ELECTRON-SPIN-RESONANCE AND ELECTRON-SPIN ECHO MODULATION STUDIES OF CU(II) CATION LOCATIONS AND ADSORBATE INTERACTIONS IN ION-EXCHANGED CU-MCM-22 ZEOLITE

MCM-22 is a medium-pore high-silica-containing zeolite. Its unique str ucture contains two noninterconnected channel systems with potential f or transition metal-based heterogeneous catalysis. Paramagnetic Cu(II) cation is ion-exchanged into MCM-22 to act as a probe for electron sp in resonance and electron spin echo modulation spectroscopic methods t o verify the location of the ion-exchangeable sites. The electron spin resonance spectra of dehydrated Cu-MCM-22 are strikingly well-resolve d and exhibit features related to both Cu-63 and Cu-65 nuclei. Interac tions with water, ammonia, methanol, pyridine, benzene, cyclohexylamin e and triethylamine adsorbed on Cu-MCM-22 are studied. Three types of ion-exchangeable extra framework site are identified. (C) 1997 Elsevie r Science B.V.