In-situ Preparation of Pd Nanoparticles in the Pore Channel of CMK-3 for Suzuki Coupling Reaction

Palladium nanoparticles (PdNPs) supported on ordered mesoporous carbon (CMK-3) were prepared by Ar glow discharge plasma technology (P-PdNPs/CMK-3) without the use of any chemical additives or surfactants and chemical method using ascorbic acid as reducing agent (AA-PdNPs/CMK-3), respectively. The PdNPs/CMK-3 catalysts were characterized by XRD, N-2 absorption-desorption and TEM analysis. The results showed that the as-prepared PdNPs were of the face-centered cubic structure, P-PdNPs/CMK-3 had an average particle size of 3.4 nm (lower than CMK-3 pore diameter of 3.7 nm), which corresponded to an average diameter of 11.1 nm for AA-PdNPs/CMK-3. The in-situ preparation of P-PdNPs/CMK-3 had a higher dispersion of Pd species and mainly formed inside the pore channels of CMK-3, but distributed on the outer surface of support for AA-PdNPs/CMK-3. The yield reached 95% in the presence of 0.1 mmol% P-PdNPs/CMK-3 at 40 degrees C for 30 min towards the reaction of 4-bromonitrobenzene and phenylboronic acid, which corresponded to 86% for AA-PdNPs/CMK-3. The better stability and recyclability for P-PdNPs/CMK-3 were confirmed by the hot filtration and recycling test. (C) 2017 Elsevier Inc. All rights reserved.