Valorisation of CO2 with epoxides: Influence of gas/liquid mass transfer on reaction kinetics

- Estimation of mass transfer coefficient and enhancement factor of a chemical reaction for CO2 valorisation by using epoxides.
- Study of a gas liquid reaction presenting an intermediary behaviour between kinetic and diffusional regime.
- Estimation of kinetic parameters.

The influence of gas/liquid mass transfer on the valorisation reaction of CO2 with epoxides using epichlorohydrin in a stirred batch reactor was investigated in this study. The rate of absorption of CO2 into the liquid was studied in a dynamic way between 50 and 90 °C and at different stirring speeds (100-500 rpm). Two different systems were observed: (i) CO2/epichlorohydrin and (ii) CO2/epichlorohydrin/catalyst, in order to compare and determine the mass transfer coefficient and the enhancement of the absorption when the latter takes place in the presence of a catalyst. The results suggest that the valorisation reaction followed a slow reaction regime in which the reaction did not occur in the mass transfer film but instead took place within the liquid bulk. Therefore, the reaction rate seemed to control the overall process, but according to the specific reaction regime found, both the liquid holdup and the interfacial area should be enhanced to increase the rate of the reaction and the efficiency of the process. Under the conditions studied in this work, the mass transfer coefficient of the liquid phase (kLa) was found to be in the range of 1.0 × 10−3 to 1.0 × 10−2 s−1 and the enhancement factor (E) was between 0.4 and 0.9.

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