Help! ! Regarding the removal of trace water from dichloromethane
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There is a process for the dehydration of chloromethane. At present, we use a low-temperature dehydration method, but the main problem with this approach is that the moisture content remains relatively high; it is currently between 0.05% and 0.1%. We would like to reduce this level to below 0.03%, as moisture has a significant impact on subsequent processes – the lower the moisture content, the better. Do any of the experts have any good suggestions?
How should it be handled now? Does dichloromethane also have an azeotrope with water?
Calcium oxide can be used to remove water; molecular sieves have also been used for this purpose in the laboratory, and they work as well
Small-scale experiments are feasible, but large-scale production is not possible. Calcium chloride involves the handling of hazardous waste, and Eaton’s price of five to six thousand dollars is too high; molecular sieves require regeneration, otherwise they too cannot be used due to the associated hazardous waste issues
1. Dehydration using molecular sieves – all water can be removed by molecular sieves. Below 300 ppm. The molecular sieve is placed in a container, and the solvent flows through it; once the molecular sieve becomes ineffective, the solvent is released along with the molecular sieve. Rinse the molecular sieve with water, and use a sieve with large pore size to remove any broken particles of the molecular sieve. The washed molecular sieve is dried in a food-grade oven at 300 degrees for 24 hours; after cooling, it can be used again. That’s exactly what we do. 2. Dry it with phosphorus pentoxide; if your post-treatment process can be acidic, phosphorus pentoxide can be used. For one of our products, dichloromethane is employed, and moisture levels need to be controlled as well. After the raw materials are dissolved in dichloromethane, phosphorus pentoxide is added to carry out drying and dehumidification, so that the moisture content remains below 300 ppm. Take it, no thanks. Haha
Will the metaphosphoric or phosphoric acid formed by the reaction of water in dichloromethane with phosphorus pentoxide, which is present in the process medium, accelerate equipment corrosion? How is this type of corrosion addressed? Will a graphite heat exchanger be chosen?