transition state energy
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2019 ◽  
Author(s):  
Yongjie Xi ◽  
Andreas Heyden

Direct methane to methanol (MTM) conversion over heterogeneous catalysts is a promising route for valorization of methane. The methane C-H bond activation is considered as the key step of the MTM and is the focus of considerable research activity. However, the formed methanol typically suffers from overoxidation largely due to the cleavage of a methanol C-H bond, whose bond dissociation energy is ca. 0.5 eV lower than that of the methane C-H bond, which usually translates to a transition state energy of the methanol C-H bond cleavage that is ca. 0.55 eV lower than that of methane whenever the reactions proceed through a radical mechanism. Here, we propose a general approach for decreasing the transition state energy difference between the CH4 and CH3OH C-H bond dissociation. When a metal-oxide supported cationic transition metal atom and a neighboring oxygen on the oxide surface serve as the active site, the transition state energy difference through a surface-stabilized pathway can be noticeably narrowed as compared with that of a radical pathway.


2019 ◽  
Author(s):  
Yongjie Xi ◽  
Andreas Heyden

Direct methane to methanol (MTM) conversion over heterogeneous catalysts is a promising route for valorization of methane. The methane C-H bond activation is considered as the key step of the MTM and is the focus of considerable research activity. However, the formed methanol typically suffers from overoxidation largely due to the cleavage of a methanol C-H bond, whose bond dissociation energy is ca. 0.5 eV lower than that of the methane C-H bond, which usually translates to a transition state energy of the methanol C-H bond cleavage that is ca. 0.55 eV lower than that of methane whenever the reactions proceed through a radical mechanism. Here, we propose a general approach for decreasing the transition state energy difference between the CH4 and CH3OH C-H bond dissociation. When a metal-oxide supported cationic transition metal atom and a neighboring oxygen on the oxide surface serve as the active site, the transition state energy difference through a surface-stabilized pathway can be noticeably narrowed as compared with that of a radical pathway.


2019 ◽  
Vol 21 (45) ◽  
pp. 25328-25333 ◽  
Author(s):  
Hassan Aljama ◽  
Frank Abild-Pedersen

The search for catalysts that can efficiently convert large hydrocarbons has been an active area of research for decades.


2017 ◽  
Vol 4 (7) ◽  
pp. 1250-1260 ◽  
Author(s):  
Lei Zhang ◽  
De-Cai Fang

Effects of directing groups on the C–H activation transition state.


2012 ◽  
Vol 109 (44) ◽  
pp. 17795-17799 ◽  
Author(s):  
B. G. Wensley ◽  
L. G. Kwa ◽  
S. L. Shammas ◽  
J. M. Rogers ◽  
S. Browning ◽  
...  

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