III International Conference

PP-II-27ACTIVITY OF PALLADIUM CATALYSTS IN THE HECK REACTION DURINGITS RECOVERY BY REVERSE FLOW ADSORPTION TECHNOLOGYDjekić T., Bos S.J. 1 , van der Ham A.G.J. 1 , de Haan A.B.Department of Chemical Engineering and Chemistry, Eindhoven University of Technology,Eindhoven, The Netherlands1 Separation Technology, University of Twente, Enschede, The NetherlandsE-mail: t.djekic@tue.nl, a.b.dehaan@tue.nlReverse Flow Adsorption (RFA) is a novel technology for recovery and recycling of thehomogenous catalyst. The Heck reaction is selected as a test reaction to measure the catalyticactivity of PdCl 2 (PPh 3 ) 2 catalyst in DMF at very low concentrations. The RFA set-up is builtto continuously adsorb and desorb PdCl 2 and the Heck reaction is used in the subsequent stepto test the activity. The results show that after four cycles of continuous adsorption anddesorption of PdCl 2 , homogeneous catalyst still performs a constant activity.Although homogeneous catalysts offer a number of advantages compared toheterogeneous catalysts [1], they have a major problem: recovery. Leaching of the veryexpensive metals as well as deactivation of the homogeneous catalyst are two maindrawbacks of present recovery methods. Therefore a novel concept for the recovery andrecycling of homogeneous catalysts is proposed: Reverse Flow Adsorption (RFA) [2]. In thereverse flow adsorption, the feed periodically changes the flow direction while thehomogeneous catalyst is separated from the reaction mixture by adsorption downstream of thereactor.In this work we show that the homogenous catalyst is still active after several cycles ofthe reversible adsorption/desorption of the metal salt, PdCl 2 . The Heck reaction is selected totest the activity of the catalyst. First the Heck reaction as proposed in the work of Zhao et al.[3], is reproduced and afterwards optimized for our catalytic system. 0.1 [mmol/l] of catalystconcentration is selected to clearly show influence of the active catalyst concentration onreaction conversion. Initial RFA experiments with PdCl 2 in DMF (C=1[mmol/l]) wereperformed in the RFA experimental set-up. After each desorption cycle of the PdCl 2 , a sampleis taken and its concentration adjusted to 0.1 [mmol/l] to perform the Heck reaction. Resultsillustrate that after four cycles of continuous adsorption and desorption of PdCl 2 , ahomogenous catalyst is still active without loss of performance.Furthermore the influence of reactants, products and ligands on the adsorption of catalyst,and as well to study the reversible adsorption of active catalyst form combined with a Heck211