Research On Nano-TiO₂ Used In Selective Hydrogenation Of Acetylene To Ethylene

Selective hydrogenation of acetylene to ethylene is an important reaction in chemical industry for the elimination of acetylene which poisons the catalyst used in subsequent ethylene polymerization processes and eventually degrades the quality of the produced polyethylene. In this paper, the nano Pd/TiO₂ catalyst was prepared by both impregnation and precipitation method, and the catalyst prepared by precipitation was characterized by XRD, TEM and UV-Vis. What's more, the catalytic performance of nano Pd/TiO₂ in the selective hydrogenation of acetylene to ethylene was investigated in this thesis.The experimental results showed that the average diameter of anatase TiO₂ particle was 20 nm when the catalyst was calcined at 500℃. The type of the TiO₂ still was anatase when the temperature raised to 600℃or 700℃. The transformation from TiO₂ to rutile was promoted when the Zn was added to the Pd/TiO₂, and the 25% rutile TiO₂ and ZnTiO3 was produced when the Pd-Zn/TiO₂ was calcined at 600℃. The results also showed that the amount of rutile TiO₂ and ZnTiO3 wasn't changed whe the temperature raised to 700℃By the method of UV-Vis, the catalyst's ability to absorb the visible light was altered when the Zn was added, and the absorption wavelength shifted to length wave. When the Pd content raised from 0.05% to 0.15%, the absorption was improved obviously. When the Pd content was 0.2%, the absorption was decreased instead.The nano Pd/TiO₂ catalyst performed excellently in the reaction of selective...