Continuous CO2 Capture in Dual Fluidized Beds Using Silica Supported Amine

In this study, a supported amine sorbent was prepared by impregnating silica particles (150∼300 um) with methanol solution of polyethylenimine (PEI with the molecular weight of 600 g· mol-1) to immobilize amine into the pores of the silica support. The optimal CO2 capacity of the PEI-based sorbent was as high as 2.0 mmol· g-1. During the adsorption and desorption of 10 times, the CO2 capacity of the PEI-based sorbents kept stable, indicating PEI-based sorbents had excellent thermal stability.Dual bubbling fluidized bed reactors were constructed to demonstrate the process feasibility of continuous CO2 capture from flue gases with supported amine sorbent. Long-term stable operation and continuous solids circulation between the two reactors was achieved, and the CO2 in the flue gases was continuously captured by the supported amine sorbent. Experimental results indicated that ∼84.4% CO2 capture efficiency could be achieved in the absence of water. The low regeneration temperature, high adsorption temperature and the short sorbent residence time in absorber were considered to be the limiting factors affecting the working capacity of sorbents. Water vapour could promote the adsorption process and increase the CO2 capture efficiency to approximately 90.6∼97%. The effect of water vapour on reaction mechanism between CO2 and various amine groups was discussed.