Photocatalyst Sol-Gel Multi Layers Film for High Yield CO₂ Conversion into CH₄

Abstract

Photocatalyst conversion of CO₂ into fuel-like species like CH₄, C₂H₄, C₂H₆ and CO is an attractive technique for CO₂ re-use element of carbon cycle construction. Feasibility experiments of CO₂ conversion by using TiO₂ photocatalyst mixed with several kinds of metals have been carried out, although the reforming concentrations seem to be relatively small within the order from 10 to 10²ppm. In order to promote the yield of CO₂ photocatalyst conversion as much as 10⁴ppm for re-use as fuel, innovative techniques are needed first for TiO₂ film formation. In this paper, we propose a new sol-gel and dip-coating on a copper metal substrate with multi-layers of TiO₂. In this experiment, the conversion yield by the photocatalyst film coated over a cylindrical reactor of Cu tube is examined, in which an UV lamp is set along the center line. CO₂ gas saturated with H₂O vapor is filled in the photocatalyst reactor. The conversion characteristics are tested by changing the number of TiO₂ film layer coated on the Cu substrate and the firing duration time. The chemical species are detected by a gas chromatograph at an interval of 24 hour. TiO₂ film surfaces are analyzed by SEM and EDX. As a result, film surfaces have been more roughness with increasing coating number and decreasing firing duration time. Compared with the previous studies, remarkably higher concentrations of exceeded 9000ppm for CO and 2300ppm for CH₄ have been obtained. It is known that CO is produced earlier than CH₄, C₂H₄ and C₂H₆.