Coke Relocation and Mo Immobilization in Donut-Shaped Mo/HZSM-5 Catalysts for Methane Dehydroaromatization - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Materials Chemistry A Année : 2023

Coke Relocation and Mo Immobilization in Donut-Shaped Mo/HZSM-5 Catalysts for Methane Dehydroaromatization

Hugo Cruchade
Eddy Dib
Honghai Liu
  • Fonction : Auteur
Jiujiang Wang
  • Fonction : Auteur
Xinmei Liu
Zi-Feng Yan
Zhengxing Qin
Svetlana Mintova

Résumé

Molybdenum-modified HZSM-5 catalysts are widely used for methane dehydroaromatization (MDA) but suffer from rapid deactivation due to coke formation. The limited diffusion in zeolitic catalysts promotes coke accumulation in micropores, creating concentration gradients of reactants and products within the crystals. In this study, we propose a synthesis approach to evaluate the impact of removing the crystal core in the Mo/HZSM-5 catalyst on the MDA performance. To achieve this, a parent zeolite (ZP) comprising a silicalite-1 core encased by an HZSM-5 crystal is subjected to two distinct treatments: fluorine (ZF) and alkaline (ZOH). These treatments dissolve the silicon-rich core, creating a central macropore in the crystals leading to the formation of donuts-shaped catalysts. The alkaline treatment further generates additional mesopores and silanols by leaching atoms from the zeolite framework. The MDA reaction on molybdenum-impregnated zeolite catalysts (ZP, ZF, and ZOH) at 973 K was carried out. Interestingly, the "donut"-shaped catalysts modify the nature of the coke deposition, relocating the coke from the micropores to the macropores. Consequently, the removal of the crystal core effectively mitigates catalysts deactivation caused by coke formation. Moreover, the alkaline-treated catalyst exhibits additional beneficial properties, such as increased silanols and higher surface area, which help to limit the sintering of molybdenum carbides during the MDA reaction. The new strategy improves the performance and stability of Mo/HZSM-5 catalysts in methane dehydroaromatization.

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Chimie
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Dates et versions

hal-04283486 , version 1 (13-11-2023)

Identifiants

Citer

Ming Cheng, Hugo Cruchade, Ludovic Pinard, Eddy Dib, Honghai Liu, et al.. Coke Relocation and Mo Immobilization in Donut-Shaped Mo/HZSM-5 Catalysts for Methane Dehydroaromatization. Journal of Materials Chemistry A, 2023, ⟨10.1039/D3TA05418G⟩. ⟨hal-04283486⟩
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