Deodorization of Exhaust Gas in Kraft Pulping (Part 2)

Abstract

Adsorption capacities and absorption capacities for malodorous components were estimated at 20 and 29°C. Adsorption capacity of activated carbon for methyl merccaptan was larger than that for dimethyl sulfide. For the hydrogen sulfide, activated carbon acted not only as a adsorbent but also as a catalyst, and so adsorption capacity of activated carbon for hydrogen sulfide was larger than that for formers. When mixture of dimethyl sulfide and methyl mercaptan was adsorbed on activated carbon, the total adsorption capacity of activated carbon was medium capacity between those for individual components. Because real kraft pulp blow gas is mixture of methyl mercaptan, dimethyl sulfide and others, adsorption of activated carbon for one was the mixture adsorption, and the adsorption capacity was 30 to 40%. Absorption capacity of poly-vinyl chloride for dimethyl sulfide was moderately large, but dimethyl sulfide in air was absorbed partially by poly-vinyl chloride. Absorption reaction of ferric oxide for hydrogen sulfide makes water a reaction product, therefore exact measurement of absorption is difficult. It was found that under pyrolysis gas chromatograph of activated carbon, which adsorbed methyl mercaptan, methyl mercaptan decomposed into hydrogen sulfide at 570 to 790°C.