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Hydrothermal post-synthesis of HZSM-5 zeolite to enhance the coke-resistance of Mo/HZSM-5 catalyst for methane dehydroaromatization reaction: Reconstruction of pore structure and modification of acidity

Paper ID Volume ID Publish Year Pages File Format Full-Text
44132 46004 2007 9 PDF Available
Title
Hydrothermal post-synthesis of HZSM-5 zeolite to enhance the coke-resistance of Mo/HZSM-5 catalyst for methane dehydroaromatization reaction: Reconstruction of pore structure and modification of acidity
Abstract

Hydrothermal post-synthesis of a commercial HZSM-5 zeolite in Al(NO3)3 aqueous solution resulted in the creation of a uniform microporous network and the formation of Brönsted acid sites with suitable acidic strengths through the dynamic extraction and incorporation of aluminum species between the solution and the framework. NMR and N2 adsorption–desorption isotherms measurements revealed that a dynamic extraction and incorporation of aluminum from the framework occurred during the post-synthesis treatment. XRD, XP spectra and TPR measurements of the resulting Mo/HZSM-5 catalyst indicated that the dispersion of Mo species was greatly promoted over the post-synthesized HZSM-5 zeolite, significantly facilitating the migration of Mo species into the channels. As a result, the Mo/HZSM-5 catalyst showed rather high methane conversion and selectivity of aromatics by effectively inhibiting the formation of coke during the methane dehydroaromatization reaction. Comparatively, the Mo/HZSM-5 catalyst, where the HZSM-5 zeolite was obtained by conventional hydrothermal post-synthesis, exhibited lower methane conversion and heavy coke deposits, apparently due to the substantial loss of the Brönsted acid sites and the creation of secondary pores.

Graphical abstractHydrothermal post-synthesis of a commercial HZSM-5 zeolite in Al(NO3)3 aqueous solution resulted in the creation of a uniform microporous network and the formation of Brönsted acid sites with suitable acidic strengths through the dynamic extraction and incorporation of aluminum species between the solution and the framework. NMR and N2 adsorption–desorption isotherms measurements revealed that a dynamic extraction and incorporation of aluminum from the framework occurred during the post-synthesis treatment. X-ray powder diffraction (XRD), X-ray photoelectron spectra (XPS) and temperature-programmed reduction (TPR) measurements of the resulting Mo/HZSM-5 catalyst indicated that the dispersion of Mo species was greatly promoted over the post-synthesized HZSM-5 zeolite, significantly facilitating the migration of Mo species into the channels. As a result, the Mo/HZSM-5 catalyst showed rather high methane conversion and selectivity of aromatics by effectively inhibiting the formation of coke during the methane dehydroaromatization reaction.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Hydrothermal post-synthesis; Al(NO3)3 aqueous solution; HZSM-5 zeolite; Methane dehydroaromatization
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Hydrothermal post-synthesis of HZSM-5 zeolite to enhance the coke-resistance of Mo/HZSM-5 catalyst for methane dehydroaromatization reaction: Reconstruction of pore structure and modification of acidity
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 317, Issue 2, 7 February 2007, Pages 266–274
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
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Any Questions? feel free to contact us