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

ABSTRACT

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 ß-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.