Enhanced Gas Separation Properties of Metal Organic Frameworks/ Polyetherimide Mixed Matrix Membranes

摘要

Metal organic frameworks (MOFs) are supposed to be ideal additives for mixed matrix membranes (MMMs). In this article one kind of MOFs, Cu_3(BTC)_2, is synthesized, then directly incorporated into a model polymer (Ultem?1000) using N,N-dimethylacetamide as solvent. Cu_3(BTC)_2 particles are uniformly dispersed and there are no interfacial defects in the prepared MMMs when Cu_3(BTC)_2 loading is not more than 35 wt %, seen in SEM images. Pure gas permeation tests show that gas permeability increases obviously with Cu_3(BTC)_2 loading increase, while ideal selectivities of CO_2/N_2 and CO_2/CH_4 are almost unchanged. For MMM with the best separation property, CO_2 permeability increases about 2.6 times and CO_2/N_2 selectivity remains almost unchanged. Results about gas diffusivity and solubility indicate that gas diffusivity and solubility make contribution to gas permeability increase at the same time but in different ways. Gas permeation properties of MMMs are well predicted by Maxwell or Bruggeman model.