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Ethylbenzene (EB) oxidation to oxygenated products catalyzed by carbon nanotubes (CNTs) and CNTs with confined cobalt nanoparticles (Co@C/CNTs) are conducted. Co@C/CNTs with enhanced interfacial charge transfer displays a unique activity. A kinetic model with the simplified network is established, in which seven elementary reactions with prominent features of EB oxidation are selected. The main parameters, reaction rate constant (k) and active energy (Ea) are obtained. Co@C/CNTs could speed up most elementary steps and reduce energy barriers, thus improving the overall activity. The homolytic cleavage of peroxide is confirmed to be the rate‐determining step (RDS). The k ratio (1.55) of acetophenone (AcPO)/1‐phenylethyl alcohol (PEA) is found to be close to the experimental result (rAcPO/rPEA, 1.30). The prediction of EB oxidation is simulated, showing that the synthesis of AcPO dominates the reaction route, while the addition of PEA would prohibit the reaction. [ABSTRACT FROM AUTHOR]

Aerobic oxidation of hydrocarbons yielding corresponding oxygenated products is one of the most important chemical processes. In current work, carbon nanotubes supported encapsulated cobalt nanoparticles with carbon layers (Co@C/CNTs) were synthesized and utilized as catalysts in the oxidation of ethylbenzene (EB) in the liquid phase, exhibiting high catalytic performance. The synergistic effect between Co@C and CNTs played the vital role on facilitating the decomposition of peroxides to enhance the overall activity. The inadequate covered Co@C on CNTs surface were considered as catalytic sites. Density functional theory revealed that the exist of Co nanoparticles could improve the interaction between the catalyst and intermediate free radicals, which were significant for EB oxidation. Last but not least, the electron transfer on carbon surface was enhanced by the incorporation of Co@C nanoparticles, which greatly improved the catalytic performance on EB oxidation. This study provides a new insight into the Co‐based catalysts in the aerobic oxidation of hydrocarbons. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) have excellent catalytic activity in liquid phase reaction, especially in aerobic oxidation of cumene. In previous work, the conversion of cumene was 41.8% and the selectivity of cumene hydroperoxide was 71.5%, which was catalyzed by CNTs. But a small amount of impurity Zn2+ totally blocked up the aerobic oxidation of cumene that catalyzed by CNTs, which is an unexpected discovery. By analyzing the catalytic mechanism of CNTs, the inhibition effect of Zn2+ is locked on the abstraction of H atom from cumene. The inhibition of Zn2+ is confirmed in two effects by density functional theory calculations. First, due to the strongly coordination of active oxygen species (ROS) by Zn2+, the energy barrier of initial reaction increases to 1.90 eV, which is nearly 4 times higher than that of the only ROS promoted‐process. Second, the interaction of Zn2+ and RO· or ROO· to inhibits the chain propagation reaction of free radicals. This work precisely demonstrates that the inhibition effect of Zn2+ on initial reaction of cumene. The most significant thing is that the effect of metallic heteroatoms is not negligible in organic oxidation reaction. [ABSTRACT FROM AUTHOR]

The electrooxidation of methanol – the anodic reaction of direct methanol fuel cells – suffers from slow kinetics. Here, we report an enhanced current density for a Pt catalyst supported on nitrogen‐doped carbon nanotube (N−CNT) decorated FeP. X‐ray photoelectron spectra show that the introduction of FeP increases the binding energy of the Pt nanoparticles. The results show that Pt/FeP15%/N−CNT displays a 3.4 times higher forward peak current density compared to commercial Pt/C. The improved performance is attributed to a change in the electronic state of the Pt nanoparticles through the electronic interaction between Pt and FeP, evidenced by the mitigated CO poisoning. [ABSTRACT FROM AUTHOR]

