CATALYSTS PREPARED FROM ACTIVATED ALUMINUM-ALLOYS - V - FORMATION OF COPPER-CONTAINING, NICKEL-CONTAINING, COBALT-CONTAINING, OR ZINC-CONTAINING ALUMINA CATALYSTS

The formation of novel copper-, nickel-, cobalt-, and zinc-containing alumina catalysts prepared by the interaction of water with indium-and gallium-modified aluminum alloys containing copper, nickel, cobalt, a nd zinc is studied using the thermal methods of analysis, XRD, adsorpt ion methods, TPR, IR spectroscopy, and XPS. The samples that were not subjected to thermal treatment are shown to contain pseudoboehmite (PB ) and bayerite (B) as well as the intermetallides (aluminides) of copp er, nickel, or cobalt, the In, Al, Zn, and Cu metals, the oxide (in th e case of the copper alloy) or hydroxyaluminate (in the case of the zi nc ahoy) of the metal. With increasing concentration of an active comp onent, the relative content of B increases and that of PB decreases. D uring thermolysis, PB and B are transformed into various low-temperatu re modifications of Al2O3 and zinc hydroaluminate is converted into a solid solution ZnO-Al2O3. Under the oxidative conditions at temperatur es below 550 degrees C, the In, Zn, and Cu metals form In2O3, ZnO, and CuO, respectively, while at elevated temperatures (similar to 1000 de grees C), the high-temperature modifications of Al2O3 and the aluminum spinels (of zinc, copper, or nickel) appear. Under the reductive cond itions at temperatures below 690 degrees C, In2O3 is transformed into indium metal, Co3O4 and cobalt-containing compounds are converted to b eta-Co, CuO is transformed into Cu, and nickel-containing compounds yi eld metallic Ni. According to XPS data, the phase of gallium was not f ound in any sample. The Lewis acidity (measured using pyridine as a pr obe) in the activated copper-containing catalysts is a function of the surface concentration of copper, indium, and gallium. Copper-, nickel -, cobalt-, and zinc-containing catalysts have a nonuniform pore struc ture and a developed surface area, which slightly changes in the wide temperature range (120-600 degrees C). With increasing metal content, independently of its nature, the specific surface areas of the catalys ts drop nearly in the same way.