Desulfurization of hexyl sulfide and hexanethiol using supercritical water

Desulfurization of hexyl sulfide and hexanethiol using supercritical water (SCW) was investigated by combining experimental and computational methods to study the desulfurization of alkyl sulfides and thiols in SCW. Desulfurization was conducted for 0 ∼ 30 min at 400 °C using thermal decomposition and SCW decomposition (24.7 ∼ 25.6 MPa), and the reaction pathways were built using the automated Reaction Mechanism Generator (RMG) and Gaussian 09. In thermal decomposition, C6-hydrocarbons (hexane, hexene) are main products, but in SCW, C5-hydrocarbon (pentane) in addition to C6-hydrocarbons are main products with higher alkane to alkene ratio. For the reaction pathways, in SCW, water participates as catalysts and reactants donating hydrogens with inhibited production of cyclic sulfides while in thermal decomposition, the hydrogen was deficient producing aromatic sulfur compounds such as thiophenes and alkyl-thiacycloalkanes. This study is expected to clarify the decomposition reactions of alkyl sulfides and alkyl thiols in SCW.