Graphene-membranes prepared by layer-by-layer deposition of graphene flakes on porous ceramic supports

• Graphene flakes were coated layer-by-layer by a self-assembling process • Single gas permeances decrease by an increase of layer numbers • The γ-Al2O3 substrate with continuous reduced pore sizes shows a smooth surface of 55 nm • The smoother the used substrate the lower the single gas permeances after coating • 8L γ-Al2O3 reached a selectivity of H2/CO2 = 5.12 and H2/SF6 = 10.28 @ 200 °C • Thermal treatment under hydrogen or nitrogen introduces defects into the graphene layer at elevated temperature Porous ceramic substrates are an excellent alternative for gas separation in industrial processes at high temperature and pressure conditions. A coating of graphene supports permeances and gas separation based on modified separation pathways determined by the single layer. Graphene is an excellent material for membranes that can be used under aggressive conditions. The double self-assembly (DSA) process developed for this purpose was used to fabricate very thin graphene membranes by layer-by-layer deposition of graphene flakes on flat porous ceramic substrates. The permeances of individual gases such as He, H 2 , CO 2 , N 2 , CH 4 and SF 6 decrease with the number of graphene layers. This is most pronounced up to a graphene layer number of 8 but strongly depends on the utilized ceramic substrate. Furthermore, for 8x coated membranes the selectivity of H 2 /CO 2 and H 2 /SF 6 increases to 5.12 and 10.28 at a process temperature of 200 °C. The influence of a thermal pre-treatment under N 2 and H 2 from 400 °C up to 800 °C on the permeances is shown and Raman measurements were carried out for qualitative observation of the defect behavior.