Investigating the Influence of Mesoporosity in Zeolite Beta on its Catalytic Performance for the Conversion of Methanol to Hydrocarbons

Handle URI:
http://hdl.handle.net/10754/576101
Title:
Investigating the Influence of Mesoporosity in Zeolite Beta on its Catalytic Performance for the Conversion of Methanol to Hydrocarbons
Authors:
Liu, Zhaohui; Dong, Xinglong ( 0000-0001-6478-8819 ) ; Zhu, Yihan; Emwas, Abdul-Hamid M.; Zhang, Daliang; Tian, Qiwei ( 0000-0002-4709-7378 ) ; Han, Yu ( 0000-0003-1462-1118 )
Abstract:
Hierarchically porous zeolite Beta (Beta-MS) synthesized by a soft-templating method contains remarkable intra-crystalline mesoporosity, which reduces the diffusion length in zeolite channels down to several nanometers and alters the distribution of Al among distinct crystallographic sites. When used as a catalyst for the conversion of methanol to hydrocarbons (MTH) at 330 oC, Beta-MS exhibited a 2.7-fold larger conversion capacity, a 2.0-fold faster reaction rate, and a remarkably longer lifetime than conventional zeolite Beta (Beta-C). The superior catalytic performance of Beta-MS is attributed to its hierarchical structure, which offers full accessibility to all catalytic active sites. In contrast, Beta-C was easily deactivated because a layer of coke quickly deposited on the outer surfaces of the catalyst crystals, impeding access to interior active sites. This difference is clearly demonstrated by using electron microscopy combined with electron energy loss spectroscopy to probe the distribution of coke in the deactivated catalysts. At both low and high conversions, ranging from 20% to 100%, Beta-MS gave higher selectivity towards higher aliphatics (C4-C7) but lower ethene selectivity compared to Beta-C. Therefore, we conclude that a hierarchical structure decreases the residence time of methylbenzenes in zeolite micropores, disfavoring the propagation of the aromatic-based catalytic cycle. This conclusion is consistent with a recent report on ZSM-5 and is also strongly supported by our analysis of soluble coke species residing in the catalysts. Moreover, we identified an oxygen-containing compound, 4-methyl-benzaldehyde, in the coke, which has not been observed in the MTH reaction before.  
KAUST Department:
Advanced Membranes and Porous Materials Research Center; Physical Sciences and Engineering (PSE) Division; Imaging and Characterization Core Lab
Citation:
Investigating the Influence of Mesoporosity in Zeolite Beta on its Catalytic Performance for the Conversion of Methanol to Hydrocarbons 2015:150826134504006 ACS Catalysis
Publisher:
American Chemical Society (ACS)
Journal:
ACS Catalysis
Issue Date:
26-Aug-2015
DOI:
10.1021/acscatal.5b01350
Type:
Article
ISSN:
2155-5435; 2155-5435
Additional Links:
http://pubs.acs.org/doi/10.1021/acscatal.5b01350
Appears in Collections:
Articles; Advanced Membranes and Porous Materials Research Center; Advanced Nanofabrication, Imaging and Characterization Core Lab; Physical Sciences and Engineering (PSE) Division; Physical Sciences and Engineering (PSE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorLiu, Zhaohuien
dc.contributor.authorDong, Xinglongen
dc.contributor.authorZhu, Yihanen
dc.contributor.authorEmwas, Abdul-Hamid M.en
dc.contributor.authorZhang, Daliangen
dc.contributor.authorTian, Qiweien
dc.contributor.authorHan, Yuen
dc.date.accessioned2015-08-31T14:24:11Zen
dc.date.available2015-08-31T14:24:11Zen
dc.date.issued2015-08-26en
dc.identifier.citationInvestigating the Influence of Mesoporosity in Zeolite Beta on its Catalytic Performance for the Conversion of Methanol to Hydrocarbons 2015:150826134504006 ACS Catalysisen
dc.identifier.issn2155-5435en
dc.identifier.issn2155-5435en
dc.identifier.doi10.1021/acscatal.5b01350en
dc.identifier.urihttp://hdl.handle.net/10754/576101en
dc.description.abstractHierarchically porous zeolite Beta (Beta-MS) synthesized by a soft-templating method contains remarkable intra-crystalline mesoporosity, which reduces the diffusion length in zeolite channels down to several nanometers and alters the distribution of Al among distinct crystallographic sites. When used as a catalyst for the conversion of methanol to hydrocarbons (MTH) at 330 oC, Beta-MS exhibited a 2.7-fold larger conversion capacity, a 2.0-fold faster reaction rate, and a remarkably longer lifetime than conventional zeolite Beta (Beta-C). The superior catalytic performance of Beta-MS is attributed to its hierarchical structure, which offers full accessibility to all catalytic active sites. In contrast, Beta-C was easily deactivated because a layer of coke quickly deposited on the outer surfaces of the catalyst crystals, impeding access to interior active sites. This difference is clearly demonstrated by using electron microscopy combined with electron energy loss spectroscopy to probe the distribution of coke in the deactivated catalysts. At both low and high conversions, ranging from 20% to 100%, Beta-MS gave higher selectivity towards higher aliphatics (C4-C7) but lower ethene selectivity compared to Beta-C. Therefore, we conclude that a hierarchical structure decreases the residence time of methylbenzenes in zeolite micropores, disfavoring the propagation of the aromatic-based catalytic cycle. This conclusion is consistent with a recent report on ZSM-5 and is also strongly supported by our analysis of soluble coke species residing in the catalysts. Moreover, we identified an oxygen-containing compound, 4-methyl-benzaldehyde, in the coke, which has not been observed in the MTH reaction before.  en
dc.language.isoenen
dc.publisherAmerican Chemical Society (ACS)en
dc.relation.urlhttp://pubs.acs.org/doi/10.1021/acscatal.5b01350en
dc.rightsThis document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Catalysis, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/10.1021/acscatal.5b01350.en
dc.titleInvestigating the Influence of Mesoporosity in Zeolite Beta on its Catalytic Performance for the Conversion of Methanol to Hydrocarbonsen
dc.typeArticleen
dc.contributor.departmentAdvanced Membranes and Porous Materials Research Centeren
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentImaging and Characterization Core Laben
dc.identifier.journalACS Catalysisen
dc.eprint.versionPost-printen
dc.contributor.affiliationKing Abdullah University of Science and Technology (KAUST)en
kaust.authorLiu, Zhaohuien
kaust.authorDong, Xinglongen
kaust.authorZhu, Yihanen
kaust.authorEmwas, Abdul-Hamid M.en
kaust.authorZhang, Daliangen
kaust.authorTian, Qiweien
kaust.authorHan, Yuen
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