Pore Characteristics for Efficient CO 2 Storage in Hydrated Carbons

Development of new approaches for carbon dioxide (CO ) capture is important in both scientific and technological aspects. One of the emerging methods in CO capture research is based on the use of gas-hydrate crystallization in confined porous media. Pore dimensions and surface functionality of the pores play important roles in the efficiency of CO capture. In this report, we summarize work on several porous carbons (PCs) that differ in pore dimensions that range from supermicropores to mesopores, as well as surfaces ranging from hydrophilic to hydrophobic. Water was imbibed into the PCs, and the CO uptake performance, in dry and hydrated forms, was determined at pressures of up to 54 bar to reveal the influence of pore characteristics on the efficiency of CO capture and storage. The final hydrated carbon materials had H O-to-carbon weight ratios of 1.5:1. Upon CO capture, the H O/CO molar ratio was found to be as low as 1.8, which indicates a far greater CO capture capacity in hydrated PCs than ordinarily seen in CO -hydrate formations, wherein the H O/CO ratio is 5.72. Our mechanistic proposal for attainment of such a low H O/CO ratio within the PCs is based on the finding that most of the CO is captured in gaseous form within micropores of diameter