Inoperative protonic sites in highly exchanged L-zeolites

Abstract

It has been shown that highly exchanged L zeolites have hydroxyls vibrating at 3740, 3730, 3680 and 3630 cm^–1 and a large number of strongly interacting hydroxyls. The structural 3630 cm^–1 hydroxyls, stable under the conditions of catalytic experiments, are strongly acidic toward pyridine. Their inactivity in catalysis for less basic molecules such as hydrocarbons suggests that protons in these highly exchanged samples become inoperative either because they form hydroxyl nests or because they move to inaccessible cavities.