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dc.contributor.author
Wang, Zichun
dc.contributor.author
Jiang, Yijiao
dc.contributor.author
Baiker, Alfons
dc.contributor.author
Huang, Jun
dc.date.accessioned
2021-02-18T08:48:25Z
dc.date.available
2021-01-30T03:32:43Z
dc.date.available
2021-02-18T08:48:25Z
dc.date.issued
2020-11-17
dc.identifier.issn
0001-4842
dc.identifier.issn
1520-4898
dc.identifier.other
10.1021/acs.accounts.0c00459
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/466839
dc.description.abstract
Conspectus Silica–alumina catalysts, including zeolites and amorphous silica–aluminas (ASAs), are among the most widely used solid acid catalysts and supports to produce petrochemicals, fine chemicals, and renewable energy. The coordination, distribution, and interactions of aluminum in ASAs have an enormous impact on their acidic properties and catalytic performance. Unsaturated tetracoordinated aluminum (AlIV) species are commonly accepted as the key sites in generating catalytically active Brønsted acid sites (BASs) in silica–alumina catalysts. Extensive efforts focus on increasing the concentration of AlIV as the main route to enhance their Brønsted acidity for efficient catalysis. However, increasing the AlIV concentration either weakens the acid strength in zeolites or lowers Brønsted acidity in ASAs at high Al/Si ratios, impeding acidity enhancement of these popular catalysts. “Pentacoordinated aluminum (AlV) species” are potential unsaturated Al species like AlIV but rarely observed in silica–aluminas, and thus, are widely considered unavailable for BAS formation or surface reactions. In this Account, we will describe novel strategies for the controlled synthesis of AlV-enriched ASAs using flame-spray pyrolysis (FSP) techniques and highlight the contribution of AlV species in acidity enhancement, together with their structure–activity relationship in the conversion of biomass-derived compounds into valuable chemicals. Using various in situ and advanced 2D solid-state NMR (SSNMR) experiments, the studies of the acidic properties and local structure of AlV-enriched ASAs reveal that AlV species can highly populate on ASA surfaces, promote BASs formation, and facilitate adaptable tuning of BASs from moderate to zeolitic strength by synergy with neighboring Al sites. Moreover, the BASs with enhanced acidity can work jointly with surface Lewis acid sites or metal active species for bifunctional catalysis on AlV-enriched ASAs. Compared to zeolites, these AlV-enriched ASAs are highly active in acid-catalyzed biomass conversion, including alcohol dehydration and sugar conversion reactions, as well as in promoting the performance of supported metal catalysts in chemoselective hydrogenation of aromatic ketones. These new insights provide a state-of-the-art strategy for strongly enhancing the acidity of these popular silica–alumina catalysts, which offers an interesting potential for a wide range of acid and multifunctional catalysis.
en_US
dc.language.iso
en
en_US
dc.publisher
American Chemical Society
en_US
dc.title
Pentacoordinated Aluminum Species: New Frontier for Tailoring Acidity-Enhanced Silica–Alumina Catalysts
en_US
dc.type
Review Article
dc.date.published
2020-10-22
ethz.journal.title
Accounts of Chemical Research
ethz.journal.volume
53
en_US
ethz.journal.issue
11
en_US
ethz.journal.abbreviated
Acc. chem. res.
ethz.pages.start
2648
en_US
ethz.pages.end
2658
en_US
ethz.identifier.wos
ethz.publication.place
Washington, DC
en_US
ethz.publication.status
published
en_US
ethz.date.deposited
2021-01-30T03:32:47Z
ethz.source
WOS
ethz.eth
yes
en_US
ethz.availability
Metadata only
en_US
ethz.rosetta.installDate
2021-02-18T08:48:41Z
ethz.rosetta.lastUpdated
2021-02-18T08:48:41Z
ethz.rosetta.versionExported
true
ethz.COinS
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