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Open AccessFeature PaperArticle

The Role of Non-Framework Lewis Acidic Al Species of Alkali-Treated HZSM-5 in Methanol Aromatization

Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan
Division of Chemical Engineering, Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu 30011, Taiwan
Author to whom correspondence should be addressed.
Catalysts 2017, 7(9), 259;
Received: 5 August 2017 / Revised: 23 August 2017 / Accepted: 23 August 2017 / Published: 1 September 2017
(This article belongs to the Special Issue Zeolites and Catalysis)
PDF [6510 KB, uploaded 1 September 2017]


Mesoporous HZSM-5 prepared by alkaline treatment (also termed desilication) has drawn significant attention due to its potential in large-scale production and in versatile applications, such as separation and catalysis. Alkali-treated HZSM-5 contains considerable amounts of non-framework (amorphous) Lewis acidic Al species on the external surface, and is deemed to be essential in affecting its catalytic performances. This study intends to clarify the catalytic nature of amorphous Al species of alkali-treated HZSM-5 in methanol aromatization. Physicochemical characterizations, including N2 adsorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), magic-angle-spinning nuclear magnetic resonance (MAS NMR), inductively coupled plasma (ICP) analysis, NH3 temperature-programmed desorption (TPD), and methanol-TPD, were performed. The outcomes showed that non-framework Al promotes the hydride transfer in mesoporous HZSM-5, thereby facilitating the aromatization reaction. Among aromatic products, durene can be promoted by non-framework Al through methylation/transalkylation of other aromatics, particularly xylenes, instead of being promoted by reduced space confinement in mesoporous HZSM-5. View Full-Text
Keywords: aluminum; alkaline treatment; Lewis acid; HZSM-5; methanol aluminum; alkaline treatment; Lewis acid; HZSM-5; methanol

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Lai, P.-C.; Hsieh, C.-Y.; Chen, C.-H.; Lin, Y.-C. The Role of Non-Framework Lewis Acidic Al Species of Alkali-Treated HZSM-5 in Methanol Aromatization. Catalysts 2017, 7, 259.

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