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Yang Y, Shin YK, Ooe H, Yin X, Zhang X, van Duin ACT, Murase Y, Mauro JC. Aqueous Stability of Metal-Organic Frameworks Using ReaxFF-Based Metadynamics Simulations. J Phys Chem B 2023. [PMID: 37418387 DOI: 10.1021/acs.jpcb.3c00563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2023]
Abstract
Aqueous stability is a critical property for the application of metal-organic framework (MOF) materials in humid conditions. The sampling of the free energy surface for a water reaction is challenging due to a lack of a reactive force field. Here, we developed a ReaxFF force field for simulating the reaction of zeolitic imidazole frameworks (ZIFs) with water. We carried out metadynamics simulations based on ReaxFF to study the reaction of water with a few different types of MOFs. We also conducted an experimental water immersion test and characterized the XRD, TG, and gas adsorption properties of the MOFs before and after the immersion test. By considering the energy barrier for a hydrolysis reaction, the simulation results are in good agreement with the experiments. MOFs with open structures and large pores are found to be unstable in metadynamics simulations, where the water molecule can attack or bond with the metallic node relatively easily. In contrast, it is more difficult for water to attack the Zn atom in the ZnN4 tetrahedral structure of ZIFs. We also found that ZIFs with the -NO2 functional groups have higher water stability. Discrepancies between the metadynamics simulation and gas adsorption experiments have been accounted for from the phase/crystallinity change of the structure reflected in the X-ray diffraction and thermogravimetry analysis of the MOF samples.
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Affiliation(s)
- Yongjian Yang
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Yun Kyung Shin
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Hideaki Ooe
- Murata Manufacturing Co., Ltd., 1-10-1, Higashikotari, Nagaokakyo, Kyoto 617-8555, Japan
| | - Xinyang Yin
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Xueyi Zhang
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Adri C T van Duin
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Yasuhiro Murase
- Murata Manufacturing Co., Ltd., 1-10-1, Higashikotari, Nagaokakyo, Kyoto 617-8555, Japan
| | - John C Mauro
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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Ahmad W, Koley P, Dwivedi S, Lakshman R, Shin YK, van Duin ACT, Shrotri A, Tanksale A. Aqueous phase conversion of CO 2 into acetic acid over thermally transformed MIL-88B catalyst. Nat Commun 2023; 14:2821. [PMID: 37198184 DOI: 10.1038/s41467-023-38506-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 05/05/2023] [Indexed: 05/19/2023] Open
Abstract
Sustainable production of acetic acid is a high priority due to its high global manufacturing capacity and numerous applications. Currently, it is predominantly synthesized via carbonylation of methanol, in which both the reactants are fossil-derived. Carbon dioxide transformation into acetic acid is highly desirable to achieve net zero carbon emissions, but significant challenges remain to achieve this efficiently. Herein, we report a heterogeneous catalyst, thermally transformed MIL-88B with Fe0 and Fe3O4 dual active sites, for highly selective acetic acid formation via methanol hydrocarboxylation. ReaxFF molecular simulation, and X-ray characterisation results show a thermally transformed MIL-88B catalyst consisting of highly dispersed Fe0/Fe(II)-oxide nanoparticles in a carbonaceous matrix. This efficient catalyst showed a high acetic acid yield (590.1 mmol/gcat.L) with 81.7% selectivity at 150 °C in the aqueous phase using LiI as a co-catalyst. Here we present a plausible reaction pathway for acetic acid formation reaction via a formic acid intermediate. No significant difference in acetic acid yield and selectivity were noticed during the catalyst recycling study up to five cycles. This work is scalable and industrially relevant for carbon dioxide utilisation to reduce carbon emissions, especially when green methanol and green hydrogen are readily available in future.
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Affiliation(s)
- Waqar Ahmad
- Department of Chemical and Biological Engineering, Monash University, Clayton, 3800, Australia
| | - Paramita Koley
- Department of Chemical and Biological Engineering, Monash University, Clayton, 3800, Australia
| | - Swarit Dwivedi
- Department of Chemical and Biological Engineering, Monash University, Clayton, 3800, Australia
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Rajan Lakshman
- Department of Chemical and Biological Engineering, Monash University, Clayton, 3800, Australia
| | - Yun Kyung Shin
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Adri C T van Duin
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Abhijit Shrotri
- Institute for Catalysis, Hokkaido University, Sapporo, 001-0021, Japan
| | - Akshat Tanksale
- Department of Chemical and Biological Engineering, Monash University, Clayton, 3800, Australia.
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Hypocrystalline ceramic aerogels for thermal insulation at extreme conditions. Nature 2022; 606:909-916. [PMID: 35768591 PMCID: PMC9242853 DOI: 10.1038/s41586-022-04784-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 04/20/2022] [Indexed: 01/07/2023]
Abstract
Thermal insulation under extreme conditions requires materials that can withstand complex thermomechanical stress and retain excellent thermal insulation properties at temperatures exceeding 1,000 degrees Celsius1–3. Ceramic aerogels are attractive thermal insulating materials; however, at very high temperatures, they often show considerably increased thermal conductivity and limited thermomechanical stability that can lead to catastrophic failure4–6. Here we report a multiscale design of hypocrystalline zircon nanofibrous aerogels with a zig-zag architecture that leads to exceptional thermomechanical stability and ultralow thermal conductivity at high temperatures. The aerogels show a near-zero Poisson’s ratio (3.3 × 10−4) and a near-zero thermal expansion coefficient (1.2 × 10−7 per degree Celsius), which ensures excellent structural flexibility and thermomechanical properties. They show high thermal stability with ultralow strength degradation (less than 1 per cent) after sharp thermal shocks, and a high working temperature (up to 1,300 degrees Celsius). By deliberately entrapping residue carbon species in the constituent hypocrystalline zircon fibres, we substantially reduce the thermal radiation heat transfer and achieve one of the lowest high-temperature thermal conductivities among ceramic aerogels so far—104 milliwatts per metre per kelvin at 1,000 degrees Celsius. The combined thermomechanical and thermal insulating properties offer an attractive material system for robust thermal insulation under extreme conditions. Hypocrystalline ceramic aerogels with a zig-zag architecture show high thermal stability under thermal shock and exposure to high temperature, providing a reliable material system for thermal insulation at extreme conditions.
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