Evaluation of platinum-honeycomb catalysts for the destructive oxidation of low concentrations of odorous compounds in air

Abstract

The destructive oxidation of malodorous compounds known to occur in process emissions was investigated using commercial catalysts containing platinum, supported on alumina, carried by a ceramic honeycomb (“platinum-honeycomb” catalysts). Initially parameters relevant to catalyst evaluation were examined: temperature, space-velocity (SV), honeycomb cell size and odorant inlet concentration in the range 10–100 vpm. The catalytic oxidation of single odorant compounds (100 vpm in air), viz. acrolein, n- butanal , n- propylamine , toluene, n- butyric acid, 1,1,1-trichloroethane and dimethyl sulphide, was measured in terms of removal and total oxidation to CO 2 as a function of temperature. The performance of Pt-honeycomb catalysts for destructive oxidation was compared with published data for Co 3O 4 granular catalysts measured under identical reaction conditions. When single sulphur compounds (100 vpm dimethyl sulphide, methyl mercaptan, carbonyl sulphide or hydrogen sulphide in air) were oxidised over Pt-honeycomb catalysts (SV ~ 25,000h −1), sulphur dioxide formation exhibited complex behaviour, and separate observations of SO 2 oxidation were also made. In mixtures of odorants, n- butanal oxidation was inhibited by the presence of 100 vpm methyl mercaptan, H 2S or COS, (the temperature for 80% butanal oxidation was increased by 50–100° C) whereas SO 2 had little effect. The inhibiting effect of H 2S in the range 0–140 vpm was determined.