Assembling copper and cerium into TNU-9-type periodic microporous organosilicas for the selective catalytic reduction of NOx by NH3

Abstract

TNU-9-type periodic microporous organosilicas material containing Ce and Cu was assembled by organic-inorganic hybrid method and then calcined to acquire CuCex@PMO-TNU-9 catalyst. The effect of cerium on the structure-performance relationship was studied. The results indicated that the (CuCex@PMO-TNU-9 x = 1.0, 1.5 and 2.0) catalysts were successfully prepared, whereas CuCe2.5@PMO-TNU-9 was not successfully prepared due to the excess of the precursor resulting in the difference of hydrolysis rate between the organosilane precursor and white carbon black. The CuCe2@PMO-TNU-9 catalyst showed higher NH3-SCR activity than Cu@PMO-TNU-9, which was because that the interaction between Ce and Cu could form Cu2++Ce3+↔Cu++Ce4+ redox cycle, which promoted the oxidation of NO to NO2, forming “fast SCR” reaction. More importantly, CuCe2@PMO-TNU-9 catalyst had excellent the resistance of H2O and SO2 due to the excellent hydrophobicity of the TNU-9 zeolite and the sacrificial site Ce protecting the active site Cu.