Al改性Cu/ZnO催化剂催化苯胺制备二甲基苯胺

Al-modified Cu/ZnO catalysts catalyze the preparation of dimethylaniline from aniline

摘要:

通过沉积沉淀法对Al改性Cu/ZnO催化剂进行研究,并利用XRD、BET、NH₃-TPD等对催化剂进行表征。同时对苯胺和甲醇N-甲基化反应制备N,N-二甲基苯胺(N,N-DMA)进行研究,对沉积沉淀法制备的催化剂进行了焙烧条件考察及对N-甲基化反应进行工艺条件优化。结果表明,在拟薄水铝石为铝源、Cu/Zn/Al摩尔比为1:3:1、焙烧温度为400 ℃,焙烧时间为3 h,反应温度为250 ℃,反应压力为1.5 MPa,进料空速为0.3 h^_-1,氮气流量为150 mL/min,苯胺与甲醇摩尔比为为1:7时,苯胺N-甲基化反应效果最佳,苯胺转化率达99.8%,N,N-DMA选择性达92.8%,催化剂进行了720 h稳定性实验,苯胺转化率稳定在99%以上,N,N-DMA选择性稳定在90%以上,催化剂稳定性较好。

Abstract:

The Al-modified Cu/ZnO catalysts were studied by deposition precipitation method, and the catalysts were characterized by XRD, BET and NH₃-TPD.At the same time, the preparation of N,N-dimethylaniline (N,N-DMA) by N-methylation of aniline and methanol was studied. The calcination conditions of the catalysts prepared by the deposition precipitation method were investigated and the process conditions were optimized for the N-methylation reaction. The results show that when pseudo-boehmite is the aluminum source, the molar ratio of Cu/Zn/Al is 1:3:1, the calcination temperature is 400 ℃, the calcination time is 3 h, the reaction temperature is 250 ℃, and the reaction pressure is 1.5 MPa, When the feed space velocity is 0.3 h^_-1, the nitrogen flow rate is 150 mL/min, and the molar ratio of aniline to methanol is 1:7, the N-methylation reaction of aniline was the best, and the conversion rate of aniline reaches 99.8%, N,N -DMA selectivity reaches 92.8%. The catalyst has undergone a 720h stability test. The aniline conversion rate is stable above 99%, and the N,N-DMA selectivity is stable above 90%. The catalyst has good stability.