Highly efficient and durable metal-organic framework material derived Ca-based solid sorbents for CO2 capture

Calcium looping is a promising technology for CO2 capture, although traditional calcium-based sorbents undergo a rapid loss of capacity after repeated cycles. Improving the toughness of sorbents can be accomplished with the use of stabilizer compounds, but at the cost of sorption performance. Minimizing the stabilizer content whilst maintaining high thermal stability is an effective pathway to solve this bottleneck. Here, a facile MOF-templated synthesis route is for the first time reported to yield highly efficient Al2O3-stabilized, Ca-based sorbents. Cyclic performance experiments and detailed characterization techniques are employed to identify the effects of synthesis factors on the structure-performance relationship of the synthesized CO2 sorbents. Calcium aluminum solid solution and its homogeneous mixture with CaO at the nanoscale provide for high thermal stability. The different CO2 uptake behavior for the synthesized sorbents primarily results from the influence of synthesis factors on the crystallization rates and coordination modes between metal ion and organic ligands. The stabilizer content (i.e. Al2O3) can be as low as 4.44 wt% and yet maintain a favorable thermal stability. Compared to that of the limestone-derived CO2 sorbents, the best MOF-derived sorbent can achieve about 500% times the CO2 sorption capacity after 30 repeated CO2 uptakes and sorbent regenerations.