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.     

酶/酸水解毛叶木姜子中键合态香味成分的比较

采用AmberliteXAD-2树脂吸附洗脱分离毛叶木姜子中的键合态香气物质前体,将分离得到的键合态香气物质前体在AR2000酶、果胶酶和酸3种条件下分别进行水解释放,采用气相色谱-质谱联用法(GC-MS)对水解后的键合态香气物质进行分离分析。结果表明:3种水解条件得到的键合态香气物质共有90种,主要为萜烯类和含氧萜类物质。其中,香叶醇在2种酶水解条件下均含量高,果胶酶水解条件下含量最高达21798.79μg/L;共34种香气物质具有明显香气特征,2种酶水解下最显著的香气特征为花香和甜香;酸水解条件下最显著的香气特征为花香。酶水解与酸水解条件下得到的键合态香气物质存在明显差异,果胶酶水解条件下所检出的香气物质种类多且含量较高。因此,果胶酶处理更有利于毛叶木姜子键合态香气成分的释放。     

Degradation of cellulosic and hemicellulosic substrates using a chelator‐mediated Fenton reaction

The involvement of catechol and hydroxamate chelators, along with hydrogen peroxide and Fe³⁺, in the degradation of cellulosic and hemicellulosic substrates was examined with the purpose of improving our current knowledge of the non‐enzymatic mechanisms involved in wood biodegradation by fungi. It could be demonstrated that a catechol chelator‐mediated Fenton reaction not only clearly degraded hemicellulosic substrates but also significantly accelerated and increased the effectiveness of degradation reactions. On the other hand, when a hydroxamate chelator‐mediated Fenton reaction was used, an inhibitory effect was observed. When cellulosic substrates underwent a chelator‐mediated Fenton reaction, no significant difference in degradation was observed between catechol and hydroxamate chelator‐mediated reactions. However, a catechol‐mediated reaction did accelerate the degradation of cellulosic substrates at the beginning of reactions. In addition, it was observed that with a chelator‐mediated Fenton reaction, oxidation of cellulose proceeds depolymerization. Copyright © 2005 Society of Chemical Industry     

Naegeli茶螺烷合成方法的改进

对Naegeli报道的以β-紫罗兰酮为原料经乙酸异丙烯酯酯交换、硼氢化钠还原成逆紫罗兰醇再环化合成茶螺烷的方法进行了改进,改进后的合成方法反应副产物巨豆三烯含量从15%降至4%,反应时间明显缩短,茶螺烷的收率从75%提高至84.5%。     

生物柴油制备方法的应用研究进展

生物柴油以其优良的环境友好性和可再生性引起广泛关注,但较高的生产成本是其商业化生产和应用的障碍之一。综述了生物柴油的化学转酯化法和以游离脂肪酶、固定化脂肪酶、全细胞为催化剂的生物转酯化法的工业研究进展,同时还指出了采用生物转酯化法制备生物柴油时面临的一些问题。     

离子液介质中生物催化与生物转化的研究进展

Ionic liquids have negligibly low vapor pressure, high stability and polarity. They are regarded as green solvents. Enzymes, especially lipases, as well as whole-cell of microbe, are catalytically active in ionic liquids or aqueous-ionic liquid biphasic systems. Up to date, there have been many reports on enzyme-exhibited features and enzyme-mediated reactions in ionic liquids. In many cases, remarkable results with respect to yield, catalytic activity, stability and (enantio-, regio-) selectivity were obtained in ionic liquids in comparison with those observed in conventional media. Accordingly, ionic liquids provide new possibilities for the application of new type of solvent in biocatalytic reactions.     

Lipase-catalyzed transesterification of phosphatidylcholine at controlled water activity

The incorporation of a free fatty acid into thesn-1 position of phosphatidylcholine by lipase-catalyzed transesterification was investigated. The thermodynamic water activity of both the enzyme preparation and the substrate solution was adjusted to the same value prior to the reaction. The reaction rate increased with increasing water activity but the yield of modified phosphatidylcholine decreased due to hydrolysis. By using a large excess of the free fatty acid (heptadecanoic acid), the hydrolysis reaction was slowed down, so a higher yield was obtained at a given degree of incorporation. The best results were obtained withRhizopus arrhizus lipase immobilized by adsorption on a polypropylene support. With this preparation, a yield of 60% and nearly 50% incorporation of heptadecanoic acid (100% incorporation in thesn-1 position) was obtained at a water activity of 0.064. The enzyme preparation had good operational stability and position specificity. Little incorporation (<1%) was observed in thesn-2 position, when almost all the fatty acid in thesn-1 position was exchanged.     

The pseudo-single-phase,base-catalyzed transmethylation of soybean oil

The base-catalyzed transmethylation of soybean oil has been studied under conditions whereby the reaction starts as a single phase, but later becomes two phases as glycerol separates. Methanol/oil molar ratios of 6∶1 were used at 23°C. The catalysts were sodium hydroxide (0.5, 1.0, and 2.0 wt%), potassium hydroxide (1.0 and 1.4 wt%), and sodium methoxide (0.5, 1.0, and 1.35 wt%), all concentrations being with respect to the oil. Oxolane (tetrahydrofuran) was used to form a single reaction phase. The reactions deviated from homogeneous kinetics as glycerol separated, taking with it most of the catalyst. When 1.0 wt% sodium hydroxide was used, the methyl ester content reached 97.5 wt% after 4 h, compared with 85–90 wt% in the two-phase reaction. