Kinetics Assessment of the Homogeneously Catalyzed Hydroformylation of Ethylene on an Rh Catalyst

The homogeneously catalyzed hydroformylation of ethylene to propanal using an Rh(H)(PPh₃)₃(CO) catalyst has been assessed experimentally in a gas–liquid batch reactor and via microkinetic modeling, based on Wilkinson’s dissociative mechanism. A higher reaction rate was observed with increasing temperature, up to 100 °C. Even higher temperatures resulted in catalyst deactivation, which was also attributed to lower total pressures and PPh₃/rhodium molar ratios. The model and its parameters were statistically significant and could be used to simulate the trends observed in the experimental data. Activation energies for the insertion of ethylene and the oxidative addition of H₂ of 42 and 48 kJ mol^–1, respectively, were obtained. Ethylene insertion and oxidative addition of H₂ were identified as the most kinetically relevant steps in the reaction mechanism.