Synthesis and characterization of a basic molecular sieve: Nitrogen-incorporated SAPO-34

Microporous nitrogen-incorporated SAPO-34 molecular sieves were synthesized by thermal post-treatment of SAPO-34 in flowing dry ammonia at elevated temperatures. The results of property characterized by DRIFTS of CO2 adsorption and CO2–TPD showed that basic sites existed on the surface of nitridized samples probably due to the presence of nitrogen-containing species incorporating into the framework of SAPO-34 molecular sieves. The changes in structure of nitrogen-incorporated samples were investigated by 27Al MAS NMR, 31P MAS NMR spectra X-ray diffraction and BET surface area measurements. It was found that nitrogen-incorporated SAPO-34 still kept good crystallinity and high specific surface area of precursors. And N-containing species had incorporated into the framework of samples during nitridation, in which N atom presumably bounded to Al and P atoms formed N-containing groups, but unfortunately some of them were not ascribed.