27Al and 31P NMR Investigations of Soluble Aluminophosphate Species in Alcohol–Water Mixtures

Abstract

In this work, phosphorus-31 and aluminum-27 nuclear magnetic resonance techniques were used to characterize the distribution of soluble aluminophosphate species in methanol + water and ethanol + water mixtures. The assignment of the peaks to aluminate species was attempted, clarifying earlier work and producing information on the different aluminophosphate complexes. Nine peaks were observed at −0.41, −6.4, −7.5, −7.9, −13.1, −13.9, −16.6, −18.1 and −20.6 ppm. Four new peaks appeared in the 31 P NMR spectra of the alcoholic aluminophosphate solutions and their intensities changed with changes of the alcohol:water volume ratio. These new peaks were observed in the presence of methanol or ethanol but not in aqueous solutions.