The problem with distillation methods

Oil refineries mostly rely on continuous fractional distillation to separate crude oil into different hydrocarbon fractions based on their boiling points. The process uses around 11% of the extracted oil energy. To make matters worse, this process is incapable of separating hydrocarbons with similar boiling points and distinct chemical structures. To separate these components, additional secondary processes must be used, further complicating oil refining.

One important industrial need is separating aliphatics (chain-like molecules) from aromatics (ring-like molecules) for crude oil-to-chemicals pathways. Aromatics like benzene, toluene and xylene are often used in consumer products, but the similar boiling points of aliphatics and aromatics mean they are difficult to separate via distillation.

Polymer membranes have been used to improve crude-oil fractionation, but they typically trade off throughput for chemical selectivity. The authors of the new study write, "Attempts using membranes such as polytriazole, hydrophobic polyamine, poly(arylene amine), microporous polyimine, and commercial oNF-2 have achieved impressive progress in enriching low molecular weight components, but all suffered from low permeance and poor selectivity for specific hydrocarbon classes, largely due to the difficulty of precisely tuning pore structure and functionality in conventional amorphous polymer membranes."