Controlling the selectivity and deactivation of H-ZSM-5 by tuning b-axis channel length for glycerol dehydration to acrolein

• Published in: Journal of industrial and engineering chemistry (Seoul, Korea) Vol. 88; pp. 127 - 136
• Main Authors: Ali, Babar, Lan, Xiaocheng, Arslan, Muhammad Tahir, Gilani, Syed Zulfiqar Ali, Wang, Huanjun, Wang, Tiefeng
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 25-08-2020; 한국공업화학회
• Subjects: Acrolein; b-Axis channels; Diffusion; Glycerol dehydration; ZSM-5 zeolites; 화학공학; Glycerol dehydration; Acrolein; Diffusion; b-Axis channels; ZSM-5 zeolites
• ISSN: 1226-086X; 1876-794X
• DOI: 10.1016/j.jiec.2020.03.037

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•A series of H-ZMS-5 with well controlled b-axis channels of 60–250nm were prepared.•Much better catalytic performance was obtained with H-ZSM-5 of 60nm b-axis channels.•Less coking and lower rate of deactivation was realized by shortening the b-axis channels.•Coking behaviors were discovered by UV-Raman spectra, TGA, EDS and iDPC-STEM.
Glycerol dehydration to value-added acrolein over zeolite catalysts is a useful approach to offer a sustainable economic route for the biodiesel industry. Glycerol dehydration over H-ZSM-5 with conventional morphology often exhibits a significant mass transfer limitation and inhibits the access to active sites in the micropores, which causes low activity, selectivity, and severe catalyst deactivation. In this study, a significant impact of b-axis channel length on acrolein selectivity and catalyst activity was revealed by using H-ZSM-5 synthesized with varied channel length in b-axis of 60, 130, 180, and 250nm. Complete glycerol conversion and high acrolein selectivity (88%) were observed over H-ZSM-5 with 60nm channels length in b-axis, due to high availability of active sites and enhanced diffusion through the shortest channels, which dramatically suppressed the coke formation. The catalysts with long b-axis channels exhibited a slow internal diffusion, leading to increased polymerization side reactions and coke formation.