Ultrathin metal–organic framework membrane production by gel–vapour deposition

Abstract Ultrathin, molecular sieving membranes composed of microporous materials offer great potential to realize high permeances and selectivities in separation applications, but strategies for their production have remained a challenge. Here we show a route for the scalable production of nanometre-thick metal–organic framework (MOF) molecular sieving membranes, specifically via gel–vapour deposition, which combines sol–gel coating with vapour deposition for solvent-/modification-free and precursor-/time-saving synthesis. The uniform MOF membranes thus prepared have controllable thicknesses, down to ~17 nm, and show one to three orders of magnitude higher gas permeances than those of conventional membranes, up to 215.4 × 10 −7 mol m −2 s −1 Pa −1 for H 2 , and H 2 /C 3 H 8 , CO 2 /C 3 H 8 and C 3 H 6 /C 3 H 8 selectivities of as high as 3,400, 1,030 and 70, respectively. We further demonstrate the in situ scale-up processing of a MOF membrane module (30 polymeric hollow fibres with membrane area of 340 cm 2 ) without deterioration in selectivity.