Performance of a silica-polyethyleneimine adsorbent for post-combustion CO₂ capture on a 100 kg scale in a fluidized bed continuous unit

Polyethyleneimine (PEI)/silica adsorbents have been considered as a promising candidate for post-combustion CO₂ capture, but the limited process study has been performed on a pilot-scale unit. Herein we report the 150 h continuous test results using a 100 kg sample of silica-PEI on a fluidized bed continuous unit. The CO₂ removal efficiency and dynamic sorption capacity were evaluated continuously by changing a number of variables. For the sorption reactor, the changing variables were inlet H₂O concentrations of 0–8.3 vol%, inlet CO₂ concentrations of 12.0–21.5 vol%, bed temperatures of 50–70 °C and the bed differential pressures of 176–370 mmH₂O. For the desorption reactor operated at the bed temperature of 129–130 °C, inlet H₂O concentrations of 8.0–13.5 vol%, inlet CO₂ concentrations of 14.6–81.2 vol% and bed differential pressures of 430–580 mmH₂O were used. During continuous operation, CO₂ removal efficiencies of over 90% were achieved with dynamic sorption capacities of 7.5 wt%. Solid sample collected during continuous operation were analyzed by TGA and ¹³C NMR to identity the decrease of CO₂ adsorption capacity and the extent of thermo-oxidative side reactions. Slow oxidative degradation of the silica-PEI occurred because the transporting adsorbent was exposure to the non-humidified air in the solid transport system.