Effect of TiO₂ doping on the characteristics of macroporous Al₂O₃/TiO₂ membrane supports

A cost-effective tubular macroporous ceramic support consisting of alumina and titania was prepared by extrusion and subsequent heat treatment. An Al₂O₃/TiO₂ composite support with high porosity (41.4%), an average pore size of 6.8 μm and sufficient mechanical strength (32.7 MPa) was obtained after sintering at 1400 °C. The formation mechanism of this support as investigated with X-ray micromapping, SEM and XRD indicated that the appearance of Al₂TiO₅ plays a key role in the fabrication of high performance composite membrane supports at relatively low temperature. The amount of Al₂TiO₅ present in the composite has a strong impact on the properties of supports, especially with regard to the mechanical strength. A composite of 85 wt.% Al₂O₃/15 wt.% TiO₂ sintered at 1400 °C for 2 h exhibited both high permeability (pure water flux of 45 m³ m^-2 h^-1 bar^-1), together with an excellent corrosive resistance towards hot NaOH and HNO₃ solutions.