Microstructure of some oxide catalysts

Abstract

When investigating two-component catalysts, some structural properties of two-component oxide catalysts (nonreduced and reduced) composed of nickel and zinc oxides as well as nickel and cobalt oxides, having varying content of both basic components, have been examined. Some samples were prepared f rom various starting materials (nitrates, carbonates) some of them were irradiated by a neutron Ra-Be generator. It was established that both the temperature of calcination employed and ionizing radiation applied, are of little effect on structural properties of the systems investigated. In all the systems consisting of nickel and zinc oxides, format ion of solid solution of cubic structure, which is accompanied by occurrence of microstress in the sample, may be observed in the region of 0—30 mol% of ZnO. Reduction of this system leads, in addition to metallic nickel, probably also to cubic alloy Ni -Zn and to an alloy of both metals, having a structure not yet established more closely. During preparation of the system consisting of nickel and cobalt oxides, primarily the spinel structure C o O . C o 2 0 3 is produced, in addition to the NiO phase. Moreover, also a more complicated, but up to now not more closely determined structural type is produced. In the reduced nickel-cobalt system, format ion of a substitutional nickel-cobalt solution with disordered substitution within total concentration range of 0—100% was proved. With samples of a higher cobalt content also a hexagonal cobalt phase can be observed.