Selective aerobic oxidation of hydrocarbons undergoes a free‐radical chain reaction to yield corresponding value‐added products is the significant process in the chemical industry. Nanocarbons with heteroatoms doping as free‐metal catalysts have been proved to be excellent alternatives in various fields of reactions. In this work, nitrogen doped carbon nanotubes (NCNTs) were applied for the aerobic oxidation of ethylbenzene (EB) in the liquid‐phase. The catalytic performance was unexpectedly suppressed, even lower than the control experiment, which is totally different from earlier publications. Mechanistic studies demonstrated that N doping would inhibit the abstraction of α‐H from EB molecule and end the radical propagation, thus suppressing the overall activity. Addition of TBHP would be helpful for the α‐H abstraction and forming alkyl radicals, which start the Franck‐Rabinowitch cage reaction and promote radical propagation in the presence of carbon catalysts. Herein, a higher catalytic efficiency with 46 % EB conversion and 72 % AcPO selectivity were obtained over NCNTs with O2 and TBHP as dual‐oxidants. [ABSTRACT FROM AUTHOR]

Cyclo[18]carbon (C18) as a special molecular allotrope of carbon composed of two‐coordinate carbon atoms has recently been manufactured and characterized by atomic manipulation. Herein, we analyze the electrochemical reduction characteristics of carbon dioxide (CO2) on typical carbon materials (graphene, C60, carbon nanotubes and C18) using density functional calculations. Encouragingly, C18 shows excellent CO2 reduction activity compared to other carbon materials. [ABSTRACT FROM AUTHOR]

In this study it is demonstrated that carbon nanotubes (CNTs) with doped nitrogen atoms in graphitic domains (NCNTs) can act as a new class of metal-free catalysts exhibiting excellent activity in the aerobic oxidation of cumene. We proved that NCNTs can promote the decomposition of hydroperoxide cumene with exceptionally high activity, resulting in strongly increased cumene conversion and extraordinarily high selectivity to acetophenone and 2-benzyl-2-propanol. The incorporation of nitrogen altered the surface electron structure of the CNTs and tuned the reactivity and selectivity. DFT calculations revealed that the remarkable improvement of catalytic performance of NCNTs is caused by the strong interaction between hydroperoxide cumene and the NCNTs. NCNTs also exhibited desirable recyclability after four cycling tests. This study not only provides a novel method for the cumene oxidation to high-value-added products at moderate reaction temperatures and oxygen atmospheric pressure, but also gives new insights into the effect of surface nitrogen doping on carbon-catalyzed liquid-phase oxidation of aromatic hydrocarbons. [ABSTRACT FROM AUTHOR]

As some of the most interesting metal-free catalysts, carbon nanotubes (CNTs) and other carbon-based nanomaterials show great promise for some important chemical reactions, such as the selective oxidation of cyclohexane (C6H12). Due to the lack of fundamental understanding of carbon catalysis in liquid-phase reactions, we have sought to unravel the role of CNTs in the catalytic oxidation of C6H12 through a combination of kinetic analysis, in situ spectroscopy, and density functional theory. The catalytic effect of CNTs originates from a weak interaction between radicals and their graphene skeletons, which confines the radicals around their surfaces. This, in turn, enhances the electron-transfer catalysis of peroxides to yield the corresponding alcohol and ketone. [ABSTRACT FROM AUTHOR]

It was reported for the first time that carbon nanotubes (CNTs) as metal-free catalyst exhibited an excellent activity in the selective oxidation of ethylbenzene (EB) to acetophenone (AcPO) in the liquid-phase with oxygen as the oxidant. The reasonable mechanism responsible for the liquid-phase oxidation of EB on CNTs was proposed. The results demonstrated that the CNTs played an important role in the decomposition of 1-phenylethyl hydroperoxide (PEHP) and contributed to the production of AcPO, owing to π-π interactions between the radical species and peroxides and the graphene sheets of the CNTs. Surface carboxylic groups of the CNTs were unfavorable to EB oxidation. Adsorption energies of the radical species and peroxides on pristine and modified CNTs with carboxylic groups were calculated by DFT. These theoretical calculations were well consistent with the experimental results, and also supported the presented mechanistic pathway of EB oxidation on CNTs. This study not only presents a facile and effective alternative to cobalt-based catalysts for the selective oxidation of EB to AcPO but also gives new insight into the effect of surface structures on carbon-catalyzed reactions, and further pushes forward the research on carbon catalysis. [ABSTRACT FROM AUTHOR]