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Methanol Conversion to Aromatics over Ga–supported HZSM‐5 with Evolved Meso‐ and Microporosities by Desilication
Author(s) -
Lai PoChen,
Chen ChaoHuang,
Lee ChiouHwang,
Lin YuChuan
Publication year - 2016
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201601292
Subject(s) - catalysis , methanol , selectivity , chemistry , fluid catalytic cracking , economic shortage , brønsted–lowry acid–base theory , chemical engineering , inorganic chemistry , organic chemistry , linguistics , philosophy , government (linguistics) , engineering
Abstract Methanol conversion to aromatics (MTA) is developing due to envisioning shortage in aromatics. In this work, HZSM‐5 (Si/Al=11.5) was desilicated with varying alkalinities and impregnated with 1 wt% Ga for MTA. Our most effective catalyst improved meso‐ and microporosities, and possessed sufficient numbers of (GaO) + ‐Brønsted acid sites. Improved mesoporosity accelerates inward and outward diffusions in ZSM‐5 matrix: the former promotes hexahydrated Ga 3+ transfer into cavities to form (GaO) + ‐Brønsted acid phases during impregnation, while the latter suppresses cracking by shortening residence time of yielded aromatics in ZSM‐5 channels. Micropores with a narrow pore size distribution around 0.55 nm can boost aromatics selectivities, especially for o‐ and m‐xylenes. A maximal aromatics selectivity of 60.1 % was achieved at 500 °C after moderate alkali treatment (NaOH=0.05 M) of HZSM‐5. However, high aromatics output inevitably penalized catalyst durability because of higher coking rate.