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Pore Structure of USY Zeolites in Dependence on Steaming Condition
Author(s) -
Lutz Wolfgang,
Shutilov Roman A.,
Gavrilov Vladimir Yu.
Publication year - 2014
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201300403
Subject(s) - zeolite , mesoporous material , microporous material , steaming , silicic acid , chemical engineering , sorption , materials science , porosity , decomposition , catalysis , chemistry , adsorption , inorganic chemistry , organic chemistry , composite material , food science , engineering
Thermo‐chemical dealumination of zeolite Y is accompanied by formation of different mesopore types. Closed mesopores in the nuclei and open pores at the crystal surface occur due to decomposition of its corresponding frameworks which are unstable in steam. Third type of lattice mesopores is formed inside the microporous bulk after removal of aluminum atoms if the remaining hydroxyl nests dehydroxylate. This process leads to a rearrangement of the zeolite framework. In contrast to the observed phenomenon, the defects are healed by migrating of ortho‐silicic acid (H 4 SiO 4 ) from the surface to the hydroxyl nests under conditions of suitable steaming. Since mesopores in USY zeolites (ultra stable Y) reduce their catalytic activity and the sorption capacity, they could be minimized by a proper treatment.