Pervaporation Membrane Module for Dimethyl Carbonate Purification
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Solution Overview
Problem
Current methods for separating dimethyl carbonate from its azeotrope with methanol, such as pressure swing distillation, result in high energy consumption and costs due to the formation of an azeotrope, which complicates efficient separation and requires additional distillation processes, leading to low recovery rates and high investment costs.
Innovation Solution
A method and apparatus utilizing pervaporation, where a pervaporation membrane module is integrated between an atmospheric and a high-pressure distillation column to selectively separate methanol from dimethyl carbonate, employing membranes like silica, organic-inorganic hybrid silica, or polymeric membranes to enhance separation efficiency and reduce energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If extractive distillation method is used to separate dimethyl carbonate from methanol azeotrope, then separation effectiveness is improved, but additional distillation process is required resulting in low recovery rate and high energy consumption
Solution Approach 1:
The patent introduces an extractive distillation agent (acetonitrile) as an intermediary substance that modifies the relative volatility between dimethyl carbonate and methanol, enabling effective separation. The agent forms a ternary azeotrope with methanol and water, allowing dimethyl carbonate to be separated at atmospheric pressure while the agent can be recovered and recycled, thus improving separation effectiveness without excessive energy consumption
Solution Approach 2:
The patent changes the volatility parameters of the mixture by introducing the extractive distillation agent, which alters the relative volatility relationship between components. This parameter change enables separation at atmospheric pressure rather than requiring high-pressure operations, reducing energy consumption while maintaining separation effectiveness
2Manufacturing precision
If pressure swing distillation method is used to separate dimethyl carbonate from methanol azeotrope, then separation is achieved, but operating costs increase due to high-pressure operations and large recycle streams
Solution Approach 1:
The patent changes the separation mechanism from pressure-based to composition-based by introducing the extractive distillation agent. This allows atmospheric pressure operation instead of high-pressure operations, significantly reducing equipment size, operating costs, and energy consumption while maintaining effective separation
Solution Approach 2:
The extractive distillation agent acts as a mediator that enables separation at atmospheric pressure by modifying the azeotropic behavior of the dimethyl carbonate-methanol system. The agent creates a new separation pathway that avoids high-pressure operations and large recycle streams, reducing operating costs
3Manufacturing precision
If multiple distillation columns are used in extractive distillation process, then separation effectiveness is improved, but investment costs increase due to application of multiple columns
Solution Approach 1:
The extractive distillation agent serves multiple functions: it modifies relative volatility for separation, forms a removable azeotrope with methanol and water, and can be easily recovered and recycled. This multi-functionality allows effective separation with a single distillation column rather than multiple columns, reducing investment costs while maintaining separation effectiveness
Solution Approach 2:
The extractive distillation agent is designed to be easily recovered from the bottom product through simple distillation and recycled back to the process. This recovery and reuse mechanism eliminates the need for multiple columns and associated high investment costs, while maintaining continuous effective separation
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 significantly reduces heat consumption and process costs by effectively separating dimethyl carbonate to high purity (>99.9%) while minimizing equipment size and operational expenses compared to traditional pressure swing distillation methods.
Implementation Method 1
a pervaporation membrane module disposed between the atmospheric distillation column and the high pressure distillation column and allowing for permeation of the methanol to separate the methanol from the mixture
Data Source
Figure 1~2
AI summary
An apparatus for separating dimethyl carbonate using pervaporation includes: an atmospheric distillation column and a high pressure distillation column distilling a mixture containing dimethyl carbonate and methanol and separating dimethyl carbonate from the mixture; and a pervaporation membrane module disposed between the atmospheric distillation column and the high pressure distillation column and allowing for permeation of the methanol to separate the methanol from the mixture, thereby reducing heat consumption and a process cost as compared to the case of only using an existing pressure swing distillation method.