Preparation, characterization and excellent catalytic activity of Cu/SBA-15 nanomaterials

Abstract

Cu/SBA-15 nanomaterials were synthesized by means of a simple impregnation reduction method using excess NaBH₄ as reducing agent. The morphology and structure of synthesized materials were characterized by powder X-ray diffraction, N₂ adsorption–desorption isothermal and transmission electron microscope. The catalytic activity of Cu/SBA-15 toward the reducing reaction of p-nitrophenol was investigated using UV–Vis spectroscope as monitor and discussed further from the viewpoints of reactive kinetics and thermodynamics. Results show that the ordered structure of mesoporous materials was still remained as Cu nanoparticles incorporated into SBA-15, and that the specific surface areas and pore diameters of materials enlarged. Cu/SBA-15 as catalytic exhibited an excellent catalytic activity and over 99.0% of p-nitrophenol was reduced into p-aminophenol. The time to complete reaction shortened as increasing of reaction temperature as well as Cu nanoparticles loaded amount. The activity energy of reduction reaction was 64.09 kJ mol⁻¹ and the rate constants increased as rise of the reaction temperatures from the pseudo-first-order reaction model. The thermodynamic analysis reveals that the activity parameters of reaction were as follows: enthalpy change 61.65 kJ mol⁻¹, entropy change −87.68 J mol⁻¹ K⁻¹, and Gibbs free energy change increased slightly as increasing the reaction temperature.