Catalytic effect on hydrogen sulphide generation from a tar sand

A sample of solvent-extracted sand from the Cerro Negro tar-sand deposit was found to have catalytic activity in the gas-phase desulphurization of tert.-butanethiol. The activity of the sand was compared with those of silica and silica-alumina standards. Pretreatment effect on the thiol conversion were attributed to hydrocarbons remaining on the surface after solvent extraction. The activity was related to ammonia adsorption and increased on introducing water vapour with the feed. A carbonium-ion mechanism for the surface reaction is proposed. It is suggested that underground generation of hydrogen sulphide during steam injection could be catalytically assisted if thiols are formed prior to hydrogen sulphide formation from the complex sulphur compounds in the tar.