| Great expectation for Zirconium oxide in catalysis has been done because of their amphoteric surfactants center and good ion exchange capacity. Zirconium oxide can be used not only as catalyst but also as supports and auxiliaries. There must be more active centers on zirconium, which can enhance the charge transfer efficiency, improve the charge transfer properties, and reduce the diffusion resistance in the catalyst channel of reactant molecules and product molecules, if well-developed pore structure and high specific surface area existed on them.The purpose of this paper, is to prepare long-range order, thermally stable mesoporous zirconia materials in a nonaqueous system. Through changing the templates (CTAB, P123, F127, Brij56, etc.), introducing auxiliary templates(CNT, phenolic resin, SBA-15, etc.), we obtained different samples. X-ray diffraction, N2 adsorption-desorption, infrared Spectroscopy, electron microscope, are employed to analyze samples to get the best conditions.Using the single-template, mesoporous zirconia materials are successful synthetized in the absolute-alcohol. The optimal amount of the templates is n(CTAB):n(Zr)=0.18,n(P123):n(Zr)=0.0008)n(F127):n(Zr)=3.6×105,n(Brij56):n( Zr)=0.013. The isotherms of the samples calcined in muffle at 400℃ for 3h, are typical type IV isotherms. The BET surface areas of these samples are between 140-172m2/g, pore size distributions are between 2.5-3.0nm, pore volume is between 0.15-0.22cm3/g.After calcined at 650℃ the samples impregnated by H2SO4, (NH4)2S2O8, (NH4)2SO4, can still maintain good mesoporous structure, and mainly exit as tetragonal zirconia. After impregnated by H2SO4 and calcined at 500℃, The samples’the BET surface areaes are between 109-132m/g, pore size distributions are between 2.8-3.1nm, pore volume are between 0.12-0.27cm3/g.The mesoporous zirconia sulfide by H2SO4, (NH4)2S2O8, (NH4)2SO4, then calcined at 500℃,550℃ and 600℃, took the conversions about 70% in the reaction of cyclohexanol with acetic acid at 100℃ for 1h. All the three samples took the conversions above 80% in the reaction of cumene cracking at 300℃. After calcined at 550℃,600℃, the conversions close to 90% and the conversions still more than 80% in 40min later. Mesoporous zirconia synthetized with four different templates, impregnated by H2SO4, show good catalysis activity in the anisole acylation reactions. The conversion of acetic anhydride was above 70% after reaction at 80℃ for 1h. Morever, they have a good selectivity in this reaction, all the selectivity ratio of on-products and ortho-product were above 80%.Mesoporous zirconia with the crystal structure can be successfully synthesized in the mixed template system. The mixing sequence, mixing ratio, and total mixed amounts of the templates have great influence on the structure of the prepared mesoporous zirconia. When n(P123):n(F127):(Zr)=1:2:100, the catalyst structure is the best one. The isothermal of catalyst synthesized by mixed-template correspond to the typical H1 hysteresis loop. Pore size and pore volume were heightened significantly, to 6.3nm and 0.28 cm3/g. Through the TEM, the worm-like mesoporous structures on mesoporous zirconia prepared in the mixed system are more uniform than in the single-template system. When modified CNT and phenolic resin used as the hard-template, the regularity of the mesoporous zirconia and thermal stability of the catalyst have been improved. After calcination at 400℃ for 3h, the samples synthesised by hard-template are mainly formed as tetragonal zirconia, while the samples synthesised by single-template formed the tetragonal phase and monoclinic phase. When carbonized SBA-15 used as hard template, spherical mesoporous zirconia with high thermal stability were synthesised. Tetragonal zirconia can be observed after the sample calcined at 1000℃. And mesoporous structure are still perfect even the catalyst calcined at 650℃ for 6h, and the BET surface area is 342m2/g for this sample. |
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