Development of K and N based composite CO₂ sorbents (KN) dried with a supercritical fluid

The objective of this research was to develop composite CO₂ sorbents for overcoming the shortcomings of the corresponding individual sorbents. The composite sorbents were synthesized with K₂CO₃, 3-aminopropyltriethoxysilane (APTES), tetraethylorthosilicate (TEOS) and dried either with supercritical or conventional technique. Comparative experiments demonstrated that supercritical fluid drying (SCFD) was better than conventional drying (CD) in preparing CO₂ sorbents with more developed pore structure and thus higher CO₂ sorption capacity. The composite sorbent prepared with SCFD was tested under various conditions for their effects on CO₂ sorption capacity. The optimal K:N mole ratio for preparation of the composite sorbent and the reaction conditions for achieving the highest sorption capacity were obtained. In addition, the sorbent proved to be regenerable. Thus, supercritical drying is an effective technique for preparation of a promising composite CO₂ sorbent.