Adsorption and Separation Mechanism of Methanol-Toluene Azeotropes on Porous Carbon Materials: Insights from Theoretical and Experimental Studies.

Currently, research on the adsorption of methanol and toluene by carbon-based materials has mainly focused on the adsorption performance of a single compound. However, there has been minimal investigation into the adsorption and separation of toluene and methanol azeotropes, and their potential mechanisms are still unclear. In this work, theoretical calculations were employed to investigate the effect of oxygen-containing functional groups and the pore size distribution of porous carbon on the adsorption and separation of methanol and toluene. Our findings indicate that methanol adsorption is dictated by both oxygen groups and microporous structures, whereas at high pressures the pore structure dominates. Toluene, on the other hand, shows minimal sensitivity to oxygen groups and is predominantly controlled by the pore structure. Notably, pore sizes greater than 0.7 nm are crucial determinants of toluene/methanol selectivity, while oxygen-containing functional groups have a negative effect on the selectivity. To validate these theoretical insights, we synthesized three distinct types of porous carbon with varying pore sizes and oxygen contents. Experimental adsorption and separation performances confirmed the theoretical predictions, offering valuable guidance for designing tailored adsorbents for efficient methanol-toluene separation.