Heterogeneous reactions of carbonyl sulfide on mineral oxides: mechanism and kinetics study

摘要

The heterogeneous reactions of carbonyl sulfide (OCS) onthe typical mineral oxides in the mineral dust particles were investigatedusing a Knudsen cell flow reactor and a diffuse reflectance UV-visspectroscopy. The reaction pathway for OCS on mineral dust was identifiedbased on the gaseous products and surface species. The hydrolysis of OCS andsucceeding oxidation of intermediate products readily took place on α-AlO, MgO, and CaO. Reversible and irreversible adsorptionof OCS were observed on α-FeO and ZnO, respectively, whereas noapparent uptake of OCS by SiO and TiO was observed. Thereactivity of OCS on these oxides depends on both the basicity of oxides andthe decomposition reactivity of oxides for HS. Based on the individualuptake coefficients and chemical composition of authentic mineral dust, theuptake coefficient (γ) of mineral dust was estimated to bein the range of 3.84×10–2.86×10. The globalflux of OCS due to heterogeneous reactions and adsorption on mineral dustwas estimated at 0.13–0.29 Tg yr, which is comparable to theannual flux of OCS for its reaction with ·OH.