摘要
用化学还原法制备了Ni-La-B非晶态合金催化剂,并采用X射线衍射、透射电镜、差热分析、X射线光电子能谱、电感耦合等离子光谱和H2程序升温脱附技术对催化剂进行了表征,研究了La含量对催化剂微观结构及其催化二硝基甲苯(DNT)加氢制二氨基甲苯(DAT)性能的影响.结果表明,随着助剂La含量的增加,Ni-La-B催化剂中非晶态结构的长程无序程度增大,催化剂平均粒径逐渐由70nm左右减小至10nm左右,分布更加均匀;同时降低了Ni吸附H2的强度,使H2吸附物种更易于在催化剂表面流动并参与反应.另外,La助剂还显著提高了催化剂的热稳定性和抗氧化性.在二硝基甲苯加氢反应中,催化剂性能随着La加入量提高至6%(摩尔分数)时,1MPa低压条件下DNT转化率和DAT选择性均达100%.当La加入量为8%时,催化剂的Ni活性中心数明显减少,其活性下降.
Ni-La-B amorphous alloy catalyst was prepared by KBH4 reduction for liquid phase hydrogenation of dinitrotoluene （DNT） to diaminotoluene （DAT）. The effect of La content on microstructttre and catalytic performance of Ni-La-B amorphous alloy catalyst for DNT hydrogenation was investigated. The catalyst was characterized by X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, X-ray photoelectron spectroscopy, inductively coupled plasma emission spectroscopy, and H2 temperature-programmed desorp- tion. The results showed that the addition of La could enhance the degree of long-range disorder, reduce the particle diameter from 70 to 10 nm, weaken the strength of Ni-H bond, and improve the thermal stability and antioxidation. The increasing of La addition from 0 to 6% （molar fraction） led to the enhancement of catalytic performance. When the addition of La was 0.6%, Ni-La-B catalyst exhibited the highest performance for low-pressure （1 MPa） DNT hydrogenation, the conversion of DNT and selectivity for DAT reached 100%. Further increas- ing of La addition from 6% to 8% led to decrease of the surface Ni content and the catalytic activity obviously.
出处
《催化学报》
SCIE
EI
CAS
CSCD
北大核心
2012年第8期1374-1382,共9页
基金
国家重点基础研究发展计划(973计划
2012CB723105)~~
关键词
二硝基甲苯
甲苯二胺
非晶态合金
镍基催化剂
镧助剂
dinitrotoluene
diaminotoluene
amorphous alloy
nikel-based catalyst
lanthanum modification
