EXPERIMENTAL ASSESSMENT OF CO2 ABSORPTION RATES FOR AQUEOUS SOLUTIONS OF HEXYLAMINE, DIMETHYLCYCLOHEXYLAMINE AND THEIR BLENDS

Highly emissive fossil origin CO2 systems are mainly combustion based. Presenting considerable investment costs and potential leaks into the environment as drawbacks, conventional amine solvent based processes remain the most mature technological option for CO2 capture. In the regeneration step of solvents, the energy consumed in these processes is provided by steam at temperatures ranging from 120 °C till 140 °C. In order to avoid this level of temperature that fosters amine degradation, a novel series of thermomorphic solvents are studied. These solvents aim at minimizing energy consumption while improving CO2 capture and potentially replacing the consumption of steam by using waste heat. This paper presents the selection of lipophilic amine based solvents and compares the performance of hexylamine 3M aqueous solutions and the mixture of dimethylcyclohexylamine/hexylamine in aqueous solutions at different compositions. Both absorption and regeneration rates for the selected lipophilic mixtures show outstanding results compared to the benchmark solvent monoethanolamine (MEA). Absorption of CO2 was performed in a Lewis cell for temperatures 20, 30 and 40 °C. Results obtained show the impact of amine blends on the kinetics of absorption and enable novel solvents to be suggested for low energy carbon capture processes. Data collected enables apparent kinetic constants for each of the blends to be calculated. Hexylamine and dimethylcyclohexylamine aqueous blends have demonstrated higher capability to absorb CO2 at high rates. In fact, the kinetics remain similar to those of hexylamine aqueous solvents, while the regeneration tests show a rate increase induced by the dimethylcyclohexylamine