Hydrothermal Stabilization of Rich Al–BEA Zeolite by Post-Synthesis Addition of Zr for Steam Catalytic Cracking of n-Dodecane

Abstract

The steam cracking of n-dodecane was performed over Zr-modified BEA zeolite. The parent H–BEA zeolite was modified via Zr introduction following earlier treatment (desilication and dealumination). The procedure allowed for achievement of a Si/Zr molar ratio of 100. The changes in BEA crystallinity were observed by X-ray diffraction. The energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance studies were used to confirm the quantity and position of Zr particles in the framework. Changes in the catalyst acidity were also monitored using pyridine FTIR. The addition of zirconium to the BEA framework prevents dealumination as a result of presence of steam as well as improved the catalyst lifetime from 30 min to 4 h. Dodecane cracking results showed that the introduction of Zr to the BEA framework after desilication is more efficient to protect framework Al in the presence of steam compared to dealumination post-treatment.