Structural and catalytic properties of flame-made CoO_x/silica catalysts for the CO₂-assisted dehydrogenation of ethane were observed to vary strongly depending on the Co-loading (0.1–4.5 wt%). X-ray diffraction showed that both fresh and spent catalysts were amorphous. UV–vis, XPS and XAS indicated that at Co-loadings lower than about 1 wt% highly dispersed tetrahedral Co²⁺ strongly bound to the silica matrix in a cobalt silicate like mixed oxide phase, was the prevalent cobalt species. At higher Co-loadings the presence of CoO_x clusters became significant. All cobalt species showed strong resistance towards reduction, as shown by TPR. Comparative XAS analyses of catalysts exposed to ambient atmosphere and thermally pretreated catalysts (400 °C, vacuum for 2 h) showed that the presence of water facilitates the transformation of tetrahedrally to octahedrally coordinated Co²⁺. Best catalytic performance was achieved with a catalyst containing 0.75 wt% Co, affording 46% ethane conversion at 85% selectivity to ethene under the standard reaction conditions applied (700 °C, CO₂/C₂H₆ ratio of 2.5 and gas hourly space velocity of 6000 L kg⁻¹ h⁻¹). Some coke deposition in the form of disordered and graphitic carbon was observed with all Co-loaded catalysts. The catalyst with optimal Co-loading (0.75 wt%) showed nearly stable performance during 10 h time-on-stream.

结构和火焰制成的CoO催化性能_X为CO /二氧化硅催化剂₂中观察到的乙烷脱氢-assisted依赖于共同负载量（0.1-4.5重量％），以改变强烈。X射线衍射表明，新鲜催化剂和废催化剂都是无定形的。UV-vis，XPS和XAS表明，在钴含量低于1 wt％的情况下，与硅酸盐钴（如混合氧化物相）牢固结合的高度分散的四面体Co ²⁺是氧化硅，是普遍存在的钴。在较高的共负载下，CoO _x的存在集群变得很重要。如TPR所示，所有钴物种均显示出强烈的抗还原性。对暴露于环境大气中的催化剂和经过热处理的催化剂（400°C，真空2 h）进行的比较XAS分析表明，水的存在促进了四面体配体向八面体配体的Co ²⁺的转化。使用含0.75 wt％Co的催化剂可获得最佳催化性能，在所应用的标准反应条件下（700°C，CO ₂ / C ₂ H ₆比为2.5和气体时空），在46％的乙烷转化率下，对乙烯的选择性为85％。速度6000 L kg ^-1  h ^-1）。在所有负载钴的催化剂上均观察到一些无序和石墨碳形式的焦炭沉积。具有最佳共担载量（0.75重量％）的催化剂在运行10小时的时间内表现出近乎稳定的性能。