Co助剂对Ni-B非晶态催化剂微观结构和加氢性能的影响

通过化学还原法制备了一系列Ni-B非晶态合金催化剂,研究了n(KBH4)/n(Ni)和Co含量对Ni-B非晶态合金催化剂微观结构及其催化二硝基甲苯(DNT)合成甲苯二胺(TDA)性能的影响。通过XRD和H2-TPD技术对催化剂微观结构表征表明,随着n(KBH4)/n(Ni)的增大,NiB2含量增多,催化剂的加氢性能先增大后减小;当n(KBH4)/n(Ni)=4时,Ni-B非晶态合金的催化加氢性能最优。Co助剂的引入增大了Ni-B非晶态合金的无序程度,降低了Ni活性中心对H2的吸附强度,使得H2物种更容易在催化剂表面流动并参加反应,进一步增大了Ni-B催化DNT加氢合成TDA的活性和选择性。当Co的摩尔分数为6%时,Ni-Co-B非晶态合金催化剂的性能最优,DNT转化率为96.8%,TDA的选择性达100%。

Influence of Co on Microstructure and Catalytic Performance of Ni-B Catalyst for Dinitrotoluene Hydrogenation

A series of amorphous Ni-La-B catalyst was prepared by KBH4 reduction for liquid phase hydrogenation of dinitrotoluene(DNT) to diaminotoluene(TDA).The effect of n(KBH4)/n(Ni) and Co content on microstructure and catalytic performance of Ni-B amorphous alloy catalyst was investigated.The characterizations of XRD and H2-TPD show that the content of NiB2 increased and the hydrogenation performance of Ni-B first increased and then decreased with increasing n(KBH4)/n(Ni).When n(KBH4)/n(Ni)=4,the performance of Ni-B was the best.The addition of Co enhanced the extent of long-range disorder,weakened the strength of Ni-H bond and further enhanced the performance of Ni-B.When Co addition was 0.6%(molar concentration),Ni-Co-B catalyst exhibited the best catalytic performance for dinitrotoluene hydrogenation,the conversion of the DNT and the selectivity of TDA were 96.8% and 100,respectively.