N -Aryl–linked spirocyclic polymers for membrane separations of complex hydrocarbon mixtures

Separating organics without distillation Hydrocarbon distillation is a widespread and energy-intensive process. Membranes might offer an alternative approach, but few can survive immersion in organic solvents nor are they able to extract relatively small molecules. Thompson et al. developed a series of polymers of intrinsic microporosity that they used for membrane-based separations of organic compounds in an organic solvent (see the Perspective by Brennecke and Freeman). The new membrane has a molecular weight cutoff of 253 daltons, far lower than existing ones closer to 600 daltons. The polymers were used to separate light shale crude oil and succeeded in fractionation of molecular weights of about 170 daltons. Science this issue p. 310 ; see also p. 254