Study On The Supported Nanosized Zro₂/Al₂O₃ Composite Supports And Ni Based Catalysts

ZrO₂ is a catalyst support with good chemical stability, oxidation-reduction properties and acidity-alkalescence on its surface. ZrO₂ can interact rather intensively with active phases, and has extensive applications in hydrogenation, synthesis of F-T and oxidation reaction. Nano ZrO₂ has high specific surface area and its surface defects is rich, but nano ZrO₂ particles are prone to agglomerate and reduce the specific surface area under high temperature. This dissertation takes the route of the following processes: for the sake of stablizing nano ZrO₂ and increasing the specific surface area, nano ZrO₂ was loaded on Al₂O₃ support with large pores to prepare nano ZrO₂/Al₂O₃ composite supports; the composite supports can both bring the best of nano ZrO₂ by reducing the agglomeration of particles and take advantage of the higher specific surface, good pore size distribution and good thermal stability of Al₂O₃ support at the same time. Highly dispersed active metal composition loading on the composite supports would contribute to the activity and stability of the reforming of CO₂ for CH₄. Therefore, the synthesis, structure characteristics, surface properties, thermal stabiltiy, and absorption properties, reduction properties of ZrO₂/Al₂O₃ composite supports and activity of Ni/ZrO₂/Al₂O₃ catalysts were systematically investigated in this dissertation.This dissertation consists of the following parts: preparation of the nano ZrO₂/Al₂O₃ composite supports by loading monolayer distributed and size controllable ZrO₂ particles on Al₂O₃ support with enlarged pores by using supercritical, microwave and contraction-distillation drying process; systematical investigation of the interaction between ZrO₂ particles and Al₂O₃ support, the surface properties, acid-alkalescence, crystal structure of the composite supports; studies of the activity and stability of Ni/ZrO-2/Al₂O₃ in the process of the reforming of CO₂ for CH₄.Al₂O₃ with large pores was prepared by sol-gel method using A1(NO₃)₃ as raw material. Optimal experimental parameters were determined by orthogonal experiments as following: pH=10, 3% surfactant, pore enlarger(PEG-20000) 8%, aging temperature 80°C, microwave drying. The influence of calcination temperature on the specific surface, pore size distribution and crystal structure was studied, and results showed that the Al₂O₃ calcinated at...