Mesoporous Silica (MCM-41) Containing Dispersed Palladium Nanoparticles as Catalyst for Dehydrogenation, Methanolysis, and Reduction Reactions

Generating highly dispersed metal NPs of the desired size on surfaces such as porous silica is challenging due to wettability issues. Here, we report highly active and well-dispersed Pd incorporated mesoporous MCM-41 (Pd@MCM) using a facile impregnation via a molecular approach based on hydrogen bonding interaction of a palladium β-diketone complex with surface silanol groups of mesoporous silica. Controlled thermal treatment of so obtained materials in air, argon, and hydrogen provided the catalysts characterized by electron microscopy, nitrogen physisorption, X-ray diffraction and spectroscopy. Gratifyingly, our catalyst provided the lowest ever activation energy (14.3 kJ/mol) reported in literature for dehydrogenation of NaBH4 . Moreover, the rate constant (7×10-3  s-1 ) for the reduction of 4-nitrophenol outperformed the activity of commercial Pd/C (4×10-3  s-1 ) and Pd/Al2 O3 (5×10-3  s-1 ) catalysts.

Preparation of Large-Size, Superparamagnetic, and Highly Magnetic Fe3O4@PDA Core⁻Shell Submicrosphere-Supported Nano-Palladium Catalyst and Its Application to Aldehyde Preparation through Oxidative Dehydrogenation of Benzyl Alcohols

Large-size, superparamagnetic, and highly magnetic Fe3O4@PDA core-shell submicrosphere-supported nano-palladium catalysts were prepared in this study. Dopamine was encapsulated on the surface of Fe3O4 particles via self-polymerization and then protonated to positively charge the microspheres. PdCl42- was dispersed on the surface of the microspheres by positive and negative charge attraction and then reduced to nano-palladium. With air as oxidant, the catalyst can successfully catalyze the dehydrogenation of benzyl alcohols to produce the corresponding aldehydes at 120 °C.