This book focuses on theoretical and computational studies by the editor’s group on the direct hydroxylation of methane, which is one of the most challenging subjects in catalyst chemistry. These studies of more than 20 years include gas-phase reactions by transition-metal oxide ions, enzymatic reactions by two types of methane monooxygenase (soluble and particulate MMO), catalytic reactions by metal-exchanged zeolites, and methane C–H activation by metal oxide surfaces. Catalyst chemistry has been mostly empirical and based on enormous experimental efforts. The subject of the title has been tackled using the orbital interaction and computations based on extended Hückel, DFT, and band structure calculations. The strength of the theoretical studies is in the synergy between theory and experiment. Therefore, the group has close contacts with experimentalists in physical chemistry, catalyst chemistry, bioinorganic chemistry, inorganic chemistry, and surface chemistry. This resulting book will be useful for the theoretical analysis and design of catalysts.
Author(s): Kazunari Yoshizawa (Editor)
Edition: 1, 2020 Ed.
Publisher: Springer
Year: 2020
Language: English
Pages: 167
Contents
Orbital Concept for Methane Activation
1 Introduction
2 C–H Bond Activation of Methane
2.1 Molecular Orbitals of Methane
2.2 Orbital Concept for Methane Activation Based on Second-Order Perturbation
2.3 Methane Activation by sMMO Model
3 Reaction Mechanism for the Direct Hydroxylation of Methane
3.1 Methane Hydroxylation by the FeO+ Species
3.2 Methane Hydroxylation Mechanisms by sMMO
3.3 Methane Hydroxylation Mechanisms by pMMO
4 Conclusions
References
Theoretical Study of the Direct Conversion of Methane by First-Row Transition-Metal Oxide Cations in the Gas Phase
1 Introduction
2 Electronic Structures of MO+ Ions
3 Potential-Energy Diagrams for the Methane-To-Methanol Conversion
3.1 Conversion of Methane to Methanol by ScO+, TiO+, and VO+
3.2 Conversion of Methane to Methanol by CrO+ and MnO+
3.3 Conversion of Methane to Methanol by FeO+, CoO+, and NiO+
3.4 Conversion of Methane to Methanol by CuO+
4 Surface Crossing and Spin–Orbit Coupling
4.1 Crossing Seams of Potential-Energy Surfaces
4.2 Spin–Orbit Coupling of Methane Conversion
5 Summary
References and Notes
Enzymatic Methane Hydroxylation: sMMO and pMMO
1 Experimental Background
2 History of Computational Approach
3 Key Factors in Determining Reactivity of MMOHQ Toward Methane
4 Proposed Mechanisms for the Methane to Methanol Conversion by MMOHQ
5 Details in Mechanisms for the Methane Hydroxylation by MMOHQ
5.1 Nonradical Mechanism
5.2 Radical Rebound Mechanism
5.3 Nonsynchronous Concerted Mechanism
6 Mechanism for Methane Hydroxylation on pMMO
7 Conclusions, Emerging Issues, and Challenges
References and Notes
Mechanistic Understanding of Methane Hydroxylation by Cu-Exchanged Zeolites
1 Introduction
2 Methane Hydroxylation by [Cu2(μ-O)]2+ and [Cu3(μ-O)3]2+ in Zeolites
2.1 Mechanism of C–H Activation
2.2 Mechanism of CH3OH Formation
3 Conclusion
References
Oxidative Activation of Metal-Exchanged Zeolite Catalysts for Methane Hydroxylation
1 Introduction
2 Oxidative Activation of Fe-Exchanged Zeolites
2.1 N2O Decomposition on FeII-ZSM-5
2.2 H2O2 Decomposition on [FeIII–(μO)2–FeIII]-ZSM-5
3 Oxidative Activation of Cu-Exchanged Zeolites
3.1 N2O Decomposition on 2CuI-ZSM-5
3.2 O2 Activation on 2[CuI2]-MOR and [CuIII2CuI(ΜO)]-MOR
4 Conclusion
References
Dynamics and Energetics of Methane on the Surfaces of Transition Metal Oxides
1 Introduction
2 Kinetics of Methane on Surface
2.1 Langmuir Model
2.2 Two Mechanisms: Direct Mechanism and Trapping-Mediated Mechanism
3 Energetics of Methane on Surface
3.1 How Strongly Methane Can be Adsorbed on the Surface?
3.2 PdO, IrO2, and RuO2
3.3 Adsorption of Methane on a Metal Oxide
3.4 C–H Bond Dissociation of Methane on a Metal Oxide Surface
4 Conclusions and Outlook
Appendix
References
Machine Learning Predictions of Adsorption Energies of CH4-Related Species
1 Introduction
2 Machine Learning Prediction of Adsorption Energies
2.1 DFT Calculations of Adsorption Energies
2.2 ML Methods
2.3 ML Prediction of Adsorption Energies
2.4 ML Prediction of ECH3–ECH2 Values for Methane Utilization
3 Conclusion
References
Theoretical Approach to Homogeneous Catalyst of Methane Hydroxylation: Collaboration with Computation and Experiment
1 Introduction
2 Computational Methods
3 Organometallic Approaches
4 Biomimetic Approaches
5 Theoretical Predictions for a Methane Hydroxylation Catalyst
6 Summary and Outlook
References
