Epoxidation Reactor Iodide Purification Absorbent
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Solution Overview
Problem
The existing processes for producing alkylene carbonate and/or alkylene glycol from alkenes face challenges with iodide-containing impurities poisoning the epoxidation catalyst, leading to reduced selectivity and catalyst durability in the epoxidation process.
Innovation Solution
A process that involves contacting an epoxidation feed containing an alkene, oxygen, and epoxidation recycle gas with an epoxidation catalyst, followed by using a purification absorbent capable of reducing iodide-containing impurities in the recycle gas stream, either in separate vessels upstream from the epoxidation reactor or within a multi-tubular shell-and-tube heat exchanger, to improve catalyst performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an iodide-containing carboxylation catalyst is used in the alkylene oxide absorber, then the conversion of alkylene oxide to alkylene carbonate and/or alkylene glycol is enhanced, but iodide-containing impurities are generated that poison the epoxidation catalyst
Solution Approach 1:
The harmful iodide-containing impurities are extracted from the recycle gas stream using a purification absorbent positioned upstream from the epoxidation reactor. This removes the toxic substances before they can reach and poison the epoxidation catalyst, while allowing the beneficial carboxylation reaction to continue in the absorber.
Solution Approach 2:
A purification absorbent acts as an intermediary substance between the carboxylation catalyst and the epoxidation catalyst. This absorbent selectively captures iodide-containing impurities from the gas stream, preventing direct contact with the epoxidation catalyst while allowing other process components to pass through.
2Reliability
If the purification absorbent is positioned in separate vessels upstream from the epoxidation reactor, then the catalyst protection is effective, but the device complexity increases
Solution Approach 1:
The purification function is merged with the existing epoxidation reactor by positioning the purification absorbent within the reactor upstream from the reactor tubes. This integration eliminates the need for separate purification vessels, reducing device complexity while maintaining effective catalyst protection.
Solution Approach 2:
The epoxidation reactor is designed to serve multiple functions: it houses both the purification absorbent for iodide removal and the epoxidation catalyst for alkene conversion. This multi-functionality reduces the overall number of equipment pieces needed in the process.
3Device complexity
If the purification absorbent is positioned within the epoxidation reactor upstream from the reactor tubes, then the device complexity is reduced, but the space for catalyst and absorbent contact is limited
Solution Approach 1:
The reactor interior is segmented into distinct zones: a purification zone containing the absorbent upstream from the reactor tubes, and an epoxidation zone with the catalyst downstream. This spatial segmentation allows both functions to operate simultaneously without interfering with each other, maximizing the use of available reactor volume.
Solution Approach 2:
The purification absorbent is positioned in the gas phase space above the liquid level in the reactor, utilizing the vertical dimension. This allows the absorbent to contact the recycle gas stream as it passes through the reactor, effectively using three-dimensional space rather than just horizontal area.
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 enhances the selectivity, activity, and longevity of the epoxidation catalyst by reducing iodide-containing impurities, thereby improving the overall efficiency of the alkylene oxide conversion to alkylene carbonate and/or alkylene glycol.
Implementation Method 1
contacting at least a portion of the epoxidation recycle gas with a purification absorbent capable of reducing the quantity of iodide-containing impurities
Implementation Method 2
contacting an epoxidation feed comprising an alkene, oxygen, and an epoxidation recycle gas with an epoxidation catalyst in an epoxidation reactor
Implementation Method 3
contacting an epoxidation feed comprising an alkene, oxygen, and an epoxidation recycle gas with an epoxidation catalyst
Implementation Method 4
contacting the epoxidation reaction product with a lean absorbent in the presence of an iodide-containing carboxylation catalyst in an alkylene oxide absorber
Implementation Method 5
contacting the epoxidation reaction product with a lean absorbent in the presence of an iodide-containing carboxylation catalyst
Data Source
AI summary
The invention provides a reaction system for the production of an alkylene carbonate and/or an alkylene glycol comprising: an epoxidation zone containing an epoxidation catalyst located within an epoxidation reactor; a carboxylation zone containing an iodide-containing carboxylation catalyst located within an alkylene oxide absorber; and one or more purification zones containing a purification absorbent capable of reducing the quantity of iodide-containing impurities in a feed comprising a recycle gas, which purification zones are located upstream from the epoxidation zone; and a process for the production of an alkylene carbonate and/or an alkylene glycol.