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

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, H₂, CO₂, N₂, CH₄ and SF₆ 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 H₂/CO₂ and H₂/SF₆ increases to 5.12 and 10.28 at a process temperature of 200 °C. The influence of a thermal pre-treatment under N₂ and H₂ 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.