Separation of Xylene Isomers: A Review of Recent Advances in Materials

The xylene isomers p-xylene, o-xylene, and m-xylene are aromatic hydrocarbons comprising with two methyl groups located at different positions on a benzene ring. The mixture originates from catalytic reforming of crude oil, and each individual isomer acts as a valuable intermediate; however, similar physicochemical properties make their separation difficult. This Review focuses on materials employed for their separation, such as metal–organic frameworks, molecular sieves, organics, and graphene quantum dots. Recent advances in separation of xylene isomers are summarized, including adsorption, membrane, and chromatographic separation techniques, and adsorption capacity and selectivity combined with mechanisms of separation are discussed.