title: Phosphatation of zeolite H-ZSM-5: a combined microscopy and spectroscopy study.
abstract: A variety of phosphated zeolite H-ZSM-5 samples are investigated by using a combination of Fourier transfer infrared (FTIR) spectroscopy, single pulse (27)Al, (29)Si, (31)P, (1)H-(31)P cross polarization (CP), (27)Al-(31)P CP, and (27)Al 3Q magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, scanning transmission X-ray microscopy (STXM) and N2 physisorption. This approach leads to insights into the physicochemical processes that take place during phosphatation. Direct phosphatation of H-ZSM-5 promotes zeolite aggregation, as phosphorus does not penetrate deep into the zeolite material and is mostly found on and close to the outer surface of the zeolite, acting as a glue. Phosphatation of pre-steamed H-ZSM-5 gives rise to the formation of a crystalline tridymite AlPO4 phase, which is found in the mesopores of dealuminated H-ZSM-5. Framework aluminum species interacting with phosphorus are not affected by hydrothermal treatment. Dealuminated H-ZSM-5, containing AlPO4 , retains relatively more framework Al atoms and acid sites during hydrothermal treatment than directly phosphated H-ZSM-5.
authors.affiliation: Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterial Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht (The Netherlands).
authors.forename: Hendrik E
authors.initials: HE
authors.lastname: van der Bij
authors.forename: Luis R
authors.initials: LR
authors.lastname: Aramburo
authors.forename: Bjørnar
authors.initials: B
authors.lastname: Arstad
authors.forename: James J
authors.initials: JJ
authors.lastname: Dynes
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Bert M
authors.initials: BM
authors.lastname: Weckhuysen
keywords: IR spectroscopy; X-ray microscopy; dealumination; phosphorus; zeolites