SO2-tolerant NOx reduction over ceria-based catalysts: Shielding effects of hollandite Mn-Ti oxides

Abstract

Ceria-based catalysts are well-established alternative to commercial V-based catalysts for NOx removal via selective catalytic reduction (SCR). However, their poor SO2 tolerance prevents their practical application to NOx removal from SO2-containing flue gas. It is desirable and challenging to develop a catalytic system in which the Ce-based catalyst is protected from SO2 inactivation (especially below 300 °C, because it is difficult to decompose the sulfate product at low temperatures). In this work, we unraveled the shielding effects of hollandite Mn-Ti oxides (HMT) from SO2 poisoning, and demonstrated that HMT modified CeW (HMT/CeW) catalysts showed excellent catalytic activity and admirable SO2-tolerance at 270 °C. Interestingly, HMT inhibited the formation of sulfate and facilitated the decomposition of sulfates, thereby enabling the high reactivity of the HMT/CeW catalysts in the presence of SO2. This work provides an innovative pathway for the protection of Ce-based catalysts from SO2 poisoning and is beneficial for both academic and practical applications.