Chemisorption of hydrogen sulfide on nickel and ruthenium catalysts: I. Desorption isotherms

Abstract

Desorption isotherms for H 2S on unsupported nickel and alumina-supported nickel, nickel-platinum, nickel-cobalt, and ruthenium were calculated from elution curves of H 2S from a packed bed of each catalyst. All elution experiments were run initially at 450 °C and at H 2S concentrations in the exiting hydrogen stream from 30 to 0.1 ppm. Elution curves and isotherms for supported nickel-platinum were also obtained at 450 and 520 °C from which an estimate of the heat of H 2S chemisorption was calculated. The heat of H 2S adsorption on nickel is estimated to be 30–40 kcal/mole at 450 °C and high coverage (50–90%). The stoichiometry of sulfur adsorption was determined by comparing the total quantity of sulfur adsorbed at 450 °C with the corresponding quantity of hydrogen chemisorbed at 25 °C for each catalyst. The data suggest that H 2S chemisorption is strong and dissociative at low coverage and nondissociative at high coverages. Ruthenium apparently has a lower capacity for sulfur adsorption than nickel or nickel alloys.