In this study, the effect of adding various activators (alkyl amines) such as tetraethylenepentamine (TEPA), triethylenetetramine (TETA), diethanolamine (DEA), and monoethanolamine (MEA) on the CO2 loading of 2-amino-2-methyl-1-propanol (AMP) was investigated experimentally. With the aim of evaluating the performance of each activator on the CO2 loading, a vapor-liquid equilibrium (VLE) apparatus was used. The CO2 solubility data into TEPA + AMP + H2O, TETA + AMP + H2O, DEA + AMP + H2O, and MEA + AMP + H2O systems were measured in the range 0.281-186.3 kPa. The experiments were carried out under the fixed absorption temperature of 313 K and different molar ratios of activators to AMP. The measured solubility data were modeled using the modified Kent-Eisenberg and Deshmukh-Mather thermodynamic models. The adjustable parameters of thermodynamic models were obtained using the simplex method as an optimization algorithm. The results of the Deshmukh-Mather model showed a better prediction for experimental data than the modified Kent-Eisenberg model. By comparing the loading results in different mixing systems under constant temperature and at a constant concentration, TEPA showed the highest absorption capacity among other activators (TETA, DEA, and MEA) assessed in this study. The superiority of TEPA is due to the presence of more amine groups in TEPA compared to other activators in combination with AMP.