Ru/ZrO2催化环己酮还原胺化制备环己胺工艺

Study on Ru/ZrO2 Catalyzed Reductive Amination of Cyclohexanone to Cyclohexylamine

通过浸渍法制备Ru/ZrO2催化剂,并考察了其在环己酮还原胺化制备环己胺反应中的活性。采用X射线衍射(XRD)和氨气程序升温脱附(NH3-TPD)等方法对催化剂进行了表征并测定了其粒径分布,分析了Ru负载量、还原温度、氢气压力以及反应时间等对催化剂活性的影响。结果表明,Ru颗粒在ZrO2表面呈高度分散状态。催化剂的粒径随着Ru负载量的增加而变大,粒径过大则不利于催化剂在反应体系中分散,从而影响反应物与催化剂间的接触。催化剂的表面酸性随着还原温度的升高而降低,较低和较高的还原温度都会使得环己胺的选择性降低。催化剂的较佳负载量为5%(质量分数),适宜的还原温度为150℃。优化的反应条件下(催化剂0.05 g,环己酮2.94 g,乙醇5 mL,氨水45 mL,氢气压力2 MPa,反应温度95℃,反应时间2.25 h),环己酮的转化率可达100%,环己胺的选择性可达90%,具有良好的工业应用前景。

The performance of Ru/ZrO2 prepared by impregnation method was evaluated by reduction amination of cyclohexanone to cyclohexylamine. The catalysts were characterized by X-ray diffraction(XRD) and temperature-programmed desorption of ammonia(NH3-TPD). And their particle size distributions were also measured. The effects of Ru loading amount, catalyst reduction temperature, hydrogen pressure and reaction time on catalyst activity were investigated. The experimental results showed that Ru particles were highly dispersed on the surface of ZrO2. The particle size of the catalyst increased with the increase of Ru loading, and large particle size was unfavorable to the dispersion of the catalyst in the reaction system. The surface acidity of catalyst decreased with the increase of reduction temperature, and both lower and higher reduction temperature would lead to the decline of the selectivity to cyclohexylamine. The optimum Ru loading content of the catalyst was 5%, and the optimum reduction temperature of the catalyst was 150 ℃. Under the optimized reaction conditions(catalyst 0.05 g, cyclohexanone 2.94 g, ethanol 5 mL, ammonia 45 mL, hydrogen pressure 2 MPa, reaction temperature 95 ℃, reaction time 2.25 h), the conversion of cyclohexanone could reach 100%, the selectivity of cyclohexylamine could reach 90.0%, which is promising for industrial application.