Promotional Effects of Ti on a CeO2-MoO3 Catalyst for the Selective Catalytic Reduction of NOx with NH3.

In this study, Ti was doped to CeO2-MoO3 to promote the catalytic performance for the selective catalytic reduction of NOx with NH3 (NH3-SCR). The preparation method for CeMo0.5TiaOx (a = 0, 1, 2, 5, 10) catalysts was a stepwise precipitation method. When Ti was doped, all of the Ce-Mo-Ti catalysts exhibited remarkably improved NOx conversion and N2 selectivity than the CeMo0.5Ox without Ti. The CeMo0.5Ti5Ox with excellent activity in a broad temperature range was selected as an optimal catalyst to investigate the effects of Ti addition. The formation process analysis of the CeMo0.5Ti5Ox showed that, the Mo and Ti species first precipitated together from the mixed solution with the increase of pH, and then Ce species precipitated onto the Mo-Ti precipitates. The obtained catalyst exhibited remarkably facilitated NOx and NH3 adsorption, enhanced charge imbalance, promoted redox property, and improved surface acidity, which are all important reasons for the excellent catalytic performance of an NH3-SCR catalyst.