving water removal without requiring large membrane areas. This phase transition-based separation is much more efficient than membrane separation for this application.
Solution Approach 2:
The patent extracts water from the reaction system by separating it into a distinct overheads stream through distillation. The water is taken out of the liquid reaction phase and removed as a separate vapor phase, then condensed and discharged. This extraction approach efficiently removes water without the need for large membrane contact areas.
2Productivity
If water is not removed from the oxidative esterification reaction, then the process is simpler, but conversion and selectivity deteriorate due to water interaction with the Pd-containing catalyst
Solution Approach 1:
The patent implements continuous water removal through a coupled distillation column that operates continuously alongside the oxidative esterification reaction. The overheads stream is continuously separated and removed, maintaining low water concentration in the reactor throughout the process. This continuous action prevents catalyst deactivation and maintains high conversion and selectivity.
Solution Approach 2:
The patent merges the oxidative esterification reaction with a distillation process in a coupled reactor-distillation system. The reaction and separation occur in an integrated configuration where the distillation column is directly connected to the reactor, allowing simultaneous reaction and water removal. This combination achieves both high productivity and controlled water concentration.
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 effectively reduces water concentration in subsequent reactors, enhancing the conversion and selectivity of the oxidative esterification reaction, making the process more efficient for commercial MMA production.
Implementation Method 1
introducing the crude product stream to a distillation column to generate a column overheads stream and a column bottoms stream
Data Source
AI summary
A process for continuously removing water in situ from an oxidative esterification reaction is provided. The process includes (a) conducting a first oxidative esterification reaction in a first reactor or reaction zone, wherein the total number of reactors or reaction zones is n and n is at least 2; (b) removing a crude product stream from the first reactor or reaction zone; (c) introducing the crude product stream to a distillation column to generate a column overheads stream and a column bottoms stream; (d) passing a portion of the columns bottoms stream to the product recovery zone; and (e) passing a portion of the column overheads stream to a subsequent reactor or reaction zone. Steps (a)-(e) can be repeated.