Rational Design of Zinc/Zeolite Catalyst: Selective Formation of p‐Xylene from Methanol to Aromatics Reaction

Abstract

The production of p-xylene from the methanol to aromatics (MTA) reaction is challenging. The catalytic stability, which is inversely proportional to the particle size of the zeolite, is not always compatible with p-xylene selectivity, which is inversely proportional to the external acid sites. In this study, based on a nano-sized zeolite, we designed hollow triple-shelled Zn/MFI single crystals using the ultra-dilute liquid-phase growth technique. The obtained composites possessed one ZSM-5 layer ( � 30 nm) in the middle and two silicalite-1 layers ( � 20 nm) epitaxially grown on two sides of ZSM-5, which exhibited a considerably long lifetime (100 % methanol conversion > 40 h) as well as an enhanced shape selectivity of p-xylene (> 35 %) with a p-xylene/xylene ratio of � 90 %. Importantly, using this sandwich-like zeolite structure, we directly imaged the Zn species in the micropores of only the ZSM-5 layer and further determined the specific structure and anchor location of the Zn species.

Synergistic Catalysis of Brønsted Acid, Al-Lewis Acid, and Zn-Lewis Acid on Steam-Treated Zn/ZSM-5 for Highly Stable Conversion of Methanol to Aromatics

“…The introduction of Zn species could consume part of BAS on the surface, and the new generated Zn-LAS could obviously promote the dehydrogenation aromatization process of alkenes, the selectivity of total aromatics, and BTX could increase from 25.6 and 14.1% to 34.5 and 18% of NZ-60, respectively. 53 In addition, the selectivity of light alkanes was significantly decreased from 27 to 19%. Interestingly, the introduction of Zn species on SNZ-60 with low acid density also significantly improved aromatics selectivity, which was increased from 26.7 to 37.4%, higher than the NZ-60.…”

Advanced Transmission Electron Microscopy for Identification of Atomic‐Scale Configurations of Zeolite‐Supported Metal Catalysts

“…[ 7 ] Moreover, Wang et al . [ 8 ] directly observed isolated single‐Zn complexes residing in the 10‐membered‐ring straight channels of ZSM‐5 by iDPC‐STEM. These results indicate that iDPC‐STEM technique is capable of imaging the non‐noble metal species in straight channels of zeolites at the atomic scale.…”

Design and synthesis of core shells HZSM-5@MCM-41 with variable acidity and mesoporosity for lignin-catalyzed fast pyrolysis to prepare aromatics

“…2,[6][7][8] To solve the problem that conventional microporous zeolites are prone to carbon buildup and thus lead to catalyst deactivation, researchers have proposed various solutions. 9,10 Wang et al 9 synthesized a ZSM-5@S1 core-shell molecular sieve by design. The S1 shell of pure silicon acts as surface passivation, thereby reducing the production of carbon deposits.…”