Reactivity of titanosilicates-supported catalysts for the selective catalytic reduction of NO with NH_3

摘要

The zeolites with MEL structure were synthesized via the hydrothermal method and the zeolites-supported catalysts, such as Cu~(2+), Ga~(2+), Ge~(3+) and VO~(2+)/zeolites, wee prepared by the incipient wetness impregnation. The structures of the syunthesized zeolites were characterized by techniques of XRD, FT-IR, SIMS, ~(29)Si and (27)~Al MAS NMR. The selective catalytic reduction (SCR) if NO by ammonia was carried out with a glass reactor under a downstream flow. The synthesized TS-2 showed no significant DeNO_x activity, instead of catalyzing the ammonia oxidation at a high temperature. Furthermore, the catalytic activity of TS2 zeolite can be effectively modified and tuned up through incorporating second metal ion such sa Fe~(3+), Co~(3+), and Al~(3+), into the framework (i.e., [Fe, Ti]Zll, and [Al,Ti]Zll). Among the synthesized bimetallsoilicates, the [Fe,Ti]Zll ZEOLITE IS the most active catalyst for the SCR DENO_x with ammonia; the NO conversion and the N_2 yield reach around 80%. In addition, impregnating the metal ions on TS2 or bimetallosilicates is also a very effective way to improve the SCR DeNO_x activity. Ga~(3+)/[Fe40, Ti40]Zll are most active catalysts and show a potential for the practical applications.