Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Krakow, Poland.
Faculty of Chemical Engineering and Technology, Cracow University of Technology, Warszawska 24, 30-155 Krakow, Poland.
Molecules. 2020 Apr 23;25(8):1961. doi: 10.3390/molecules25081961.
Oxidative dehydrogenation (ODH) of light alkanes to olefins-in particular, using vanadium-based catalysts-is a promising alternative to the dehydrogenation process. Here, we investigate how the activity of the vanadium phase in ODH is related to its dispersion in porous matrices. An attempt was made to synthesize catalysts in which vanadium was deposited on a microporous faujasite zeolite (FAU) with the hierarchical (desilicated) FAU as supports. These yielded different catalysts with varying amounts and types of vanadium phase and the porosity of the support. The phase composition of the catalysts was confirmed by X-ray diffraction (XRD); low temperature nitrogen sorption experiments resulted in their surface area and pore volumes, and reducibility was measured with a temperature-programmed reduction with a hydrogen (H-TPR) method. The character of vanadium was studied by UV-VIS spectroscopy. The obtained samples were subjected to catalytic tests in the oxidative dehydrogenation of propane in a fixed-bed gas flow reactor with a gas chromatograph to detect subtract and reaction products at a temperature range from 400-500 °C, with varying contact times. The sample containing 6 wt% of vanadium deposited on the desilicated FAU appeared the most active. The activity was ascribed to the presence of the dispersed vanadium ions in the tetragonal coordination environment and support mesoporosity.
烷烃的氧化脱氢（ODH）转化为烯烃——特别是使用基于钒的催化剂——是一种很有前途的替代脱氢工艺。在这里，我们研究了钒相在 ODH 中的活性与其在多孔基质中的分散性之间的关系。尝试合成了将钒沉积在具有分级（脱硅）FAU 的微孔丝光沸石（FAU）上的催化剂，作为载体。这些方法得到了不同的催化剂，具有不同数量和类型的钒相以及载体的多孔性。通过 X 射线衍射（XRD）证实了催化剂的相组成；低温氮气吸附实验得到了它们的比表面积和孔体积，并用氢气（H-TPR）程序升温还原法测量了还原性能。通过紫外可见光谱研究了钒的性质。用气相色谱法在固定床气流反应器中进行丙烷氧化脱氢的催化测试，以在 400-500°C 的温度范围内检测产物和反应产物，接触时间不同。沉积在脱硅 FAU 上的 6wt%钒的样品表现出最高的活性。这种活性归因于在四方配位环境和载体介孔中存在分散的钒离子。
