Research Centre for Synthesis and Catalysis, Department of Chemistry, University of Johannesburg, P.O. Box 524, Auckland-Park 2006, South Africa
Antonels, N.C., Research Centre for Synthesis and Catalysis, Department of Chemistry, University of Johannesburg, P.O. Box 524, Auckland-Park 2006, South Africa; Meijboom, R., Research Centre for Synthesis and Catalysis, Department of Chemistry, University of Johannesburg, P.O. Box 524, Auckland-Park 2006, South Africa
This study discusses the preparation of various sized dendrimer encapsulated ruthenium nanoparticles (RuDEN) with the use of the generation 4 (G4), generation 5 (G5), and generation 6 (G6) hydroxyl-terminated poly(amidoamine) (PAMAM-OH) dendrimers as templating agents. The size of the nanoparticles ranges from 1.1 to 2.2 nm. These catalysts were fully characterized using UV/vis spectrophotometry, infrared (IR) spectroscopy, and transmission electron microscopy (TEM). The RuDEN catalysts were evaluated in the reduction of 4-nitrophenol (4NP) in the presence of sodium borohydride (BH4-) for various concentrations of either. The kinetic data obtained were modeled to the Langmuir-Hinshelwood equation. The model allows the relation of the apparent rate constant to the total surface area S of the nanoparticle, the kinetic constant k which is related to the rate-determining step, and the adsorption constants K4NP and KBH4 for 4NP and borohydride, respectively. These parameters were calculated for each of the RuDENs, proving the Langmuir-Hinshelwood model to be suitable for the kinetic evaluation of RuDENs in the catalytic reduction of 4NP. © 2013 American Chemical Society.
Apparent rate constant; Langmuir Hinshelwood equation; Langmuir-Hinshelwood; Langmuir-Hinshelwood models; Rate determining step; Ruthenium Nanoparticles; Sodium boro hydrides; UV/vis spectrophotometry; Catalysts; Kinetics; Metal nanoparticles; Phenols; Rate constants; Transmission electron microscopy; Dendrimers