Mo含量对Ni-Mo-B非晶态合金催化剂结构及催化二硝基甲苯加氢性能的影响

采用化学还原法制备Ni-Mo-B非晶态合金催化剂, 研究了Mo含量对二硝基甲苯加氢制备甲苯二胺催化性能的影响. 结果表明, 当Mo含量(摩尔分数)≤6%时, Mo助剂使Ni-B非晶态合金催化剂的催化活性显著提高, 选择性均达到100%. 通过XRD, TEM, DSC, XPS, ICP和H₂-TPD技术对催化剂微观结构进行了表征, 结果表明, 随着Mo助剂含量的增加, Ni-Mo-B非晶态合金催化剂中不仅非晶态结构的无序程度增大, 催化剂粒径逐渐由60 nm左右减小至15 nm左右, 而且分布更加均匀, Ni吸附中心的H₂吸附强度变弱, 使氢物种更易于在催化剂表面流动并参与反应, 同时Mo助剂还显著提高了催化剂的热稳定性和抗氧化性. 当Mo含量为6%时, Ni-Mo-B非晶态合金催化剂的催化性能最好, 在2 MPa和110℃反应条件下, 二硝基甲苯转化率达99.8%, 甲苯二胺选择性为100%.

Influence of Mo Content on Microstructure and Catalytic Performance of Ni-Mo-B Amorphous Alloy Catalyst for Dinitrotoluene Hydrogenation

A series of amorphous Ni-Mo-B catalyst was prepared by KBH4 reduction for liquid phase dinitrotoluene(DNT) hydrogenation.The results showed that Ni-B catalyst exhibited high activity and selectivity in liquid phase hydrogenation of DNT to diaminotoluene(TDA),the activity of Ni-B catalyst has been enhanced obviously by introduction of Mo,and the selectivity of TDA was 100% when the molar fraction of Mo was smaller and equal to 6%.The characterizations of XRD,DSC,TEM,XPS,ICP and H2-TPD showed that the addition of Mo could enhance the extent of long-range disorder,reduce the particle diameter from 60 nm to 15 nm,weaken the strength of Ni—H bond,improve the thermal stability and antioxidation,which resulted in the increasing activity of Ni-B.when the molar fraction of Mo was 6%,the conversion of DNT and the selectivity of TDA reached 99.8% and 100%,respectively.