A porous adsorbent for separating light hydrocarbons

A research team from King Abdullah University of Science and Technology (KAUST), Saudi Arabia, has devised a new technique than can separate paraffin, a light hydrocarbon essential to the process of producing high-quality fuels in the gas, oil and fuel industries.

Separation of light hydrocarbon is expensive and energy consuming, but the researchers found a way to synthesize a new, three-dimensional metal-organic-framework (MOF)-based porous adsorbent that can isolate normal paraffins from branched paraffins much more effectively¹. 

“This new adsorbent possesses the properties to emerge as a cost-effective and energy-efficient agent that could be used to separate hydrocarbons,” says lead researcher Mohamed Eddaoudi.    

Eddaoudi and his colleagues produced the adsorbent by linking twelve connected hexanuclear rare-earth metal-based clusters with an organic ligand. The adsorbent exhibited a face-centred-cubic topology that consisted of octahedral and tetrahedral cages sharing triangular windows, the sole access to the MOF pore system. 

They fine-tuned the access to the MOF pore system so that the triangular window aperture is slightly larger than the normal paraffins and shorter than most of the branched paraffins. This way, the adsorbent can completely separate normal paraffins from branched paraffins.  

The MOF showed significant stability when soaked in various organic and inorganic solvents for long periods, say the researchers. Even exposure to different levels of humidity didn’t alter the crystalline structure and porosity of the MOF.

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