Synthesis of Biodiesel from Soybean Oil using Heterogeneous KF/ZnO Catalyst

Biodiesel was produced by transesterification of soybean oil with methanol using ZnO loaded with KF as a solid base catalyst. It was found that the catalyst with 15 wt.% KF loading and calcined at 873 K showed the optimum activity. XRD, IR and Hammett indicator method were employed for the catalyst characterization. The results showed the activity of the catalysts was correlated with their basicity. The influence of various reaction variables on the conversion was also discussed.     

Reaction kinetics study of asymmetric polymer-polymer interface

In this study, the reaction kinetics of asymmetric polymer-polymer interface was experimentally and theoretically studied. A new rheological method correlating the change of rheological property of reactive system with the conversion of the in situ formed copolymers was applied to study the reaction kinetics of PBT/epoxy reactive system. Then, the new method was proved to be useful by comparing its results with that obtained from the conventional endgroup determination method. Moreover, the conversion of PBT/epoxy reactive system from rheological method could be well fitted by the numerical analysis, from which the kinetic constant and the diffusion constant of epoxy in PBT could be determined simultaneously.     

Modification of silk with aminated polyepichlorohydrin to improve dyeability with reactive dyes

Reactive dyes have almost complete exhaustion and ideal fixation on aminated polyepichlorohydrin pretreated silk without addition of salt or alkali. The effects of varying pretreatments and dyeing conditions were studied. The dyeing behaviour of CI Reactive Red 15 on modified silk under pH 6 was investigated. Dyeings of modified silk showed good wash fastness, dry and wet rub fastnesses as well as light fastness. The quality of the dyed silks obtained after pretreatment was shown to be satisfactory and the dyeing effluent was less polluted.     

Combustion of methane over palladium ZSM-5 and mordenite catalysts

The effect of Pd-loading on Pd-NaZSM-5 and Pd-NaMordenite catalysts prepared by ion exchange was studied for methane combustion with excess oxygen (1% CH₄, 18% O₂, balance N₂) in the temperature range 40–500°C. Fresh and calcined samples (3 h, 450°C) showed methane conversions proportional to Pd-loading on Pd-NaZSM-5 catalysts, while conversions decreased with Pd-loading on calcined Pd-NaMordenite catalysts. TOF (number of methane molecules converted per second per Pd²⁺ ion) for over exchanged Pd-NaZSM5-116 was low as compared to under exchanged Pd-NaZSM5-80 and Pd-NaZSM5-58 samples. Close TOF's were found for the last two samples at 330°C. TOF differences in Pd-NaMordenite catalysts demonstrate the heterogeneity of Pd⁺² sites due to structurally nonidentical locations of cations. TOF's appear to be related to Na/Pd ratios in both catalyst types. Apparent activation energies for Pd-NaZSM-5 materials are higher than those for Pd-NaMordenite catalysts.     

Morphologies-Controlled Synthesis and Optical Properties of Bismuth Tungstate Nanocrystals by a Low-Temperature Molten Salt Method

Well-crystallized bismuth tungstate (Bi₂WO₆) powders with different morphologies were successfully synthesized via a low-temperature molten salt method. The powders were characterized by X-ray diffraction, transmission electron microscopy, and UV-Vis, respectively. It was found that the variation of morphology of the obtained Bi₂WO₆ powder mainly depends on the different reaction temperatures and the weight ratio of LiNO₃–NaNO₃ salt to precursor. In addition, the UV-Visible absorption spectra showed that the synthesized powders had strong light absorption properties not only in the ultraviolet light but also in the visible light region.     

Supported Vanadia Catalysts for Dehydrogenation of Ethylbenzene with CO2

Alumina supported vanadia catalysts (V/Al) for selective oxidehydrogenation of ethylbenzene with CO₂ were prepared by impregnation method. During preparation the effect of promoters and calcined temperature was investigated, it was found these two items had a strong influence on the activity of V/Al catalysts. Dehydrogenation reaction with CO₂ was happened in the fixed-bed reactor at 450 °C. Results showed that 15.2% ethylbenzene conversion and 99.2% styrene selectivity were acquired when V₂K/Al catalyst was used.     

A three-dimensional model for suspension-to-membrane-wall heat transfer in circulating fluidized beds

A three-dimensional model is proposed for both furnace-side and wall-side heat transfer in circulating fluidized beds with membrane walls. Following previous publications (Int. J. Heat Mass Transfer (2003a, b)), a core-annulus flow structure is employed in the model, with consideration of the membrane wall influence on bed hydrodynamics. The model couples radiation, conduction and convection on the furnace side to conduction and convection on the wall side. Radiation in the wall layer is simulated by the moment method. A finite-element method is employed to solve the set of non-linear, partial differential equations. The solution is demonstrated for a typical example. The model gives predictions of suspension-to-wall heat transfer which show satisfactory agreement with published experimental data.     

Variability for oil and fatty acid composition in castorbean varieties

Thirty-six castorbean varieties were surveyed for oil and fatty acid composition, in order to determine variability of these seed compounds. A large variability of seed oil percentage was observed, ranging from 39.6 to 59.5%. Concerning the fatty acids, little variability was observed for ricinoleic acid, which was the most abundant in the oil, ranging from 83.65 to 90.00%. The other fatty acids appeared in small concentrations and showed a small range: 0.87 to 2.35, 0.68 to 1.84, 2.96 to 5.64, 3.19 to 5.98, and 0.34 to 0.91%, for palmitic, stearic, oleic, linoleic, and linolenic acid, respectively. Non-significant correlations were observed between fatty acids and seed oil percentage. However, significant correlations were observed among fatty acid concentrations: positive and negative ones. These significant correlations could be associated with the biosynthetic pathways of the fatty acids, which are not fully elucidated. They suggest, however, that selection for a particular fatty acid will tend to increase those positively correlated, and decrease those negative ones. Selection and plant breeding techniques could then be applied to modify the oil content of the castorbean seeds, considering the variability observed. For the fatty acid composition, however, the variability was not large enough to make substantial changes in their concentrations by selection procedures. More varieties should be surveyed to find out if such variability is available.     

Direct synthesis of electrorheological suspension containing salt of poly(methacrylic acid) and its electrorheological effect

Colloidal suspensions containing salts of poly(methacrylic acid) which exhibit high electrorheological (ER) activity were synthesized by inverse emulsion polymerization. Factors influencing the ER effect were studied. The results showed that maximum yield stress occurred at optimum amounts of both polymeric stabilizer and crosslinking agent used in the inverse emulsion polymerization as well as a certain water content of the particles, while yield stress increased with electric field strength, average diameter of the particles below 0.9 μm, or the molar ratio of the salt to the acid. The ER activity for the suspensions containing different monovalent counter ions decreased in the following order: Li⁺ > Na⁺ > K⁺ > NH₄⁺. The phenomena were discussed with the ionic polarization mechanism. © 1995 John Wiley & Sons, Inc.     

裙子变长 奢华依旧——浅析经济危机下的时装流行走向

在全球性事件的大背景下,流行趋势研究更能显示出其价值,本文通过分析经济危机下时装行业的最新动态,总结并预测时装流行及时装业发展的未来走向,可以提供给中国时装业一些思考。