In Situ Water Removal in Oxidative Esterification via Distillation
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Solution Overview
Problem
The existing methods for producing methyl methacrylate (MMA) through oxidative esterification face challenges due to water interference with the Pd-containing catalyst, reducing conversion and selectivity, and continuous water removal using membranes is not practical for commercial scale due to low separation fluxes and high membrane areas.
Innovation Solution
A process involving oxidative esterification in a reactor with continuous in situ water removal using a distillation column to generate a recycle stream with less than 1 wt% water, which is recycled back to the reactor, maintaining the water content at or below 2.5 wt% in the reactor, thereby optimizing conversion and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If membranes are used to continuously remove water from the reaction system, then water removal is achieved, but the separation flux is low and extremely high membrane areas are required
Solution Approach 1:
The invention changes the operating parameters of the distillation column, specifically operating at atmospheric pressure and with a reflux ratio of 0.5 or less, to enable efficient water removal. This parameter optimization allows the system to achieve high water removal efficiency without requiring excessive energy input or complex equipment, resolving the contradiction between water removal effectiveness and productivity
Solution Approach 2:
The invention utilizes phase transition of water from liquid to vapor through distillation to remove water from the reaction system. By condensing the vapor phase and separating the liquid phase, water is continuously removed from the oxidative esterification reaction, achieving high water removal flux without requiring large membrane areas
2Reliability
If water is removed from the oxidative esterification reaction, then conversion and selectivity are improved, but additional equipment and process complexity are introduced
Solution Approach 1:
The invention merges the water removal function with the existing product recovery process by using a distillation column that serves dual purposes: removing water from the reaction system and recovering the MMA product. This integration achieves improved conversion and selectivity without proportionally increasing process complexity, as the same equipment performs multiple functions
Solution Approach 2:
The distillation column operates with a reflux ratio of 0.5 or less, allowing the system to self-regulate water removal while maintaining product recovery. The process uses its own vapor-liquid equilibrium characteristics to achieve water separation without requiring additional energy-intensive equipment or complex control systems
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 the reactor, enhancing the conversion and selectivity of the oxidative esterification reaction, making it suitable for commercial production of MMA.
Implementation Method 1
introducing a second portion of the crude product stream to a distillation column to generate a column overheads stream and a column bottoms stream
Implementation Method 2
the MAL is reacted with molecular oxygen in an alcohol (such as methanol) typically in the presence of a Pd-containing catalyst
Data Source
Figure 1
AI summary
A process for removing water from an oxidative esterification reactor includes (a) conducting an oxidative esterification reaction in a reactor; (b) removing a crude product stream from the reactor; (c) passing a first portion of the crude product stream directly to a product recovery zone; (d) introducing a second portion of the crude product stream to a distillation column to generate a column overheads stream and a column bottoms stream; (e) passing at least a portion of the columns bottoms stream to the product recovery zone; and (f) recycling a recycle stream comprising at least a portion of the overheads stream to the reactor; wherein the recycle stream contains less than 1 weight percent (wt%) water based on the total weight of the recycle stream, wherein the weight ratio of the first portion to the second portion is at least 1 : 10, and wherein the amount of the recycle stream recycled to the reactor is such that the reactor contains less than or equal to 2.5 wt% water, based on the weight of the reactor contents.