【摘要】 制备了负载型高分散的纳米贵金属催化剂和含Ru的双金属催化剂,并考察了催化剂对吡啶及其衍生物加氢反应的催化性能.结果表明,5%Ru/C催化剂对吡啶加氢反应的催化活性高于5%Pd/C,5%Pt/C和5%Ir/C.在100℃,3.0 MPa,1h和Ru/吡啶摩尔比=2.5/1 000的条件下,5%Ru/C催化吡啶加氢的转化率大于99.9%,生成哌啶的选择性为100%.催化剂重复使用5次后,活性和选择性无明显下降.在Ru催化剂中加入少量的Pd和Ir后催化剂活性没有明显的变化.采用X射线衍射、高分辨透射电镜和X射线光电子能谱对还原后的5%Ru/C催化剂进行表征,结果表明Ru以高分散金属态存在,其平均粒径小于5 nm.不同底物的加氢反应活性为:吡啶≈2-甲基吡啶>2,6-二甲基吡啶>3-甲基吡啶>4-甲基吡啶>3,5-二甲基吡啶>2-甲氧基吡啶.更多还原

【Abstract】 The highly dispersed supported noble metal catalysts were prepared and their catalytic performance for hydrogenation of pyridine was investigated.The results indicated that the 5%Ru/C catalyst exhibited the highest activity compared with Pd/C, Pt/C and Ir/C.The order of catalyst activity was Ru/C>Pd/C>Pt/C>Ir/C.Under the optimum reaction conditions of 100 ℃,p（H₂）=3.0 MPa,and Ru/pyridine molar ratio=2.5/（1000,） pyridine could be completely converted to piperidine with a 100% selectivity over 5%Ru/C.Furthermore,the activity and selectivity of 5%Ru/C did not decrease significantly after 5 cycle runs.The activity of bimetallic catalysts Ru-Pd/C and Ru-Ir/C was slightly lower than that of Ru/C,whereas the activity of Ru-Co/C was much lower than that of Ru/C.The reduced 5%Ru/C catalyst was characterized by high resolution transmission electron microscopy,（X-ray） diffraction,and（X-ray） photoelectron spectroscopy.The results showed that ruthenium was reduced to zero valence and the average particle diameter of Ru crystallites was smaller than 5 nm.The hydrogenation reactivity of pyridine and its derivatives was in the order pyridine≈2-methylpyridine>（2,6）-dimethylpyridine>3-methylpyridine>4-methylpyridine>（3,5）-dimethylpyridine>2-methoxy-pyridine,indicating that the electron factor played an important role in the reaction process.更多还原