title: Post-Synthesis Stabilization of Germanosilicate Zeolites ITH, IWW, and UTL by Substitution of Ge for Al.
abstract: Germanosilicate zeolites often suffer from low hydrothermal stability due to the high content of Ge. Herein, we investigated the post-synthesis introduction of Al accompanied by stabilization of selected germanosilicates by degermanation/alumination treatments. The influence of chemical composition and topology of parent germanosilicate zeolites (ITH, IWW, and UTL) on the post-synthesis incorporation of Al was studied. Alumination of ITH (Si/Ge=2-13) and IWW (Si/Ge=3-7) zeolites resulted in the partial substitution of Ge for Al (up to 80 %), which was enhanced with a decrease of Ge content in the parent zeolite. In contrast, in extra-large pore zeolite UTL (Si/Ge=4-6) the hydrolysis of the interlayer Ge-O bonds dominated over substitution. The stabilization of zeolite UTL was achieved using a novel two-step degermanation/alumination procedure by the partial post-synthesis substitution of Ge for Si followed by alumination. This new method of stabilization and incorporation of strong acid sites may extend the utilization of germanosilicate zeolites, which has been until now been limited.
authors.affiliation: Department Synthesis and Catalysis, J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, v. v. i., Dolejškova 3, 182 23, Prague 8, Czech Republic.
authors.forename: Mariya V
authors.initials: MV
authors.lastname: Shamzhy
authors.affiliation: Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, 12840, Prague 2, Czech Republic.
authors.forename: Pavla
authors.initials: P
authors.lastname: Eliašová
authors.affiliation: Department Synthesis and Catalysis, J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, v. v. i., Dolejškova 3, 182 23, Prague 8, Czech Republic.
authors.forename: Dana
authors.initials: D
authors.lastname: Vitvarová
authors.affiliation: Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, 12840, Prague 2, Czech Republic.
authors.forename: Maksym V
authors.initials: MV
authors.lastname: Opanasenko
authors.affiliation: EaStCHEM School of Chemistry, University of St. Andrews, St. Andrews, KY16 9ST, UK.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Firth
authors.affiliation: EaStCHEM School of Chemistry, University of St. Andrews, St. Andrews, KY16 9ST, UK.
authors.forename: Russell E
authors.initials: RE
authors.lastname: Morris
keywords: ITH; IWW; UTL; alumination; zeolites