金属卟啉仿生催化烷烯混烃共氧化的性能及作用机制

Efficient catalytic selective oxidation of hydrocarbon remains a significant task in current industrial processes. However, the direct biomimetic catalytic oxidation of alkane or alkene always suffers lots of problems such as rigid reaction conditions, low efficiency and poor selectivity. Our previous studies demonstrated that the conversions of alkane and alkene were improved simultaneously when alkene was added in the oxidation system. But the mutual promotion mechanism in the biomimetic co-oxidation of alkane and alkene is not clear. From the preliminary mechanistic investigation, it was proposed that the interaction of substrate radicals could be closely related with the improved efficiency. Further experimental studies proved that the efficiency of alkane-alkene co-oxidation was influenced by the process of free radicals generation and transfer..On the basis of biomimetic co-oxidation of alkane and alkene, various factors that influencing the co-oxidation of alkane and alkene will be investigated systematically. Meanwhile, this project aims to clarify the catalytic mechanism, radical generation and mutual promotion mechanism, radical transfer and dioxygen activation mechanism by in situ characterizations, isotope mass and quantum chemical calculations. Also, this project aims to obtain the common law of biomimetic co-oxidation of alkane and alkene. The project is expected to provide more scientific basis for enhancing the catalytic efficiency and selectivity of hydrocarbon oxidation. The project is also expected to provide theory and technology basis for the industrial biomimetic catalytic oxidation of hydrocarbons.

高效催化碳氢化合物的选择性氧化具有重要的研究意义，但在仿生催化烷烃或烯烃的直接氧化过程中，存在条件苛刻、转化效率低、选择性差等问题。前期研究表明烯烃的加入可同时促使烷烃和烯烃的转化效率得到明显提高，但是烷烃和烯烃在其仿生催化共氧化过程中的相互促进作用机制尚不明确。通过初步的机理研究，我们提出了底物自由基的相互作用是催化性能提高的可能原因，进一步的实验表明自由基的形成及传递对烷烯混烃共氧化的性能有影响。.本项目拟在仿生催化烷烯混烃共氧化的基础上，系统地对影响烷烯混烃共氧化的各种因素进行研究，并采用原位表征技术、同位素质谱、量化计算等方法，旨在阐明金属卟啉仿生催化烷烯混烃共氧化的作用机制、烷/烯基自由基的形成及相互作用、传递及氧气活化机制，获得仿生催化烷烯混烃共氧化的共性规律。本项目有望为仿生催化烃类氧化过程中活性及选择性增强提供更充分的科学依据，也为仿生催化烃类的氧化工业提供理论和技术基础。

本项目针对催化烃类氧化中存在的条件苛刻、效率低及选择性差等问题，开展了仿生催化烷烯混烃共氧化的化工基础研究。项目围绕共氧化过程中烯基和烷基自由基的形成机制、自由基的传递及协同作用机制、以及金属卟啉在烷烯混烃共氧化中的催化作用及氧气活化机制等方面的科学问题展开了系统研究，实现了烯烃如环己烯、丙烯与甲苯、二苯甲烷、正/异丁烷等烷烯混烃的共氧化过程。.通过原位电子顺磁共振及紫外等表征手段，阐明了烷烯混烃共氧化过程的烷基、烯基自由基的形成机理。通过动力学和同位素实验，证实了高价活性物种的形成及催化机理，阐明了氧气的活化机制。动力学数据进一步说明了仿生催化烷烯混烃共氧化的过程具有酶催化的特征，其模型符合米氏动力学模型。并在理论研究的基础上，实现了300t/a的仿生催化环己酮氧化制备-己内酯的技术工艺。.通过本项目的研究，为实现烷烃、烯烃高值化利用提供了重要的思路，为烃类氧化过程中活性及选择性增强提供更充分的科学依据，也为仿生催化烃类的氧化工业提供理论和技术基础。