NiCoB/TiO_2非晶态金属催化剂制备及其催化还原硝基物性能

Preparation of NiCoB/TiO_2 amorphous alloy catalyst and its application in catalytic reduction of p-Nitrobenzamide

采用沉淀浸渍法制备了NiCoB/TiO_2非晶态合金催化剂,并对催化剂进行了H_2-TPR、XRD、XPS和SEM表征。结果表明:NiCo金属颗粒以非晶态的形式负载在TiO_2载体上,分散性较好,平均粒径为200 nm。在将该催化剂应用于对硝基苯甲酰胺还原制备对氨基苯甲酰胺的反应中,以水合肼为还原剂,考察了催化剂中金属负载量、Ni-Co金属的比例、催化剂的用量对对硝基苯甲酰胺催化还原反应的影响,并对反应条件进行优化。实验结果证明,较佳的反应条件为甲醇为溶剂,反应温度60℃,水合肼的用量为n(原料)∶n(水合肼)=1∶3,金属负载量为5%,最合适的金属质量比例为Ni∶Co=1∶1,催化剂用量占原料质量分数20%。在此条件下,对硝基苯甲酰胺的转化率大于99%,对氨基苯甲酰胺的选择性大于99%。

NiCoB/TiO2 amorphous alloy catalyst was prepared by precipitation impregnation method.The catalysts were characterized by H2-TPR,XRD,XPS and SEM.The results showed that Ni-Co was supported on TiO2 in the amorphous state with good dispersity.The average particle size of the catalyst was 200 nm.In the application of the catalyst in the reduction of p-nitrobenzamide to prepare p-aminobenzamide,hydrazine hydrate was used as a reducing agent.The effect of metal content,Ni-Co proportion and catalyst amount used in the catalyst on the reduction were investigated.The experimental results showed that the better reaction conditions were as following:methanol was used as the solvent;the reaction temperature was 60℃;the hydrazine hydrate amount was n(raw material):n(hydrated hydrazine)=1∶3;metal content was 5%;the most suitable Ni-Co mass proportion was 1∶1;the catalyst dosage was 20%of the raw material mass fraction.Under such conditions,the conversion of p-nitrobenzamide was greater than 99%,and the selectivity to p-aminobenzamide was also greater than 99%.