Infiltration of precursors into a porous alumina support for ZIF-8 membrane synthesis

A new synthesis method was developed to synthesize ZIF-8 membrane by infiltrating precursors into a porous alumina support as a seed-and-nutrient layer, and subsequent solvothermal synthesis. A precursor layer with a thickness of about 10 μm was formed inside the porous alumina support and the ZIF-8 membrane grew from both the seeds embedded in the precursor layer and the synthesis solution under solvothermal synthesis conditions. The effects of the solvothermal synthesis temperature and time were investigated, and a continuous and stable ZIF-8 membrane was prepared at 120 °C for 8 h. Gas permeation tests indicated the membrane synthesized at 120 °C for 8 h was continuous and compact, and had H₂/N₂ ideal selectivity of 5.7 with a H₂ permeance of 1.7 × 10⁻⁷ mol m⁻² s⁻¹ Pa⁻¹.