Alkali Metals Modified Activated Carbon for Enhanced Methanol and Acetone Selective Adsorption: A Theoretical Study

The doping of alkali metal groups（LiO-, NaO- and KO-）into activated carbons for acetone and methanol adsorption were studied by Grand Canonical Monte Carlo (GCMC) simulation and Density Function Theory (DFT). The results indicate that all alkali metals groups can significantly improve the methanol and acetone adsorption capacity at relatively low pressure (0.2 kPa). Especially the methanol and acetone adsorption capacity on PC-LiO increased by 924 and 29 times compared with PC, respectively. These results are mainly attributed to the stronger adsorption energy and electrostatic interaction of PC-LiO on VOCs molecules than that of PC. At relatively high pressure, the alkali metals groups have no obvious effect on the methanol and acetone adsorption capacity, but are determined by the pore structure due to the pore-filling adsorption mechanism. Besides, the methanol/acetone selectivity of PC-LiO is much higher than that of PC, indicating that the LiO-doped PC can improve methanol and acetone separation. The above results show that alkali metal-doped activated carbon has been proved to be one of the promising adsorbents for methanol and acetone adsorption capacity at relatively low pressure, and provides an effective alternative strategy for the design and screening of VOCs adsorbents.