Advanced Materials Research Vols. 550-553

Abstract: In this work, a visible light-activated LaVO₄/TiO₂ composite photocatalyst has been successfully synthesized via a facile coupled method. The composite was characterized by powder X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS) and spin-trapping electron paramagnetic resonance (EPR). Based on the detection of active oxygen species, a visible light-induced photocatalytic degradation mechanism of benzene on LaVO₄/TiO₂ was proposed.

Abstract: The large quantity of dyeing and printing wastewater, which contains high organics which can be hardly decomposed, is one of the main sources of water pollution. Based on summarizing the existing problems of traditional processing methods, the technology of cavitation jet and impinging streams were organically combined, which has great potential in wastewater treatment field, as a new method for degrading printing and dyeing wastewater, and then the “cavitation impinging streams (CIS)” concept was proposed, in which the superior features in wastewater degradation with CIS was expounded, and the problems to be further studied were pointed out.

Abstract: Through the measured effective diffusion coefficients of Dagang vacuum residue supercritical fluid extraction and fractionation (SFEF) fractions in FCC catalysts and SiO₂ model catalysts, the relation between pore size of catalyst and effective diffusion coefficient was researched and the restricted diffusion factor was calculated. The restricted diffusion factor in FCC catalysts is less than 1 and it is 1~2 times larger in catalyst with polystyrene (PS) template than in conventional FCC catalyst without template, indicating that the diffusion of SFEF fractions in the two FCC catalysts is restricted by the pore. When the average molecular diameter is less than 1.8 nm, the diffusion of SFEF fractions in SiO₂ model catalyst which average pore diameter larger than 5.6 nm is unrestricted. The diffusion is restricted in the catalyst pores of less than 8 nm for SFEF fractions which diameter more than 1.8 nm. The tortuosity factor of SiO₂ model catalyst is obtained to be 2.87, within the range of empirical value. The effective diffusion coefficient of the SFEF fractions in SiO₂ model catalyst is two orders of magnitude larger than that in FCC catalyst with the same average pore diameter. This indicate that besides the ratio of molecular diameter to the pore diameter λ, the effective diffusion coefficient is also closely related to the pore structure of catalyst. Because SiO₂ model catalyst has uniform pore size, the diffusion coefficient can be precisely correlated with pore size of catalyst, so it is a good model material for catalyst internal diffusion investigation.

Abstract: In this thesis, isoamyl acetate was synthesized by reaction-distillation , using acetic acid and isoamyl alcohol as starting materials, using acid ion-liquid as catalyst and extracting agent.These are some factors were investigated, including different catalysts, ratio between acid and alcohol, amount of Ion-Liquid, and reflux ratio. Technology to prepare iso-pentyl acetate was optimized with single factor experiments. Results showed that acid ion-liquids are good catalysts and extracting agents, which increased the purity and yield of iso-pentyl acetate, as well as diminished the azeotropic point of iso-pentyl acetate and acetic acid.The optimal technological conditions are as following: ratio of acid:alcohol 2:1 (mol), dosage of ion-liquid V = 2 mL, reflux ratio R = 2.5. Under this condition, purity of obtained iso-pentyl acetate is 99%, and the yield is 85%.

Abstract: Ammonium Phosphomolybdate with Dawson structure was prepared by hydrothermal synthesis and characted by means of FT-IR, UV-Vis,XRD and SEM. The synthesis of adipic acid with cyclohexanone and 30 percent hydrogen peroxide under microwave irradiation was carried out as a probe reaction to study the catalytic activity. Effects of catalyst amount,30wt.% H₂O₂ amount,microwave power, reaction time were investigated and optimized with orthogonal experiments and simple fact experiments. The results show that under the optimal condition, i.e. the mole ratio of C₆H₁₀O: H₂O₂:H₂C₂O₄•2H₂O:(NH₄)₆P₂Mo₁₈O₆₂•nH₂O =100:500:2.0:0.087, the reaction temperature was 100°C, microwave power was 400W, irradiation time was 3.5 h，the isolated yield of adipic acid could reach 72.5%．The catalyst could be reused for 5 times and the isolated of adipic acid was still above 43.2%.

Abstract: A new method of sustainable ethanol synthesis by hydrogenating dimethyl oxalate (DMO), which is easily obtained from syngas, over a Cu/SiO₂ catalyst is proposed based on previous works. The experimental results indicate that the Cu/SiO₂ catalyst exhibited a high activity under the relative mild conditions of 270°C and 2MPa with ethanol selectivity as high as 88% and extremely high DMO conversion.

Abstract: The oxidation of α-pinene with hydrogen peroxide, at 40°C and atmospheric pressure, using ethylene glycol dimethyl ether as solvent was carried out in the presence of VO(OAc)₂. The influence of solvent, reaction temperature and catalyst dosage on catalytic activity and product selectivity was studied. The major reaction products were verbenon (45.9% selectivity at 82.9% conversion). Formation of campholenic aldehyde, myrtenal, verbenol and epoxypinane was also observed.

Abstract: Hybrid latexes containing ethyl cellulose (EC), vinyl acetate (VAc) and butyl acrylate (BA) were prepared by pre-emulsified semi-continuous seed emulsion polymerization. Influences of some synthetic parameters on the stability of emulsion polymerization were investigated. The emulsion polymerization is optimum with emulsifier 3 wt%, OP-10/ SDS 1/1 and PVA 0.5 g. The emulsion average particle size increases with EC content increase.TGA and water absorption analysis show that EC/ BA / VAc hybrid latexes films containing more BA display better thermal stability and hydrophobicity. The EC/BA/VAc latex shows good biodegradation, flexility property and is suitable for slow-release material of environmental-friendly coated fertilizer.

Abstract: The thermal decomposition behavior of precursor of Nb doped rutile TiO₂ were prepared by sol-gel method. With ultrasonic treatment of 100W and 30min were investigated in TG-DSC, XRD and DRS. It has been shown that ultrasonic treatment could be made use of the phase transition. The absorbing performance of Nb doped rutile TiO₂ treated by ultrasonic was better than that of without treatment while wavelength above 400nm. It has been shown that Nb doped TiO₂ powders(1.0%,850°C) treated by ultrasonic has been better photodegradation efficiency, and the degradation efficiency was 94.2% after 6h.

Abstract: Vanadium doped rutile titania was prepared by low temperature hydrolysis using Tetrabutyl titanate as raw material. Powers were characterized by X-ray diffraction spectrum (XRD)、diffuse reflection spectra(DRS)、fluorescence spectra (FS). At 1073K, Doped concentration have been in a certain range, Vanadiumcould be doped into the lattice of rutile TiO₂ in the way of replacement, which would cause no change in rutile TiO₂crystalline state with sunlight as the light source, pH=6.0, catalyst concentration was 1.0g.L^-1, concentration of methyl orange was 5.0mg.L^-1. It has been shown that Vanadium doped TiO₂powders(1.0%,1073K) has been the most photodegradation efficiency, and the degradation efficiency was 97.2% after 6h.