Ru/CNTs催化合成1,4-环己二胺工艺及反应机理

以碳纳米管为载体制备Ru/CNTs催化剂,系统考察反应温度、反应压力、反应时间、催化剂用量、溶剂种类、助剂和催化剂重复使用性能等对催化对苯二胺合成1,4-环己二胺的影响,同时对催化反应机理进行探讨。结果发现,反应为串联反应,较高的反应温度、反应压力、催化剂用量和较长的反应时间利于提高转化率,但过高的反应温度、反应压力和过长的反应时间会导致副反应发生,产物收率下降。适宜的反应条件为:反应温度120℃,反应压力6 MPa,反应时间3 h,对苯二胺10 g,40 mL异丙醇作溶剂,助剂氢氧化锂添加量0.1 g,5%Ru/CNTs催化剂用量0.5 g,此条件下,对苯二胺转化率100%,1,4-环己二胺收率93.87%,催化剂重复使用11次后仍保持较高活性。

Catalytic synthesis of 1,4-diaminocyclohexane over Ru/CNTs catalyst and study of reaction mechanism

Ru/CNTs catalysts were prepared with carbon nano tubes as support.The effects of reaction time,reaction temperatures,reaction pressure,catalyst dosage,solvents,additives and the repeated use performance of the catalyst on the catalytic hydrogenation of p-phenylenediamine(p-PDA) to 1,4-diaminocyclohexane(1,4-DACH) were studied as well as the reaction mechanism.The results showed that the reaction was a tandem reaction,and high reaction temperature,high reaction pressure,more catalyst dosage and longer reaction time were beneficial to improving the conversion rate.To high reaction temperature and reaction pressure and long reaction time should result in side reaction,and product yield decreased.Under the optimal reaction condition of reaction temperature 120 ℃,reaction pressure 6 MPa,reaction time 3 h,p-PDA amount 10 g,solvent isopropanol 40 mL,additive LiOH 0.1 g,5%Ru/CNTs catalyst dosage 0.5 g,p-PDA conversion and the yield of 1,4-DACH reached 100% and 93.87%,respectively.The catalyst still possessed high activity after repeated use 11 times.