Novel glucosamine-based carbon adsorbents with high capacity and its enhanced mechanism of preferential adsorption of C2H6 over C2H4

In this work, we synthesized a series of glucosamine-based carbon adsorbents with rich microporosity for effective C2H6/C2H4 adsorptive separation. Glucosamine was chosen as precursor to synthesize new microporous glucosamine-based carbon adsorbents (MGAs) and the resultant adsorbents were then characterized. Results showed that the BET surface area and pore volume of the MGAs reached as high as 3189 m(2)/g and 1.92 cm(3)/g, respectively. The FTIR and XPS results showed the presence of abundant N/O groups on carbon surface. Ethane and ethylene adsorption isotherms of the materials were then measured. The effects of N/O functionalities and micropore sizes on C2H6 and C2H4 adsorption were also elaborated by using molecular simulation. Interestingly, the materials presented preferential adsorption of ethane over ethylene with its ethane adsorption capacity reaching 7.6 mmol/g under 1 bar and 25 degrees C. Its adsorption selectivity for ethane/ethylene (1:1) was improved and higher than many MOFs, being in the range of 2.2-6.8 at < 1 bar and 25 degrees C. Molecular simulation revealed the synergistic effects of the micropore aperture size and the surface N/O functionalities of MGAs on its adsorption property, especially adsorption selectivity toward C2H6/C2H4. An increase in amounts of surface N/O functionalities in the micropores with the aperture size in 6-10 angstrom of MGAs played an important role in the enhanced interaction of C2H6 with the surfaces, thus resulting in further improvement of ethane/ethylene selectivity. Fixed-bed breakthrough experiments demonstrated the complete separation of C2H6/C2H4 mixture at room temperature by using the glucosamine-based carbons. These excellent adsorption properties make the glucosamine-based carbon materials a type of promising C2H6-selective adsorbents for the effective separation of C2H6/C2H4.