用于苯选择加氢的Ru/Al2O3-ZrO2-NiO/堇青石蜂窝整体催化剂

使用浸涂法和氨气吸收沉积法制备了新型用于苯选择加氢的具有蛋壳型分布的Ru/Al₂O₃-ZrO₂-NiO/堇青石蜂窝整体催化剂,且在固定床整体反应器中对其性能进行了测试.该催化剂显示了较优的选择性和稳定性,并且在低的ZnSO₄浓度(0.5%问题)下环己烯产物收率可达24.7%.采用N₂吸附-脱附法,电感耦合等离子体发射光谱,光学显微镜,扫描电子显微镜及能量色散X射线光谱仪等技术研究了影响催化剂性能的因素.结果表明,NiO的引入减少了涂层中的微孔含量,有利于在低的添加剂浓度下提高环己烯选择性.ZrO₂的存在抑制了涂层的烧结,保证涂层在1373K高温焙烧后仍有较大的比表面积.Ru的蛋壳分布、薄的涂层厚度、较少的微孔含量、较大的比表面积和狭窄的孔分布可能是影响整体蜂窝催化剂中该特殊催化行为的重要因素.

Ru/Al2O3-ZrO2-NiO/cordierite monolithic catalysts for selective hydrogenation of benzene

Ru/Al₂O₃-ZrO₂-NiO/cordierite catalysts with an egg-shell-like Ru distribution were prepared by conventional incipient wetness impregnation and ammonia gas absorption deposition. The performance of the catalysts in a modified monolithic fixed-bed reactor was evaluated. The catalysts exhibited good selectivity and stability. Importantly, a maximum yield of 24.7% was achieved at a low concentration of ZnSO₄ (0.5 wt%). The catalysts were characterized by N₂ adsorption, X-ray diffraction, inductively coupled plasma-atomic emission spectroscopy, optical microscopy, and scanning electron microscopy/energy-dispersive X-ray analysis. The introduction of NiO resulted in the formation of NiAl₂O₄ phase during calcination at 1373 K, reducing the proportion of small pores. Meanwhile, the presence of ZrO₂ enhanced the sintering resistance of the coating, and moderate surface area was retained after calcination. The egg-shell distribution of Ru, thin layer thickness indicating short diffusion length, small proportion of nanosized pores (e.g., 1-4 nm), moderate specific surface area, and narrow pore size distribution to facilitate Ru dispersion are thought to be important factors controlling the behavior of the present monolithic catalysts.