Air stable ligandless heterogeneous catalyst systems based on Pd and Au supported in SiO(2) and MCM-41 for Suzuki-Miyaura cross-coupling in aqueous medium

Palladium and palladium-gold containing siliceous-MCM-41 and sol-gel palladium and palladium-gold silica composites have been prepared. The catalytic performance of incorporated Pd/MCM-41, Au-Pd/MCM-41 and Pd and Au-Pd/SiO(2) sol-gel catalysts for the Suzuki-Miyaura cross-coupling reaction was determined and the influence of the matrix and the catalyst composition on the catalytic activity were also studied. The catalysts were characterized by N(2) physisorption (BET/BJH methods). X-ray diffraction, temperature programmed reduction analysis, H(2) chemisorption, atomic absorption spectrophotometry and Raman spectroscopy. The silica-containing palladium and palladium-gold catalysts prepared using the MCM-41 matrix showed greater catalytic activity than using the conventional sol-gel method; however, gold had a significant influence on this reaction. The catalyst did not undergo metal leaching and could be easily recovered and re-used (reused).