SULFUR EXCHANGE STUDIES ON A MO/AL2O3 CATALYST

A relatively simple technique was developed to assess catalyst sulfur exchange using nonradioactive hydrogen sulfide-34. Exchange of catalyst sulfur on a Mo/A12O3 catalyst with H2 34S was carried out at several temperatures. The extent of exchange was determined by a subsequent temperature-programmed oxidation, measuring the amounts of regular and heavy SO2 evolved. Exchange occurred very rapidly at each temperature studied. The extent of exchange increased with temperature up to a limiting value at the highest temperature investigated (530°C). The limiting value was ascribed to exchange of sulfur at edge sites of the MoS2 slabs. Smaller values of exchange at lower temperatures were attributed to different bonding strengths of the edge sulfur atoms. © 1994 Academic Press, Inc.