Effects of thiophene and sulfur dioxide on CO adsorption on cobalt/silica catalysts

Abstract

FTIR spectra are reported showing the effects of thiophene on CO adsorption on Co ₃ O ₄ /SiO ₂ and Co/SiO ₂ catalysts and of SO ₂ on CO adsorption on Co/SiO ₂ . Six types of cobalt adsorption site were present on reduced Co/SiO ₂ and all could be poisoned by thiophene or SO ₂ at 295 K. SO ₂ was a stronger poison than thiophene and was more resistant than thiophene to desorption at elevated temperature. Chemisorption of SO ₂ poisoned low-coordination Co0 sites more readily than Co0 sites in low-index surface planes. Non-dissociative adsorption of thiophene blocked CO adsorption at 295 K but the thiophene was largely desorbed by evacuation at 473 K. Exposure of Co/SiO ₂ to thiophene at 373 K caused dissociative chemisorption and complete poisoning of all cobalt sites.