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Highlights: [•] Carbon nanotubes (CNTs) exhibits high activity for cumene to cumene hydroperoxide. [•] Cumene oxidation catalyzed by CNTs is proved a radical-involved reaction. [•] The surface functional groups and defects are unfavorable for the catalytic activity. [•] CNTs as a metal-free catalyst for the liquid-phase oxidation displays good stability. [ABSTRACT FROM AUTHOR]

It has been widely documented that the oxygen-containing functionalities, especially carboxyl groups, on carbon surfaces play crucial roles in the catalytic wet air oxidation (CWAO) reactions. Herein, the CWAO of phenol with molecular O 2 as terminal oxidant using cylindrical and herringbone carbon nanotubes (CNTs) underwent different treatments as catalysts were conducted in batch mode. It was uncovered that the catalytic function of carboxyl groups strongly depended on the structure of CNTs. Parallel CNTs ( p -CNTs) with cylindrical graphitic walls displayed the highest catalytic activity after nitric acid oxidation, due to the carboxylated carbon debris (CDs) coating on surfaces. For herringbone CNTs ( h- CNTs), carboxyl groups are mostly linked to its sidewalls, where abundant edge carbons were exposed, providing an enhanced CWAO activity. The positively synergistic effect of carboxyl groups and adjacent edge carbons was responsible for the activation of O 2 , leading to the improved CWAO activity. This study provides a new insight into the structural effect of carbon materials on the CWAO of phenol. [ABSTRACT FROM AUTHOR]

A wide spectrum of, up to 22, organic solvents, including aprotic/protic aliphatics/aromatics, was studied to achieve a comprehensive understanding to the solvent effect on the cyclohexene oxidation. It was found that the catalytic activity was significantly influenced by the viscosity, polarity and basicity of solvents in this reaction. Among these solvents, the polar aprotic aliphatic solvents displayed higher catalytic reactivities than other types of solvents. A volcano curve was found describing the dependence of activity on solvent basicity because of the suitable stability of intermediates. Among the solvents investigated, acetonitrile afforded the highest activity and selectivity of 2-cyclohexen-1-one, because of a good compromise between strong polarity and moderate basicity. [ABSTRACT FROM AUTHOR]

In this study, carbon nanotubes (CNTs) supported Pt-cobalt phosphide (CoP) electrocatalyst (Pt/CoP/CNTs) is designed and prepared for methanol oxidation (MOR) for the first time. The modification of CoP decreases the Pt particle size significantly and increases the electrochemical surface areas due to the interaction between Pt and CoP, which is evidenced by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Among all these catalysts, Pt/4%CoP/CNTs catalyst exhibits the best MOR activity of 1600 mA mg −1 Pt , which is six times that of Pt/CNTs. Moreover, this catalyst also exhibits the higher onset current density and steady current density than the other Pt-based catalysts. The work provides a promising method to develop the highly active and stable Pt-based catalyst for direct methanol fuel cells. [ABSTRACT FROM AUTHOR]

Abstract: Iron nanowire filled carbon nanotubes (Fe@CNTs) were synthesized by chemical vapor deposition method and employed as heterogeneous catalysts for selective oxidation of ethylbenzene to acetophenone with molecular oxygen. The results showed that filled iron nanowires efficiently enhanced the catalytic activity of CNTs, arising from improving electron transfer. Moreover, Fe@CNTs could be easily separated from the reaction mixtures by external magnet and displayed excellent stability with no significant loss of catalytic activity after six cycling reactions. The result presented herein paves the way for the development of novel carbon catalysts for the liquid phase oxidation of ethylbenzene. [Copyright &y& Elsevier]

Formaldehyde (HCHO) is harmful to environment and human health, even at extremely low concentrations. Catalytic oxidation on metal oxides is an effective method for HCHO removal. Transition metal oxides have attracted much attention due to its advantages of low cost and good redox properties, but it requires the high reaction temperature and energy consumption to reach the good catalytic activity for HCHO removal. In this work, Mn-Co mixed oxides supported on carbon nanotubes (CNTs) were prepared for enhancing the low-temperature catalytic activity of HCHO removal. The results of XRD, TEM and XPS characterization confirmed the formation of CoMn 2 O 4 solid solution on CNTs. The highest relative content of Co3+, Mn3+ and active lattice oxygen were achieved at the optimal composition of 3Mn-1Co. The HCHO oxidation test showed that CoMn 2 O 4 /CNTs (3Mn-1Co) had the best catalytic activity at 160 °C, obtaining 95% HCHO (100 ppm) removal efficiency and 95% CO 2 selectivity at GHSV = 30,000 mL g cat -1 h-1. Compared with the similar catalysts previously reported in literatures, CoMn 2 O 4 /CNTs was of the lower T 90 value for HCHO oxidation. Image 1 • Mn/Co molar ratio of 3:1 was prone to form CoMn 2 O 4 solid solution on CNTs. • The formation of active lattice oxygen on CoMn 2 O 4 was beneficial to HCHO oxidation. • The combination of CNTs and Co-Mn oxides solid solution is promising to prepare catalysts for HCHO removal. [ABSTRACT FROM AUTHOR]