The reduction of NO with H2 over Ru/MgO

被引:29
作者
Hornung, A
Muhler, M [1 ]
Ertl, G
机构
[1] Ruhr Univ Bochum, Lehrstuhl Tech Chem, D-44780 Bochum, Germany
[2] Max Planck Gesell, Fritz Haber Inst, D-14195 Berlin, Germany
关键词
SCR of NO; Ru; MgO; frontal chromatography; TPD; TPSR;
D O I
10.1023/A:1019072915187
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Ruthenium supported on magnesia was found to be a highly active and selective catalyst for the reduction of NO to Na with H-2. The adsorption of NO on Ru/MgO was studied at room temperature by applying frontal chromatography with a mixture of 2610 ppm NO in He. Subsequently, temperature-programmed desorption (TPD) and temperature-programmed surface reaction (TPSR) experiments in H-2 were performed. The adsorption of NO was observed to occur partly dissociatively as indicated by the formation of molecular nitrogen. The TPD spectrum exhibited a minor NO peak at 340 K indicating additional molecular adsorption of NO during the exposure to NO at roam temperature, and two N-2 peaks at 480 K and 625 K, respectively. The latter data are in good agreement with previous results with Ru(0001) single-crystal samples, where the interaction with NH3 was found to lead to two N-2 thermal desorption states with a maximum coverage of atomic nitrogen of about 0.38. Heating up the catalyst after saturation with NO at loom temperature in a H-2 atmosphere revealed the self-accelerated formation of NH3 after partial desorption of N-2, whereby sites for reaction with H-2 become available. As a consequence, the observed high selectivity towards N-2 under steady-state reduction conditions is ascribed to the presence of a saturated N + O coadsorbate layer resulting in an enhanced rate of N-2 desorption from this layer and a very low steady-state coverage of atomic hydrogen. The formation of H2O by reduction of adsorbed atomic oxygen is the slow step of the overall reaction which determines the minimum temperature required for full conversion of NO.
引用
收藏
页码:77 / 81
页数:5
相关论文
共 24 条
  • [1] PREPARATION AND CHARACTERIZATION OF CHLORINE-FREE RUTHENIUM CATALYSTS AND THE PROMOTER EFFECT IN AMMONIA-SYNTHESIS .3. A MAGNESIA-SUPPORTED RUTHENIUM CATALYST
    AIKA, K
    TAKANO, T
    MURATA, S
    [J]. JOURNAL OF CATALYSIS, 1992, 136 (01) : 126 - 140
  • [2] Bosch H., 1986, CATAL TODAY, V2, P369, DOI DOI 10.1016/0920-5861(88)80002-6
  • [3] BOTTCHER A, IN PRESS J PHYS CHEM
  • [4] Coverage, lateral order, and vibrations of atomic nitrogen on Ru(0001)
    Dietrich, H
    Jacobi, K
    Ertl, G
    [J]. JOURNAL OF CHEMICAL PHYSICS, 1996, 105 (19) : 8944 - 8950
  • [5] CATALYSIS FOR CONTROL OF AUTOMOTIVE EMISSIONS
    DWYER, FG
    [J]. CATALYSIS REVIEWS, 1972, 6 (02): : 261 - &
  • [6] KINETIC OSCILLATIONS IN THE NO+CO REACTION ON PT(100) - EXPERIMENTS AND MATHEMATICAL-MODELING
    FINK, T
    DATH, JP
    IMBIHL, R
    ERTL, G
    [J]. JOURNAL OF CHEMICAL PHYSICS, 1991, 95 (03) : 2109 - 2126
  • [7] The kinetics of ammonia synthesis over Ru-based catalysts .1. The dissociative chemisorption and associative desorption of N-2
    Hinrichsen, O
    Rosowski, F
    Hornung, A
    Muhler, M
    Ertl, G
    [J]. JOURNAL OF CATALYSIS, 1997, 165 (01) : 33 - 44
  • [8] CATALYTIC REDUCTION OF NITRIC-OXIDE ON RUTHENIUM
    KLIMISCH, RL
    TAYLOR, KC
    [J]. INDUSTRIAL & ENGINEERING CHEMISTRY PRODUCT RESEARCH AND DEVELOPMENT, 1975, 14 (01): : 26 - 29
  • [9] KLIMISCH RL, 1975, CATALYTIC CHEM NITRO, P305
  • [10] CATALYTIC CHEMISTRY OF NITRIC-OXIDE .2. REDUCTION OF NITRIC-OXIDE OVER NOBLE-METAL CATALYSTS
    KOBYLINSKI, TP
    TAYLOR, BW
    [J]. JOURNAL OF CATALYSIS, 1974, 33 (03) : 376 - 384