Surface Cobalt Silicate and CoOx Cluster Anchored to SBA-15: Highly Efficient for Cyclohexane Partial Oxidation

Density functional theory study of selective aerobic oxidation of cyclohexane: the roles of acetic acid and cobalt ion

A computational study of cyclohexane autoxidation and catalytic oxidation to a cyclohexyl hydroperoxide intermediate (CyOOH), cyclohexanol, and cyclohexanone has been conducted using a hybrid density functional theory method. The activation of cyclohexane and O₂ is the rate-determining step in the formation of CyOOH due to its relatively high energy barrier of 41.2 kcal/mol, and the subsequent reaction behavior of CyOOH controls whether the production of cyclohexanol or cyclohexanone is favored. Using CH₃COOH or (CH₃COO)₂Co as a catalyst reduces the energy barriers required to activate cyclohexane and O₂ by 4.1 or 7.9 kcal/mol, respectively. Employing CH₃COOH improves the CyOOH intramolecular dehydration process, which favors the formation of cyclohexanone. The energy barrier to the decomposition of CyOOH to CyO·, an important precursor of cyclohexanol, decreases from 35.5 kcal/mol for autoxidation to 25.9 kcal/mol for (CH₃COO)₂Co catalysis. (CH₃COO)₂Co promotes the autoxidation process via a radical chain mechanism. The computational results agree with experimental observations quite well, revealing the underlying role of CH₃COOH and Co ion in cyclohexane oxidation. Graphical abstract Through DFT analysis of cyclohexane autoxidation and catalytic oxidation, we reveal the mechanism of the effects of CH₃COOH and Co²⁺ on the reaction routes.

Simultaneous investigation of the structure and surface of a Co/alumina catalyst during Fischer–Tropsch synthesis: discrimination of various phenomena with beneficial or disadvantageous impact on activity

Simultaneous investigation of structure and surface of a Co/Al₂O₃ catalyst during Fischer–Tropsch synthesis: identification of beneficial and disadvantageous phenomena.