负载型固体碱催化制备3,4-二甲基呋咱的方法研究

Synthesis of 3,4-dimethylfurazan over supported solid basic catalysts

通过不同载体并采用浸渍法制备了KOH/CaO、KOH/MgO以及K_2CO_3/CaO 3种负载型固体碱催化剂,并应用于催化二甲基乙二肟脱水制备3,4-二甲基呋咱反应。考察了催化剂质量分数、反应温度、反应时间对催化剂性能的影响。实验结果表明,在3种催化剂活性组分质量分数为10%、反应温度为160℃、反应时间为60 min的条件下,3,4-二甲基呋咱的收率依次为92%、65%和63%。对KOH/CaO催化剂的催化条件进行了正交实验优化,结果表明,在催化剂质量分数为8%、反应温度为160℃、反应时间为50 min的最优条件下,3,4-二甲基呋咱的最高收率可达92%。KOH/CaO催化剂在重复使用3次后,仍有较高的催化活性。

Three kinds of solid basic catalysts including KOH/CaO,KOH/MgO and K2CO3/CaO are prepared by the impregnation method through different supporters and then are applied in the catalytic preparation of 3,4-dimethylfurazan by intramolecular dehydration of dimethylglyoxime.The influences of catalyst dosage,reaction temperature and time on the preparation of 3,4-dimethylfurazan from dehydration of dimethylglyoxime are investigated. The experimental results indicate that the yields of 3,4-dimethylfurazan are about 92%,65% and 63%,respectively over KOH/CaO,KOH/MgO and K2CO3/CaO when the mass fraction of catalyst active ingredients is 10% and the reaction lasts for 1 h at 160℃. The catalytic conditions for the as-prepared KOH/CaO catalyst are optimized via orthogonal experiments.It is found that the highest yield of 3,4-dimethylfurazan can reach 92% under the optimal conditions of the catalyst dosage 8%,reaction temperature 160℃,and reaction time 50 min. More important,this KOH/CaO catalyst remains a high catalytic activity after three cycles of uses.