Tricyanohexane Purification via Low-Pressure Distillation
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Solution Overview
Problem
Conventional processes for producing cyanocarbons, such as adiponitrile, are inefficient in recovering residual tricyanohexane (TCH) due to decomposition at high temperatures, leading to impurities and reduced separation efficiency.
Innovation Solution
A process involving low-pressure distillation columns with high reboiler temperatures to separate adiponitrile and TCH streams, reducing decomposition and achieving high purity levels of TCH by controlling temperature and pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional high-temperature distillation is used to separate TCH from adiponitrile process streams, then separation efficiency is reduced and decomposition occurs, but this is the traditional approach that has been widely used
Solution Approach 1:
The patent changes the pressure parameter from conventional atmospheric pressure to vacuum pressure (low pressure). This parameter change allows distillation to occur at lower temperatures, preventing TCH decomposition while maintaining effective separation. The vacuum distillation condition is the key parameter modification that resolves the contradiction between separation efficiency and decomposition.
Solution Approach 2:
The patent performs preliminary removal of high-boiling components before the main distillation step. This preliminary action prevents these components from interfering with the TCH separation and reduces the risk of decomposition during the main distillation process, thereby improving overall separation efficiency and reliability.
2Productivity
If multiple distillation steps are used to purify TCH to high purity levels, then productivity increases, but process complexity increases
Solution Approach 1:
The patent segments the purification process into distinct functional units: a preliminary separation step for high-boiling components, followed by a vacuum distillation step for TCH purification. This segmentation allows each unit to be optimized for its specific function, achieving high purity and throughput while keeping individual units relatively simple.
Solution Approach 2:
The patent uses a significant parameter change (vacuum pressure) in the main distillation step that enables high purification efficiency in a single step. This dramatic parameter modification reduces the need for multiple sequential distillation columns, thereby maintaining productivity while reducing overall process complexity.
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
The process effectively recovers TCH with less than 10% impurities and reduces decomposition, enhancing separation efficiency and purity, overcoming the limitations of conventional methods.
Implementation Method 1
separating the first overhead lights stream in one or more distillation columns to form a second overhead lights stream comprising low-boiling components, a second bottoms heavies stream comprising high-boiling components, and a TCH stream comprising TCH and less than 10 wt. % impurities
Implementation Method 2
the distillation column is a low pressure distillation column. In some cases, the low pressure distillation column is operated under vacuum
Implementation Method 3
the reboiler is operated at a temperature greater than 250° C.
Data Source
AI summary
The present disclosure relates generally to processes for recovering tricyanohexane (TCH) via purification of by-product or co-product streams of adiponitrile production. In particular, the present disclosure relates to a process for purifying tricyanohexane (TCH), the process having the steps of (a) separating an adiponitrile process stream comprising adiponitrile and TCH to form a first overhead lights stream comprising low-boiling components and high-boiling components and a first bottoms heavies stream comprising high-boiling components and solid impurities; and (b) separating the first overhead lights stream in a distillation column to form a second overhead lights stream comprising low-boiling components, a second bottoms heavies stream comprising high-boiling components, and a TCH stream comprising TCH and less than 10 wt. % impurities; wherein the distillation column is a low pressure distillation column.