MIT researchers have developed an innovative membrane that can separate components of crude oil by molecular size, potentially replacing the energy-intensive process of distillation. This advancement could significantly reduce the energy consumption and environmental impact associated with refining oil into fuels such as gasoline, diesel, and heating oil. Currently, refining processes rely on heating crude oil to high temperatures to separate its components based on their boiling points, a method that accounts for approximately 6% of global carbon dioxide emissions. The new membrane offers an alternative by filtering molecules according to size and shape, eliminating the need for boiling.

According to Zachary P. Smith, associate professor of chemical engineering at MIT and senior author of the study, the new method represents a transformative approach to separation technology. Instead of relying on thermal energy, the membrane uses molecular sieving to isolate specific components from crude oil. The membrane is a thin film that resists swelling—a common issue with previous membranes—and can be manufactured using interfacial polymerization, a technique already common in industrial settings. This makes the technology not only effective but also scalable.

The research, published in Science, was led by Taehoon Lee, a former MIT postdoc and now an assistant professor at Sungkyunkwan University in South Korea. Traditionally, polymer membranes used for such separations, such as PIM-1, allowed fast molecular transport but suffered from excessive swelling when exposed to hydrocarbons. To overcome this, the MIT team modified membranes originally developed for reverse osmosis water desalination. They replaced the amide bonds in standard polyamide membranes with more rigid and hydrophobic imine bonds, resulting in a material that maintains its porosity and does not swell in the presence of oil.

To further refine the membrane’s ability to separate hydrocarbons, the team introduced triptycene—a rigid, shape-persistent molecule that helps form pores of precise size. This enabled the membrane to allow smaller molecules to pass through while blocking larger ones, without losing structural integrity. In tests, the membrane was able to separate a mixture of toluene and triisopropylbenzene with high efficiency, concentrating toluene by a factor of 20. It also successfully separated components of a real industrial blend of naphtha, kerosene, and diesel.

The researchers suggest that a series of these membranes could eventually replace large distillation columns in refineries. Each membrane could filter out specific fractions of crude oil, making the entire process more energy-efficient. Because the membrane fabrication method is already widely used in water treatment, adapting it for oil separation could be relatively straightforward. Smith and Lee believe this technology could pave the way for a new era in oil refining—one that is cleaner, cheaper, and more sustainable.

By Impact Lab