Protonic acid sites in stabilized Y zeolites after reduction of M2+ cations with hydrogen

Abstract

After reduction with hydrogen, stabilized Y zeolites containing metal cations exhibit new OH groups with characteristic IR bands. Their frequencies at 3640–3630 and 3550 cm^–1 correspond to OH groups of the non-defect faujasite skeleton, which is present both in the original zeolite lattice and in the partially dealuminated lattices of stabilized samples. The occupation of cationic positions by various types of cations (Na⁺, AlO⁺, Cu²⁺etc.) does not permit occupation of the bridging protonic sites in their microenvironment. The properties of protons created after reduction of metal cations are controlled by the equalized electronegativity of the skeletal oxygens.