Kinetics and mechanism of phase transfer catalyzed synthesis of aromatic thioethers by H2S-rich methyldiethanolamine

Hydrogen sulphide (H2S) removal and its efficient utilization is a big challenge for many petroleum refinery industries now-a-days. The present investigation involves absorption of H2S in aqueous methyldiethanolamine (MDEA) followed by sulphidation of benzyl chloride (BC) by H2S-rich MDEA to yield dibenzyl sulphide (DBS) selectively using tetrabutylphosphonium bromide (TBPB) as a phase transfer catalyst. Ninety per cent selectivity of DBS was obtained at some level of process condition. A suitable mechanism has been proposed. An empirical kinetic model was also developed and correlated with experimental data. The present work has a potential to be used as an alternative to Claus process.