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Tuning Zeolite Properties for a Highly Efficient Synthesis of Propylene from Methanol
Author(s) -
Palčić Ana,
Ordomsky Vitaly V.,
Qin Zhengxing,
Georgieva Veselina,
Valtchev Valentin
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201803136
Subject(s) - zeolite , crystallization , catalysis , selectivity , methanol , materials science , ethylene , chemical engineering , acid strength , diffusion , zsm 5 , organic chemistry , chemistry , thermodynamics , physics , engineering
A series of nanosized ZSM‐5 samples was synthesized at 170, 150, 120, and 100 °C. Experimental data show that the decrease of crystallization temperature leads to significant changes in zeolite properties. Crystals synthesized at 100 °C exhibit many framework defects with lower acid‐site density, strength, and a larger external surface area. The selectivity to light olefins and the propylene‐to‐ethylene ratio increases as the crystallization temperature decreases. A propylene‐to‐ethylene ratio of above 6 with the highest selectivity to propylene of 53 % was obtained over ZSM‐5 catalyst prepared at 100 °C. The stability of the nanosized zeolite in methanol to olefins (MTO) was also improved compared to the industrial sample with a similar Si/Al ratio. This catalytic performance is a result of the decrease in the acid‐site density, strength, and the crystals’ size, providing a shorter diffusion path and larger external surface area. The presence of structural defects and a different external surface in the crystals has been shown to play an important role in the MTO catalyst performance.