A thorough and comprehensive study of different parameters affecting the sorbents prepared by impregnating polyethyleneimine (PEI) on silica for CO2 capture has been conducted. The CO2 capture performances of resulting sorbents were evaluated on both packed-bed and fluidized -bed reactors. Obtained results indicated that CO2 adsorption-desorption performances of sorbents are greatly affected by the operation temperature in both simulated flue gas from coal fired power plant (SCF) and natural gas combined cycle power plant (NGCC). The optimal adsorption temperatures are from 50 to 80 degrees C for NGCC flue gas and from 70 to 90 degrees C for SCF flue gas, while the optimal regeneration temperatures are from 110 to 130 degrees C for both flue gas. Adsorbent containing 30 to 35 wft PEI fluidized well with both simulated flue gas and steam. Results from this study revealed that PEI impregnated silica is a promising sorbents for CO2 capture process, using a fluidized-bed reactor, from both coal-fired power and natural gas combined cycle power plants. (C) 2016 Elsevier B.V. All rights reserved.