Preparation and characterization of polyimide/Al2O3 hybrid films by sol-gel process

A sol-gel process has been developed to prepare polyimide (PI)/Al2O3 hybrid films with different contents of Al2O3 based on pyromellitic dianhydride (PMDA) and 4,4'-oxydianiline (ODA) as monomers. FESEM and TEM images indicated that Al2O3 particles are relatively well dispersed in the polyimide matrix after ultrasonic treatment of the sol from aluminum isopropoxide and thermal imidization of the gel film. The dimensional stability, thermal stability, mechanical properties of hybrid PI films were improved obviously by an addition of adequate Al2O3 content, whereas, dielectric property and the elongation at break decreased with the increase of Al2O3 content. Surprisingly, the corona-resistance property of hybrid film was improved greatly with increasing Al2O3 content within certain range as compared with pure PI film.

Bluish-white emission from radical carbonyl impurities in amorphous Al2O3 prepared via the Pechini-type sol-gel process

Many efforts have been devoted to exploring novel luminescent materials that do not contain expensive or toxic elements, or do not need mercury vapor plasma as the excitation source. In this paper, amorphous Al2O3 powder samples were prepared via the Pechini-type sol-gel process. The resulting samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), photoluminescence (PL) excitation and emission spectra, kinetic decay, and electron paramagnetic resonance (EPR).

Enhanced luminescence of BPO4 by mixing with SiO2 and Al2O3

In this paper, BPO4-xSiO(2) (X: SiO2/BPO4 molar ratio, 0-70%) and BPO4-xAl(2)O(3) (X: Al2O3/BPO4 molar ratio, 0-20%) powder samples were prepared by the Pechini-type sol-gel (PSG) process using glycerol and poly(ethylene glycol) as additives. The structure and optical properties of the resulting samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), diffuse reflection spectra, photoluminescence (PL) excitation and emission spectra, kinetic decay, and X-ray photoelectron spectra (XPS), respectively. It was found that the Pechini-type sol-gel-derived BPO4-xSiO(2) annealed at 1000 degrees C and BPO4-xAl(2)O(3) annealed at 960 degrees C exhibited bright bluish-white emissions centered at 428 and 413 nm, respectively. The luminescence decay curve analysis indicates that each sample has two kinds of lifetimes (more than 0.4 ms and less than 10 ns) and two types of kinetic decay behaviors, which can be fitted into a double-exponential function and a single-exponential function, respectively.

Selective hydrogenation of nitrobenzene to aniline in dense phase carbon dioxide over Ni/gamma-Al2O3: Significance of molecular interactions

The selective hydrogenation of nitrobenzene (NB) over Ni/gamma-Al2O3 Catalysts Was investigated using different media of dense phase CO2, ethanol, and n-hexane. In dense phase CO2, the total rate of NB hydrogenation was larger than that in organic solvents under similar reaction conditions; the selectivity to the desired product, aniline, was almost 100% over the whole conversion range of 0-100%. The phase behavior of the reactant mixture in/under dense phase CO2 was examined at reaction conditions. In situ high-pressure Fourier transform infrared measurements were made to study the molecular interactions Of CO2 with the following reactant and reaction intermediates: NB, nitrosobenzene (NSB), and N-phenylhydroxylamine (PHA). Dense phase CO2 strongly interacts with NB, NSB, and PHA, modifying the reactivity of each species and contributing to positive effects on the reaction rate and the selectivity to aniline. A possible reaction pathway for the hydrogenation of NB in/under dense phase CO2 over Ni/gamma-Al2O3 is also proposed.

(R,R)-DPEN-modified Ru/gamma-Al2O3 - An efficient heterogeneous catalyst for enantioselective hydrogenation of acetophenone

An efficient enantioselective catalyst of 5 wt.% Ru/-gamma-Al2O3 modified with R,R-1,2-diphenylethylene-diamine ((R,R)-DPEN) for the hydrogenation of a non-activated aromatic ketone of acetophenone has been investigated, a relatively high enantiomeric excess (ee) of 60.5% was obtained at both the conversion and selectivity larger than 99%, it was about three times higher than the ee values reported up to now for acetophenone hydrogenation with the supported transition metal catalysts modified by chiral reagents. The influences of some reaction parameters such as phosphine ligand, substrate/catalyst/modifier molar ratios, base, solvent, pressure and reaction temperature have been discussed. The chiral modifier of (R,R)-DPEN was very important in controlling the enantioselectivity through adsorption competing with other substrates on the surface of active metal species. The phosphine ligand and base were also important and indispensable in the present reaction.

用于烟气脱硝的堇青石基CuO/γ-Al2O3催化剂及制法和应用

一种用于烟气脱硝的堇青石基ＣｕＯ／γ－Ａｌ↓［２］Ｏ↓［３］催化剂重量百分比组成为：堇青石载体为７８．７－９３．８％，Ａｌ↓［２］Ｏ↓［３］为５－１６％，ＣｕＯ为１．２－５．３％。采用以高强度堇青石蜂窝陶瓷为基体，在其上涂敷载体γ－Ａｌ↓［２］Ｏ↓［３］后在浸渍一定浓度的ＣｕＯ。本发明具有采用简易高效的涂层方法，减少了γ－Ａｌ↓［２］Ｏ↓［３］膜的涂层裂痕，增加了γ－Ａｌ↓［２］Ｏ↓［３］涂层的牢固度。增加了γ－Ａｌ↓［２］Ｏ↓［３］的上载量；提高了催化剂的脱硝活性，寿命和稳定性的优点。

一种CuO/Al2O3脱硫剂的再生方法

一种ＣｕＯ／Ａｌ＃－［２］Ｏ＃－［３］脱硫剂的再生方法是将吸硫的ＣｕＯ／γ－Ａｌ＃－［２］Ｏ＃－［３］脱硫剂在含氨气气氛中还原再生，再生温度为３５０－５００℃，空速为５００－３０００ｈ＃＋［－１］，再生时间为３０－９０分钟。本发明的再生过程简单，易操作，二次脱硫活性稳定，可实现脱硫温度下的有效还原再生；再生过程中生成的ＳＯ＃－［２］在低温条件下可与未反应的ＮＨ＃－［３］结合生成固体硫酸铵盐，不仅简化了再生后续处理工序，而且可增强本再生方法的经济效益，降低了脱硫综合成本。