SURFACE PHENOMENA DURING THE OXIDATIVE COUPLING OF METHANE OVER LI/MGO

被引:90
作者
PEIL, KP [1 ]
GOODWIN, JG [1 ]
MARCELIN, G [1 ]
机构
[1] UNIV PITTSBURGH,DEPT CHEM & PETR ENGN,PITTSBURGH,PA 15261
关键词
D O I
10.1016/0021-9517(91)90331-W
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
This paper details an investigation of the oxidative coupling of methane for reaction temperatures up to 645°C over MgO and Li/MgO catalysts using steady-state isotopic transient kinetic analysis (SSITKA). Oxygen-exchange experiments in the absence of methane resulted in a quantification of the lattice oxygen diffusivity and total oxygen uptake. The catalyst had three more-or-less distinct regions: (1) the physical surface at which exchange between the gas phase and the solid occurred, (2) several subsurface atomic layers readily available for exchange, and (3) the bulk oxide. Using isotopic switches of oxygen and methane under steady-state reaction, the active intermediates along the carbon and oxygen reaction pathways were quantified. Lattice oxygen was found to play a significant role in the oxidation process under steady-state reaction. CO and CO2 appeared to be formed via a multistep surface oxidation pathway while ethane was formed via surface-generated intermediates along a parallel pathway. Sites involved with the generation of intermediates for selective coupling were found to have a lower activity than sites active for the generation of nonselective intermediates. © 1991.
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收藏
页码:143 / 155
页数:13
相关论文
共 52 条
[1]  
Amenomiya Y., 1986, J PHYS CHEM-US, V90, P4785, DOI [10.1021/j100411a015, DOI 10.1021/J100411A015]
[2]   MASS-SPECTROMETRIC STUDIES OF THE LOW-PRESSURE OXIDATION OF METHANE ON SAMARIUM SESQUIOXIDE [J].
AMOREBIETA, VT ;
COLUSSI, AJ .
JOURNAL OF PHYSICAL CHEMISTRY, 1989, 93 (13) :5155-5158
[3]   OXIDATIVE COUPLING OF METHANE OVER ULTRAFINE CRYSTALLINE MGO DOPED WITH LI - ROLE OF LOWER COORDINATIVE SURFACE SITES PRODUCED BY LI-DOPING [J].
ANPO, M ;
SUNAMOTO, M ;
DOI, T ;
MATSUURA, I .
CHEMISTRY LETTERS, 1988, (04) :701-704
[4]   OXIDATIVE COUPLING OF METHANE OVER LEAD-OXIDE CATALYST - KINETIC-STUDY AND REACTION-MECHANISM [J].
ASAMI, K ;
SHIKADA, T ;
FUJIMOTO, K ;
TOMINAGA, HO .
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, 1987, 26 (11) :2348-2353
[5]   ON THE ACTIVITY OF FISCHER-TROPSCH AND METHANATION CATALYSTS - A STUDY UTILIZING ISOTOPIC TRANSIENTS [J].
BILOEN, P ;
HELLE, JN ;
VANDENBERG, FGA ;
SACHTLER, WMH .
JOURNAL OF CATALYSIS, 1983, 81 (02) :450-463
[6]   TRANSIENT KINETIC METHODS [J].
BILOEN, P .
JOURNAL OF MOLECULAR CATALYSIS, 1983, 21 (OCT) :17-24
[7]   GAS-PHASE COUPLING OF METHYL RADICALS DURING THE CATALYTIC PARTIAL OXIDATION OF METHANE [J].
CAMPBELL, KD ;
MORALES, E ;
LUNSFORD, JH .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1987, 109 (25) :7900-7901
[8]  
CARLSAW HS, 1959, CONDUCTION HEAT SOLI
[9]   GAS-PHASE RADICAL FORMATION DURING THE REACTIONS OF METHANE, ETHANE, ETHYLENE, AND PROPYLENE OVER SELECTED OXIDE CATALYSTS [J].
DRISCOLL, DJ ;
LUNSFORD, JH .
JOURNAL OF PHYSICAL CHEMISTRY, 1985, 89 (21) :4415-4418
[10]   FORMATION OF GAS-PHASE METHYL RADICALS OVER MGO [J].
DRISCOLL, DJ ;
MARTIR, W ;
WANG, JX ;
LUNSFORD, JH .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1985, 107 (01) :58-63