Methanol-to-hydrocarbons conversion over MoO3/H-ZSM-5 catalysts prepared via lower temperature calcination: a route to tailor the distribution and evolution of promoter Mo species, and their corresponding catalytic properties
Methanol-to-hydrocarbons conversion over MoO3/H-ZSM-5 catalysts prepared via lower temperature calcination: a route to tailor the distribution and evolution of promoter Mo species, and their corresponding catalytic properties
A series of MoO3/H-ZSM-5 (Si/Al=25) catalysts were prepared via calcination at a lower-than-usual temperature (400 oC) and subsequently evaluated in the methanol-to-hydrocarbon reaction at that same temperature. The catalytic properties of those catalysts were compared with the sample prepared at the more conventional, higher temperature of 500 oC. For the lower temperature preparations, molybdenum oxide was preferentially dispersed over the zeolite external surface, while only the higher loading level of MoO3 (7.5 wt% or higher) led to observable inner migration of the Mo species into the zeolite channels, with concomitant partial loss of the zeolite Brønsted acidity. On the MoO3 modified samples, the early-period gas yield, especially for valuable propylene and C4 products, was noticeably accelerated, and is gradually converted into an enhanced liquid aromatic formation. The 7.5 wt% MoO3/H-ZSM-5 sample prepared at 400oC thereby achieved a balance between the zeolite surface dispersion of Mo species, their inner channel migration and the corresponding effect on the intrinsic Brønsted acidity of the acidic zeolite. That loading level also possessed the highest product selectivity (after 5h reaction) to benzene, toluene and xylenes, as well as higher early-period valuable gas product yields in time-on-stream experiments. However, MoO3 loading levels of 7.5wt% and above also resulted in earlier catalyst deactivation by enhanced coke accumulation at, or near, the zeolite channel openings. Our research illustrates that the careful adoption of moderate/lower temperature dispersion processes for zeolite catalyst modification gives considerable potential for tailoring and optimizing the system’s catalytic performance
1-21
Liu, Bonan
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France, Liam
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Wu, Chen
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Jiang, Zheng
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Kuznetsov, Vladimir
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Al-mergren, Hamid
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Alkinany, Mohammad
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Aldrees, Saud
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Xiao, Tiancun
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Edwards, Peter P.
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Liu, Bonan
aee83a08-ec61-43b1-a1c4-219d50c0df28
France, Liam
1a6963e8-01ea-4c89-8604-3e70069e1330
Wu, Chen
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Jiang, Zheng
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Kuznetsov, Vladimir
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Al-mergren, Hamid
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Alkinany, Mohammad
24cf4777-c32f-4d5b-8229-8178891442f0
Aldrees, Saud
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Xiao, Tiancun
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Edwards, Peter P.
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Liu, Bonan, France, Liam, Wu, Chen, Jiang, Zheng, Kuznetsov, Vladimir, Al-mergren, Hamid, Alkinany, Mohammad, Aldrees, Saud, Xiao, Tiancun and Edwards, Peter P.
(2015)
Methanol-to-hydrocarbons conversion over MoO3/H-ZSM-5 catalysts prepared via lower temperature calcination: a route to tailor the distribution and evolution of promoter Mo species, and their corresponding catalytic properties.
Chemical Science, .
(doi:10.1039/C5SC01825K).
Abstract
A series of MoO3/H-ZSM-5 (Si/Al=25) catalysts were prepared via calcination at a lower-than-usual temperature (400 oC) and subsequently evaluated in the methanol-to-hydrocarbon reaction at that same temperature. The catalytic properties of those catalysts were compared with the sample prepared at the more conventional, higher temperature of 500 oC. For the lower temperature preparations, molybdenum oxide was preferentially dispersed over the zeolite external surface, while only the higher loading level of MoO3 (7.5 wt% or higher) led to observable inner migration of the Mo species into the zeolite channels, with concomitant partial loss of the zeolite Brønsted acidity. On the MoO3 modified samples, the early-period gas yield, especially for valuable propylene and C4 products, was noticeably accelerated, and is gradually converted into an enhanced liquid aromatic formation. The 7.5 wt% MoO3/H-ZSM-5 sample prepared at 400oC thereby achieved a balance between the zeolite surface dispersion of Mo species, their inner channel migration and the corresponding effect on the intrinsic Brønsted acidity of the acidic zeolite. That loading level also possessed the highest product selectivity (after 5h reaction) to benzene, toluene and xylenes, as well as higher early-period valuable gas product yields in time-on-stream experiments. However, MoO3 loading levels of 7.5wt% and above also resulted in earlier catalyst deactivation by enhanced coke accumulation at, or near, the zeolite channel openings. Our research illustrates that the careful adoption of moderate/lower temperature dispersion processes for zeolite catalyst modification gives considerable potential for tailoring and optimizing the system’s catalytic performance
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Accepted/In Press date: 6 June 2015
e-pub ahead of print date: 11 June 2015
Organisations:
Faculty of Engineering and the Environment
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Local EPrints ID: 378350
URI: http://eprints.soton.ac.uk/id/eprint/378350
ISSN: 1478-6524
PURE UUID: f755f1d8-e7c5-474d-8f7e-5acec27c5180
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Date deposited: 02 Jul 2015 08:46
Last modified: 15 Mar 2024 03:47
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Contributors
Author:
Bonan Liu
Author:
Liam France
Author:
Chen Wu
Author:
Vladimir Kuznetsov
Author:
Hamid Al-mergren
Author:
Mohammad Alkinany
Author:
Saud Aldrees
Author:
Tiancun Xiao
Author:
Peter P. Edwards
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