THE EFFECT OF O-2 ON THE THERMAL-ACTIVATION OF ZEOLITE-BETA

The process of converting ''as-synthesized'' zeolites which contain or ganic templating agents generally begins by calcining the material to remove the organic material. Most often, this initial calcining step i s performed in the presence of O-2 which is thought to help burn out r esidue which forms during the thermal breakdown of the organic templat e. We have discovered that O-2 promotes the formation of residue from tetraethylammonium ions in zeolite beta (BEA), probably by participati ng directly in a polymerization process. This discovery has also been extended to tetrapropylammonium ions in MFI and to simple amine adsorb ates such as 1-propanamine adsorbed on acid sites in both BEA and MFI. We therefore believe that this is a general rule which may be applied to all amine templates in zeolites. A more efficient route to organic template removal is to first calcine the material in the absence of O -2 SO that the polymerization process which involves Oz is suppressed. This results in a material which has only a trace of residue which ca n be removed by heating briefly in O-2 at a moderate temperature. Mate rials initially calcined in O-2 require either a lengthy treatment at a moderate temperature or a shorter treatment at a higher temperature to completely remove the residue. (C) 1996 Academic Press, Inc.