TGA-DTA STUDY ON CALCINATION OF ZEOLITIC CATALYSTS

Template decomposition upon calcination of EMO and EMT zeolites has be en studied using thermal analysis techniques. For both samples, desorp tion of water occurs below 200 degrees C and template decomposition at 250-450 degrees C. It is concluded that the template decomposition in EMO and EMT zeolites is relatively slow and is not structure-sensitiv e; it is accompanied by rapid desorption of the products, XRD studies on the calcined samples show no decrease in their crystallinity. Howev er, both NMR- and IR-spectroscopy indicate partial distortion of the f ramework and formation of Lewis acid sites. A non-destructive activati on of zeolites prepared with organic templates is proposed. (C) 1997 E lsevier Science B.V.