| 摘要: | 在過去的文獻中，含鉬和釩的複合氧化物經加入碲、鈮、鈀、鉭、或鎳等金屬形成的多金屬複合氧化物，已被用來作為氧化脫氫的催化劑。本研究中利用泥漿法來製備複合氧化物觸媒並經450-600℃的熱處理。觸媒鑑定部分，以X光繞射儀(XRD)、掃描式電子顯微鏡(SEM)、穿透式電子顯微鏡(TEM)、高解析度穿透式電子顯微鏡(HRTEM)、X光光電子能譜儀(XPS)等來鑑定觸媒之物理、化學特性和表面性質。此研究的複合氧化物經鑑定分析後發現具有M1晶相、M2晶相、MoO3、Mo3Nb2O11、TeMo5O16、Mo6V9O40或Mo5O14結構。使用TiO2當作載體可均勻分散複合氧化物，避免其團聚，以得到顆粒較小的氧化物並可增加其反應面積。利用泥漿法製備多金屬複合氧化物，可於含碲之氧化物中發現M1相及M2相的存在。Mo-V-Nb-Te複合氧化物經過H2O2清洗可洗去較無活性之M2相。若欲得到較具活性的晶相，如M1相或Mo5O14 結構，則需在製備過程中處於低pH值狀態(pH< 3)。本研究討論利用泥漿法製備含鉬、釩複合氧化物觸媒，其過程經加入碲、鈮、載體後，導致不同晶相的形成，以及更改製備條件後增加觸媒對部分氧化脫氫的活性相。;Molybdenum and vanadium based multi-metal oxides, which was added with niobium (Nb), tellurium (Te), palladium (Pd), tantalum (Ta), and nickel (Ni) and so on, have been used as the catalyst for this reaction. In this study, all of the catalysts were prepared by a slurry method and heat treated at 450-600℃. These catalysts were characterized by X–ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), and X-ray photoelectron spectroscopy (XPS). The crystalline phases in these samples were M1 phase, M2 phase, MoO3, Mo3Nb2O11, TeMo5O16, Mo6V9O40, and Mo5O14-like structure. Using TiO2 as the support yielded a smaller particle size of multi-metal oxides, keep the multi-metal oxide particles high dispersion and prevent from sintering. The presences of M1 phase and M2 phase were found in Te-containing oxides. After washing Mo-V-Nb-Te oxides with H2O2 solution, the M2 phase was dissolved and active phases were obtained. The multi-metal oxides should prepare at lower pH value (pH< 3) to obtain more active phases, such as M1 phase and Mo5O14-like structures. The Mo-V-based oxides with tellurium, niobium, and TiO2 were prepared by a slurry method to cause the formation of different crystalline phases. By changing the preparation conditions, one can increase the crystalline phases of the oxides. |
