photocatalytic water splitting combine with CO2 reduction in twin reactor

• Main Authors: Wei-Hsuen Lee, 李韋萱
• Other Authors: Chi-Sheng Wu
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/56583461581685991156

碩士 === 國立臺灣大學 === 化學工程學研究所 === 100 === Global warming becomes an serious problem nowadays. Greenhouse gas is one of the primary causes of global warming, such as CO2, N2O, etc. One of the promising solutions is to perform photoreduction of CO2 to produce fuel. CO2 can be reduced in water vapor or H2 by photocatalyst. Use H2 to reduce CO2 by photocatalyst under light irradiation is more possible based on thermodynamics. In this study, CO2 photoreduction is applied into a novel twin photoreactor, which can separate H2 and hydrocarbon from O2. We employed sol-gel derived InTaO4 and solid state method derived CuAlGaO4 loaded with different cocatalysts NiO, Cu, Pt and Rh to test its activity in the twin reactor. We used 300W xenon lamp as the visible light source and Fe3+ pre-treated Nafion membrane to separate two sides of half-reaction. We add commercial WO3 as oxygen catalyst into oxidation-side half reactor and adjusted pH value of both sides to 2.6. Pt/CuAlGaO4 showed activity for CO2 reduction to form methanol. The optimum amount of Pt cocatalyt is 1wt%. In this case, methanol, H2, and O2 produced with stoichiometric amounts. The yields of H2, methanol and CO were 0.43μmol/g‧hr, 1.80μmol/g‧h, 0.16μmol/g‧h. Under this condition we can get (H2+3‧CH3OH+CO):O2 molar ratio close to 2:1. The quantum efficiency is around 0.002%. Evolusion of product in a stoichiometric ratio indicated that water was consumed as a reducing reagent for the CO2 reduction. Combined Pt/SrTiO3:Rh and Pt/CuAlGaO4 together in reduction side under AM1.5G Xe lamp, (H2+3‧CH3OH+CO):O2 molar ratio is 1.89, and quantum efficiency is 0.0051%. Use Pt/CuAlGaO4 under AM1.5G Xe lamp, (H2+3‧CH3OH+CO):O2 molar ratio is 1.95, and quantum efficiency is 0.0035%.