Nanosized metallic particles embedded in silica and carbon aerogels as catalysts in the Mizoroki–Heck coupling reaction

We have prepared silica, organic, and carbon aerogels doped with metallic Ni and Pd through sol-gel processes. Silica aerogel nanocomposites have been synthesized by impregnation, with Ni(acac)2 or Pd(acac)2, of the silica wet gels followed by ethanol supercritical drying. Organic aerogels were prepared by sol-gel copolymerization of formaldehyde with the potassium salt of 2,4-dihydroxybenzoic acid, followed by ion exchange with either Ni(NO3)2·6H2O or Pd(OAc)2 and CO2 supercritical drying. No special reduction step was needed. Organic aerogels were further carbonized to obtain carbon aerogels. Pd organic and carbon aerogels containing 20–40% palladium nanoparticles are good catalysts for the Mizoroki–Heck reaction.