Homogeneous versus Heterogeneous Catalysts

The water-gas shift rates are obviously much lower when heterogenized in comparison with the Rh complexes in homogeneous solutions of the amines (also see Tables 30-33). Kinetics for nitrobenzene reduction were performed for the cis-[Rh(CO)2(2-picoline)2]PF6 catalyst, and reported in 2000. Kinetics displayed a first order dependence on Pco over the range 0-1.9 atm in the temperature range 80-120 °C. As with the kinetics previously reported by Lima Neto and coworkers,121 it was suggested that the CO addition preceded the rate limiting step. A non-linear dependence on the rate versus Rh concentration, as with the previous study, suggested participation by both mononuclear and polynuclear species. 

Glasnov, T.N., Findening, S and Kappe, C.O. (2009) Heterogeneous versus homogeneous palladium catalysts for ligandless Mizoroki-Heck reactions a comparison of batch/microwave and continuous-flow processing. Chem. Eur. J., 15 (4), 1001-1010. 

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