Reactive Distillation for Dialkyl Carbonate and Diol Production
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Solution Overview
Problem
Existing processes for producing dialkyl carbonate and diol from cyclic carbonate and aliphatic monohydric alcohol fail to achieve high cyclic carbonate conversion, selectivity, and high-purity diol with high UV transmittance and low aldehyde content without complicating the process, such as by feeding water into a diol distillation purification step.
Innovation Solution
A continuous process using a tray column type multi-stage distillation column where cyclic carbonate and aliphatic monohydric alcohol are fed and reacted in the presence of a catalyst, with specific residence times and temperatures in the tray and column bottom portions, satisfying the condition 780 ≤ α + 1.24 × β ≤ 5150, where α and β represent temperature and residence time factors, to optimize reaction conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a completely batch reaction system or continuous flow reaction system is used, then the process is simple to operate, but the cyclic carbonate conversion is low due to equilibrium limitations
Solution Approach 1:
The patent combines the reaction system and distillation system into an integrated reactive distillation process. The reaction vessel is equipped with a distillation column that continuously removes products from the reaction zone, merging two separate unit operations into one unified system that overcomes equilibrium limitations while maintaining operational simplicity.
Solution Approach 2:
The patent implements continuous removal of reaction products through distillation during the reaction process. This continuous action prevents the reaction from reaching equilibrium by constantly removing products, thereby maintaining high conversion rates throughout the reaction period rather than allowing the reaction to stall at equilibrium conversion levels.
2Manufacturing precision
If a batch reaction system with distillation column is used to increase cyclic carbonate conversion, then the conversion improves, but the process complexity increases
Solution Approach 1:
The patent merges the reaction vessel and distillation column into a single integrated reactive distillation system. This combination eliminates the need for separate reaction and distillation units, reducing overall process complexity while maintaining high conversion capabilities through continuous product removal during reaction.
Solution Approach 2:
The integrated system performs multiple functions simultaneously: it conducts the transesterification reaction, removes water through distillation, separates products, and maintains reaction equilibrium all within one unified apparatus. This multi-functionality reduces the number of separate units needed and simplifies the overall process flow.
3Ease of manufacture
If traditional reaction systems are used, then the process is straightforward, but the diol purity and UV transmittance are insufficient
Solution Approach 1:
The patent performs preliminary separation and purification of the diol product through the integrated distillation system during the reaction process itself. By removing water and other impurities continuously during reaction, the system prepares the product in advance for final isolation, ensuring high purity and UV transmittance without requiring complex post-reaction treatment steps.
4Manufacturing precision
If water is fed into diol distillation purification step to improve UV transmittance, then the diol quality improves, but the process becomes complicated
Solution Approach 1:
The integrated reactive distillation system performs self-purification by continuously removing water and impurities during the reaction process itself. The system serves its own purification needs through the built-in distillation capability, eliminating the need for separate water-fed purification steps and maintaining process simplicity while achieving high diol quality.
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 simultaneously achieves high cyclic carbonate conversion, high selectivity for dialkyl carbonate and diol, and high-purity diol with high UV transmittance and low aldehyde content without the need for complicated purification steps, ensuring efficient and stable production.
Implementation Method 1
continuously withdrawing a low boiling point component containing a produced dialkyl carbonate from an upper portion of the distillation column, and continuously withdrawing a high boiling point component containing a produced diol from a lower portion of the distillation column
Implementation Method 2
bringing the starting materials into contact with a catalyst present in the distillation column so as to bring about reaction
Data Source
Figure 1
AI summary
It is an object of the present invention to provide, for a case of producing a dialkyl carbonate and a diol from a cyclic carbonate and an aliphatic monohydric alcohol, a process that simultaneously satisfies the cyclic carbonate conversion being high, the selectivities for the dialkyl carbonate and diol to be produced being high, and a high-purity diol having a high UV transmittance and a low aldehyde content being obtained without carrying out complicated treatment such as feeding water into a diol distillation purification step. The present invention discloses a process for the production of the dialkyl carbonate and the diol in which, when producing the dialkyl carbonate and the diol by reacting the cyclic carbonate and the aliphatic monohydric alcohol together in the presence of a catalyst in a transesterification reactor comprising a tray type continuous multi-stage distillation column, reaction conditions (residence times, temperatures) in the distillation column are controlled to be specific conditions.