Catalytic reaction system for rapid selective oxidation of alkyl sulphide

• Published in: Journal of hazardous materials 2019-11, Vol.379, p.120830-120830, Article 120830
• Main Authors: Hong Le, Ngan, Han, Yo-han, Jung, Hyunsook, Cho, Joungmo
• Format: Article
• Language: English
• Subjects: Acid catalyst; Brønsted and Lewis sites; Rapid sulfoxidation; Recycling test
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2019.120830

[Display omitted] •Catalytic reaction system of tribromide/nitrate allows a rapid sulfoxidation of CEES.•Addition of acid significantly facilitate activity of catalytic loop and oxidation of CEES.•Brønsted acids keep a high amount of key precursors while Lewis acids consume them.•Amberlyst-15 exhibits the best catalytic performance for CEES sulfoxidation.•Heterogeneous catalyst can be applied to repeatedly oxidize CEES without regeneration. Highly efficient catalytic reaction systems are developed to rapidly and selectively oxidize 2-chloroethyl ethyl sulfide (CEES). In the systems, precursors containing bromide(s) and nitrate anions are chosen for the development of cyclic catalytic loop and the effect of acids on the selective oxidation of CEES are investigated by the addition of several homogeneous acid catalysts. The experimental results reveal that addition of acid results in a higher concentration of tribromide, which is reported as a key component for the observed activity in the catalytic solution. As a consequence, a dramatic improvement in catalytic activity is observed, especially when the molar amount of acid is controlled to be more than twice the initial concentration of tribromide. For the efficient design of a catalytic system, heterogeneous acid catalysts possessing different ratios of Brønsted to Lewis acid sites are also considered. Compared to reaction systems catalysed by homogeneous acids, similar reaction behaviour is observed for the reaction with Amerlyst-15, while those with other heterogeneous catalysts, containing Lewis or mixed acid sites in their structure, exhibits an adverse effect of selective sulfoxidation, mainly due to the adsorption of anions onto Lewis sites and consequential deconstruction of the catalytic loop.