Fixed-Bed Reactor for Beta-Mercaptoethanol Synthesis
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Solution Overview
Problem
The existing methods for producing beta-mercaptoethanol (BME) via the conversion of ethylene oxide in continuous stirred-tank reactors are limited by low conversion efficiency and the formation of undesirable byproducts such as thiodiglycol and other heavy products.
Innovation Solution
A process involving a reactor with a fixed bed containing a solid catalyst comprising a heterogeneous ion exchange resin, where hydrogen sulfide and ethylene oxide are reacted in a mole ratio ranging from 9:1 to 20:1, allowing for the selective production of beta-mercaptoethanol with minimal byproduct formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a continuous stirred-tank reactor (CSTR) is used for the reaction of ethylene oxide with hydrogen sulfide, then the reaction can proceed continuously, but the conversion of ethylene oxide is limited and undesirable byproducts such as thiodiglycol are produced
Solution Approach 1:
The patent changes the fundamental reaction parameters by switching from a CSTR to a fixed-bed reactor configuration and using a solid base catalyst instead of traditional liquid or homogeneous catalysts. This parameter change enables both continuous operation and high conversion efficiency with improved selectivity for beta-mercaptoethanol while minimizing byproduct formation
Solution Approach 2:
The patent replaces the mechanical stirring system of a CSTR with a fixed-bed reactor system where the catalyst remains stationary and the reactants flow through it. This substitution eliminates the need for continuous stirring while achieving better conversion and selectivity through the fixed-bed configuration and solid catalyst interaction
2Quantity of substance
If excess hydrogen sulfide is used in the reaction, then the reaction can proceed, but conversion of ethylene oxide is limited and byproducts increase
Solution Approach 1:
The patent introduces a solid base catalyst as an intermediary that facilitates the reaction between ethylene oxide and hydrogen sulfide. This catalyst mediator enables the reaction to proceed efficiently with improved selectivity, allowing better conversion of ethylene oxide to beta-mercaptoethanol while reducing byproduct formation even in the presence of excess hydrogen sulfide
3Ease of manufacture
If traditional catalysts are used in the reaction, then the reaction can occur, but selectivity to beta-mercaptoethanol is low and heavy byproducts are formed
Solution Approach 1:
The patent employs composite solid base catalysts with specific surface properties and basic sites that are optimized for this reaction. These composite catalyst materials provide both the necessary catalytic activity for reaction feasibility and the selective properties needed to produce beta-mercaptoethanol with high selectivity while minimizing heavy byproduct formation
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 process achieves high selectivity and conversion of ethylene oxide to beta-mercaptoethanol, significantly reducing the production of undesirable byproducts and improving the overall efficiency of the reaction.
Implementation Method 1
reacting, in a reactor having a fixed bed containing a solid catalyst comprising a heterogeneous ion exchange resin, hydrogen sulfide and ethylene oxide in the presence of the solid catalyst to yield a reaction product comprising beta-mercaptoethanol
Data Source
Figure 1
AI summary
A process includes reacting, in a reactor having a fixed bed containing a solid catalyst which contains a heterogeneous ion exchange resin, hydrogen sulfide and ethylene oxide in the presence of the solid catalyst to yield a reaction product which contains beta-mercaptoethanol. A reactor system includes the reactor, an ethylene oxide stream, a hydrogen sulfide stream, a fixed bed containing the solid catalyst placed in the reactor, and an effluent stream containing the reaction product. During steady state operation of the reactor in the process and the reactor system, the hydrogen sulfide and the ethylene oxide are present in a mole ratio in a range of about 9:1 to about 20:1.