ON THE RELATION BETWEEN CATALYTIC PERFORMANCE AND MICROSTRUCTURE OF POLYCRYSTALLINE SILVER IN THE PARTIAL OXIDATION OF METHANOL

被引:76
作者
SCHUBERT, H
TEGTMEYER, U
HEREIN, D
BAO, X
MUHLER, M
SCHLOGL, R
机构
[1] Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, D-14195
关键词
METHANOL OXIDATION; CONVERSION TO FORMALDEHYDE; SILVER; SURFACE OXYGEN; STM; IMR-MS; ADSORPTION-INDUCED RESTRUCTURING; ATOMIC STRUCTURE; TEXTURE; X-RAY DIFFRACTION;
D O I
10.1007/BF00814233
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
Electrolytic silver was investigated as partial oxidation catalyst for the conversion of methanol to formaldehyde. Using the mass spectrometric technique as on-line detector the relation between feed composition and temperature was determined allowing us to conclude that two simultaneous reaction pathways operate under steady state conditions. The microstructure was analysed by XRD and STM. A pronounced restructuring of the surface on the mesoscopic scale was detected. The atomic structure of the gamma oxygen phase was determined on the (111) face of facets grown during reaction. The two reaction pathways find their counterparts in two distinctly different surface microstructures providing different geometries for the respective active sites. After prolonged time on stream the high surface mobility of the silver atoms removes all mesoscopic restructuring without changing the conversion characteristics. The observed restructuring is thus considered as a frozen large scale image of the continuously changing surface under reaction conditions.
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页码:305 / 319
页数:15
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