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Environmentally-benign catalysts for the selective catalytic reduction of NOxfrom diesel engines: structure–activity relationship and reaction mechanism aspects

“…During the reduction of NO x with ethanol and propene on , and ÀNCO (n) for the cases of (A), and (C), respectively, and (E) time dependence of N 2 and CO 2 concentration calculated from the mass signals for the cases of (C). (Reproduced with permission from Elsevier Inc.) 165 Ag/Al 2 O 3 , the two peaks at 2258-2262 and 2230-2235 cm À1 were detected by Ukisu et al, 198 Kameoka et al, 23,199 and Sumiya et al 29,168 The high-frequency peak was assigned to Al-NCO, while the low-frequency one was attributed to adsorption on Ag sites (Ag-NCO). To identify the adsorption sites of -NCO on the Ag/Al 2 O 3 surface, DFT calculations were performed by Gao and He.…”

Evidence for the formation, isomerization and decomposition of organo-nitrite and -nitro species during the NOx reduction by C3H6 on Ag/Al2O3

“…In our TPD experiment, the desorption peaks resulted from the decomposition of enolic species were also detected, however, only trace of products were observed (results not shown). In the region of 2300-2100 cm À1 , -NCO and -CN peaks were observed at 2229 and 2146 cm À1 , respectively [3,[13][14][15][16][17].…”

“…It is well known that isocyanate species (-NCO) species is a vital intermediate for the SCR of NO x over Ag/Al 2 O 3 catalyst [1][2][3][4][5][6]13], and its high productivity indicates a high efficiency of NO x reduction by ethanol or hydrocarbons [14][15][16][17]. Up to now, however, organo-nitrite and -nitro species (R-ONO and R-NO 2 ), as true intermediates in the SCR of NO x by hydrocarbons, are still a matter of debate.…”

FTIR, TPD and DFT studies of intermediates on Ag/Al2O3 during the selective catalytic reduction of NO by C2H5OH

“…Switching the fed gas to NO + O 2 resulted in a sharp decrease in the intensity of enolic species peaks accompanied by a corresponding increase in the intensity of a new NCO peak at 2229 cm −1 [2,3,17], indicating that the enolic species is important to the formation of NCO. It was widely accepted that the NCO species could be a crucial intermediate in the SCR-NO x over Ag/Al 2 O 3 , and its high productivity would result in high efficiency of NO x reduction by C 2 H 5 OH or hydrocarbons [5,[18][19][20]. Since the enolic species plays an important role in NCO formation, this species must also be another crucial intermediate in the C 2 H 5 OH-SCR of NO.…”