A ‘trapdoor’ filtering method that admits large molecules and excludes small ones could significantly reduce the cost of separating and storing carbon dioxide.
Most uses of molecular sieves (zeolites) depend on these materials being able to discriminate on the basis of size, letting small molecules move into the zeolite pores and keeping large molecules out. However, Australian researchers recently discovered a new separation mechanism in one particular kind of molecular sieve, where the target molecules – in this case carbon dioxide – induce some of the atoms in the zeolite structure to move aside temporarily so that the target molecules can enter the structure.