Effect of Morphology of Platinum Nanoparticles on Benzene Oxidation Activity.

The effect of morphology of Platinum (Pt) nanoparticles supported on alumina (γ-Al2O3) for complete catalytic oxidation of volatile organic compounds (VOCs) was investigated. Pt nanoparticles were synthesized through a simple method comprising of reduction followed by calcination of metal precursor coated chitosan templates using three different reducing agents: sodium borohydride (NaBH4), hydrazine (N2H4) and hydrogen (H2). The morphology and facet orientation of Pt nanoparticles were influenced by the reducing agents. The catalytic oxidation performance studies of these Pt nanoparticles loaded on γ-Al2O3 for VOCs showed strong dependence of their activities on their morphologies. High indexed facet (220) Pt nanosheets synthesized through NaBH4 reduction showed superior catalytic oxidation activity compared to the catalysts prepared using other reducing agents. Cyclic performance studies on these catalysts showed stable benzene oxidation performance implying their thermal stability. The absence of any shape directing agents in the synthesis of Pt nanoparticles with homogeneous morphologies and preferential orientation is an aspect that can be extended to other catalytic applications.

Theoretical study on the mechanism of aqueous synthesis of formic acid catalyzed by [Ru3+]-EDTA complex.

Because formic acid can be effectively decomposed by catalysis into very pure hydrogen gas, the synthesis of formic acid, especially using CO and H2O as an intermediate of the water gas shift reaction (WGSR), bears important application significance in industrial hydrogen gas production. Here we report a theoretical study on the mechanism of efficient preparation of formic acid using CO and H2O catalyzed by a water-soluble [Ru(3+)]-EDTA complex. To determine the feasibility of using the [Ru(3+)]-EDTA catalyst to produce CO-free hydrogen gas in WGSR, two probable reaction paths have been examined: one synthesizes formic acid, while the other converts the reactants directly into CO2 and H2, the final products of WGSR. Our calculation results provide a detailed mechanistic rationalization for the experimentally observed selective synthesis of HCOOH by the [Ru(3+)]-EDTA catalyst. The results support the applicability of using the [Ru(3+)]-EDTA catalyst to efficiently synthesize formic acid for hydrogen production. Careful analyses of the electronic structure and interactions of different reaction complexes suggest that the selectivity of the reaction processes is achieved through the proper charge/valence state of the metal center of the [Ru(3+)]-EDTA complex. With the catalytic roles of the ruthenium center and the EDTA ligand being carefully understood, the detailed mechanistic information obtained in this study will help to design more efficient catalysts for the preparation of formic acid and further to produce CO-free H2 at ambient temperature.