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

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

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%.

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 selec- tivity of TDA reached 99.8% and 100%, respectively.