Research Progress of Low-Temperature SCR DeNOx Catalysts

Abstract

Low-temperature SCR DeNOx process is considered to be a potential technique to meet the stringent environment regulations. It can avoid the problem such as blocking and eroding often generated in medium temperature, polluting and poisoning caused by alkali elements and so on. In this paper, a review of DeNOx catalysts about noble metals, molecular sieve, carbon-based and metal oxides catalyst was presented. The affecting factors of the low-temperature activation were comprehensively expounded, such as precursor introduction method, preparation method, supporter pretreatment and catalyst structure. Then mechanism of SO2 poisoning and effect of active compositions were analyzed. The dual effect of SO2 on the activity of low temperature catalysts mainly results from the formation of certain sulfur-containing species on catalyst surface. Water vapor decreased the number of available active sites attributed to competitive adsorption among H2O and other reactants. Moreover, the co-existence of H2O and SO2 resulted in the decrease of activity obviously. So the way to improve resistance of SO2 and H2O poisoning was summed up. Finally, future research and development directions in the developing low-temperature SCR for removal of NOx technology were proposed.