Consecutive heating/cooling cycles over a platinum aluminophosphate oxynitr
ide (Pt-AlPON) catalyst with a high nitrogen content (17.8 wt %) have been
studied by diffuse reflectance infrared spectroscopy (DRIFTS). Heating step
s to 500 degrees C produces the desorption of part of the nitrogenous speci
es of the catalyst (NE4+, NH3, -NH2, -NH-) as gaseous ammonia. During the t
reatment at room temperature, N-2 saturated with water produces a hydrolysi
s reaction that transforms part of the bulk nitride ions into NH4+ surface
species. These species are easily removed from the catalyst surface during
the next heating step. As a result of combined successive hydrolysis/heatin
g processes, the catalyst loses practically all its nitrogen content, reach
ing a structure similar to that of its AlPO4 precursor.