Phosphatation of Zeolite H-ZSM-5: A Combined Microscopy and Spectroscopy Study

• Published in: Chemphyschem Vol. 15; no. 2; pp. 283 - 292
• Main Authors: van der Bij, Hendrik E., Aramburo, Luis R., Arstad, Bjørnar, Dynes, James J., Wang, Jian, Weckhuysen, Bert M.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 03.02.2014; WILEY‐VCH Verlag; Wiley; Wiley Subscription Services, Inc
• Subjects: Chemistry; Colloidal state and disperse state; dealumination; Exact sciences and technology; General and physical chemistry; Ion-exchange; IR spectroscopy; Microscopy; NMR; Nuclear magnetic resonance; phosphorus; Porous materials; Spectrum analysis; Surface physical chemistry; X-ray microscopy; Zeolites; Zeolites: preparations and properties; Crystalline phase; X ray microscopy; X-ray microscopy; Acidic site; Cross polarization; Pulse; Phosphorus; Aluminium; Water vapor; Porous material; Physisorption; IR spectroscopy; Mesoporosity; Aggregation; Magic angle; Infrared spectrometry; Dealumination; Hydrothermal treatment; zeolites; Nuclear magnetic resonance; dealumination; phosphorus
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201300910

A variety of phosphated zeolite H‐ZSM‐5 samples are investigated by using a combination of Fourier transfer infrared (FTIR) spectroscopy, single pulse 27Al, 29Si, 31P, 1H‐31P cross polarization (CP), 27Al‐31P CP, and 27Al 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. Tried and tested: The effect of phosphorus modification of zeolite H‐ZSM‐5 greatly depends on the applied phosphatation route. By using a multi‐pronged spectroscopic approach it is established that phosphatation of H‐ZSM‐5 promotes zeolite aggregation, external phosphorus deposits, and causes no dealumination. Phosphatation of pre‐steamed H‐ZSM‐5 gives rise to the formation of an extra‐framework crystalline tridymite AlPO4 phase.