Researchers from the Korea Advanced Institute of Science and Technology (KAIST) and the Georgia Institute of Technology passed crude oil through a bare porous polyacrylonitrile (PAN) membrane. PAN is a chemically stable, inexpensive polymer commonly used as a support material in industrial membranes.

At room temperature, heavy hydrocarbons stuck to the pore walls, gradually narrowing them and forming separation channels smaller than 2 nanometers, the study says. Unlike approaches that add a selective coating to a membrane, the method relies on the membrane changing as hydrocarbons accumulate. The researchers reported permeation rates about 23 times higher than those of previously reported crude-oil membranes, with stable performance over 28 consecutive days.

The membrane could be installed as a modular filtration unit through simple refinery retrofits, the researchers said. In simulations, using it before conventional distillation reduced energy consumption by 31.6%, carbon dioxide emissions by 37.6%, cooling water use by 20.7% and operating costs by 36%. The approach could avoid heating crude oil above 350 °C (662 F) at the start of processing, but would not eliminate distillation.

“The PAN membranes with their surprising separation mechanism – dramatically increase the productivity of the membrane unit, to the point where industry should seriously consider adopting the technology,” said Professor Ryan Lively of Georgia Tech. KAIST study co-first authors Dr. Jihoon Choi and Dr. Hyeokjun Seo said they aim to control the pore-narrowing process and explore uses in plastic recycling, biofuel purification and other chemical processes. The researchers also identified potential applications in petrochemicals and waste-plastics recycling.