Effect of postsynthesis preparation procedure on the state of copper in CuBEA zeolites and its catalytic properties in SCR of NO with NH3

Abstract

Copper-containing BEA zeolites, Cu2.0SiBEA and Cu2.0HAlBEA, with 2wt% of Cu were prepared by a two-step postsynthesis method and a conventional wet impregnation, respectively. These zeolites were characterized by XRD, DR UV–vis, EPR, FTIR and TPR physicochemical techniques. The incorporation of Cu into framework of SiBEA was evidenced by XRD. The state of copper in both zeolites was investigated by DR UV–vis and EPR. The acidity of Cu2.0SiBEA and Cu2.0HAlBEA was determined by FTIR of adsorbed CO and pyridine. The reducibility of the Cu species present in both zeolites was studied by TPR and their catalytic properties were investigated in selective catalytic reduction of NO with NH3. Both Cu2.0SiBEA and Cu2.0HAlBEA zeolite catalysts showed very high activity in this reaction with the NO conversion higher than 80% and N2 selectivity higher than 95% in the temperature range between 473 and 623K. The higher NO conversion and N2 selectivity in SCR of NO with ammonia at the high temperature range for the Cu2.0HAlBEA than for Cu2.0SiBEA suggest that the strong Brønsted and Lewis acidic sites related to the framework and extra-framework aluminum atoms play an important role in SCR of NO process.