Reaction Mechanism for the Oxidation of Aromatic Contaminants Present in Feed Gas to Claus Process

Claus process, consisting of a furnace and catalytic reactors, is used to recover sulfur from H2S found in raw natural gas and gases from refineries. H2S is accompanied by contaminants such as benzene, toluene, xylenes (collectively called BTX), other hydrocarbons, NH3, CO2, N2 and sulfur compounds. Among these, BTX have attracted several research activities as they form soot and sulfur-hydrocarbons in catalytic units that clog and deactivate the catalysts. This work focusses on BTX oxidation by SO2 as a potential solution that can be carried out in a BTX destruction unit placed between Claus furnace and catalytic units. To determine the extent of BTX destruction by SO2, reaction mechanisms are developed using density function theory. The rates of elementary reactions are evaluated using transition state theory. The pathways leading to the formation of CO and SO are obtained.