Revealing of K and SO2 poisoning mechanism on CuCeOx catalyst for low-temperature CO oxidation

The application of CuCeOx catalysts for CO elimination in industrial sintering flue gases containing alkali metals is still a challenge. The effect mechanism of K species or/and SO2 poisoning on low temperature CO oxidation of CuCeOx catalyst was investigated. The results illustrated that the activity of CC-K2O catalyst was lower than that of CC-KCl catalyst, and the co-poisoning of K species and SO2 had more serious influence on CO conversion. The K species or/and SO2 poisoning resulted in the decrease of specific surface area and pore volume. In addition, K species or/and SO2 poisoning reduced the concentrations of Cu+, Ce3+ and chemisorbed oxygen species. Besides, K species or/and SO2 poisoning decreased the amount of oxygen vacancies and impaired the reducibility, which inhibited adsorption activation of oxygen and redox cycle. Furthermore, the CO oxidation on CC catalyst followed both MvK mechanism and L-H mechanism. The hydroxyl groups were involved in the reaction as an active oxygen species to generate active intermediate of bicarbonate which was easily decomposed. The KCl and K2O poisoning displayed fewer carbonyl and carbonate active intermediates, and the participation of hydroxyl groups in CO oxidation was inhibited. The co-existence of K species and SO2 further reduce the production of active intermediates, and the regeneration of hydroxyl was also blocked, thus resulting in lower activity.