Synthesis, Characterization And Application Of ZrO₂ And ZrO₂-SiO₂ Mixed-Oxide Aerogel

In recent years, zirconia and its mixed-oxides have been studied extensively due to their superior physicochemical properties, such as higher thermal and chemical stability, catalytic activity and strong surface acidity. But zirconia has its shortcomings such as little surface areas et al. There are two effective ways to get over these disadvantages, the first is preparing zirconia as aerogel or other ultrafine powder; the second is mixing it with other oxides such as SiO2 to prepare ZrO2-SiO2 mixed-oxides.Because of maleic anhydride (MA)'s availability and lower price which become possible by the construction of large fluid bed plants, according to Alusuisse-Lumnus and BP/UCB technologies, MA may be considered as a good feedstock nowadays. Hydrogenation of MA to succinic anhydride, y-butyrolactone, tetrahydrofuran and 1,4-butanediol has been highly interesting in the industrial view, since all these useful organic compounds are important intermediate synthesis of various fine chemicals. But the conversion of MA and the selectivity to target product are different with various catalysts or reaction conditions. In this dissertation, nickel catalyst carried on zirconia and its mixed-oxides were prepared by sol-gel method followed by supercritical fluid drying and impregnation method.The dissertation is composed of two sections. Firstly, it focuses on the preparation and characterization of zirconia aerogel and its mixed-oxides. Secondly, it is about the the preparation, characterization and application of nickel catalysts based on zirconia aerogel and its mixed-oxides.In the first section, using zirconyl nitrate dihydrate as starting material, zirconia aerogel of high specific surface area was prepared by heating zirconium nitrate solution with an alcohol-aqueous mixture followed by supercritical drying method. The specific area of ZrO2 aerogel could reach 675.6m2/g, which was much higher than that ofdocuments. It was very interesting that after roasted in 1000℃ the particle size of the zirconia was bigger than 30nm, the tetragonal phase still existed. And a series of mesoporous SiO2-ZrO2 aerogels with various zirconia content (10wt%-90wt%) were prepared by the sol-gel method followed by supercritical drying. The characterization results showed that i) the aerogels have Type VI (BDDT) profile which is the typical of mesopores in the interval between 2