STUDY OF THE ACTIVITY OF GA-ZSM-5 IN THE DE-NOX PROCESS BY A COMBINATION OF QUANTUM-CHEMISTRY, MOLECULAR-DYNAMICS, AND COMPUTER-GRAPHICS METHODS

被引:56
作者
HIMEI, H [1 ]
YAMADAYA, M [1 ]
KUBO, M [1 ]
VETRIVEL, R [1 ]
BROCLAWIK, E [1 ]
MIYAMOTO, A [1 ]
机构
[1] TOHOKU UNIV,FAC ENGN,DEPT MOLEC CHEM & ENGN,SENDAI,MIYAGI 98077,JAPAN
关键词
D O I
10.1021/j100033a015
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
A combination of quantum chemistry (QC), molecular dynamics (MD), and computer graphics (CG) methods was applied for investigation of the adsorption and the mechanism of methane activation on Ga3+-exchanged ZSM-5 catalyst. Quantum chemical density functional calculations were performed for the system of a MD-derived model cluster of zeolite and methane or water molecules. In the initial step the methane molecule was found to undergo weak physical adsorption on a Ga site at a distance between gallium and carbon atoms of 2.9 Angstrom and an adsorption energy of -4.90 kcal/mol. In the next step the dissociative adsorption of methane was studied. The dissociated complex with CH3 attached to Ga at 2.0 Angstrom and H bonded to extraframework oxygen appeared to be very favorable and led to energetic stabilization of -63.0 kcal/mol. On the contrary, no stable physisorbed state of water was observed, but the dissociated form of H2O appeared to be strongly bonded at the Ga site. The comparison of both processes allows for the discussion of the influence of water poisoning on the activation process. The adsorption energy of the dissociated water molecule at the optimized geometry is -77.5 kcal/mol, substantially larger than that of a physisorbed or dissociated methane molecule. This may result in prevention of methane activation, because methane adsorption on a Ga site already poisoned by water seems too weak to allow for any further transformation.
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页码:12461 / 12465
页数:5
相关论文
共 41 条
  • [21] SELECTIVE CATALYTIC REDUCTION OF NO WITH METHANE ON GALLIUM CATALYSTS
    LI, YJ
    ARMOR, JN
    [J]. JOURNAL OF CATALYSIS, 1994, 145 (01) : 1 - 9
  • [22] CATALYTIC REDUCTION OF NITROGEN-OXIDES WITH METHANE IN THE PRESENCE OF EXCESS OXYGEN
    LI, YJ
    ARMOR, JN
    [J]. APPLIED CATALYSIS B-ENVIRONMENTAL, 1992, 1 (04) : L31 - L40
  • [23] SELECTIVE CATALYTIC REDUCTION OF NOX WITH METHANE OVER METAL EXCHANGED ZEOLITES
    LI, YJ
    ARMOR, JN
    [J]. APPLIED CATALYSIS B-ENVIRONMENTAL, 1993, 2 (2-3) : 239 - 256
  • [24] NOX REDUCTION OVER A CU/MORDENITE CATALYST
    MABILON, G
    DURAND, D
    [J]. CATALYSIS TODAY, 1993, 17 (1-2) : 285 - 292
  • [25] THE CHEMICAL-STATE OF GALLIUM IN WORKING ALKANE DEHYDROCYCLODIMERIZATION CATALYSTS - INSITU GALLIUM K-EDGE X-RAY ABSORPTION-SPECTROSCOPY
    MEITZNER, GD
    IGLESIA, E
    BAUMGARTNER, JE
    HUANG, ES
    [J]. JOURNAL OF CATALYSIS, 1993, 140 (01) : 209 - 225
  • [26] CATALYTIC REMOVAL OF NITROGEN MONOXIDE OVER RARE-EARTH ION-EXCHANGED ZEOLITES IN THE PRESENCE OF PROPENE AND OXYGEN
    MISONO, M
    KONDO, K
    [J]. CHEMISTRY LETTERS, 1991, (06) : 1001 - 1002
  • [27] DEVELOPMENT OF RYUGA FOR 3-DIMENSIONAL DYNAMIC VISUALIZATION OF MOLECULAR-DYNAMICS RESULTS
    MIURA, R
    YAMANO, H
    YAMAUCHI, R
    KATAGIRI, M
    KUBO, M
    VETRIVEL, R
    MIYAMOTO, A
    [J]. CATALYSIS TODAY, 1995, 23 (04) : 409 - 416
  • [28] COMPUTER-AIDED-DESIGN OF ACTIVE CATALYSTS FOR THE REMOVAL OF NITRIC-OXIDE
    MIYAMOTO, A
    HIMEI, H
    OKA, Y
    MARUYA, E
    KATAGIRI, M
    VETRIVEL, R
    [J]. CATALYSIS TODAY, 1994, 22 (01) : 87 - 96
  • [29] MIYAMOTO A, 1993, COMPUTER AIDED INNOV, V2, P1025
  • [30] MIYAMOTO A, 1993, SEKIYU GAKKAISHI, V36, P282