摘要
钼和镧是好的镍硼触媒的促进剂, 对于对氯硝基苯氢化反应有好的效果, 因此同时加入钼和镧在镍硼触媒上应该是有趣的研究题目. 本研究利用化学还原法制备了一系列含有不同量镧的镧钼镍触媒, 醋酸镍、钼酸胺及硝酸镧同时加入含有甲醇的水溶液中. 以X光绕射, 穿透式电子显微镜、高分辨率电子显微镜及X光光电能谱仪鉴定了这些触媒. 对氯硝基苯氢化反应是在批次反应器中于333 K、1.2 MPa氢气压力及500 r/min转速下操作. 即使在镍钼硼中加入很少量的镧, 对提高活性及对氯苯胺的选择性都有显著的效果, 加入适量的镧可以抑制镍钼硼的长范围的结晶排列, 并保持镍钼硼在非结晶状态. 镧以氧化态存在, 其功效为阻隔物, 避免镍钼硼聚集, 但是过量的镧会有相反的效果, 镧和镍的适当比例是0.2.
Mo and La have been independently reported to be good promoters of NiB nanocluster in the hy- drogenation of para-chloronitrobenzene(p-CNB).However,a bi-promoter effect of Mo and La in NiB catalysts has not previously been investigated.In this work,a series of La-Mo-doped,nanosized NiB catalysts with different La contents were prepared by chemical reduction and were character- ized by X-ray diffraction,transmission electron microscopy,high-resolution transmission electron microscopy,and X-ray photoelectron spectroscopy.The liquid-phase hydrogenation of p-CNB was carried out in a batch reactor at 333 K,1.2 MPa H2 pressure and at a spinning rate of 500 r/min. Even doping a small amount of La in NiMoB had a significant effect on its activity and selectivity to p-chloroaniline.The addition of an appropriate amount of La suppressed the growth and long-range order of NiMoB and helped the NiMoB maintain its amorphous state.La was determined to be pre- sent in its oxide form and to act as a spacer,preventing NiMoB from sintering and aggregation. However,a high amount of La had an opposite effect,and the optimum ratio of La:Ni was 0.2.
出处
《催化学报》
CSCD
北大核心
2013年第11期2018-2028,共11页
关键词
硼化镍
镧
氢化反应
含氯硝基苯
含氯苯胺
Nickel
Lanthanum boride
Hydrogenation
Chloronitrobenzene
Chloroaniline
