The State of Chromium Cations in Crapo-5 Metalaluminophosphate: Uv-Visible and IR Spectroscopy Characterization

Abstract

Cr-APO-5 metalaluminophosphate is studied by UV-visible and IR spectroscopy. It is characterized by the presence of Cr3+ and Cr2+ ions in the framework with predominating Cr3+ ions via isomorphous substitution, as well as some minor amount of extra-framework Cr3+ species, presumably in the state close to α-Cr2O3 that can be partially reduced to Cr2+ species in CO or H2.

Keywords: zeolite-like materials, aluminophosphates, chromium, Spectroscopy, isomorphous substitution