NITROGEN INCORPORATION IN ALPO4-5 MOLECULAR-SIEVES BY THERMAL AMMONOLYSIS

AlPO4-5 samples were treated with NH3 or NH3/CO mixtures at temperatures up to 1173 K.The samples were characterized by powder X-ray diffraction (XRD), infrared (i.r.) spectroscopy, and high-resolution solid-state nuclear magnetic resonance (n.m.r.) spectroscopy (Al-27, P-31, H-1, and natural abundance N-15). At all temperatures, ammonia was adsorbed by the molecular sieve through the coordination of one or two NH3 molecules with aluminum to yield five- and six-fold coordinated Al. During ammonium treatment above 1073 K, oxygen bridges were broken, leading to -P-NH2 and -Al-OH terminal groups. -Al-NH-P- bridging groups were not observed.