Mechanistic study on adsorptive removal of tert-butanethiol on Ag-Y zeolite under ambient conditions

摘要

The dynamics and surface chemistry of tert-butanethiol (TBT) adsorptive removal over silver-exchanged Y zeolite (Ag-Y) were studied under ambient conditions. Saturation uptake on Ag-Y was higher than that on H-Y and Na-Y. The structural analyses by a combination of X-ray diffraction, Ag K-edge X-ray absorption near-edge structure (XANES)/extended X-ray absorption fine structures (EXAFS), Ag L-III-edge XANES, S K-edge XANES, and in situ UV-vis show that the AgSH molecule, Ag2S monomer, and Ag4S2 cluster are the dominant silver species in TBT-saturated Ag-Y. Dynamic changes in adsorbed intermediates, gas-phase products, and the silver sulfides were followed by in situ FTIR, mass spectroscopy and in situ UV-vis, respectively. The results show the following reaction mechanism: (1) formation of iso-butene and adsorbed H2S on the Ag+ site via C-S cleavage of hydrogen-bonded TBT initially adsorbed on the Ag+ site; (2) conversion of the adsorbed H2S to AgSH and H+ on zeolite; (3) the reaction of two Ag-SH species to yield Ag2S and H+ on zeolite.