Papers by Author: Hai Fu Guo

Abstract: The new type of solid superacid S₂O₈^2-/SnO₂-SiO₂ was prepared by precipitation and hydrothermal aging method with ammonium persufate as soaker instead of sulphuric acid. The samples with different tin oxide content were characterized by FT-IR, XRD, BET, TG/DTA and Hammett indicators techniques. Catalytic activities for esterification of butanol and acetic acid were also investigated. As a result, most sulfate-ion in surface of S₂O₈^2-/SnO₂-SiO₂ coordinate with Sn bidentatly, and the acidic strength of S₂O₈^2-/SnO₂-SiO₂ is related to the content of tin oxide. Besides, introducing appropriate Si can improve the combination of the tin with SO₄^2- thus increases the amount of acid. Catalyst S₂O₈^2-/SnO₂-SiO₂ reveals high catalytic activity and stability in the esterification at very large range of composition.

Abstract: A new rare earth solid superacids catalyst SO₄^2-/TiO₂-SnO₂-Dy₂O₃ was prepared by coprecipitation-impregnating method, and the optimum preparation conditions were obtained. The physic- chemical properties of the catalyst was characterized by FTIR, TG-DTA, XRD and BET. The results showed the prepared catalyst is superacid with good thermal stability and high specific surface area. The sulfuric groups were proved to be chelated and bridgingly connected on the surface of the catalyst.

Abstract: Zeolites mordenite (MOR) and β decorated with high dispersion degree and loading content of CuO composite (symbolized as CuO/zeolite) were prepared via a novel method-the stepped hydrothermal synthesis. The resultant composite were characterized with details by powder XRD, ICP-AES, H₂-TPR and TEM techniques. Shown by experiment, the stepped hydrothermal synthetic method adopted in the present research using urea as alkali source as well as benefiting from the ultrasonic wash treatment hardly damages the zeolitic framework structure. Compared with ammonia, high dispersion degree and loading level of CuO are yielded as a consequence of the employment of urea as alkali source. Besides, the ultrasonic wash treatment not only removes some CuO precursors that deposit on the external surface of the porous support but also produces a uniform distribution of CuO particles with smaller dimension on the surface of zeolites: CuO are dispersed in nanoscale of about 4-8 nm on mordenite and 2-5 nm on zeolite β. The present synthetic strategy could be therefore applied as a novel general method for the manufacture of functional materials in a wide spectrum.