Possible molecular structure of promoted Lewis acidity sites in ZnZSM-5

It is suggested that the abnormal methane IR frequency shift obsd. in ZnZSM-5 zeolites is caused by adsorptive interaction of CH4 with particularly strong Zn2+ Lewis sites. Various mol. structures of zinc ion species in high-silica zeolites are discussed, and it is concluded that increased Lewis acidity of a site is assocd. with decreased structural stability. It is shown that Zn2+ in zeolite cationic position with distantly placed A1 ions can produce obsd. shift of vibrational frequencies for adsorbed methane mol. [on SciFinder (R)