H. E. SWIFT,F. E. LUTINSKI,AND W. L. KEHL
3268
Investigation of the Metallic Phases in Reduced, Impregnated Nickel and Nickel-Copper Silica-Alumina Catalysts
by Harold E. Swift, Frank E. Lutinski, and William L. Kehl Gulf Research & Development Company, Pithburgh, Pennsylvania (Received January 18, 1966)
An investigation of the reduced copper-nickel silica-alumina system has revealed the presence of a copper-nickel alloy phase which was identified by X-ray diffraction. In addition to the copper-nickel phase, metallic nickel and copper may be present on the catalyst surface. To make the system more complex there is also a nickel phase that is not removed by carbon monoxide. Such a phase was found on nickel silica-alumina catalysts. Hydrogen chemisorption, carbon monoxide extraction, cyclohexane dehydrogenation, and n-octane hydrocracking studies indicate that the properties of the nickel silica-alumina catalyst system are greatly modified by the addition of copper to the system,
Introduction
Experimental Section
The physicochemical and catalytic properties of nickel-copper alloys have been discussed very extensively in the literature. Of particular interest in many of these studies has been the relationship between the d-band character of the alloys and their catalytic activity towards certain chemical reactions.'-16 Most of the work has been done with unsupported alloys, and the subject of supported alloys, especially in impregnated catalysts, has received little attention. Studies using nickel-copper alloys supported on kieselguhrs and a l ~ m i n a " ~have '~ been reported. These supported nickel-copper alloys were prepared by the precipitation of mixed carbonates from an aqueous solution containing nickel and copper nitrates onto the support, followed by drying and reduction with hydrogen. Alloys of Pt-Rh, Pd-Rh, Pt-Ru, and Os-Pt on impregnated alumina catalysts have also been reported.l9 However, the existence and nature of the alloys were definitely not established, and Bond statesa that supported alloys are naturally suspect. The work presented in this paper is concerned primarily with the examination of the metallic phase or phases formed on reduction of impregnated nickel and nickel-copper silica-alumina catalysts. I t has been found that a nickel-copper alloy phase is formed when impregnated nickel-copper silica-alumina catalysts are reduced with hydrogen.
The catalysts used in this study were prepared by impregnating various supports with an aqueous solu-
Zhe Joumal of Physierrl Chemistry
(1) G.Reinacker and G. Vormum, 2.anorg. allgem. Chem., 283, 287 (1956). (2) G.Reinacker and E. A. Bommer,
