Grafting of VO x/TiO 2 catalyst on anodized aluminum plates for structured catalytic reactors

Abstract

Structured reactors are promising to carry out exothermic reactions because the heat transfer is better controlled than in usual packed-bed reactors. However the coating by oxide powders which must exhibit catalytic activity/selectivity while being mechanically stable is not so straightforward. We have studied the parameters to be controlled to coat aluminum walls by V 2O 5/TiO 2 catalysts which are used in the mild oxidation of hydrocarbons and NO x abatement. The dip-coating technique using metallic alcoholates has been chosen for the grafting of TiO 2 on Al 2O 3/Al, which is controlled by X-ray Photoelectron Spectroscopy (XPS). A monolayer of TiO 2 is first grafted, and then a porous film of TiO 2-anatase is deposited by sol–gel. Finally, VO x species are grafted on titania and their loading again determined by XPS. Techniques such as Laser Raman Spectroscopy, Scanning Electron Microscopy are used to characterize the samples after each step, and the porous texture is determined. The layers are mechanically and thermally stable. The dispersion and nature of VO x species on TiO 2/Al 2O 3/Al are similar to what is found in literature for TiO 2 powders, showing thereby that the shaping of anatase support on plates has not modified the chemical properties of VO x /TiO 2-anatase system.