二氧化鈦光觸媒薄膜進行光催化分解氣相正丙醇之動力研究

Kinetic study for Photocatalytic Degradation of 1-Propanol in Air using Thin Film TiO2 Photocatalyst

揮發性有機物廣泛地使用在工業與家庭上，為人們帶來舉多便利；然而，這些有機物釋放到大氣中，與氮氧化物進行光化學作用，形成光化學性高氧化物，進而傷害人與農作物。本研究以批次實驗，探討不同因子（初始濃度、溫度、氧含量與溼度）對正丙醇光催化分解之影響，並以反應動力式模擬反應過程正丙醇的濃度變化。實驗結果發現反應過程正丙醇的濃度變化可以一階反應動力式模擬。初始濃度越高，反應速率越快，在低濃度反應速率與初始濃度成正比，在高濃度反應速率幾乎為定值。二氧化鈦光催化氧化正丙醇的初始反應速率用Langmuir-Hinshelwood反應動力式描述，可得反應速率常數k=66.6ppm/sec，吸附平衡常數K=1.35×10-3ppm）-1。氧含量越高正丙醇氧化速率越快。在100℃-200℃的範圍，反應溫度越高正丙醇氧化速率越慢。溼度越高，正丙醇分解速率越快，但溼度大於980ppm，正丙醇分解速率受到抑制。另外，發現正丙醇光催化過程中產生中間產物丙醛與最終產物二氧化碳。

Volatile organic compounds (VOCs) are used extensively in a variety of industrial and domestic application. The serious problem related to the emission of VOCs is that they participate in the photochemical reaction and also in the formation of photochemical oxidants. The oxidants damage human and vegetation. This work presents a photocatalysis-based method to treat and purify air because of its broad applicability to common, oxidizable air contaminants. The effects of temperature, oxygen content, humidity, and 1-propanol concentration on the photooxidation of 1-propanol were investigated. The photocatalytic decomposition reaction of 1-propanol obeyed the first-order equation. The initial rate of 1-propanol degradation could be well described by the Langmuir-Hinshelwood rate form. The specific reaction rate constant and the equilibrium adsorption were 66.6 ppm/sec and =1.35 × 10-3 (ppm)-1, respectively. Higher temperature inhibited the oxidation of 1-propanol. The decomposition rate was increased with increasing the oxygen content. The rate of 1-propanol oxidation was increased when water vapor was increased from 458 ppm to 980 ppm and decreased at higher than 980 ppm. Propanal and carbon dioxide were detected as the by-product and final product of reaction for photocatalytic oxidation of 2-propanol in gas-phase.