MULTINUCLEAR NMR-STUDIES ON THE THERMAL-STABILITY OF SAPO-34

Thermal stability and the effect of water-coordination of a silicoaluminophosphate, SAPO-34, were investigated on the basis of multinuclear NMR studies. Crystalline silicoaluminophosphates (SAPOs) have been found as a new family of synthetic molecular sieves. The expected applications of SAPOs are as adsorbents and catalysts. Thermal stability is one of the crucial factors in applying SAPOs as automotive exhaust catalysts. 27Al-, 29Si-, and 31P-NMR spectra and XRD as a function of temperature showed the microporous structure of SAPO-34 to be stable up to 1000°C. The effect of water-coordination on the 27A1- and 31P-NMR spectra also showed the adsorptive properties of SAPO-34 to be stable up to 1000°C. In this paper. SAPO-34 was found to be promising as an automotive exhaust catalyst with a microporous structure and high heat resistance. © 1993 Academic Press, Inc.