Molecular cages, in which guest molecules cling to the cages’ outer surfaces rather than enter an internal cavity, could cut the environmental impact of separating mixtures of industrial chemicals, research from KAUST suggests.

Molecular separations performed at scale by the chemical industry collectively account for as much as 15 percent of global energy consumption. One of the most energy-intensive separations involves benzene derivatives, called xylenes, which are produced as a mixture of three isomeric forms that must be separated for their various industrial uses. The most valuable isomer, para-xylene, is a key ingredient in polyester and polyethylene terephthalate (PET) polymer manufacture.

“Conventionally, these isomers are separated by energy-demanding methods, such as fractional crystallization,” says Basem Moosa, a research scientist in Niveen Khashab’s lab. “Alternative techniques that require less heat would lower the carbon footprint and overall pollution of xylene separation,” he adds.

Read more...