Reactive Ethylene Glycol Absorption for Higher MEG Selectivity
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Solution Overview
Problem
Existing processes for producing ethylene glycol from ethylene oxide suffer from low conversion rates, high byproduct formation, and poor selectivity for monoethylene glycol, necessitating improvements in reactive absorption technology.
Innovation Solution
A process involving a reactive absorber with vertically stacked trays, using a lean absorbent and catalysts that promote carboxylation and hydrolysis, optimizing conditions such as ethylene oxide and carbon dioxide concentrations, and temperatures to enhance ethylene oxide conversion to ethylene carbonate and ethylene glycol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ethylene oxide is reacted with water in a non-catalytic process, then the process is simple, but the selectivity to monoethylene glycol is poor and byproduct formation is high
Solution Approach 1:
The patent introduces catalytic reactions to change the chemical reaction parameters, thereby improving selectivity to monoethylene glycol while maintaining process feasibility. The catalysts promote specific reaction pathways that favor MEG formation over byproducts.
Solution Approach 2:
The patent uses carbon dioxide as an intermediary substance in the reactive absorption process. CO2 reacts with ethylene oxide to form ethylene carbonate, which then hydrolyzes to monoethylene glycol. This intermediary pathway significantly improves selectivity compared to direct hydrolysis.
2Device complexity
If conventional absorption processes are used, then equipment requirements are met, but ethylene oxide conversion is low and byproduct formation is high
Solution Approach 1:
The patent combines absorption and catalytic reaction functions into a single reactive absorption process. The lean absorbent stream performs both absorption of ethylene oxide and catalytic conversion to ethylene carbonate and MEG, eliminating the need for separate reaction equipment and improving overall conversion efficiency.
Solution Approach 2:
The lean absorbent stream serves multiple functions: it absorbs ethylene oxide from the gas phase, provides catalysts for carboxylation and hydrolysis reactions, and facilitates heat transfer. This multi-functionality improves productivity without increasing device complexity.
3Productivity
If catalysts are added to promote carboxylation and hydrolysis, then conversion of ethylene oxide improves, but process complexity increases
Solution Approach 1:
The catalysts are incorporated into the recirculating lean absorbent stream, which automatically distributes them throughout the absorption process. The system self-regulates catalyst concentration through the recirculation loop, improving conversion without requiring complex external catalyst management 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
Achieves higher conversion of ethylene oxide to ethylene carbonate and ethylene glycol with reduced byproduct formation and improved selectivity to monoethylene glycol, minimizing ethylene oxide leakage and optimizing downstream processes.
Implementation Method 1
allowing the gas composition to pass upwards through an absorption section of vertically stacked trays while a lean absorbent passes downwards through the absorption section
Implementation Method 2
in the presence of one or more catalysts that promote carboxylation and hydrolysis to produce a fat absorbent stream comprising ethylene glycol and ethylene carbonate
Implementation Method 3
in the presence of one or more catalysts that promote carboxylation and hydrolysis to produce a fat absorbent stream comprising ethylene glycol and ethylene carbonate
Data Source
AI summary
A process for the preparation of ethylene glycol comprising the steps of: a) supplying a first gas composition comprising ethylene oxide and carbon dioxide to an ethylene oxide absorber and allowing the gas composition to pass upwards through an absorption section; b) supplying a lean absorbent to the top of the absorption section and allowing the lean absorbent to pass downwards through the absorption section; c) intimately contacting the gas composition with lean absorbent on the trays in the absorption section in the presence of one or more catalysts to produce a fat absorbent stream comprising ethylene glycol and ethylene carbonate; d) withdrawing fat absorbent from the absorber; and e) withdrawing a second gas composition from the top of the absorber.