Various forms of cobalt catalysts have been studied extensively for selective aerobic oxidation of hydrocarbons. However, it remains unclear whether cobalt can directly activate molecular oxygen under mild reaction conditions. Here we investigated the catalytic roles of cobalt in ethylbenzene oxidation with and without a hydroperoxide initiator. The contribution of different cobalt species was studied by varying the metal loading on Co-impregnated ZSM-5 samples. Quantitative EPR was used to determine the impact of cobalt catalysts on the free radical concentrations. This work provided strong evidence that cobalt, in several different forms, catalyzes hydrocarbon oxidation by facilitating peroxy bond cleavage, instead of direct oxygen activation.

已经广泛研究了各种形式的钴催化剂用于烃的选择性好氧氧化。但是，尚不清楚钴在温和的反应条件下是否能直接活化分子氧。在这里，我们研究了钴在有和没有氢过氧化物引发剂的乙苯氧化中的催化作用。通过改变共浸渍ZSM-5样品上的金属负载量，研究了不同钴物种的贡献。定量EPR用于确定钴催化剂对自由基浓度的影响。这项工作提供了有力的证据，表明几种不同形式的钴通过促进过氧键的裂解而不是直接的氧活化来催化碳氢化合物的氧化。