Surface science studies of selective catalytic reduction of NO: Progress in the last ten years

NO dissociation and reduction by H 2 on Pd(1 1 1): A first-principles study

“…However, the O atom produced from NO dissociation usually has strong adsorption energy on PGMs, which poisons the catalysts and thereby limiting the low-temperature activity of PGMs for NO decomposition. Currently, selective catalytic reduction (SCR) has been widely considered as one of effective approaches for the removal of NO employing ammonia, carbon monoxide, hydrogen as well as hydrocarbons (HC s ) [7][8][9][10][11] as reducing agents and has been introduced in many material applications. Among these reducing agents, hydrogen, which is produced in the automotive and stationary sources (from watergas-shift reaction or from hydrocarbons), was reported to be very effective in the catalytic reduction of NO x (H 2 -SCR) to N 2 especially under lean-burn conditions.…”

The Effect of Gamma-Al2O3Support on the NO Adsorption on Pd4Cluster

“…[4][5][6] Nitric oxide has an odd number of electrons and is one of the most versatile molecules, making its chemistry and adsorption process of particular interest. 13 The adsorption of NO on the supported catalyst surface has been investigated by both experimental 7,[14][15][16][17][18][19][20] and theoretical procedures. [21][22][23][24][25][26][27][28][29] NO adsorbs on small Pd clusters through its nitrogen atom in a tilted orientation, preferentially in the hcp threefold and bridge sites, 27 although the relative binding energies are strongly dependent on the size and geometry of the cluster employed.…”

Understanding the Role of Hyponitrite in Nitric Oxide Reduction

“…18 Even before these challenges were recognized, though, there had been considerable interest in understanding the mechanism of heterogeneous NO reduction in catalytic converters. [20][21][22][23][24][25] Many research groups have examined this reaction, and the generally accepted mechanism is thought to involve initial NO dissociation to form surface bound nitride and oxide (Scheme 1a). 18,[24][25][26][27][28][29][30][31] However, more recent experimental work suggests an 4 alternate mechanism could also be operative.…”

“…[20][21][22][23][24][25] Many research groups have examined this reaction, and the generally accepted mechanism is thought to involve initial NO dissociation to form surface bound nitride and oxide (Scheme 1a). 18,[24][25][26][27][28][29][30][31] However, more recent experimental work suggests an 4 alternate mechanism could also be operative. In this pathway, NO reduction proceeds via a "hyponitrite-like" (NO) 2 dimer (Scheme 1b), 20,22,[32][33][34] and, in fact, this intermediate has been detected directly with IR spectroscopy on Ag(111) at low temperatures (70 K).…”