Formation of the Phase Composition, Porous Structure, and Morphology of Membrane Catalysts Based on Tungsten Carbides

Abstract

Membrane catalysts are prepared by the chemical vapor-phase deposition of tungsten oxides on a corundum porous microfiltration membrane. The massive layer of tungsten oxides formed on the substrate is converted to carbides by temperature-programmed carbidization with С3Н8/Н2 and СН4/Н2 mixtures. Changes in the porous structure and phase composition of the catalytic layer at stages of vapor-phase deposition and carbidization of oxides deposited on the corundum substrate are considered. Dependence of the depth of distribution of tungsten compounds on the deposition temperature is studied by electron scanning microscopy and X-ray spectroscopy. A relationship is established between the synthesis conditions of tungsten carbide-based membrane catalysts and their phase composition, porous structure characteristics, and morphology.