Selective Hydrogenation of Benzene to Cyclohexene over a Ru-Zn catalyst with Diethanolamine as an Additive

Abstract

A Ru-Zn catalyst was prepared by co-precipitation, and the effect of adding diethanolamine on benzene selective hydrogenation to cyclohexene was investigated. The catalyst was characterized by N 2 physisorption, transmission electron microscopy, X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy, and temperature-programmed reduction. Diethanolamine reacted with ZnSO 4 in the slurry to form (Zn(OH) 2 ) 3 (ZnSO 4 )(H 2 O) 3 and diethanolamine sulfate. The amount of (Zn(OH) 2 ) 3 (ZnSO 4 )(H 2 O) 3 adsorbed on the catalyst surface increased with increasing diethanolamine amount. The synergism of (Zn(OH) 2 ) 3 (ZnSO 4 )(H 2 O) 3 and diethanolamine sulfate improved the cyclohexene selectivity of the Ru-Zn(4.9%) catalyst. With a diethanolamine dosage of 0.3 g, (Zn(OH) 2 ) 3 (ZnSO 4 )(H 2 O) 3 was highly dispersed on catalyst surface and the sample after hydrogenation was characterized. This catalyst exhibited the best performance with a cyclohexene selectivity and yield of 75.5% and 63.6%, respectively, at the benzene conversion of 84.3% in the third run. Moreover, the benzene conversion and cyclohexene selectivity were stable above 75% and cyclohexene yield was above 58% in the fourth run. 采用共沉淀法制备了 Ru-Zn 催化剂, 考察了二乙醇胺的添加对 Ru-Zn 催化剂上苯选择加氢制环己烯性能的影响, 并采用 N 2 物理吸附、透射电镜、X 射线衍射、X 射线荧光、傅里叶变换红外和程序升温还原等手段对催化剂进行了表征. 结果表明, 二乙醇胺可以与浆液中 ZnSO 4 反应生成 (Zn(OH) 2 ) 3 (ZnSO 4 )(H 2 O) 3 和硫酸二乙醇胺盐. 随着二乙醇胺用量的增加, 化学吸附在催化剂表面的 (Zn(OH) 2 ) 3 (ZnSO 4 )(H 2 O) 3 增多, 它与硫酸二乙醇胺盐的协同作用提高了 Ru-Zn(4.9%) 催化剂上苯选择加氢生成环己烯的选择性. 当二乙醇胺用量为 0.3 g 时, (Zn(OH) 2 ) 3 (ZnSO 4 )(H 2 O) 3 在 Ru-Zn(4.9%) 催化剂加氢后样品的表面高度分散, 反应性能最佳, 循环使用第 3 次时苯转化率为 84.3%, 环己烯选择性和收率分别达 75.5% 和 63.6%; 使用至第 4 次时, 反应 25 min 时苯转化率和环己烯选择性仍可达 75% 以上, 环己烯收率为 58% 以上. With a diethanolamine dosage of 0.3 g, (Zn(OH) 2 ) 3 (ZnSO 4 )(H 2 O) 3 was promoted to be highly dispersed on a Ru-Zn(4.9%) catalyst and ZrO 2 particles, and this gave a cyclohexene selectivity and yield of 75.5% and 63.6%, respectively, at the benzene conversion of 84.3%.