Supported MO_x (M= Mo, V) on mixed CeO₂-TiO₂ were investigated for the oxidative dehydrogenation of ethane (ODHE) using CO₂ as a mild oxidant. Raman spectroscopic characterization of the synthesized catalysts under dehydrated conditions suggest that surface MoO_x species prefer to anchor on the crystalline domains of TiO₂. Upon increasing the amount of CeO₂ in the mixed oxide support, an intense and broad band at ~930cm^-1 underscored that the prevalent species tend to be polymeric (MoO_x)_n domains. On the other hand, in the case of VO_x catalysts, a gradual shift in the symmetric stretching of the vanadyl (V=O) Raman band with increasing CeO₂ content was observed that points at the gradual anchoring of the surface vanadia species on both TiO₂ and CeO₂ thus highlighting the possible existence of the amorphous VO_x to be located at the interface of the two mixed oxides. The catalytic behavior of Mo and V were distinct. As the ceria content in the support increased, MoO_x catalysts promoted the ODHE via Mars van Krevelen mechanism while VO_x catalysts appeared to favor ethane direct dehydrogenation. Investigation of structure-function relationships via in-situ Raman spectroscopic efforts revealed that adding ceria not only changed the redox properties of the support but also improved those of the deposited metal oxide. We also show that upon incorporation of ceria into the support, CO₂ directly participates in the reoxidation of the dispersed MoO_x species during catalysis. This effect was distinct from the reaction of CO₂ in the reverse water gas shift reaction. Operando Raman spectra revealed that the presence of CO₂ enhances the stability of the bridging Mo–O–Mo bond of polymeric molybdena domains, which is proposed to affect the relative contribution of oxidative versus non-oxidative pathways in ethane dehydrogenation.

研究了在混合的CeO ₂ -TiO ₂上负载的MO _x（M = Mo，V ）使用CO ₂作为弱氧化剂，对乙烷（ODHE）的氧化脱氢的作用。在脱水条件下合成催化剂的拉曼光谱表征表明，表面MoO _x物种更喜欢锚定在TiO ₂的晶域上。随着混合氧化物载体中CeO ₂含量的增加，在约930cm ^-1处出现一条宽而宽的带， 这表明该普遍的物种倾向于是聚合的（MoO _x）_n 域。另一方面，在VO _x的情况下催化剂，随着CeO ₂含量的增加，钒基（V = O）拉曼光谱带的对称拉伸逐渐移动，发现其指向表面钒物种逐渐锚固在TiO ₂和CeO _2上，从而突出了可能存在的非晶VO _x位于两种混合氧化物的界面。Mo和V的催化行为是不同的。随着载体中二氧化铈含量的增加，MoO _x 催化剂通过Mars van Krevelen机理促进了ODHE，而VO _x 催化剂似乎有利于乙烷直接脱氢。通过原位拉曼光谱法研究结构-功能关系发现，添加二氧化铈不仅改变了载体的氧化还原性质，而且改善了沉积的金属氧化物的氧化还原性质。我们还表明，在载体中掺入二氧化铈后，CO ₂直接参与催化过程中分散的MoO _x物种的再氧化。该效果与逆水煤气变换反应中的CO ₂的反应不同。Operando拉曼光谱揭示了CO ₂的存在 增强了聚合物钼结构域的Mo–O–Mo桥键的稳定性，这被提议影响乙烷脱氢中氧化和非氧化途径的相对贡献。