Effect of K and Ca on catalytic activity of Mn-CeO_x/Ti-PILC

Abstract

Mn-CeO_x/Ti-pillared clay (PILC) is an attractive catalyst for selective catalytic reduction of NO_x at low temperature because of its low cost. The poisoning of K and Ca on the catalyst of Mn-CeO_x/Ti-PILC is an important problem because K and Ca are always in presence in flue gas. To investigate the effect of K and Ca on the physicochemical characters of the catalysts, the techniques of NH₃-temperature programmed desorption (TPD), H₂-temperature programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS) were used to analyze the fresh and deactivated catalysts of Mn-CeO_x/Ti-PILC. (Ca)Mn-CeO_x/Ti-PILC and (K)Mn-CeO_x/Ti-PILC are denoted for the dopes of the catalyst of Mn-CeO_x/Ti-PILC with Ca and K, respectively. The activities of Mn-CeO_x/Ti-PILC, (Ca)Mn-CeO_x/Ti-PILC and (K)Mn-CeO_x/Ti-PILC for NH₃-selective catalytic reduction (SCR) reaction at low temperature were investigated. The results showed that with the dopes of K and Ca on the catalysts, the SCR activities of the catalysts decreased greatly, and K exhibited more poisoning effect than Ca. With the dopes of K and Ca, the acidity, the redox property and chemisorbed oxygen on the surfaces of the catalysts were decreased, which resulted in a decreasing in SCR activity.

Keywords

Mn-CeO_x/Ti-pillared clay (PILC) / low-temperature selective catalytic reduction (SCR) / K and Ca poisoning effect

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