Microstructure,strength and CO 2 separation characteristics of α -alumina supported γ -alumina thin film membrane

Abstract

In this work, a mesoporous γ-Al₂O₃ membrane was synthesised on an α-Al₂O₃ substrate by a sol–gel dip coating process. The membranes were characterised using SEM, field emission SEM, X-ray diffractometry and N₂ adsorption/desorption measurements (Brunauer–Emmett–Teller analyses). The characterisation results revealed that a flawless γ-alumina membrane layer with 3·5 μm thickness and 2·1 nm average pore size was achieved. Subsequent separation tests indicated that CO₂ could be separated from N₂ by the mesoporous γ-Al₂O₃ membrane. In spite of the difficulties of the separation, the optimised microstructure achieved for the prepared membrane led to desirable and regular permeation behaviour. It was also observed that separation could be more efficient in high pressure permeation conditions. The prepared substrate fulfilled the required strength and permeability for the thin γ-Al₂O₃ membrane film under these conditions. Accordingly, an optimised completely ceramic membrane structure, applicable for CO₂ separation applications, was achieved.