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Rawal P, Gupta P. Unidentical Twins: Geometrically Similar but Chemically Distinct Metal-Free Sites in Boron Oxide for Methane Oxidation to HCHO, CO and CO 2. Chemistry 2024; 30:e202401050. [PMID: 38606609 DOI: 10.1002/chem.202401050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 04/12/2024] [Accepted: 04/12/2024] [Indexed: 04/13/2024]
Abstract
Metal-free boron-based catalysts such as boron oxide (B2O3) and boron nitride (h-BN) are promising catalysts for methane oxidation to HCHO and CO. The B2O3 catalyst contains various probable boron sites (B1 to B6), which may be responsible for methane oxidation. In this work, we utilized density functional theory to compare two relevant geometrically identical boron sites (B2 and B4) for their reactivities. The two sites are explored in-detail for the conversion of methane to formaldehyde (M2F), carbon monoxide and carbon dioxide. The B4 site activates the methane C-H bond easily as compared to the B2 site. In M2F conversion, the rate-determining step for the B2 site is the co-activation of dioxygen and methane, whereas over the B4 site, formaldehyde formation is the rate-determining step. The computationally-determined RDS for the B4 site coincides well with the reported experiments. It is further revealed that this site also prefers the formation of CO over CO2, which is in-line with the experiments in literature. It is also shown through orbital analysis that methanol formation does not occur during methane oxidation. We employed descriptors such as condensed Fukui functions and global electrophilicity index to chemically distinct these twin sites.
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Affiliation(s)
- Parveen Rawal
- Computational Catalysis Center, Department of Chemistry, Indian Institute of Technology Roorkee, 247667, Roorkee, Uttarakhand, India
| | - Puneet Gupta
- Computational Catalysis Center, Department of Chemistry, Indian Institute of Technology Roorkee, 247667, Roorkee, Uttarakhand, India
- Center for Sustainable Energy, Indian Institute of Technology Roorkee, 247667, Roorkee, Uttarakhand, India
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2
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Zhou H, Chen F, Liu D, Qin X, Jing Y, Zhong C, Shi R, Liu Y, Zhang J, Zhu Y, Wang J. Boosting Reactive Oxygen Species Formation Over Pd and VO δ Co-Modified TiO 2 for Methane Oxidation into Valuable Oxygenates. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2311355. [PMID: 38363051 DOI: 10.1002/smll.202311355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 02/06/2024] [Indexed: 02/17/2024]
Abstract
Direct photocatalytic methane oxidation into value-added products provides a promising strategy for methane utilization. However, the inefficient generation of reactive oxygen species (ROS) partly limits the activation of CH4. Herein, it is reported that Pd and VOδ co-modified TiO2 enables direct and selective methane oxidation into liquid oxygenates in the presence of O2 and H2. Due to the extra ROS production from the in situ formed H2O2, a highly improved yield rate of 5014 µmol g-1 h-1 for liquid oxygenates with a selectivity of 89.3% is achieved over the optimized Pd0.5V0.2-TiO2 catalyst at ambient temperature, which is much better than those (2682 µmol g-1 h-1, 77.8%) without H2. Detailed investigations also demonstrate the synergistic effect between Pd and VOδ species for enhancing the charge carrier separation and transfer, as well as improving the catalytic activity for O2 reduction and H2O2 production.
