Effects of calcination temperature on Mn species and catalytic activities of Mn/ZSM-5 catalyst for selective catalytic reduction of NO with ammonia

A series of Mn/ZSM-5 catalysts for the selective catalytic reduction of NO with NH3 was prepared by precipitation method at different calcination temperature. X-ray diffraction, X-ray photoelectron spectroscopy, H2 temperature-programmed reduction and N2 adsorption/desorption technologies were conducted to explore the effects of calcination temperature on the physical and chemical properties of Mn/ZSM-5 catalysts. Results suggested that when calcined at lower temperatures (<500 C) MnO), existed in the form of Mn304 and amorphous Mn02 on the catalyst surface. However, when calcined at 600 C Mn203 species which is unfavorable for the SCR process were formed and became the major phase at 700 C. On the other hand, with the increase of calcination temperatures, the surface Mn concentration and the specific surface area of catalysts both decreased. The catalytic activity test indicated that the Mn/ZSM-5 catalyst calcined at 300 C demonstrated the best performance for NO removal, with almost 100% NO conversion in the range of 150-390 C. According to the characterization results, the enrichment of surface Mn, surface Mn304 and amorphous Mn02 species may account for its superior catalytic activity. C) 2014 Elsevier B.V. All rights reserved.