Brønsted acid sites based on penta-coordinated aluminum species

Zichun Wang; Yijiao Jiang; Olivier Lafon; Julien Trébosc; Kyung Duk Kim; Catherine Stampfl; Alfons Baiker; Jean Paul Amoureux; Jun Huang

doi:10.1038/ncomms13820

Brønsted acid sites based on penta-coordinated aluminum species

Zichun Wang, Yijiao Jiang, Olivier Lafon, Julien Trébosc, Kyung Duk Kim, Catherine Stampfl, Alfons Baiker, Jean Paul Amoureux, Jun Huang^*

^*Corresponding author for this work

School of Engineering

Research output: Contribution to journal › Article › peer-review

147 Citations (Scopus)

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Abstract

Zeolites and amorphous silica-alumina (ASA), which both provide Brønsted acid sites (BASs), are the most extensively used solid acid catalysts in the chemical industry. It is widely believed that BASs consist only of tetra-coordinated aluminum sites (Al^IV) with bridging OH groups in zeolites or nearby silanols on ASA surfaces. Here we report the direct observation in ASA of a new type of BAS based on penta-coordinated aluminum species (Al^V) by ²⁷Al-{¹ H} dipolar-mediated correlation two-dimensional NMR experiments at high magnetic field under magic-angle spinning. Both BAS-Al^IV and-Al^V show a similar acidity to protonate probe molecular ammonia. The quantitative evaluation of ¹H and ²⁷Al sites demonstrates that BAS-Al^V co-exists with BAS-Al^IV rather than replaces it, which opens new avenues for strongly enhancing the acidity of these popular solid acids.

Original language	English
Article number	13820
Pages (from-to)	1-5
Number of pages	5
Journal	Nature Communications
Volume	7
DOIs	https://doi.org/10.1038/ncomms13820
Publication status	Published - 15 Dec 2016

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Copyright the Author(s) 2016. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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@article{d338ef95458c4683a4a4130910be47c2,

title = "Br{\o}nsted acid sites based on penta-coordinated aluminum species",

abstract = "Zeolites and amorphous silica-alumina (ASA), which both provide Br{\o}nsted acid sites (BASs), are the most extensively used solid acid catalysts in the chemical industry. It is widely believed that BASs consist only of tetra-coordinated aluminum sites (AlIV) with bridging OH groups in zeolites or nearby silanols on ASA surfaces. Here we report the direct observation in ASA of a new type of BAS based on penta-coordinated aluminum species (AlV) by 27Al-\{1 H\} dipolar-mediated correlation two-dimensional NMR experiments at high magnetic field under magic-angle spinning. Both BAS-AlIV and-AlV show a similar acidity to protonate probe molecular ammonia. The quantitative evaluation of 1H and 27Al sites demonstrates that BAS-AlV co-exists with BAS-AlIV rather than replaces it, which opens new avenues for strongly enhancing the acidity of these popular solid acids.",

author = "Zichun Wang and Yijiao Jiang and Olivier Lafon and Julien Tr{\'e}bosc and \{Duk Kim\}, Kyung and Catherine Stampfl and Alfons Baiker and Amoureux, \{Jean Paul\} and Jun Huang",

note = "Copyright the Author(s) 2016. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.",

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doi = "10.1038/ncomms13820",

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T1 - Brønsted acid sites based on penta-coordinated aluminum species

AU - Wang, Zichun

AU - Jiang, Yijiao

AU - Lafon, Olivier

AU - Trébosc, Julien

AU - Duk Kim, Kyung

AU - Stampfl, Catherine

AU - Baiker, Alfons

AU - Amoureux, Jean Paul

AU - Huang, Jun

N1 - Copyright the Author(s) 2016. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

PY - 2016/12/15

Y1 - 2016/12/15

N2 - Zeolites and amorphous silica-alumina (ASA), which both provide Brønsted acid sites (BASs), are the most extensively used solid acid catalysts in the chemical industry. It is widely believed that BASs consist only of tetra-coordinated aluminum sites (AlIV) with bridging OH groups in zeolites or nearby silanols on ASA surfaces. Here we report the direct observation in ASA of a new type of BAS based on penta-coordinated aluminum species (AlV) by 27Al-{1 H} dipolar-mediated correlation two-dimensional NMR experiments at high magnetic field under magic-angle spinning. Both BAS-AlIV and-AlV show a similar acidity to protonate probe molecular ammonia. The quantitative evaluation of 1H and 27Al sites demonstrates that BAS-AlV co-exists with BAS-AlIV rather than replaces it, which opens new avenues for strongly enhancing the acidity of these popular solid acids.

AB - Zeolites and amorphous silica-alumina (ASA), which both provide Brønsted acid sites (BASs), are the most extensively used solid acid catalysts in the chemical industry. It is widely believed that BASs consist only of tetra-coordinated aluminum sites (AlIV) with bridging OH groups in zeolites or nearby silanols on ASA surfaces. Here we report the direct observation in ASA of a new type of BAS based on penta-coordinated aluminum species (AlV) by 27Al-{1 H} dipolar-mediated correlation two-dimensional NMR experiments at high magnetic field under magic-angle spinning. Both BAS-AlIV and-AlV show a similar acidity to protonate probe molecular ammonia. The quantitative evaluation of 1H and 27Al sites demonstrates that BAS-AlV co-exists with BAS-AlIV rather than replaces it, which opens new avenues for strongly enhancing the acidity of these popular solid acids.

UR - https://www.scopus.com/pages/publications/85006313114

UR - http://purl.org/au-research/grants/arc/DP150103842

U2 - 10.1038/ncomms13820

DO - 10.1038/ncomms13820

M3 - Article

C2 - 27976673

AN - SCOPUS:85006313114

SN - 2041-1723

VL - 7

SP - 1

EP - 5

JO - Nature Communications

JF - Nature Communications

M1 - 13820

ER -

Brønsted acid sites based on penta-coordinated aluminum species

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