Novel glucose-based adsorbents (Glc-As) with preferential adsorption of ethane over ethylene and high capacity

Abstract

In this work, we reported novel glucose-based adsorbents (Glc-As) with high C2H6/C2H4 adsorption capacity and selectivity. Starch sugar (e.g., glucose, 50wt%) was used as carbon source to prepare novel glucose-based carbon materials for C2H6/C2H4 separation. The BET surface area of the resulting Glc-As can reach as high as 2073m2/g, and their pore diameters fell into the region of micropores benefiting adsorption of light hydrocarbons. FTIR spectra and XPS were applied to analysize the surface chemistry of the samples. It showed the presence of O functionalities in Glc-As, and its contents decreased with increasing KOH/C ratio at which the sample was activated. Glc-As achieved superior high C2H6 adsorption capacity of 7.98mmol/g at 288K and 1bar, which was benefited from the abundant micropores. More importantly, Glc-As exhibited greatly preferential adsorption of C2H6 over C2H4, with the C2H6/C2H4 adsorption selectivity in the range of 2.02–5.98 at pressure below 100kPa, higher than most reported adsorbents possessing preferential adsorption of C2H6 over C2H4. This could ascribe to the higher polarizability and larger kinetic diameter of C2H6, resulting in its stronger interaction with the pore surfaces of Glc-As compared to C2H4, and exhibiting in significantly preferential adsorption of ethane over ethylene. Besides, adsorption heat calculation showed that the isosteric heats of C2H6 adsorption on Glc-As were higher than the isosteric heats of C2H4. Fixed bed experiments showed that C2H4/C2H6 mixture can be well separated in the fixed bed packed with Glc-As. In sum, Glc-As as new carbon materials possess not only excellent stability, but also excellent adsorption properties for separation of C2H6 and C2H4, It would be promising adsorbents for the effective separation of ethane/ethylene.