DCDPS Crystallization via Water Evaporation Cooling
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Solution Overview
Problem
Current processes for obtaining 4,4'-dichlorodiphenyl sulfone (DCDPS) face challenges in efficient separation from organic solvents, energy efficiency, and environmental sustainability, particularly when using carboxylic acids as solvents with high boiling points or poor solubility in water.
Innovation Solution
A process involving cooling the organic mixture with water to shift the saturation point by evaporating and condensing water, then recycling it into the mixture, or using a coolable surface to reduce the temperature, allowing for efficient crystallization of DCDPS while minimizing energy consumption and avoiding solvent evaporation at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the organic mixture is cooled by evaporating the carboxylic acid solvent to shift the saturation point, then crystallization of DCDPS can be achieved, but high energy consumption is required due to the high boiling point of carboxylic acids
Solution Approach 1:
Water is introduced as an intermediary substance to induce crystallization. By adding water to the carboxylic acid solution of DCDPS, the saturation point is shifted, causing DCDPS to crystallize out of the solution. This eliminates the need to evaporate the high-boiling carboxylic acid solvent, dramatically reducing energy consumption while achieving efficient crystallization.
2Manufacturing precision
If conventional cooling methods are used to crystallize DCDPS, then separation from organic solvent can be achieved, but solvent recycling is difficult and environmental sustainability is compromised
Solution Approach 1:
The process enables recovery and recycling of the carboxylic acid solvent. After DCDPS crystallizes upon water addition, the mother liquor containing the carboxylic acid can be separated and reused in subsequent crystallization cycles. This reduces waste and improves environmental sustainability while maintaining efficient separation of DCDPS from the solvent.
3Productivity
If high temperature evaporation is used to concentrate the organic mixture for crystallization, then DCDPS can be separated, but the color quality of DCDPS deteriorates
Solution Approach 1:
The method changes the concentration parameters by adding water instead of using thermal evaporation. By adjusting the water-to-organic-mixture ratio, the saturation point of DCDPS is shifted, causing crystallization at low temperatures. This preserves the color quality of DCDPS while achieving efficient separation, avoiding the degradation caused by high-temperature processing.
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 method achieves efficient separation of DCDPS with improved color quality and reduced energy consumption, even with carboxylic acids that have poor solubility in water, and allows for the recycling of solvents, enhancing environmental sustainability.
Implementation Method 1
reducing the pressure in the crystallization vessel to a pressure at which the water starts to evaporate
Implementation Method 2
cooling the liquid mixture obtained in (a1a) to a temperature below the saturation point of DCDPS by (i) reducing the pressure in the crystallization vessel to a pressure at which the water starts to evaporate
Implementation Method 3
condensing the evaporated water by cooling
Implementation Method 4
cooling the liquid mixture obtained in (a1a) to a temperature below the saturation point of DCDPS... to obtain a suspension comprising crystallized DCDPS
Implementation Method 5
bringing the organic mixture into contact with at least one coolable surface and thereby reducing the temperature in the organic mixture
Data Source
Figure 1
AI summary
The invention relates to a process for obtaining 4,4'-dichlorodiphenyl sulfone from an organic mixture comprising 4,4'-dichlorodiphenyl sulfone and a linear C6 to C10 carboxylic acid as organic solvent, comprising: (a) cooling the organic mixture by (a1a) mixing the organic mixture with water in a crystallization vessel to obtain a liquid mixture; (a1b) cooling the liquid mixture obtained in (a1a) to a temperature below the saturation point of 4,4'-dichlorodiphenyl sulfone by (i) reducing the pressure in the crystallization vessel to a pressure at which the water starts to evaporate, (ii) condensing the evaporated water by cooling, (iii) mixing the condensed water into the liquid mixture in the crystallization vessel, to obtain a suspension comprising crystallized 4,4'-dichlorodiphenyl sulfone; or by (a2) bringing the organic mixture into contact with at least one coolable surface and thereby reducing the temperature in the organic mixture with a cooling rate in the range from 5 to 50 K/h until a temperature in the range from 10 to 30°C is reached, wherein the organic mixture and the at least one coolable surface have a temperature difference which is kept during the whole cooling process in the range from 1 to 30 K to obtain a suspension comprising crystallized 4,4'-dichlorodiphenyl sulfone. (b) carrying out a solid-liquid-separation of the suspension obtained in (a1b) or in (a2) to obtain a residual moisture containing solid 4,4'-dichlorodiphenyl sulfone as product and mother liquor comprising the organic solvent and water.