USE OF METHANOL AS A PROBE TO STUDY THE ADSORPTION SITES OF DIFFERENT MGO SAMPLES

被引:40
作者
BENSITEL, M [1 ]
SAUR, O [1 ]
LAVALLEY, JC [1 ]
机构
[1] ISMRA UNIV,CNRS,URA 0414,6 BLVD MARECHAL JUIN,F-14050 CAEN,FRANCE
关键词
D O I
10.1016/0254-0584(91)90086-A
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Methanol adsorption on activated MgO has been studied by gravimetry and FT-IR spectroscopy. It gives rise to three kinds of species: i) one reversibly adsorbed at room temperature (species H) coordinated to Mg2+ sites but also strongly H-bonded to unsaturated O2- sites; ii) two methoxy species characterized by a nu-(O-C) band at 1115 cm-1 (species I) and 1090 cm-1 (species II) resulting both from the dissociation in methanol of the O-H bond as shown by use of CH3(OH)-O-18. Considering that faces of the (100) type are preferentially exposed, species H and I are postulated to be formed on regular faces, while species II formation involves the presence of defects, such as Mg2+ cations in a low coordination state. Extension of the study to five MgO samples, the surface of which varies from 12 m2 g-1 (smoke) to 565 m2 g-1 (ex-carbonate), shows that the proportion of defects increases with the surface area, reaching more than 25 % of the total amount of methanol adsorption sites in the case of high surface area samples.
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页码:309 / 320
页数:12
相关论文
共 17 条
[11]   ACTIVE-SITES FOR HYDROGEN ADSORPTION ON MAGNESIUM-OXIDE [J].
ITO, T ;
KURAMOTO, M ;
YOSHIOKA, M ;
TOKUDA, T .
JOURNAL OF PHYSICAL CHEMISTRY, 1983, 87 (22) :4411-4416
[12]   SURFACE-AREA AND THE MECHANISM OF HYDROXYLATION OF IONIC OXIDE SURFACES [J].
JONES, CF ;
REEVE, RA ;
RIGG, R ;
SEGALL, RL ;
SMART, RS ;
TURNER, PS .
JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS I, 1984, 80 :2609-&
[13]   CATALYTIC ALUMINAS - SURFACE MODELS AND CHARACTERIZATION OF SURFACE SITES [J].
KNOZINGER, H ;
RATNASAMY, P .
CATALYSIS REVIEWS-SCIENCE AND ENGINEERING, 1978, 17 (01) :31-70
[14]   COADSORPTION OF METHANOL AND CARBON-DIOXIDE ON ALUMINA [J].
LAMOTTE, J ;
SAUR, O ;
LAVALLEY, JC ;
BUSCA, G ;
ROSSI, PF ;
LORENZELLI, V .
JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS I, 1986, 82 :3019-3023
[15]   FT-IR STUDY OF THE STRUCTURE AND REACTIVITY OF METHOXY SPECIES ON THO2 AND CEO2 [J].
LAMOTTE, J ;
MORAVEK, V ;
BENSITEL, M ;
LAVALLEY, JC .
REACTION KINETICS AND CATALYSIS LETTERS, 1988, 36 (01) :113-118
[16]   A STUDY OF THE ADSORPTION SITES ON THORIA BY SCANNING-TRANSMISSION ELECTRON-MICROSCOPY AND FOURIER-TRANSFORM INFRARED-SPECTROSCOPY - ADSORPTION AND DESORPTION OF WATER AND METHANOL [J].
MONTAGNE, X ;
LYNCH, J ;
FREUND, E ;
LAMOTTE, J ;
LAVALLEY, JC .
JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS I, 1987, 83 :1417-&
[17]   ADSORPTION AND DESORPTION OF METHYL ALCOHOL ON MAGNESIUM OXIDE [J].
TENCH, AJ ;
GILES, D ;
KIBBLEWHITE, JF .
TRANSACTIONS OF THE FARADAY SOCIETY, 1971, 67 (579) :854-+