scholarly journals Approaches for Selective Oxidation of Methane to Methanol

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 194 ◽  
Author(s):  
Richa Sharma ◽  
Hilde Poelman ◽  
Guy B. Marin ◽  
Vladimir V. Galvita
Keyword(s):  
Selective Oxidation ◽  
Active Site ◽  
Density Functional ◽  
Spectroscopic Studies ◽  
Methane Activation ◽  
Chemical Looping ◽  
Intermediate Species ◽  
Functional Theory ◽  
Oxidation Of Methane ◽  
Industrial Standards

Methane activation chemistry, despite being widely reported in literature, remains to date a subject of debate. The challenges in this reaction are not limited to methane activation but extend to stabilization of the intermediate species. The low C-H dissociation energy of intermediates vs. reactants leads to CO2 formation. For selective oxidation, nature presents methane monooxygenase as a benchmark. This enzyme selectively consumes methane by breaking it down into methanol. To assemble an active site similar to monooxygenase, the literature reports Cu-ZSM-5, Fe-ZSM-5, and Cu-MOR, using zeolites and systems like CeO2/Cu2O/Cu. However, the trade-off between methane activation and methanol selectivity remains a challenge. Density functional theory (DFT) calculations and spectroscopic studies indicate catalyst reducibility, oxygen mobility, and water as co-feed as primary factors that can assist in enabling higher selectivity. The use of chemical looping can further improve selectivity. However, in all systems, improvements in productivity per cycle are required in order to meet the economical/industrial standards.

scholarly journals Experimental and theoretical investigation of oxidative methane activation on Pd–Pt catalysts

RSC Advances ◽  
2019 ◽  
Vol 9 (20) ◽  
pp. 11385-11395
Author(s):  
Wenjie Qi ◽  
Zehao Huang ◽  
Zheming Chen ◽  
Lijuan Fu ◽  
Zhigang Zhang
Keyword(s):  
Density Functional Theory ◽  
Theoretical Investigation ◽  
Active Site ◽  
Bimetallic Catalysts ◽  
Density Functional ◽  
Methane Activation ◽  
Pt Catalysts ◽  
Functional Theory ◽  
Rate Determining Step

Density functional theory and measurements of rate are used to provide evidence for the rate determining step and requirements of the active site for CH4 combustion on Pd–Pt bimetallic catalysts in five different distinct kinetic regimes.

scholarly journals Cation-exchanged zeolites for the selective oxidation of methane to methanol

2018 ◽  
Vol 8 (1) ◽  
pp. 114-123 ◽  
Author(s):  
Ambarish R. Kulkarni ◽  
Zhi-Jian Zhao ◽  
Samira Siahrostami ◽  
Jens K. Nørskov ◽  
Felix Studt
Keyword(s):  
Transition Metal ◽  
Selective Oxidation ◽  
Metal Cation ◽  
Active Site ◽  
Methane Activation ◽  
Transition Metal Cation ◽  
Trade Off ◽  
Oxidation Of Methane ◽  
Active Site Motif

Development of an ideal methane activation catalyst presents a trade-off between stability and reactivity of the active site that can be achieved by tuning the transition metal cation, active site motif and the zeolite topology.

scholarly journals Catalyzed Ethanol Chemical Looping Gasification Mechanism on the Perfect and Reduced Fe2O3 Surfaces

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1663
Author(s):  
Laixing Luo ◽  
Xing Zheng ◽  
Jianye Wang ◽  
Wu Qin ◽  
Xianbin Xiao ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Reaction Mechanism ◽  
Density Functional ◽  
Oxygen Carrier ◽  
Catalytic Decomposition ◽  
Density Functional Theory Calculations ◽  
Chemical Looping ◽  
Functional Theory ◽  
Barrier Energy ◽  
Gasification Technology

Biomass chemical looping gasification (CLG) is a novel gasification technology for hydrogen production, where the oxygen carrier (OC) transfers lattice oxygen to catalytically oxidize fuel into syngas. However, the OC is gradually reduced, showing different reaction activities in the CLG process. Fully understanding the CLG reaction mechanism of fuel molecules on perfect and reduced OC surfaces is necessary, for which the CLG of ethanol using Fe2O3 as the OC was introduced as the probe reaction to perform density functional theory calculations to reveal the decomposition mechanism of ethanol into the synthesis gas (including H2, CH4, ethylene, formaldehyde, acetaldehyde, and CO) on perfect and reduced Fe2O3(001) surfaces. When Fe2O3(001) is reduced to FeO0.375(001), the calculated barrier energy decreases and then increases again, suggesting that the reduction state around FeO(001) favors the catalytic decomposition of ethanol to produce hydrogen, which proves that the degree of reduction has an important effect on the CLG reaction.

scholarly journals Computational Study of Methane C–H Activation by Main Group and Mixed Main Group–Transition Metal Complexes

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2794
Author(s):  
Carly C. Carter ◽  
Thomas R. Cundari
Keyword(s):  
Transition Metal Complexes ◽  
Active Site ◽  
Density Functional ◽  
Computational Study ◽  
Divalent Metal ◽  
Main Group ◽  
Free Energies ◽  
Functional Theory ◽  
Activation Barriers ◽  
Experimental Values

In the present density functional theory (DFT) research, nine different molecules, each with different combinations of A (triel) and E (divalent metal) elements, were reacted to effect methane C–H activation. The compounds modeled herein incorporated the triels A = B, Al, or Ga and the divalent metals E = Be, Mg, or Zn. The results show that changes in the divalent metal have a much bigger impact on the thermodynamics and methane activation barriers than changes in the triels. The activating molecules that contained beryllium were most likely to have the potential for activating methane, as their free energies of reaction and free energy barriers were close to reasonable experimental values (i.e., ΔG close to thermoneutral, ΔG‡ ~30 kcal/mol). In contrast, the molecules that contained larger elements such as Zn and Ga had much higher ΔG‡. The addition of various substituents to the A–E complexes did not seem to affect thermodynamics but had some effect on the kinetics when substituted closer to the active site.

Insight into the active site and reaction mechanism for selective oxidation of methane to methanol using H2O2 on a Rh1/ZrO2 catalyst

2020 ◽  
Vol 44 (4) ◽  
pp. 1632-1639 ◽  
Author(s):  
Qi Zhao ◽  
Bing Liu ◽  
Yuebing Xu ◽  
Feng Jiang ◽  
Xiaohao Liu
Keyword(s):  
Reaction Mechanism ◽  
Selective Oxidation ◽  
Active Site ◽  
Oxidation Of Methane ◽  
Methanol Formation ◽  
Zro2 Catalyst ◽  
Insight Into

Five-coordinated Rh leads to the over-oxidation of CH4, while four-coordinated Rh stabilizes CH3 and facilitates methanol formation via the CH3OOH intermediate.

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