Methanol Conversion to Aromatics over Ga–supported HZSM‐5 with Evolved Meso‐ and Microporosities by Desilication. Issue 20 (29th November 2016)

• Record Type: Journal Article
• Authors: Lai, Po‐Chen; Chen, Chao‐Huang; Lee, Chiou‐Hwang; Lin, Yu‐Chuan
• Is Part Of: ChemistrySelect. Volume 1:Issue 20(2016)
• Page Start: 6335
• Page End: 6344
• Publication Date: 2016-11-29
• Subjects: aromatics -- desilication -- gallium -- methanol -- ZSM-5; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.201601292
• Languages: English
• ISSNs: 2365-6549

Abstract

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. Abstract : Optimal desilication condition: An optimal alkaline treatment for Ga‐doped, desilicated ZSM‐5 (Si/Al=11.5) was discovered. Sufficient amount of (GaO) + ‐Brønsted acid sites, enlarged mesopores, and uniformed micropores promote aromatics in methanol aromatization.