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以活性炭为载体,负载氯化钯溶液,制备钯/炭催化剂,在循环使用于催化脂肪腈加氢制备单烷基二甲基叔胺时发现,催化剂活性持续下降。通过氮吸附、热重分析、X射线能谱和透射电子显微镜等手段,对催化剂失活前后的表面积、孔径分布变化、催化剂的失重状况、Pd的价态变化以及Pd晶粒的粒径变化研究表明,导致钯/炭催化剂失活的原因主要是反应过程中积炭的生成、Pd的价态变化和Pd晶粒粒径的增大。
The activated carbon as a carrier, palladium chloride solution was loaded to prepare a palladium / carbon catalyst, which was used to catalyze the hydrogenation of fatty nitrile to produce monoalkyldimethyl tertiary amine. It was found that the activity of the catalyst decreased continuously. The changes of surface area, pore size distribution, catalyst weight loss, Pd valence and Pd grain size change before and after deactivation were investigated by nitrogen adsorption, thermogravimetric analysis, X-ray energy dispersive spectroscopy and transmission electron microscopy It is indicated that the main reasons leading to the deactivation of palladium / carbon catalysts are the formation of coke during the reaction, the valence change of Pd and the increase of Pd grain size.