Highly Efficient Separation of Toluene and n-Heptane by Amorphous Cucurbit[7]uril Solids

Separating toluene from n-heptane is a challenging task in the petroleum industry. Traditional methods face problems including elevated energy usage, intricate technical procedures, and residual extractants. Herein, we developed an environmentally friendly, low energy consuming and economically efficient adsorption separation method. This study employed cucurbit[7]uril (Q[7]) as an adsorbent to efficiently separate toluene from a mixture of toluene and n-heptane. The purity of toluene was obtained to be 99.38 % from the mixed vapors and 99.65 % from the mixed liquids. The kinetic experiment results demonstrate that the adsorption behavior of toluene was chemisorption. Density functional theory calculations show that the structure of toluene@Q[7] is more stable. In addition, vacuum heating can remove toluene from the Q[7] cavity, resulting in a guest-free Q[7], which can be repeated for the adsorption separation process without loss of performance. This study has the potential value of addressing the pressing need for efficient resource utilization in light of diminishing petroleum supplies.