Mechanism of adsorptive removal of tert-butanethiol under ambient conditions with silver nitrate supported on silica and silica-alumina

Vapor-phase adsorptive removal of tert-butanethiol (TBT) over silver nitrate supported on silica (AgSi) and silica-alumina (AgSiAl) is tested under ambient conditions. Saturation uptakes on AgSi and AgSiAl are close to that on Ag-exchanged Y zeolite, which was shown to have high sulfur capacity in the literature. The structural analyses by XRD, TEM, Ag K-edge XANES/EXAFS, and in situ UV-vis show that the reaction of Ag species on these samples with TBT yields AgSH species, Ag2S monomer, Ag4S2 cluster, and Ag2S particles. Dynamic changes in adsorbed intermediates and the silver sulfides were followed by in situ FTIR and in situ UV-vis, and the following reaction mechanism is presented: (1) reaction of Ag+ with TBT to produce butenes and AgSH species; (2) reaction of the two AgSH to produce Ag2S monomer and H2S; (3) aggregation of Ag2S monomer to (Ag2S), clusters and Ag2S particle.