The utilization of CO₂ as an oxidant has recently attracted increasing attention due to its mild oxidizing properties allowing higher product selectivities to be achieved e.g. in propane oxidative dehydrogenation (ODH). In this communication we address mechanistic aspects of propane ODH over silica supported vanadia (VO_x/SiO₂) catalysts in the presence of CO₂ as oxidizing agent. The use of operando UV Raman spectroscopy reveals distinct changes in the surface vanadia structure including breakage of VOV bonds and a partial reduction of vanadyl, as well as the formation of support hydroxyl groups, while the presence of CO₂ is observed to prevent coke deposition. Our results are fully consistent with the occurrence of two parallel pathways, i.e., direct ODH (one step) and dehydrogenation followed by a reverse water-gas shift reaction (two step), supporting previous literature proposals.

CO ₂作为氧化剂的利用最近受到越来越多的关注，因为其温和的氧化特性允许实现更高的产物选择性，例如在丙烷氧化脱氢 (ODH) 中。在这篇通讯中，我们讨论了在 CO ₂作为氧化剂存在下，丙烷 ODH 在二氧化硅负载的氧化钒 (VO _x /SiO ₂ ) 催化剂上的机理方面。使用operando UV拉曼光谱揭示了表面氧化钒结构，包括第V破损明显变化ö V键和氧钒基的部分还原，以及支持的羟基的形成，而CO的存在₂观察到防止焦炭沉积。我们的结果与两条平行途径的发生完全一致，即直接 ODH（一步）和脱氢，然后是反向水煤气变换反应（两步），支持先前的文献提议。