Exploration of room temperature synthesis of palladium containing cubic MCM-48 mesoporous materials

Pd-MCM-48 mesoporous materials were synthesized by a modified Stober synthesis method in 4 h at room temperature. Pd nanoparticles were prepared by using Na-2[PdCl4] and Pd(acac)(2) as Pd precursors, and their influence in the preparation of the cubic MCM-48 mesoporous phase was investigated. In addition, Pd(0) nanoparticles was prepared separately and added to the synthesis gel. The influence of varying the Pd precursor, solvent media, the time of addition of Pd precursor, and the concentration of NaBH4 reducing agent used for preparation of Pd(0) and its effect for the formation of the cubic phase were investigated. These resultant materials were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Visible spectroscopy, nitrogen physisorption, and CO-Pulse titration. Reusability studies assessing a material prepared using Pd(0)-DMAP encapsulated nanoparticles that were reduced with 0.1 N NaBH4 i.e. 3%Pd-MCM-48-D-N01 indicate that the yields for the hydrogenation of trans-cinnamic acid are greater than 95% even after 8 catalytic cycles, and at which the cubic phase was maintained under our experimental conditions. (C) 2014 Elsevier Inc. All rights reserved.