REVERSE FLOW ADSORPTION TECHNOLOGY FOR THE RECYCLING OF HOMOGENEOUS CATALYSTS: SELECTION OF SUITABLE ADSORBENTS

摘要

A promising concept for the recovery of homogeneous catalysts is Reverse Flow Adsorption. In actual homogeneous catalyzed processes, a homogeneous transition-metal catalyst is at equilibrium with its individual components: the free transition-metal center and ligands. Therefore, to apply Reverse Flow Adsorption, a combination of two adsorbents has to be used to reversibly adsorb: the transition-metal center and its ligands. The transition-metal center can be adsorbed by a suitable ligand immobilized onto a solid carrier, while the ligand is adsorbed by an immobilized transition-metal. Dichlorobis(triphenylphosphine)cobalt(Ⅱ), dissolved in 1-butanol has been selected as a homogeneous model catalyst. The adsorption of Co(Ⅱ) and PPh_3 has been determined for two groups of functionalized adsorbents: 1) nitrogen (Amberlyst A21) and phosphor (polymerbounded PPh_3) functionalized adsorbents and 2) transition-metal (Ag~+ and Co~(2+)) functionalized Amberlyst 15. The Co(Ⅱ) adsorption decreased, as predicted by the HSAB theory, according to: N > P. Transition-metal functionalized adsorbents proved the adsorption of the PPh_3 according to: Ag~+ > Co~(2+).