Effect of Molybdenum on the Behavior of Sulfated and Non-sulfated Titanium Pillared Clay in the Selective Catalytic Reduction of NO by Ammonia

Abstract

New mixed sulfated and non-sulfated molybdenum titanium pillared clay, from two starting clays, were prepared with various molybdenum amounts and different sulfate concentrations. The mixed pillared clays were characterized by chemical analysis, X-ray Diffraction, N2-physisorption and NH3-temperature programmed desorption. Subsequently, they were tested as catalysts for the selective catalytic reduction of nitrogen oxide (SCR-NO) by ammonia. The samples are microporous and their properties are dependent of the molybdenum and sulfate contents. Bronsted and Lewis acid sites exist on the catalyst surface and their number depends on the molybdenum amount retained by the clay as well as the sulfate concentration. Catalytic results in the SCR-NO by ammonia are discussed in terms of the physicochemical properties of the solids. At higher temperatures, the best molybdenum-titanium-pillared clay showed superior catalytic performance than a commercial catalyst. The best catalyst exhibited a favorable SCR performance above 400 °C and had a large operating temperature window (400–550 °C).