Ž . Journal of Molecular Catalysis A: Chemical 158 2000 325–329 www.elsevier.comrlocatermolcata Physicochemical study of active sites of metal catalysts for alcohol partial oxidation A.N. Pestryakov a, ) , V.V. Lunin b a Tomsk State UniÕersity of CiÕil Engineering, Tomsk 634003, Russia b Chemistry Department, Moscow State UniÕersity, Moscow 119899, Russia Abstract Ž . The active electronic states of the supported metal catalysts Ag, Cu, Au in the processes of alcohol partial oxidation were studied by the methods of IR spectroscopy of adsorbed CO, electron spectroscopy of diffuse reflectance, X-ray diffraction, XPS, EXAFS, ESR and electron microscopy. Comparison of the obtained catalytic and spectroscopic data revealed that one-charged cations M q are the active sites of the local interaction on the metal catalyst surface in the processes of alcohol oxidation. The catalyst selectivity strongly depends on the effective charge of the surface active sites. q 2000 Elsevier Science B.V. All rights reserved. Keywords: Metal catalysts; Silver; Copper; Gold; Alcohol oxidation 1. Introduction Catalysts based on the metals of the Cu subgroup are widely used for the processes of oxidation of alcohols to aldehydes. Silver cata- lysts are the most used, but in some cases, the ` ` complex Ag Cu and Ag Au systems are ap- plied as well. In spite of long-standing studies, the question of the mechanism of alcohol oxida- tion and of the nature of the active sites is still under discussion. As a rule, active sites on ` silver catalysts are considered in terms of M O binding energy or to be different form of oxy- gen adsorbed on metal surface, i.e. O 2y ,O y , O y , while the electronic states of the metals are 2 w x not adequately investigated 1,2 . ) Corresponding author. Fax: q 7-3822-753-362. Ž . E-mail address: anp@tspace.ru A.N. Pestryakov . The aim of the present paper was to study the nature of the active sites of the metal catalysts in alcohol partial oxidation. 2. Experimental Samples in the range of 1–10 wt.% Mersup- port were prepared for investigation of elec- tronic and catalytic properties of silver, copper and gold. The metals was deposited by impreg- Ž . nation of the support using AgNO , Cu NO 3 32 and H AuCl , followed by thermal decomposi- 3 6 tions of these substances. An amount of 1–10 wt.% of modifying additions of Zr, Ce, La and Cs oxides were deposited on the support from metal nitrate or acetate solutions, followed by thermal decomposition of those salts to oxides. Aluminosilicate, aerosil SiO , g- and a-Al O , 2 2 3 MgO and pumice were used as supports. 1381-1169r00r$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž . PII: S1381-1169 00 00099-6