Heat-Transfer Analysis of the Promotion of the CO₂ Reduction Performance of a P₄O₁₀/TiO₂ Photocatalyst Using a Black Body Material

Abstract

Since photocatalytic reactions are surface reactions, enhancing gas movement around the photocatalyst could improve photocatalytic CO2 reduction performance. A new approach using black body material to enhance the gas movement around the photocatalyst based on the natural thermosiphon movement of gases around a photocatalyst has been proposed and confirmed experimentally, but the heat-transfer mechanism of the phenomena has not yet been clarified. The aim of this study is to clarify the corresponding heat-transfer mechanism. This study calculated the temperature of the CO2/NH3 gas mixture around a P4O10/TiO2 photocatalyst using the heat-transfer formula. No difference was found between the temperature increase (Tg) from the temperature at the beginning of the CO2 reduction experiment (Tini) and the temperature of the CO2/NH3 gas mixture measured experimentally via thermocouple (Te) under the following illumination conditions: a Xe lamp with visible light (VIS) + infrared light (IR) and IR only. The heat-transfer model proposed in this study predicts Tg well under illumination from a Xe lamp with VIS + IR as well as under IR illumination only. On the other hand, the difference found between Tg and Te was as large as 10 °C under illumination from a Xe lamp with ultraviolet light (UV) + VIS + IR.

Keywords

• heat-transfer analysis
• P₄O₁₀/TiO₂ photocatalyst
• CO₂ reduction with NH₃
• black body material
• infrared light
• mass-transfer promotion