Molecular layering of phosphorus oxide structures on the surface of gamma alumina

Abstract

Phosphorus oxide structures were synthesized on the surface of porous gamma alumina, with phosphorus oxychloride and water vapors used as reagents for successive and alternating (up to four times) treatment of a solid-phase matrix by the molecular layering method with in situ monitoring of the process. It was shown that this procedure yields a double-phase system constituted by a core (aluminum oxide) and shell (amorphous phosphorus oxide layer) with a prescribed chemical composition and structure with characteristics dependent on the number of molecular layering cycles. With increasing treatment rate (from 1 to 4) of the solid-phase matrix with halide and water vapors, the concentration of phosphorus in the samples steadily grows. In the process, the specific surface area, pore volume, and pore size in the double-phase system being formed become smaller. The results obtained in the study are of interest for development of catalytic, sorption, and other functional systems of the core–shell type.