Diaryl Carbonate Production via Reactive Distillation
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Solution Overview
Problem
Current methods for producing diaryl carbonate, such as diphenyl carbonate, are inefficient due to high energy consumption and require multiple distillation columns, leading to increased costs and unwanted by-products, which complicate the production process and waste management.
Innovation Solution
A method and apparatus that utilize a reduced number of reactive distillation columns, incorporating a first and second reactive distillation column, rectification columns, and additional processing units like flash vessels and evaporators, to minimize by-products and enhance energy efficiency by optimizing temperature and pressure conditions, and recycling streams to produce purified diaryl carbonate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional multiple distillation columns are used for diaryl carbonate production, then product purity can be achieved, but energy consumption increases and device complexity increases
Solution Approach 1:
The patent combines reaction and distillation operations into a single reactive distillation column, where the transesterification reaction and separation occur simultaneously. This integration eliminates the need for separate reaction vessels and multiple distillation columns, reducing both energy consumption and device complexity while maintaining product purity through in-situ separation of products and reactants
Solution Approach 2:
The reactive distillation column performs multiple functions simultaneously: it serves as both a reaction vessel for the transesterification process and a separation unit for purifying the diaryl carbonate product. The column also facilitates product removal to drive reaction equilibrium, combining reaction, separation, and process control functions in a single unit operation
2Manufacturing precision
If traditional multiple distillation columns are used for diaryl carbonate production, then product purity can be achieved, but device complexity and investment costs increase
Solution Approach 1:
The patent combines reaction and distillation operations into a single reactive distillation column, where the transesterification reaction and separation occur simultaneously. This integration eliminates the need for separate reaction vessels and multiple distillation columns, reducing both energy consumption and device complexity while maintaining product purity through in-situ separation of products and reactants
Solution Approach 2:
The reactive distillation column is divided into distinct functional zones: a reaction zone where transesterification occurs, a separation zone where products and reactants are separated by volatility differences, and a reflux zone that controls product removal. This segmentation allows simultaneous reaction and separation while maintaining simple overall equipment configuration
3Productivity
If conventional reaction processes are used, then complete reaction can be achieved, but unwanted by-products increase
Solution Approach 1:
The patent continuously removes the desired diaryl carbonate product from the reaction zone through distillation as it forms. By extracting the product from the reaction mixture, the process prevents secondary reactions and by-product formation that would occur if the product remained in contact with reactants, while maintaining complete conversion through equilibrium displacement
Solution Approach 2:
The reactive distillation process rapidly removes the diaryl carbonate product from the reaction zone as soon as it forms, minimizing its residence time in the reaction environment. This rapid product removal prevents subsequent decomposition or side reactions, ensuring high selectivity and reducing by-product formation while maintaining reaction completeness
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 significantly reduces energy consumption and operating costs by minimizing the number of processing equipment needed, achieving higher yields of purified diaryl carbonate with reduced by-products, as demonstrated by specific examples showing energy savings of up to 19% compared to traditional methods.
Implementation Method 1
a first reactive distillation column (C21) to produce alkyl aryl carbonate and alkyl alcohol; recovering from the first reactive distillation column (C21) a first top stream (stream 5) comprising dialkyl carbonate and alkyl alcohol, a first bottom stream (stream 6) comprising alkyl aryl carbonate
Implementation Method 2
introducing the first side stream (stream 13) to a first rectification column (C81); recovering from the first rectification column (C81) a third bottom stream (stream 12) comprising alkyl aryl ether and a third top stream (stream 14) comprising dialkyl carbonate and alkyl alcohol
Implementation Method 3
introducing the second bottom stream (stream 15) to a flash vessel (V51); recovering from the flash vessel (V51) a fifth bottom stream (stream 10) comprising catalyst and diaryl carbonate, and a fifth top stream (stream 9) comprising diaryl carbonate, alkyl aryl carbonate and aromatic alcohol
Implementation Method 4
introducing the fifth bottom stream (stream 10) to an evaporator (C52); and recovering from the evaporator (C52) a sixth top stream (stream 11) comprising diaryl carbonate
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A method for production of diaryl carbonate comprising: (a) introducing reactants to a first reactive distillation column (C21); (b) recovering a first top stream (stream 5), a first bottom stream (stream 6), and a first side stream (stream 13); (c) introducing the first bottom stream (stream 6) into a second reactive distillation column (C32) without passing through another reactive distillation column; (c1) recovering from the second reactive distillation column (C32) a second bottom stream (stream 15), and a second top stream (stream 16); (d) introducing the first side stream (stream 13) to a first rectification column (C81); (d1) recovering from the first rectification column (C81) a third bottom stream (stream 12) and a third top stream (stream 14); (e) introducing the first top stream (stream 5) into a second rectification column (C41); and (e1) recovering from the second rectification column (C41) a fourth top stream (stream 7) and a fourth bottom stream (stream 8). The apparatus comprising a first reactive distillation column (C21), a second reactive distillation column (C32), a first rectification column (C81), a second rectification column (C41), and a plurality of lines for transporting reactant and product streams is also claimed.