A series of MWW-type zeolites of increasing
Si/Al ratio were investigated with respect to their acidic
properties. Concentration of the Brønsted acid centers
located at the external crystal surface was invariant for the
entire series. Ethanol conversion to ethyl-tert-butyl ether,
proceeding only at the external surface, was also constant.
The OH groups in MWW zeolites were found to be
homogeneous with proton affinity value equal to
1142.7 kJ/mol.
keywords in English:
MWW zeolites, ETBE synthesis, external surface acidity, IR and NMR studies