Preparation, characterizations, and catalytic characteristics of Pd nanoparticles encapsulated in mesoporous silica

Pd nanoparticles of 6-10 nm in size have been synthesized by formalin reduction method and incorporated into mesoporous SBA-15 silica during hydrothermal synthesis. Characterizations of the Pd nanoparticles encapsulated in mesoporous silica (Pd/SBA-15) reveal that the Pd nanoparticles in the range of 6-10 nm are encapsulated within the surfactant micelles during mesoporous silica formation and well dispersed within the mesoporous SBA-15 channels. The pore size increases and the surface area decreases with the incorporation of the Pd nanoparticles into SBA-15. The catalytic activity of Pd/SBA-15 was investigated in Heck coupling reactions with activated and non-activated aryl substrates. The Pd/SBA-15 composite exhibits an excellent catalytic activity, low Pd leaching, and reuse ability of at least five recycles in air for the Heck carbon-carbon coupling reaction. (C) 2008 Elsevier Inc. All rights reserved.