TY - JOUR
T1 - Mechanisms of the various nitric oxide reduction reactions on a platinum-rhodium (100) alloy single crystal surface
AU - Hirano, H.
AU - Yamada, T.
AU - Tanaka, K. I.
AU - Siera, J.
AU - Cobden, P.
AU - Nieuwenhuys, B. E.
N1 - Funding Information:
FinanciaI support by the Ministery of Education of Japan by the Grant-in aid (No 01609003) for Scientific Research on Priority Areas and by the NetherlandsO rganization for Scientific Research (NW01 through a Grant (B.E.N.) are gratefullya cknowledged.
PY - 1992/2/1
Y1 - 1992/2/1
N2 - The reduction of nitric oxide with hydrogen was studied over a Pt0.25-Rh0.75(100) alloy surface used as a model catalyst for the automotive three-way catalyst. This paper emphasizes the mechanisms of the different reactions leading to the products dinitrogen, ammonia and nitrous oxide. For this purpose the reaction was studied under various experimental conditions including reactivity measurements both in the 10-7 mbar range under steady-state conditions and in the 10 mbar range with varying NO/H2 ratio. In addition, the thermal decomposition of NO and the reactions of NO + NH3 were investigated. 15NO and 15NH3 were used in order to gather additional information concerning the mechanisms of the formation reactions of the various N-containing products. The surface was characterized by using low-energy electron diffraction. Auger electron spectroscopy and thermal desorption spectroscopy. The main conclusions emerging from these studies are: (a) N2 can be formed by combination of 2 N adatoms in the whole temperature range used (350-1300 K) provided that sufficient N adatoms are available. (b) Below 600 K the main contribution to N2 formation is via NOads + Nads → N2+ Oads. At higher temperatures the dominant mechanism is 2Nads → N2. (c) N2O and NH3 are formed via Nads + NOads → N2O, and Nads + 3Hads → NH3 the contributions of which respectively decre increase with increasing temperature, (d) The selectivities to N2, NH3 and N2O are determined by the relative concentrations of NOads, Nads and Hads which vary with the experimental conditions such as the temperature.
AB - The reduction of nitric oxide with hydrogen was studied over a Pt0.25-Rh0.75(100) alloy surface used as a model catalyst for the automotive three-way catalyst. This paper emphasizes the mechanisms of the different reactions leading to the products dinitrogen, ammonia and nitrous oxide. For this purpose the reaction was studied under various experimental conditions including reactivity measurements both in the 10-7 mbar range under steady-state conditions and in the 10 mbar range with varying NO/H2 ratio. In addition, the thermal decomposition of NO and the reactions of NO + NH3 were investigated. 15NO and 15NH3 were used in order to gather additional information concerning the mechanisms of the formation reactions of the various N-containing products. The surface was characterized by using low-energy electron diffraction. Auger electron spectroscopy and thermal desorption spectroscopy. The main conclusions emerging from these studies are: (a) N2 can be formed by combination of 2 N adatoms in the whole temperature range used (350-1300 K) provided that sufficient N adatoms are available. (b) Below 600 K the main contribution to N2 formation is via NOads + Nads → N2+ Oads. At higher temperatures the dominant mechanism is 2Nads → N2. (c) N2O and NH3 are formed via Nads + NOads → N2O, and Nads + 3Hads → NH3 the contributions of which respectively decre increase with increasing temperature, (d) The selectivities to N2, NH3 and N2O are determined by the relative concentrations of NOads, Nads and Hads which vary with the experimental conditions such as the temperature.
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U2 - 10.1016/0039-6028(92)90463-G
DO - 10.1016/0039-6028(92)90463-G
M3 - Article
AN - SCOPUS:0026818278
SN - 0039-6028
VL - 262
SP - 97
EP - 112
JO - Surface Science
JF - Surface Science
IS - 1-2
ER -