New insights into improved SO2&H2O resistance over MoCrCeOx catalyst by CTAB for medium-low temperatures NH3-SCR: Regulation of surface acid and oxygen species

Selective catalytic reduction (NH3-SCR) of NH3 is the most efficient NOx removal technology. Improving the SO2/ H2O resistance of SCR catalyst is of great importance for its industrial application. The Mo(0.3)-CrCeOx catalysts synthesized by the citric acid method exhibited excellent high concentration SO2 resistance but poor H2O tolerance. In this work, cetyltrimethylammonium bromide (CTAB) was used to improve SO2&H2O resistance over Mo(0.3)-CrCeOx catalyst at medium-low temperatures. The mechanism of CTAB modification and the discrepancy to citric acid (CA) method were investigated. The results indicated that the CTAB catalyst had a large specific surface area, and was conducive to forming a specific structural strength. The enhancement of surface acidity of CTAB is the reason for the further enhancement of SCR activity. The regulation of hydroxyl oxygen to promote the activation of Br & Oslash;nsted acid sites is the key factor to SO2&H2O resistance. In addition, the in-situ DRIFTS results revealed the different mechanisms of the two catalysts. This paper raised the deactivation reason of sol-gel catalyst caused by SO2&H2O and presented an effective modification strategy.