Buffer Vessels Stabilize Halide Content in Cyclic Carbonate Distillation
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Solution Overview
Problem
The continuous process for preparing cyclic carbonate using a supported dimeric aluminium salen complex faces challenges with reactor overheating and difficulties in downstream distillation due to high halide compound content in the reactor effluent, leading to unstable operation and purity issues.
Innovation Solution
The process involves continuously reacting an epoxide compound with carbon dioxide in the presence of a supported dimeric aluminium salen complex activated by a halide compound, with the reaction occurring in a slurry reactor where the cyclic carbonate product is liquid, and using buffer vessels to stabilize the halide compound content before distillation, ensuring consistent operation and high-purity product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a slurry reactor with liquid cyclic carbonate is used to avoid overheating, then temperature control is improved, but halide compound accumulates in the reactor effluent causing distillation difficulties
Solution Approach 1:
A buffer vessel is introduced as an intermediary component between the reactor and distillation column. This buffer vessel temporarily stores the reactor effluent, allowing the halide compound concentration to be averaged over time. The buffer acts as a mediator that decouples the reactor operation from the distillation operation, enabling stable distillation even when the reactor periodically releases high concentrations of halide compound during catalyst reactivation cycles.
2Productivity
If the catalyst is reactivated by adding halide compound, then catalytic activity is restored, but halide compound content in effluent increases causing downstream processing issues
Solution Approach 1:
The buffer vessel provides beforehand cushioning by pre-storing effluent with varying halide compound concentrations before it reaches the distillation column. When catalyst reactivation causes a spike in halide compound content, the buffer vessel absorbs this shock, releasing a more consistent concentration to the distillation column. This prior cushioning prevents harmful fluctuations in halide compound content from reaching the downstream processing equipment.
3Productivity
If multiple reactors are used with regeneration cycles, then continuous production is maintained, but halide compound content varies significantly in the product stream
Solution Approach 1:
The buffer vessel merges the effluent streams from multiple reactors undergoing different regeneration cycles. By combining these streams and allowing them to mix in the buffer, the variations in halide compound content from individual reactors are averaged out. This merging approach maintains continuous production while stabilizing the composition of the combined stream entering the distillation column.
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 results in a more stable distillation process and achieves high-purity cyclic carbonate production by averaging halide compound content, allowing the same distillation equipment to be used across all cycle steps and maintaining desired product purity.
Implementation Method 1
reacting an epoxide compound with carbon dioxide in the presence of a supported dimeric aluminium salen complex which catalyst is activated by a halide compound
Implementation Method 2
the deactivated dimeric aluminium salen complex is reactivated by contacting the complex with a halide compound acting as an activating compound
Implementation Method 3
the liquid cyclic carbonate product acts as an efficient heat transfer medium which avoids overheating
Implementation Method 4
the cyclic carbonate product as present in the liquid cyclic carbonate product stream is separated from the halide compound in a distillation step wherein a purified cyclic carbonate product is obtained
Data Source
AI summary
The invention is directed to a process to continuously prepare a cyclic carbonate product by reacting an epoxide compound with carbon dioxide in the presence of a supported dimeric aluminium salen complex. The process is performed in a reactor comprising a slurry of the supported dimeric aluminium salen complex and liquid cyclic carbonate product. The produced cyclic carbonate is discharged from the reactor while the supported dimeric aluminium salen complex remains in the reactor. The liquid carbonate product is purified by means of distillation. Between the reactor and the distillation one or more buffer vessels are present having a volume of between 5 and 50 m3 per kmol of dimeric aluminium salen complex as present in the reactor.