COMPARISON OF ACID-BASE PROPERTIES OF FAU, EMT, LTL AND MOR (NA FORMS) IN BENZENE ADSORPTION AND ALKYLATION OF ANILINE WITH METHANOL

Five different Na or K forms of 12R window zeolites (X, Y, EMT, LTL an d MOR) were studied regarding the adsorption of an aromatic model mole cule (benzene) and catalytic reaction involving an aromatic ring (alky lation of aniline with methanol), The benzene adsorption occurs on the cations (Lewis acid sites) on all the zeolites and on the oxygen of t he 12R window on FAU and MOR and on EMT in the presence of ammonia. Th e absence of any interaction with the oxygen in KL, even in the presen ce of ammonia, and by contrast the hi,oh adsorption on these sites in MOR suggest that a molecular recognition effect directs the location o f benzene within the large window (chemical and geometric requirements ) in a way that is specific for each structure, The alkylation of anil ine at 673 K may involve cations to give C-alkylation or basic framewo rk oxygen to catalyze N-alkylation. The activity at short time-on-stre am may be ranked NaX > NaY > NaEMT > NaL > NaMOR. A rapid aging is obs erved for NaX and NaL. The more selective samples are NaL and NaMOR wh ich give a high N-alkylation. The comparison of the various zeolite st ructures suggests that in addition to the acid-base properties of the zeolites, geometric effect, characteristic of each structure may gover n the selectivity.