Pilot scale fabrication of lanthanum tungstate supports for H<inf>2</inf> separation membranes

Abstract

This paper reports the fabrication of asymmetric tubular geometry lanthanum tungstate-based membranes for high temperature H2 separation applications. As starting materials, powders with the compositions La28-yW4+yO54+δ (y = 0.848), La28-yW4+yO54+δ (y = 1) and La28-y(W1-xMox)4+yO54+δ (x = 0.3, y = 1) were synthesized by solid state reaction method. Porous, thick-wall tubes made of lanthanum tungstate-based powders with high gas permeability (7–8 x10-15 m2 at 2 bar overpressure) and homogeneous porous microstructure were made by combining a cost-effective solid-state synthesis and thermoplastic extrusion method. Deposition of lanthanum tungstate-based dense thin film (∼20 μm) was achieved on top of porous supports through dip coating technique. The influence of conformation routes, thermal debindering and sintering processes were investigated in detail to achieve defect free H2 transport membranes. Asymmetric geometry membranes with ∼20 μm dense layer thickness supported on porous tubular (∼ 7.5 mm diameter and ∼0.8 mm thick) supports.

As a result, a procedure for proton conducting ceramics manufacture was established which can be deployed to fabricate high temperature catalytic membrane reactors for synthetic fuel from gas-to-liquid (GTL) processes.