Solid-solid Photocatalytic Reaction of Malonic Acid. Allowed Limit Amount of H₂O to Give Characteristic Product Selectivity

Abstract

This paper deals with solid-solid photocatalysis; i.e. photocatalytic reaction for a solid substrate using Pt/TiO₂ powdered photocatalyst (solid) under illumination. Malonic acid reacts to CO₂ and a small amount of other minor products in an aqueous suspension of powdered photocatalyst under Ar atmosphere. In the case of the solid-solid system, CH₄ was also produced from malonic acid as a major product together with CO₂. The change of products distribution was observed and the changing behavior of products distribution with an addition of water was examined. Our result showed that the allowed limit amount of water to change the selectivity could be determined. Scheme of product switching was also discussed.