Study On The Preparation, Characterization And Properties Nano-Solide Superacid SO₄～(2-)/ZrO₂ Catalysts

The objective of this paper is to combine organically the merits of solid superacid and nanometer materials and to prepare a new solid surperacid. Furthermore, comparing it with the solid superacid prepared in common methods, we obtain some conclusions. The main contents are as follows:Firstly, we prepared the nanometer-size ZrO₂ of teteagonal tape and monoclinic tape that were synthesized by the urea homogeneous precipitation method, then immersed ZrO₂ into sulphuric acid to prepare the nanometer-size Superacid SO4²-/ZrO₂.Secondly, the acid strength, specific surface, size and the feature, the structure of acid center and the Sulphur and carbon content have been characterized by FT-IR, XRD, SEM, BET, TGA-DTA and Hammett indicator. Using the Esterificational Reaction and the Pentane Isomerization Reaction as probes, catalytic activity of these superacids which were prepared by different process conditions such as different concentration of H₂SO₄, immersing time, calcinated temperature, calcinated time has been researched. The relationship among preparing process parameters, structure and its catalytic activity has been discussed. Also, the mechanism of the Deactivation and Regeneration of the selectedcatalyst has been investigated.Thirdly, the results show that:A Both SO4 7nssf-ZrO2 and SO4 7nsct-ZrO2- are superacid . The size of ZrO2 and SO/VZrC^ particle are in the range of 10-100 nm. The tetragonal nanometer-size SO4 7nssf-ZrO2 can endure higher sulfuric acid than SO427nsct-ZrO2.B The two series of solid catalysts have high catalytic activity in the Esterificational Reaction and the pentane Isomerization Reaction. Different preparative conditions were required in Esterificational Reaction and Pentane Isomerization Reaction. The acid strength in Esterificational Reaction was widely allowed, but some certain acid strength was limited in Pentane Isomerization Reaction at a lower temperature.C The two series of solid catalysts' catalytic performance were evaluated by the esterification of acetic acid and n-butanol. The optimum preparation condition of the catalysts were : calcination temperature: 100°C-650°C, calciation time: lh, the sulphuric acid concentration is not an important factor in this reaction. The yield of butyl acetate was 99%.D The isomerization of n-pentane on SO427nssf-ZrO2 and SO427nsct-ZrO2 was investaged. The optimum prepatation condions of the catalyst SO427nssf-ZrO2 were : the sulphidic concentration: 2.5mol/L, immersing time: 0.5h, calcinated temperature: 650 °C ,activation temperature: 600°C;The optimum prepatation condions for the catalyst SO427nsct-ZrO2 are : the sulphidic concentration: 0.75mol/L, immersing time: 0.5h, calcinated temperature: 650 °C , activation temperature: 600°C.E After the catalysts used for some times , they would lose their activity. Because hydrocarbons was cumulated on the catalyst surface, these hydrocarbons covered the acidic site on the catalyst surface, and some sulfur on the surface was lost. The used catalysts were calcinated in order to eliminate the hydrocarbons on it;then, immersed into H2SO4, dried and culcinated. The results showed that it was an effective method in regenerating the deactivited catalyst.