One-pot generation of mesoporous carbon supported nanocrystalline calcium oxides capable of efficient CO2 capture over a wide range of temperatures

Abstract

Ordered mesoporous carbon-supported calcium oxide materials have been rationally synthesized for the first time. Large specific surface area, high content of nanosized calcium oxides can be easily obtained and tuned. The structure, porosity and the particle size evolution as a function of calcium content and carbonization temperature are extensively characterized and well correlated with their CO₂ sorption properties. The composite materials are of significance for CO₂ physisorption at ambient temperatures with high capacity and selectivity over N₂. Meanwhile, the nanocrystalline calcium oxides are highly active for CO₂ chemisorption, with tuneable and high CO₂ capacity at 200–500 °C. An almost complete initial conversion and fast reaction kinetics at a low temperature (450 °C) and low CO₂ pressure can be achieved within minutes. Cyclic stability is also substantially improved due to the confinement effect of the CaO nanoparticles within the mesopores. These materials would be suitable for CO₂ separation over a wide range of temperatures.