Benzyl alcohol oxidation was carried out in toluene as solvent, in the presence of the potentially inhibiting oxidation products benzaldehyde and benzoic acid. Benzoic acid, or a product of benzoic acid, is identified to be the inhibiting species. The presence of a basic potassium salt (K 2 CO 3 or KF) suppresses this inhibition, but promotes the formation of benzyl benzoate from the alcohol and aldehyde. When a small amount of water is added together with the potassium salt, an even greater beneficial effect is observed, due to a synergistic effect with the base. A kinetic model, based on the three main reactions and four major reaction components, is presented to describe the concentration-time profiles and inhibition. The inhibition, as well as the effect of the base, was captured in the kinetic model, by combining strong benzoic acid adsorption and competitive adsorption with benzyl alcohol. The effect of the potassium salt is accounted for in terms of neutralization of benzoic acid. OPEN ACCESSCatalysts 2014, 4 90

No abstract

The narrow sized and highly homogeneous dispersed Pd nanoparticles have been synthesized on nitric acid functionalized multi-walled carbon nanotubes (CNTs) without a capping agent. TEM images show that the extremely small Pd nanoparticles with an average size of about 1.5 nm were homogeneously dispersed on the surface of CNTs. The characterization results indicate that the pretreatment with nitric acid not only improve the dispersion of Pd, but also enhance the strong interaction between Pd nanoparticles and CNTs, thereby preventing their agglomeration and leaching in the liquid phase. On pretreatment with HNO 3 , it is possible to generate more acidic groups on the surface of CNTs without a significant change in textural properties. The catalytic performance of aforementioned material was investigated for selective oxidation of benzyl alcohol. Pd/CNTs exhibits high activity (~98% conversion) and selectivity (~90%) toward benzaldehyde with excellent reusability. The high activity of the catalyst was attributed to the small size, high dispersion of Pd nanoparticles and higher accessibility of reactants. A careful analysis of kinetic data suggests that there are different sites for the disproportionation and oxidation reactions. The excellent reusability of Pd/CNTs catalyst makes this material a promising candidate for selective benzyl oxidation. Further, the results of present 2 study show that it is possible to synthesize uniformly dispersed Pd nanoparticle on various carbon supports without a capping agent.

No abstract