CuPd Bimetallic Nanoparticles Supported on Magnesium Oxide as an Active and Stable Catalyst for the Reduction of 4-Nitrophenol to 4-Aminophenol (Pages: 51-62)
María V. Morales1, José M. Conesa1,2, Inmaculada Rodríguez-Ramos2, Mariana Rocha3, Cristina Freire3 and Antonio Guerrero-Ruiz1
1Departamento de QuímicaInorgánica y QuímicaTécnica, Facultad de Ciencias, UNED, Senda del Rey 9, 28040, Madrid, Spain; 2Instituto de Catálisis y Petroleoquímica, CSIC, C/ Marie Curie 2, Cantoblanco, 28049, Madrid, Spain and 3REQUIMTE/LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, 4169-007 Porto, Portugal
Abstract: In this work, we report the synthesis and characterization of a catalyst based on bimetallic CuPd nanostructures generated over a magnesium oxide support. Its catalytic activity and reusability have been tested in the reduction of 4-nitrophenol as a model reaction using NaBH4 as the source of hydrogen for the reduction of the nitro-group. The structure, composition and morphology of the catalysts were studied by N2physisorption, X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The reaction kinetics of reduction of 4-nitrophenol to 4-aminophenol has been followed by UV-visible spectrophotometry, and its apparent rate constant has been determined and compared with its monometallic counterparts. All the tested catalysts exhibited remarkable high activity and excellent stability upon reuse for multiple consecutive cycles. We found out that a small loading addition of Pd to Cu catalyst greatly improved the catalytic activity in comparison with the monometallic samples. Our characterization results pointed out a higher metallic dispersion degree as the main explanation for this enhanced performance. CuPd/MgO is highly competitive or outperforms the catalytic activity of other bimetallic systems reported in literature.
Keywords: Wastewaters treatment, 4-Nitrophenol degradation, Model reaction, Heterogeneous bimetallic catalysts, Metallic particle size, Rate constant, Recyclability, Magnesium oxide support.