Pd/TiO_(2)-ZnO异质结用于光催化CO_(2)氧化乙烷脱氢制乙烯

Photocatalytic oxidative dehydrogenation of ethane to ethylene with CO_(2) over Pd/TiO_(2)-ZnO heterojunction

采用化学还原法与研磨法,分别制备Pd/TiO_(2)与Pd/TiO_(2)-ZnO催化剂,用于光催化CO_(2)氧化乙烷脱氢制乙烯。通过Raman、TGA技术研究光照后催化剂上积碳生成情况,利用XRD、HRTEM、XPS技术表征催化剂活性中心颗粒大小范围与价态范围,采用ESR、UV-Vis DRS、UPS技术考察催化剂光学性质与能带结构,通过原位漫反射傅里叶红外光谱技术分析Pd/TiO_(2)-10%ZnO光催化CO_(2)氧化乙烷脱氢制乙烯反应机理。研究表明,加入ZnO,不会对Pd/TiO_(2)催化剂原有活性中心Pd颗粒大小范围、Pd^(0)与Pd^(2+)比例范围产生影响,但是会与Pd/TiO_(2)之间构成异质结,提高光生载流子分离效率,促进光照条件下羟基自由基生成。ZnO的加入,也促进了乙烷直接裂解产生积碳,导致体系中氢气含量增加。

Pd/TiO_(2) and Pd/TiO_(2)-ZnO catalysts were prepared by chemical reduction and grinding methods respectively for photocatalytic CO_(2) oxidative dehydrogenation of ethane to ethylene.Carbon deposition of the catalysts were studied by Raman and TGA.The particle size range and valence range of active sites of the catalysts were characterized by XRD,HRTEM and XPS.The optical properties and bandgap structure of the catalysts were investigated by ESR,UV-Vis DRS and UPS.The mechanism of photocatalytic oxidative dehydrogenation of ethane to ethylene with CO_(2) over Pd/TiO_(2)-10%ZnO was examined with in situ diffuse reflectance Fourier transform infrared spectroscopy.The addition of ZnO was proved not effecting the range of Pd particle size and the ratio of Pd^(0) to Pd^(2+) in Pd/TiO_(2) catalyst.A heterojunction formed between ZnO and Pd/TiO_(2) effectively improves the separation efficiency of photogenerated carriers,promotes the formation of hydroxyl radicals under light condition.The addition of ZnO also promote the direct cracking of ethane to produce carbon deposition,resulting in the increase of hydrogen content in the system.