过渡金属-V-B-MCM-41催化剂的制备及其丙烷氧化脱氢性能

Preparation of Transition Metal-V-B-MCM-41 Catalytic and Their Performance for Oxidative Dehydrogenation of Propane

摘要: 采用水热–焙烧法制备一系列不同过渡金属离子(X = Cr³⁺, Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺)掺杂的V-B-MCM-41催化剂，对其进行X-射线衍射、N₂物理吸附–脱附、紫外–可见漫反射光谱表征，并考察不同过渡金属离子掺杂对其丙烷氧化脱氢(ODHP)制丙烯催化性能的影响。结果表明：掺杂不同过渡金属离子，催化剂仍可保持类似MCM-41的介孔结构。但Cr³⁺掺杂使催化剂表面缺陷位增多，增加VO_x物种的分散性和氧化活性，可明显提升催化剂ODHP催化活性，其起活温度可低至350℃，且其丙烷转化率明显优于其他催化剂，丙烯选择性随反应温度升高无明显降低，550℃时丙烷转化率达32%，丙烯收率为17%。

Abstract: A series of transition metal ion (Cr³⁺, Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺ or Zn²⁺)-doped V-B-MCM-41 were prepared via a hydrothermal-calcination method. The catalysts were characterized by X-ray diffraction, N₂ physisorption-desorption and UV-Vis diffuse reflectance spectroscopy. The effect of different transition metal ions on their catalytic performance for the oxidative dehydrogenation of propane to propylene were investigated. The results revealed that the catalysts with incorporation of various transition metal ions retained the mesoporous structure analogous to MCM-41. However, the incorporation of Cr³⁺ significantly increased the surface defect sites of the catalyst and the dispersion and oxidation activity of VO_x species, thereby enhancing the catalytic activity for the oxidative dehydrogenation of propane. The Cr-doped catalyst exhibited low activation temperature of 350˚C. Notably, it outperformed other catalysts in propane conversion, achieving 32% at 550˚C with propylene yield of 17%. Moreover, the propylene selectivity showed negligible decline with increasing reaction temperature.