非晶态Ni-Cu-Ce-B催化剂的表征及其苯酚加氢表面作用机理

Characterization of Amorphous Ni-Cu-Ce-B Catalysts and Their Surface Interaction Mechanism in Phenol Hydrogenation

以NiCl2、Cu(NO3)2、Ce(NO3)3为原料,KBH4为还原剂,采用浸渍法和化学还原法制备了负载型和非负载型Ni-Cu-Ce-B非晶态催化剂,通过差示扫描量热仪(DSC)、物理吸附仪(BET法)、扫描电子显微镜(SEM)和X射线衍射仪(XRD)等手段对催化剂进行了表征。以苯酚加氢制备环己酮为反应体系,考察了助剂Cu、Ce对Ni-B/γ-Al2O3催化剂活性和选择性的影响及其表面作用机理。结果表明,加入Cu、Ce的Ni-B合金晶化温度有所提高,热稳定性加强,将其负载于γ-Al2O3后催化剂的比表面积大大增加,活性组分分散均匀。Cu与Ni之间的电子转移和Ce对于催化剂碱性的提高有利于增加环己酮选择性。

Supported and non-supported amorphous Ni-Cu-Ce-B catalysts were prepared by combining impregnation and chemical reduction methods,with NiCl2,Cu(NO3)2 and Ce(NO3)3 as raw materials and KBH4 as reducing agent.These catalysts were characterized by differential scanning calorimetry(DSC),physical adsorption instrument(BET method),scanning electron microscope(SEM)and X-ray diffractometer(XRD).The surface interaction mechanism and catalytic performance of Cu and Ce modified Ni-B/γ-Al2 O3 catalysts were studied by the hydrogenation of phenol to cyclohexanone as probe reaction.The results demonstrated that introducing Cu and Ce atoms favors increasing the lowest crystallized temperature,thus strengthening the thermal stability.When they are located on theγ-Al2 O3 support,both specific surface area and dispersity of active components can be significantly improved. Moreover,promoting the electronic transfer between Cu and Ni and the enhancement of the basicity by doping Ce are beneficial to increase the selectivity of cyclohexanone.