Mass transfer effects during homogeneous 1-octene hydroformylation in CO2CO2-expanded solvent: Modeling and experiments

CO2CO2-expanded liquids (CXLs) represent a continuum of reaction media that combine the reaction benefits provided by organic solvents and the environmental benefits provided by supercritical CO2CO2 (scCO2)scCO2) in an optimal manner. Homogeneous hydroformylation of 1-octene using an unmodified rhodium catalyst (Rh(acac)(CO)2)(Rh(acac)(CO)2) was successfully demonstrated employing CXLs as reaction media [Jin, H., Subramaniam, B., 2004. Homogeneous catalytic hydroformylation of 1-octene in CO2CO2-expanded solvent media. Chemical Engineering Science 59, 4887–4893]. The reported experimental study, however, showed a long induction period of nearly 2 h, following which reaction occurs. A detailed reactor model incorporating reaction kinetics, mass transfer rates and phase equilibrium is presented to systematically investigate the effects of mass transfer and catalyst activation on induction period in 1-octene hydroformylation in CXL. Complementary experiments performed in stirred autoclave reactors equipped with an in situ ReactIR probe validate the cause of the induction period predicted by the model.