Heat Capacity of CO₂-Loaded Aqueous Methyldiethanolamine + Piperazine + Sulfolane Solutions

Abstract

Heat capacities of CO 2 -loaded aqueous N-methyldiethanolamine (MDEA) and piperazine (PZ) and sulfolane (SFL) solutions were experimentally measured. MDEA, PZ, and SFL concentrations in aqueous solutions were selected in the ranges (0.192−0.360), (0−0.113), and (0−0.156) on the mass fraction scale, respectively. Solubility and heat capacity were measured simultaneously at temperatures from 303.15 to 363.15 K, at 20 K steps, and at pressures up to about 1000 kPa using the previously developed experimental setup. The results show that the mixture heat capacities decrease with increasing CO 2 loading at each constant temperature and increase with increasing temperature in all loading values. A modified Setchenow equation was employed to correlate the solutions' heat capacities. The average and maximum percent relative deviation, ARD and MRD%, of the correlated heat capacities from the experimental data were 0.52 and 1.65%, respectively, indicating quite good correlative accuracy of the model used. The Setchenow model developed was employed to predict the heat capacities of fresh/unloaded and CO 2 -loaded, aqueous MDEA and MDEA + PZ solutions reported in the literature. The average percent deviation of Setchenow-predicted heat capacities from reported data was 1.5%, further indicating quite good consistency of our data with the reliable experimental data previously reported.