Highly selective removal of thiophene from benzene by cucurbit[6]uril in both mixed vapors and solutions

Abstract

The separation of benzene and thiophene presents a significant challenge in the chemical industry, particularly in the pursuit of obtaining high purity benzene. Conventional approaches employed for benzene and thiophene separation have drawbacks such as excessive energy consumption, intricate technical procedures, and the persistence of extractant remnants. Herein, we developed an adsorptive separation method characterized by its environmentally friendly nature, low energy consumption, simplicity in operation, and most importantly, high selectivity in separation. In this paper, cucurbit[6]uril (Q[6]) was employed as an adsorbent for effectively separating thiophene from a mixture of benzene and thiophene both in a solid–vapor and solid–liquid interface, with a selectivity of 99.3% at solid–vapor and 100% at solid–liquid interfaces. Excellent results were also obtained in the simulations of practical industrial separation with lower thiophene content. The selectivity arises from the formation of a host–guest complex between Q[6] and thiophene, while benzene does not form such a complex under the experimental conditions. In addition, the thiophene trapped within the Q[6] cavity can be eliminated through heating under vacuum or immersion in an organic solvent, yielding a guest-free Q[6] that can be reused without obvious reduction of separation performance. High-purity benzene and thiophene were obtained through this purification process. This work provides a new strategy for separating other important compounds with similar boiling points and offers inspiration for using supramolecular hosts in other energy-intensive separation methods.