Direct evidence for manganese substitution in a framework site in manganese aluminophosphate MnAPO-11 molecular sieve from the adsorbed water coordination configuration deduced by electron spin echo modulation analysis

Abstract

Electron spin echo modulation analysis of 0.1 mol% Mn (relative to P) in MnAPO-11 with adsorbed D 2 OP shows two deuteriums at 0.24 nm and two at 0.36 nm from Mn. This suggests that two waters hydrate an MnO 4 configuration with a D-O bond orientation for the waters as expected for a negatively charged site. When Mn substitutes for Al in the AlPO 4 -11 framework it forms a negatively charged site, whereas Mn would form a positively charged site in an extraframework position