Fully Aromatic Nonfluorinated Polyurea Membranes for Crude Oil Fractionation

Membrane separation has been recognized as an emerging platform to realize energy-saving and low-carbon crude oil fractionation. As a promising candidate, fluorinated polymer membranes have manifested superior capacity in crude oil fractionation due to their preferential nonpolar channel chemistry. However, these membranes are limited by the use of fluorinated monomers and an unstable channel architecture. In this study, we present a facile strategy to elaborate fully aromatic nonfluorinated polyurea (FANFPU) membranes that feature low-polar channel chemistry and highly rigid channel architecture, allowing for efficient and stable crude oil fractionation. The FANFPU membranes were fabricated by interfacial polymerization of 1,3,5-tris(4-aminophenyl) benzene and toluene diisocyanate using a binary solvent of ionic liquid and water to modulate the diffusion behavior of monomers for obtaining an optimized microporous structure. Despite the absence of the fluorine atom, the FANFPU membranes have the highest water contact angle compared with aliphatic amine-based polyurea membranes and conventional polyamide membranes. We demonstrate that the FANFPU membranes are highly permeable to nonpolar solvents while maintaining good rejection and great thermal stability, even under aggressive polar aprotic solvents. Moreover, the FANFPU membranes can be implemented for effectively enriching the light components in crude oil mixtures and exhibit a 2.4-fold increase in permeance from 20 to 80 °C. Our findings provide valuable insights for the development of crude oil fractionation membranes toward sustainable petrochemical engineering.