TY - JOUR
T1 - Tailoring and identifying Brønsted acid sites on metal oxo-clusters of metal-organic frameworks for catalytic transformation
AU - Liang, Weibin
AU - Wang, Xuelong
AU - Yang, Wenjie
AU - Zhao, Shufang
AU - Wiley, Dianne
AU - Haynes, Brian S.
AU - Jiang, Yijiao
AU - Liu, Ping
AU - Huang, Jun
N1 - Copyright the Author(s) 2023. 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 - 2023/1/25
Y1 - 2023/1/25
N2 - Metal-organic frameworks (MOFs) with Brønsted acidity are an alternative solid acid catalyst for many important chemical and fuel processes. However, the nature of the Brønsted acidity on the MOF’s metal cluster or center is underexplored. To design and optimize the acid strength and density in these MOFs, it is important to understand the origin of their acidity at the molecular level. In the present work, isoreticular MOFs, ZrNDI and HfNDI (NDI = N,N′-bis(5-isophthalate)naphthalenediimide), were prepared as a prototypical system to unravel and compare their Brønsted and Lewis acid sites through an array of spectroscopic, computational, and catalytic characterization techniques. With the aid of solid-state nuclear magnetic resonance and density functional calculations, Hf6 oxo-clusters on HfNDI are quantitatively proved to possess a higher density Brønsted acid site, while ZrNDI-based MOFs display stronger and higher-population Lewis acidity. HfNDI-based MOFs exhibit a superior catalytic performance in activating dihydroxyacetone (DHA) and converting DHA to ethyl lactate, with 71.1% selectivity at 54.7% conversion after 6 h. The turnover frequency of BAS-dominated Hf-MOF in DHA conversion is over 50 times higher than that of ZSM-5, a strong BAS-based zeolite. It is worth noting that HfNDI is reported for the first time in the literature, which is an alternative platform catalyst for biorefining and green chemistry. The present study furthermore highlights the uniqueness of Hf-based MOFs in this important biomass-to-chemical transformation.[Graphic presents]
AB - Metal-organic frameworks (MOFs) with Brønsted acidity are an alternative solid acid catalyst for many important chemical and fuel processes. However, the nature of the Brønsted acidity on the MOF’s metal cluster or center is underexplored. To design and optimize the acid strength and density in these MOFs, it is important to understand the origin of their acidity at the molecular level. In the present work, isoreticular MOFs, ZrNDI and HfNDI (NDI = N,N′-bis(5-isophthalate)naphthalenediimide), were prepared as a prototypical system to unravel and compare their Brønsted and Lewis acid sites through an array of spectroscopic, computational, and catalytic characterization techniques. With the aid of solid-state nuclear magnetic resonance and density functional calculations, Hf6 oxo-clusters on HfNDI are quantitatively proved to possess a higher density Brønsted acid site, while ZrNDI-based MOFs display stronger and higher-population Lewis acidity. HfNDI-based MOFs exhibit a superior catalytic performance in activating dihydroxyacetone (DHA) and converting DHA to ethyl lactate, with 71.1% selectivity at 54.7% conversion after 6 h. The turnover frequency of BAS-dominated Hf-MOF in DHA conversion is over 50 times higher than that of ZSM-5, a strong BAS-based zeolite. It is worth noting that HfNDI is reported for the first time in the literature, which is an alternative platform catalyst for biorefining and green chemistry. The present study furthermore highlights the uniqueness of Hf-based MOFs in this important biomass-to-chemical transformation.[Graphic presents]
UR - http://www.scopus.com/inward/record.url?scp=85146164476&partnerID=8YFLogxK
UR - http://purl.org/au-research/grants/arc/DP180104010
U2 - 10.1021/acscentsci.2c01140
DO - 10.1021/acscentsci.2c01140
M3 - Article
C2 - 36712491
AN - SCOPUS:85146164476
SN - 2374-7943
VL - 9
SP - 27
EP - 35
JO - ACS Central Science
JF - ACS Central Science
IS - 1
ER -