| The template method has become an important way to prepare nanomaterials for its unique superiority in controlling the granule's size, the appearance and the grain-size distribution. Especially, the soft template method, which provides the cavity of dynamieal equilibrium and the passageway's size and the shape enhanging with the experimental condition, becomes the preponderant way to prepare nanomaterials. In this text, Mesoporous cerium-iron solid solution with fluorite cubic structure and high specific surface area was prepared by the hydrothermal method and hydrothermal method with nonionic surfactant polyethylene glycol (PEG) and sodium dodecyl benzene sulfonate(SDBS) as templates. The influence of synthesis parameters on BET, pore structure and thermal stability were investigated.The samples were aslo characterized by XRD, FT-IR, H2-TPR, TEM and BET.Hydrothermal method was used to prepare CexFe1-xO2 solid solution. The influence of the molar ratio of Ce/Fe and coprecipitation temperature on specific surface area, crystal phase and reduction performance are investigated. The XRD pattem show that the molar ratio of Ce/Fe has significant influence on phase component. The solid solution with single phase could be obtained When x=0.9,0.8,0.7,0.6 while the samples with a impurity phase of octagon FeO(OH) were prepared when x=0.5. The BET results show that coprecipitation temperature have influence on specific surface area. The prepared sample's specific surface area is of 143.7 m2·g-1 at an coprecipitation temperature of 10℃(±0.05). With the temperature increasing, the sample's specific surface area decreases. The TEM images show that the as-prepared sample Ce0.9Fe0.1O2 is of worm-like mesoporous structure. The H2-TPR results show that the as-prepared sample has a better reducibility.Under the system that using PEG-4000 as template, the influence of the amount of PEG-4000, hydrothermal temperature on specific surface area, the influence of pH value and temperature on phase were investigated. The solid solution with single phase could be obtained when pH value is about 10(±0.05) while the samples with a impurity phase were prepared when pH value is 9(±0.05). On the contrary, the hydrothermal temperature has less influence on the phase of the sample, but with temperature increasing, the sample has a better crystallinity. The low-angle XRD results show that mesoporous structure of the sample is deposited homogeneously. The BET results show that PEG-4000 content and hydrothermal temperature have influence on specific surface area when the molar ratio of Ce/Fe is 0.3, hydrothermal temperature is 150℃, the prepared sample's specific surface area is of 160.6 m2·g-1. The TEM images show that the samples of Ce0.9Fe0.1O2 possess worm-like mesopore. The FT-IR results show that PEG-4000 cooperated with inorganic precursor and the residual PEG-4000 can be removed by calcination at 500℃. The as-prepared samples possess poor thermal stability, the specific surface area decreased to 43.2 m2·g-1 and the pore collapsed dramatically after calcination at 700℃for 1 h.Under the system that using SDBS as template, the influence of the amount of SDBS on specific surface area and the sample's thermal stability were investigated. The BET results show that SDBS's content has great influence on specific surface area and when the molar ratio of Ce/Fe is 0.4, the as-prepared sample's specific surface area is of 169.7 m2·g-1, meanwhile pore size distribution of the sample is relatively symmetrical and the average pore size is 4.5 nm. The FT-IR results show that SDBS self-assembly with Ce(OH)3 and Fe(OH)3. There is a little amount of SDBS left in sample. The TEM images show that the sample of Ce0.9Fe0.1O2 holds worm-like mesopore.The sample performs excellent thermal stability and the specific surface are decreased to 77.8 m2·g-1 after calcination at 700℃for 1h. The H2-TPR results show that the OSC and the calalytic performance of low-temperature is related to specific surface area. |
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