光催化环己烷选择氧化合成环己酮/环己醇催化研究进展

环己烷选择性氧化合成环己醇/酮具有重要工业价值，工业上热氧化路线反应温度高、副反应多、转化率低、选择性不高，亟需条件更温和、更环保的替代路线。以太阳光为驱动的光催化环己烷氧化路线可在常温常压下实现环己烷的选择性氧化，受到极大关注。本文综述了近10年来光催化环己烷选择性氧化催化体系、反应机理和反应影响因素的研究情况，对光催化环己烷选择性氧化催化循环中环己烷分子活化、环己酮/醇形成、活性自由基再生的基元过程和催化剂失活机理进行总结和分析；对影响光催化环己烷选择性氧化的反应参数进行深入分析和讨论；指出·OH为主要的活性自由基，环己基过氧化氢是重要的中间产物，环己酮/醇主要通过环己基过氧化氢的光催化分解形成，光辐射条件（光强和波长）、溶剂、催化剂结构和表面性质都是光催化环己烷选择性氧化的重要影响因素。最后指出光催化环己烷选择性氧化规模化应用的关键是进一步提高光催化剂的寿命和稳定性以及设计结构合理、高效利用光能的光催化反应装置。

Progress in photocatalytic selective oxidation of cyclohexane to cyclohexanone/cyclohexanol

The selective oxidation of cyclohexane to cyclohexanone/ol is an industrially important process. The industrial thermal oxidation route has some disadvantages such as harsh reaction conditions, inevitable side reactions, low conversion of cyclohexane and low selectivity of cyclohexanone and cyclohexanol, which demands the development of alternative route that is more mild and environmentally friendly. The photocatalytic cyclohexane oxidation driven by sunlight can take place at normal temperature and pressure, and hence has attracted great attention. In this paper, the progress on the catalytic system, reaction mechanism and influencing factors of the photocatalytic selective oxidation of cyclohexane in last decade are reviewed. The research results on the element procedures of cyclohexane activation, cyclohexanone/ol formation and active radical regeneration as well as on the deactivation mechanism of catalysts were summarized and analyzed. In addition, the reaction parameters affecting the photocatalytic selective oxidation of cyclohexane were also analyzed and discussed in depth. It was found that ·OH was the main active radical, and cyclohexyl peroxide was the important intermediate. Cyclohexanone/alcohol was formed mainly through the photocatalytic decomposition of cyclohexyl peroxide. The light radiation parameters (incident light intensity and wavelength range), solvent and the structural and surficial properties of the catalysts are important factors affecting the reaction efficiency. Finally, it is pointed out that the key to the large-scale application of photocatalytic cyclohexane oxidation is to further improve the life and stability of the photocatalyst and to design a photocatalytic reaction device with reasonable structure and highly efficient utilization of light energy.