Co-producing Dimethyl Carbonate and Ethylene Glycol via Immobilized Catalyst
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Solution Overview
Problem
Existing processes for producing dimethyl carbonate and ethylene glycol face challenges such as high energy consumption, complex process flows, and the need for high-purity methanol recycling due to the separation of homogeneous catalysts and ethylene carbonate, which affects conversion rates.
Innovation Solution
A process utilizing a fixed bed reactor with an immobilized ionic liquid catalyst, coupled with a reactive rectification column and refining units, allows for efficient production by avoiding catalyst separation and reducing methanol purity requirements while maintaining high conversion rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a homogeneous catalyst is used to catalyze the production of ethylene carbonate from ethylene oxide and carbon dioxide, then the reaction can proceed efficiently, but the catalyst must be separated and recycled before entering alcoholysis reaction, resulting in complex process and high energy consumption
Solution Approach 1:
The patent combines the catalyst separation step with the alcoholysis reaction step by using the same catalyst for both ethylene carbonate production and subsequent alcoholysis. The catalyst that would normally need to be separated is instead directly transferred to the alcoholysis reactor, merging two previously separate operations into one continuous process flow, thereby simplifying the overall process while maintaining high reaction efficiency.
2Productivity
If a homogeneous catalyst is used to catalyze the production of ethylene carbonate, then the reaction can proceed efficiently, but higher vacuum degree and energy consumption are required when separating ethylene carbonate from the catalyst
Solution Approach 1:
The patent eliminates the energy-intensive separation step by merging the catalyst usage across both reaction stages. The catalyst is retained in the alcoholysis reactor where it continues to function, avoiding the need for vacuum separation operations that would otherwise be required to remove the homogeneous catalyst before alcoholysis, thereby significantly reducing energy consumption.
3Productivity
If the purity of the methanol fed back to the alcoholysis unit is increased to maintain high conversion rate, then the conversion rate of ethylene carbonate is maintained, but higher energy is consumed for the purification of methanol
Solution Approach 1:
The patent changes the operational parameters of the alcoholysis reaction, specifically the temperature and pressure conditions, to allow for effective reaction progression with lower purity methanol. By optimizing these parameters, the system achieves high conversion rates without requiring extensive methanol purification, thereby reducing the energy consumption associated with purification operations.
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 achieves a conversion rate of 99-99.9% ethylene oxide with reduced energy consumption and simplified process flow by using an immobilized ionic liquid catalyst and optimizing reaction conditions.
Implementation Method 1
the fixed bed reactor is filled with an immobilized ionic liquid catalyst; Carbon dioxide and ethylene oxide as raw materials are introduced into the fixed bed reactor so that the two are contacted and reacted to generate ethylene carbonate
Implementation Method 2
The ethylene carbonate is extracted from the bottom of the light-component removal tank, and mixed with an alcoholysis reaction catalyst, followed by reacting with methanol in a reactive rectification column to generate dimethyl carbonate and ethylene glycol
Implementation Method 3
During the ring opening with carbon dioxide for generating ethylene carbonate, a lot of heat is also released, thus the reaction heat needs to be removed in time during the reaction, in order to avoid the catalyst from being deactivated at high temperature
Data Source
Figure 1
AI summary
A system and a process for co-producing dimethyl carbonate and ethylene glycol. The system comprises an interconnected ethylene carbonate preparation unit and an ethylene carbonate alcoholysis unit. The ethylene carbonate preparation unit comprises a fixed bed reactor and a light-component stripping column connected to each other. The fixed bed reactor is filled with a supported ionic liquid catalyst. The process comprises the steps of: reacting carbon dioxide and ethylene oxide as raw materials in the fixed bed reactor to produce ethylene carbonate, purifying the ethylene carbonate and then mixing it with an alcoholysis reaction catalyst, and reacting the mixture with methanol in a reactive distillation tower, producing dimethyl carbonate and ethylene glycol. The process increases the conversion rate of ethylene oxide and avoids the need for a process of separating conventional homogeneous catalysts from ethylene carbonate, thereby reducing process energy consumption and simplifying process procedures.