Kinetics of Carbon Dioxide Removal Using N-Acetylglucosamine

Glucosamine, the amino sugar made from glucose, is a safe and natural reagent for post-combustion carbon dioxide capture. Its most plentiful derivative, N-acetylglucosamine (or NAG), was studied in this work with respect to its reaction kinetics in aqueous solutions. A stirred cell reactor with a flat gas-liquid interface was used, and it was found that CO₂ reacts with NAG via a pathway similar to that with alkanolamines. In the 20-100 mM range of NAG concentration, the second-order rate constant at T = 308 K was 125 kmol m^-3 s^-1. For the 303-313 K range, the activation energy was 42 kJ mol^-1. In a study on vapor-liquid equilibrium, it was found that the loading capacity of NAG (100 mM) at 303 K was 0.6 mol CO₂/mol NAG, while the equilibrium partial pressure of CO₂ was 0.8 kPa. Three rate promoters were tested, and piperazine showed better efficacy than monoethanolamine and 2-amino-2-methyl-1-propanol in aqueous NAG solutions. This work is expected to stimulate further interest in this new, green CO₂ capturing solvent.