负载型铱催化剂催化氯代硝基苯选择性加氢

用等体积浸渍法制备了Ir/γ-Al2O3催化剂,以对氯硝基苯为底物,考察了催化剂的活化温度、反应温度、氢气压力、反应时间等条件对对氯硝基苯加氢反应的影响。实验结果表明,在120℃下活化1.0h得到的Ir/γ-Al2O3催化活性最高,在n(对氯硝基苯)∶n(Ir)=3 000、反应温度50℃、氢气压力0.5MPa、乙醇为溶剂的条件下反应2.5h,对氯硝基苯的转化率和对氯苯胺的选择性均达到100.0%。用该催化剂催化邻、间氯硝基苯加氢,当底物全部转化时,生成邻、间氯苯胺的选择性分别达到99.2%和100.0%,均没有检测到脱氯产物的生成。用该催化剂催化对氯硝基苯加氢反应,催化剂循环使用8次,反应时间延长至5h,对氯硝基苯完全转化,对氯苯胺的选择性仍高达98.2%。

Selective Hydrogenation of Chloronitrobenzene over Supported-Iridium Catalyst

Ir/γ-Al2O3 catalyst used in selective hydrogenation of p-chloronitrobenzene(p-CNB) to produce p-chloroanilines(p-CAN) was prepared by impregnation method.Influences of catalyst activation temperature,reaction temperature,hydrogen pressure and reaction time on conversion of p-CNB and selectivity to p-CAN were studied.Under optimal conditions: catalyst activated at 120 ℃,mole ratio of p-CNB to Ir 3 000,reaction temperature 50 ℃,hydrogen pressure 0.5 MPa,C2H5OH as solvent and reaction time 2.5 h,both conversion of p-CNB and selectivity to p-CAN can reach 100.0%.When o-CNB and m-CNB are used as reactants,selectivities to o-CAN and m-CAN can achieve 99.2% and 100.0% respectively.After the catalyst is reused for 8 times,conversion of p-CNB and selectivity to p-CAN can still keep at 100.0% and 98.2% respectively by prolonging reaction time to 5 h.