The effect of sulfur poisoning on methane oxidation over palladium supported on γ-alumina catalysts

Abstract

The effect of sulfur on deactivation of palladium catalysts for methane oxidation has been investigated in this research. A PdO deactivation mechanism due to sulfur is proposed over the 100–400°C range. H 2S induced catalyst poisoning of PdO/γ–Al 2O 3 is attributed to the formation of aluminum sulfate. Catalyst activity decreases with increasing H 2S deposition and increasing temperature from 100 to 400°C. TGA results show that PdO promotes the reaction of H 2S with γ-Al 2O 3. Surface sulfite and sulfate groups are observed by FT-IR on poisoned catalysts and are believed to be the cause of a 25% decrease in BET surface area. Activation energy for methane oxidation of H 2S poisoned catalyst decreases due to the formation of Al 2(SO 4) 3 which causes the reaction to change from surface reaction control to pore-diffusion control. H 2 treatment at 600°C removes much of the sulfite and sulfate from the surface of poisoned catalysts and regenerates most of the fresh catalyst activity.