中文摘要：

环己醇和环己酮俗称KA油,是用于制备尼龙材料的己二酸和己内酰胺的重要中间体.工业上制取环己醇和环己酮的方法主要为苯酚加氢法、环己烯水合法和环己烷氧化法,其中环己烷氧化法的应用最为普遍,包括硼酸氧化法、过氧化物氧化法和钻盐催化氧化法三种路线.为获得适宜的环己醇和环己酮选择性,工业上环己烷氧化单程转化率通常控制在5.0%以下,从而使得产物选择性在80%以上.因此,现有环己烷氧化法生产KA油的最大挑战是如何同时获得高环己烷转化率和高KA油选择性.迄今,己有多种催化剂被尝试用于环己烷氧化反应,包括金属卟啉、金属氧化物、分子筛、碳纳米管和金属-有机骨架材料等.由于均相催化剂无法从环己烷氧化反应体系中分离出来,导致催化剂不能重复利用,因此多相催化剂的研究更受青睐.另外,由于采用氧气为氧化剂时具有环境友好和更高的原子经济性,因此氧气选择性氧化环己烷反应己逐渐成为环己烷氧化法制KA油中最具挑战性的研究.目前,氧气为氧化剂时的环己烷转化率通常低于过氧化氢和叔丁基过氧化氢等为氧化剂时的转化率,其关键在于适用于固（催化剂）液（环己烷）气（氧化剂）反应体系的高性能催化剂.本课题组前期研究了系列金属掺杂分子筛（Ce/AlPO-5,Ce-MCM-41/48和Mg-Cu/SBA-15等）对氧气催化氧化环己烷的反应性能,发现无论是稀土还是过渡金属掺杂,通过影响环己烷氧化反应的自由基产生和反应历程,可显著提高环己烷转化率或者KA油的选择性.基于此,本文选择原料易得、成本较低和氧化能力强的氧化锰（MnOx）作为具有强氧化能力的过渡金属氧化物的代表,深入研究了MnOx的焙烧温度对其结构和选择性氧化环己烷反应性能的影响,同时研究了反应条件对催化剂性能的影响.结果表明,400℃焙烧制得的催化剂（MnOx-400）比350,4

英文摘要：

The effects of calcination temperature on the physicochemical properties of manganese oxide catalysts prepared by a precipitation method were assessed by X-ray diffraction,N2 adsorption-desorption,X-ray photoelectron spectroscopy,H2 temperature-programmed reduction,O2 temperature-programmed desorption,and thermogravimetry-differential analysis.The catalytic performance of each of these materials during the selective oxidation of cyclohexane with oxygen in a solvent-free system was subsequently examined.It was found that the MnOx-500 catalyst,calcined at 500 °C,consisted of a Mn2O3 phase in addition to Mn5O8 and Mn3O4 phases and possessed a low surface area.Unlike MnOx-500,the MnOx-400 catalyst prepared at 400 °C was composed solely of Mn3O4 and Mn5O8 and had a higher surface area.The pronounced catalytic activity of this latter material for the oxidation of cyclohexene was determined to result from numerous factors,including a higher concentration of surface adsorbed oxygen,greater quantities of the surface Mn4＋ ions that promote oxygen mobility and the extent of O2 adsorption and reducibility on the catalyst.The effects of various reaction conditions on the activity of the MnOx-400 during the oxidation of cyclohexane were also evaluated,such as the reaction temperature,reaction time,and initial oxygen pressure.Following a 4 h reaction at an initial O2 pressure of 0.5 MPa and 140 °C,an 8.0% cyclohexane conversion and 5.0% yield of cyclohexanol and cyclohexanone were achieved over the MnOx-400 catalyst.In contrast,employing MnOx-500 resulted in a 6.1% conversion of cyclohexane and 75% selectivity for cyclohexanol and cyclohexanone.After being recycled through 10 replicate uses,the catalytic activity of the MnOx-400 catalyst was unchanged,demonstrating its good stability.