Study on the mechanism of sulfur poisoning in toluene catalyzed by Co3O4/γ-Al2O3 sulfur tolerant catalyst containing spinel structure

In this paper, in-situ thermal decomposition of ammonium sulfate method was used to cause sulfur poisoning of Co3O4/γ-Al2O3 catalyst rapidly and quantitatively. The pore structure, valence state of active species, surface morphology and acidity of the catalyst before and after sulfur poisoning were characterized, and its influence on catalytic combustion of toluene was studied. The results showed the crystal shape of the catalyst changed little after sulfur poisoning. As sulfur poisoning gradually deepened, the formation of sulfate blocked the pores, the high-valence cobalt decreased, strong acid sites increased, and its catalytic activity for toluene combustion gradually decreased. Formation of cobalt sulfate was a main reason for the decline in catalyst activity. Spinel phase CoAl2O4 formed outside γ-Al2O3 framework can adsorb a large amount of sulfur species to form sulfate, protecting Co3O4 and delaying the deactivation of catalysts.