Oxidative Deodorization of Sulfur Compounds with Platinum Catalysts by the Use of a Bench Scale Apparatus

Abstract

Deodorization of sulfur compounds by catalytic oxidation was carried out by the use of a bench scale apparatus. Studies on kinetics of the reaction and catalytic actvities were made with platinum catalysts supported on γ-alumina in three forms granular Pt-Al₂O₃, honeycombshaped Pt-Al₂O₃ and aluminum tubular. Pt-Al₂O₃, at 170-350°. Thiophene, dimethyl sulfide, diethyl sulfide, or hydrogen sulfide (10 ppm) was used as a sulfur compound of low concentration. For a granular catalyst and a honeycomb-shaped catalyst, rates of thiophene oxidation were of the zero-order with respect to the thiophene concentration above 10 ppm and slightly positive order below 10 ppm. Diethyl sulfide concentration dependence of its oxidation on a honeycombshaped catalyst was similar to that of thiophene oxidation, while the rate of dimethyl sulfide oxidation was of about 1/2-order with respect to the dimethyl sulfide concentration in the range 10-400 ppm. Rates of hydrogen sulfide oxidation on a honeycomb-shaped catalyst and a aluminum tubular catalyst were of the first-order with to the hydrogen sulfide concentration. There was some differece of apparent activation energy of each reaction in the kind of catalyst. However, when comparing apparent activation energies of oxidation of four sulfur compounds, apparent activation energies of dimethyl sulfide and hydrogen sulfide were lower by several kcal/mol than those of thiophene and diethyl sulfide for respective catalyst. For respective catalyst in three forms, the activities of four kinds of sulfur compounds (10ppm) at 200°C was in the following order: (C₂H₅)₂S>thiophene≥(CH₃)₂>H₂S. On the basis of the above results, it was found that the above method was practically effective for the oxidative deodorization of thiophene and diethyl sulfide, but it was difficult to obtain high conversion for the oxidative deodorization of dimethyl sulfide and hydrogen sulfide at relatively low concentration and low temperature near 200°C.