Kinetics of reactive absorption of carbon dioxide with solutions of 1,6-hexamethylenediamine in polar protic solvents

Reactive absorption of carbon dioxide with solutions of 1,6-hexamethylenediamine (HMDA) in methanol and water was studied in stirred cell and model stirred contactor at 303 ± 1 K. The volumetric rate of absorption of pure CO2, at atmospheric pressure, was measured using a soap-film meter of appropriate size. Carbon dioxide partial pressure was varied from 0.41 to 0.96 atm and concentration of liquid phase reactant HMDA was varied from 0.5 to 3.0 kmol m−3. The specific absorption rates were analysed using mass transfer with chemical reaction theory. The reaction order was found to be 0.85 with respect to CO2 and HMDA each in water as solvent. The intrinsic kinetic rate constants (km,n) at 303 ± 1 K were found to be in the range of (1.1–1.5) × 102 (kmol m−3)−0.7 s−1. In the case methanol as solvent, the reaction appeared to be the instantaneous reaction regime. These data are expected to be useful for the design and scale up of carbon dioxide absorbers in the process development for carbamates/isocyanates synthesis.

Graphical abstract. Reactive absorption of carbon dioxide with solutions of 1,6-hexamethylenediamine (HMDA) in methanol and water was studied in stirred cell and model stirred contactor at 303 ± 1 K. The reaction order was found to be 0.85 with respect to CO2 and HMDA each in water as solvent. The intrinsic kinetic rate constants (km,n) at 303 ± 1 K were found to be in the range of (1.1–1.5) × 102 (kmol m−3)−0.7 s−1. In the case methanol as solvent, the reaction appeared to be the instantaneous reaction regime.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights▶ Green technology (utilisation of nonedible oils and CO2). ▶ Heterogeneous reactions. ▶ Biofuels. ▶ Supercritical fluids.