Impact and performance of activator addition on the kinetics of CO2 absorption into aqueous MDEA solutions using stopped-flow technique

Abstract

The presence of carbon dioxide within the natural gas causes an increase in gas volume, reduces its heat value and may enhance corrosion within pipelines and processing plants. Amine-based absorption technique is a well-known and widely used method for removing CO2.The use of mixed solvents is an attractive alternative to either chemical or physical solvents alone. Mixed solvents, which combine a chemical and a physical solvent, benefit from both physical and chemical absorptions. Using the stopped flow technique, kinetic rates of CO2 in aqueous solutions of (MDEA), (MDEA + PZ), and (MDEA + sulfolane) were measured and reported in terms of pseudo-first-order rate constants (k0). The second-order reaction rate constants (k2) were regressed from the data when possible. Experiments were performed over new concentration ranges of (200–800), (200–800, 10–40), and (200–800, 10–200) mol/m3 for the above-mentioned Three systems, respectively, and at temperatures varying from (298.15–313.15 K). The absorption rates of carbon dioxide in aqueous mixed solvent solutions of were higher than those for standalone MDEA at the same concentrations at all temperatures from (298.15 to 313.15) K. The kinetic rates were highest at 298.15 K and decreased at higher temperatures for aqueous (MDEA + Sulfolane) solutions but increased with temperature for aqueous (MDEA + PZ) systems. The base catalysis mechanism was used to regress very well data for aqueous (MDEA + sulfolane ) and a hybrid model based on the combination of the Zwitterion and base catalysis mechanisms were able to successfully correlate the experimental data for the mixed aqueous (MDEA + PZ) systems. The reaction kinetics increased with the increase in temperature and concentration.