Sol-gel derived Rh/TiO2/SiO2 nanocomposite membranes

A porous borosilicate substrate has been coated with base catalysed SiO2 sol–gel nanoparticles. Onto these were deposited the vapour of titanium isopropoxide, where it reacted with the surface OH groups to give a TiO2-overcoat. This nanocomposite sol–gel derived TiO2/SiO2 membrane was then doped with 1%Rh giving Rh/TiO2/SiO2 membranes. These are shown to be coherent and crack-free, to have good permeability and activity in the isomerisation of butanes. It appears that sol–gel chemistry will allow such membranes to be totally engineered at a nm level.