Obtaining of highly-active catalysts of unsaturated compounds hydrogenation by using supercritical carbon dioxide

Abstract

Polymer frameworks have been for the first time impregnated with rhodium and palladium compounds in a supercritical carbon dioxide medium. The polymeric carriers were the mesoporous phenol-formaldehyde resin and cross-linked dendrimer networks, based on poly(propylene imine) and poly(amido amine) dendrimers. The metal compounds were rhodium acetylacetonate and palladium carboxylates including their fluoro-substituted derivatives and palladium hexafluoroacetylacetonate. Using the IR-spectroscopy method, we have shown that the metal content in the polymers was in the range of 0.3–2.0 wt.% depending on the polymer nature, cross-linking agent type and cross-linking degree. We have obtained the samples of polymer supports with nanosized metal particles through hydrogen reduction of immobilized rhodium and palladium compounds at P(H2) = 6–10 MPa, T = 60 °C, 4 h time. The average rhodium particle size was 1–2 nm. It has been shown that the obtained nanocomposites were extremely active catalysts for hydrogenation of unsaturated hydrocarbons.