Degradation of formic acid over semiconducting membranes supported on glass: effects of structure and electronic doping

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Abstract

The photocatalytic oxidation of solutions of formic acid over supported semiconducting ceramic membranes has been investigated. Sol-gel techniques were employed to coat pyrex glass supports with colloidal solutions. Subsequent firing leads to supported ceramic membranes suitable for use as photocatalysts. The structure of these membranes affects the rate of photocatalytic oxidation of formic acid. The most active titania photocatalysts are those membranes characterized by the least number of boundaries between particles. Titania membranes doped with vanadium, molybdenum, yttrium, magnesium, lithium and rutherium oxides and platinum metal have been prepared. Only those titania membranes doped with magnesium oxide, lithium oxide or platinum metal were characterized by higher activities for the degradation of formic acid than the original titania membranes. The rate of this degradation reaction can be characterized by an expression of the Langmuir-Hinshelwood-Hougen-Watson form.

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