Au/Al2O3催化剂上环己烷氧化

针对金催化剂制备过程的复杂性和氯离子残留问题,介绍一种负载型金催化剂Au/Al2O3的制备方法和考察该催化剂在环己烷氧化中的催化性能.采用浸渍-氨洗法制备Au/Al2O3催化剂,并应用电感耦合等离子体原子发射光谱(ICP-AES)、X射线衍射(XRD)和透射电子显微镜(TEM)对其进行表征.以氧气氧化环己烷制备环己酮和环己醇为研究对象,考察金质量分数、反应温度、压力、时间等因素对催化活性的影响.结果表明,随着金质量分数增加,金颗粒增大,催化剂的活性降低,在150℃、1.5MPa条件下反应3h,Au实际质量分数为0.58%的Au/Al2O3催化剂上环己烷转化率为8.96%,环己酮、环己醇和环己基过氧化氢三者的总选择性为93.52%.此外,循环实验表明Au/Al2O3催化剂具有一定的稳定性.

Study of cyclohexane oxidation over Au/Al2O3 catalyst

According to the problems of complexity and chloride ion residue in the preparation of gold catalysts,a preparation method to obtain supported gold catalyst Au/Al2O3 was introduced and its catalytic performance was tested for cyclohexane oxidation.Au/Al2O3 catalysts were prepared by an impregnation-ammonia washing method.Inductively coupled plasma-atomic emission spectrometry(ICP-AES),X-ray diffraction(XRD) and transmission electron microscopy(TEM) were used to characterize these catalysts.The effects of gold loadings,reaction temperature,pressure and reaction time on the catalytic activity for the selective oxidation of cyclohexane to cyclohexanone and cyclohexanol using molecular oxygen as oxidant were studied.The results show that the higher the gold loading is,the bigger the size of the gold particles is and the lower the catalytic activity is.Under the reaction conditions of 150 ℃,1.5 MPa and 3 h,using Au/Al2O3 catalyst with an actual gold loading of 0.58%,the cyclohexane conversion can reach 8.96% with 93.52% of total selectivity to cyclohexanone,cyclohexanol and cyclohexyl hydroperoxide.Moreover,according to the recycling test,the Au/Al2O3 catalyst exhibites good stability.