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Affiliation(s)
- Huanyu Zhou
- College of Materials Science and Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
- Jiangsu Collaborative Innovation Centre for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing, 211816, China
| | - Fan Chen
- College of Materials Science and Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
- Jiangsu Collaborative Innovation Centre for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing, 211816, China
| | - Dandan Liu
- College of Materials Science and Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
- Jiangsu Collaborative Innovation Centre for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing, 211816, China
| | - Xin Qin
- College of Materials Science and Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
- Jiangsu Collaborative Innovation Centre for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing, 211816, China
| | - Yangchi Jing
- College of Materials Science and Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
- Jiangsu Collaborative Innovation Centre for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing, 211816, China
| | - Chenyu Zhong
- College of Materials Science and Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
- Jiangsu Collaborative Innovation Centre for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing, 211816, China
| | - Rui Shi
- College of Materials Science and Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
- Jiangsu Collaborative Innovation Centre for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing, 211816, China
| | - Yana Liu
- College of Materials Science and Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
- Jiangsu Collaborative Innovation Centre for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing, 211816, China
| | - Jiguang Zhang
- College of Materials Science and Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
- Jiangsu Collaborative Innovation Centre for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing, 211816, China
| | - Yunfeng Zhu
- College of Materials Science and Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
- Jiangsu Collaborative Innovation Centre for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing, 211816, China
| | - Jun Wang
- College of Materials Science and Engineering, Nanjing Tech University, 30 South Puzhu Road, Nanjing, 211816, China
- Jiangsu Collaborative Innovation Centre for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing, 211816, China
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3
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Wang Y, Zhao W, Chen X, Ji Y, Zhu X, Chen X, Mei D, Shi H, Lercher JA. Methane-H 2S Reforming Catalyzed by Carbon and Metal Sulfide Stabilized Sulfur Dimers. J Am Chem Soc 2024; 146:8630-8640. [PMID: 38488522 PMCID: PMC10979457 DOI: 10.1021/jacs.4c00738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 03/02/2024] [Accepted: 03/05/2024] [Indexed: 03/28/2024]
Abstract
H2S reforming of methane (HRM) provides a potential strategy to directly utilize sour natural gas for the production of COx-free H2 and sulfur chemicals. Several carbon allotropes were found to be active and selective for HRM, while the additional presence of transition metals led to further rate enhancements and outstanding stability (e.g., Ru supported on carbon black). Most metals are transformed to sulfides, but the carbon supports prevent sintering under the harsh reaction conditions. Supported by theoretical calculations, kinetic and isotopic investigations with representative catalysts showed that H2S decomposition and the recombination of surface H atoms are quasi-equilibrated, while the first C-H bond scission is the kinetically relevant step. Theory and experiments jointly establish that dynamically formed surface sulfur dimers are responsible for methane activation and catalytic turnovers on sulfide and carbon surfaces that are otherwise inert without reaction-derived active sites.
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Affiliation(s)
- Yong Wang
- Department
of Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
- School
of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China
| | - Wenru Zhao
- School
of Materials Science and Engineering, Tiangong
University, Tianjin 300387, P. R. China
| | - Xiaofeng Chen
- Department
of Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Yinjie Ji
- Department
of Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
- Institute
for Integrated Catalysis, Pacific Northwest
National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
| | - Xilei Zhu
- Department
of Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Xiaomai Chen
- Department
of Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Donghai Mei
- School
of Materials Science and Engineering, Tiangong
University, Tianjin 300387, P. R. China
| | - Hui Shi
- School
of Chemistry and Chemical Engineering, Yangzhou
University, Yangzhou 225002, P. R. China
| | - Johannes A. Lercher
- Department
of Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
- Institute
for Integrated Catalysis, Pacific Northwest
National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
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Rawal P, Gupta P. Mapping the Catalytic-Space for the Reactivity of Metal-free Boron Nitride with O 2 for H 2O-Mediated Conversion of Methane to HCHO and CO. Chemistry 2024; 30:e202303371. [PMID: 38221895 DOI: 10.1002/chem.202303371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 12/31/2023] [Accepted: 01/15/2024] [Indexed: 01/16/2024]
Abstract
Transition-metal based catalysts have been widely employed to catalyze partial oxidation of light alkanes. Recently, metal-free hexagonal-boron nitride (h-BN) has emerged as a promising catalyst for the oxidation of CH4 to HCHO and CO; however, the intricate catalytic surface of h-BN at molecular and electronic levels remains inadequately understood. Key questions include how electron-deficient boron atoms in h-BN reduce O2, and whether the partial oxidation of methane over h-BN exhibits similarities to traditional transition-metal catalysts. In our study, we computationally-mapped in-detail the surface catalytic-space of h-BN for methane oxidation. We considered different structures of h-BN and show that these structures contain numerous sites for O2 binding and therefore various routes for methane oxidation are possible. The activation barriers for methane oxidation via various paths varies from ~83 to ~123 kcal mol-1. To comprehend the differences in activation barriers, we employed geometrical, orbital and distortion/interaction analysis (DIA). Orbital analysis reveals that methane activation over h-BN in presence of dioxygen follows a standard hydrogen atom transfer mechanism. It is also shown that water plays an intriguing role in reducing the barrier for HCHO and CO formation by acting as a bridge.
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Affiliation(s)
- Parveen Rawal
- Computational Catalysis Center, Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Puneet Gupta
- Computational Catalysis Center, Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
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