Study On Purification Of Carbon Tetrachloride(CTC) Containing 4-chlorobutyronitrile By Adsorption Method

The raw materials of carbon tetrachloride,the total amount of 35 thousands tons per year,were produced by Ninghua company,which contain about 1-3% of 4-chlorobutyronitrile impurity.In the existing industrial chain layout of the company,the by-product of carbon tetrachloride in the methane chloride device must be converted into ethylene tetrachloride,resulting in the content of the trichlorolacrylonitrile is about 0.5-1% in the product.In the presence of trichlorolacrylonitrile have an important influence in the Cr2O3 catalysts of the production device of refrigerant HCF125.When the content of more than15 ppm can cause catalyst irreversible poisoning.The separation of 4-chlorobutyronitrile impurities from raw material of carbon tetrachloride is easier than the removal of trichlorolacrylonitrile impurities from ethylene tetrachloride,therefore researching and developing an efficient and environment-friendly 4-chlorobutyronitrile removal technology has great social and economic benefits.Comparing with the now available 4-chlorobutyronitrile removal technology,this paper emphasized on removing 4-chlorobutyronitrile from the raw materials of carbon tetrachloride by adsorption method.Adsorbents with high selectivity adsorption and high adsorption capacity of 4-chlorobutyronitrile have been selected through investigating the adsorption performances of different types adsorbents,and the adsorption process was also optimized.The zeolite 8# adsorbent was a best one of 4-chlorobutyronitrile removal.The content of 4-chlorobutyronitrile can't be detected after adsorbed by zeolite 8# adsorbent on temperature 60?and 90?,respectively,and the purity of main product carbon tetrachloride has been enhanced obviously.With the enhancement of temperature and space velocity of carbon tetrachloride,the adsorption effect of zeolite 8# adsorbent was weaken.The best regeneration performance of zeolite 8# adsorbent was presented when the second stage regeneration temperature between 260?and 280? during the regeneration process.In addition,the regeneration performance of air is better than that of nitrogen.No matter how many times the adsorption and desorption of zeolite 8# adsorbents were carried out,the original good adsorption performance could be basically recovered.After 50 times cumulative experiments,504 grams of raw material of carbon tetrachloride were purified and 8.62 grams of 4-chlorobutyronitrile impurities were removed.In a word,zeolite 8# adsorbent has a good effect on adsorption of 4-chlorobutyronitrile impurities,can be repeatedly reused in the industry.