On the Nature of Extra-Framework Aluminum Species and Improved Catalytic Properties in Steamed Zeolites.

ABSTRACT: Steamed zeolites exhibit improved catalytic properties for hydrocarbon activation (alkane cracking and dehydrogenation). The nature of this practically important phenomenon has remained a mystery for the last six decades and was suggested to be related to the increased strength of zeolitic Bronsted acid sites after dealumination. We now utilize state-of-the-art infrared spectroscopy measurements and prove that during steaming, aluminum oxide clusters evolve (due to hydrolysis of Al out of framework positions with the following clustering) in the zeolitic micropores with properties very similar to (nano) facets of hydroxylated transition alumina surfaces. The Bronsted acidity of the zeolite does not increase and the total number of Bronsted acid sites decreases during steaming. O₅

SUBMITTER: Khivantsev K 

PROVIDER: S-EPMC9000512 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature