Catalysis of Organic..

Hu et al. 9112. Biphasic Catalytic Oxidation ofHydrocarbons UsingImmobilized Homogeneous Catalystin a Microchannel ReactorJianli Hu, Guanguang Xia, James F. White, Thomas H. Peterson and Yong WangAbstractPacific Northwest National Laboratory902 Battelle Boulevard, Richland, WA 99352Jianli.hu@pnl.govThis research relates to developing of immobilized homogeneous Co(II) catalyst anda demonstration of its performance in hydrocarbon oxidations. Although the catalystmaterial is normally a solid, it performs as if it were a homogeneous catalyst whenimmobilized by dissolution in an ionic liquid and deposited on a catalyst support.Evidence shows that after immobilization, the typical homogeneous catalyticproperties of Co(II) catalyst are still observed. Surprisingly, the immobilized catalystis also thermally stable up to 360 o C and essentially no metal leaching has beenobserved under oxidation reaction conditions up to 250 o C, and 220 psig. Becausethe obvious mass transport limitation between organic phase and catalyst phase,integration of such a catalyst system into microchannel reactor becomes extremelyattractive. Microchannel reaction technology is an advanced chemical processtechnology which has not been previously explored for biphasic catalytic oxidation,yet it appears to have the essential features required for step changes in this emergingchemical process area. One significant characteristic of such an immobilizedhomogeneous catalyst in a microchannel reactor is the high mass transportefficiencies, enhancing reaction rates and space time yields while minimizing sidereactions that can be enhanced by mass transfer limitations. The typical high ratioof geometric surface area of the reactor walls to total reactor volume in microchanneldevices should be a strong benefit to the concept. In the cyclohexane oxidationreaction, preliminary experimental results have shown 100% selectivity towardsdesired products. Compared to conventional homogeneous catalyst, turnoverfrequency of the immobilized Co(II) catalyst is almost 7 times higher than reportedfor conventional hydrocarbon oxidation reaction schemes. The uniqueness of such acatalyst-reactor integration allows homogeneous oxidation reactions to be operatedin heterogeneous mode therefore enhancing productivity and improving overallprocess economy while at the same time reducing the environmental impact ofoperating the process in the conventional fashion with a water based reaction media.