Controllable Preparation And Catalytic Activity Of NiO_x/TiO₂ For Acetonitrile Hydrogenation Reaction

Amines have a wide range of applications. Now in our country, alkylation is the main method for the preparation of monoethylamine, however, there are many difficult problems. And gas phase hydrogenation of acetonitrile can avoid these problems well.In this study, firstly, rutile was prepared by hydrothermal method. Then nickel nitrate or nickel acetate supported on rutile was prepared by impregnation method. These kinds of catalysts exhibited very low activity for gas phase hydrogenation of acetonitrile, due to the unstable rutile would become large when calcined it, during this proceed nickel particles would go into the rutile support then the NiTiO3 was forming. Thus, the rutile was pre-calcined to made it stable. Then nickel nitrate or nickel acetate supported on pre-calcined rutile was prepared by impregnation method. TG-DSC, H2-TPR, XRD, NH3-TPD and TEM were used to characterized catalysts. The activity of these catalysts increased obviously. Meanwhile, pre-calined rutile support different nickel compands exhibited different activity for hydrogenation of acetonitrile.Nickel acetate supported on P25 was also prepared by impregnation method. TG-DSC, H2-TPR, XRD, NH3-TPD, TEM and XPS were used to characterized these catalysts. Variations of the reduction temperature resulted in dispersed nickel on P25 with different oxidation state. The gas phase hydrogenation of acetonitrile reaction was found to be influenced by the nickel state. The catalyst reduced at 300 oC exhibited highest acetonitrile conversion ratio in the group, while the yield of products depends on the amount of acid sites of Ni/P25 catalysts, which can be influenced not only by P25 support, but also by the properties of supported Ni nanoparticles. Triethylamine was the initial product produced during the reaction by Ni/P25. Thus, a mechanism, concerning the first step in this reaction, was proposed.In this study, high dispersed and small particles supported on P25 was prepared by photodeposition method and photodeposition then impregnation method. ICP, TG-DSC and TEM were used to characterized these catalysts. The activity for acetonitrile conversion was pretty good over the calcined and reduced photodeposition catalysts, while yields of monoethyamine and triethylamine were changed, although the amout of nickel was low. The catalysts prepared by photodeposition then impregnation method, exhibited highest acetonitrile conversion activity, and the yield of triethylamine was high.