REMOVAL OF RESIDUAL ACIDITY FROM VINYL CHLORIDE MONOMER WITHOUT INCREASING MOISTURE CONTENT

Abstract

Production of Vinyl Chloride Monomer is associated with byproducts formation, one of them being Butadiene. Butadiene is a highly undesirable byproduct as it is a polymerization reaction inhibitor. It is removed by multistep process which includes acid wash, caustic wash, settling and drying. These steps add residual acidity to the final Vinyl Chloride Monomer product. Along with residual acidity, it adds extra moisture content as well. These components are also undesired, hence needs removal. In this project, an alternate route is proposed for the removal of butadiene, where the product stream containing butadiene is treated with hydrogen in the presence of Nickel (Ni) catalyst supported by activated Alumina. Alongside this major change, certain minor but important changes are made to the entire plant in order to minimize the formation of byproducts in the first place, and secondly, ensure energy economy. These changes include, the modification of catalyst in direct chlorination reactor from simple Ferric Chloride (FeCl3) to Ferric Chloride (FeCl3) modified by Sodium (Na). This enabled the operation of direct chlorination at higher temperature while maintaining selectivity. Operation at higher temperature makes it possible to recover heat, which can be used in distillation columns. Carbon Tetrachloride (CCl4) is introduced deliberately into cracking furnace, to increase the rate of reaction, conversion while maintaining selectivity. All these changes result in an energy efficient, environmentally friendly plant where the requirements of removal of residual acidity and ensuring minimum moisture content are met in an economical way.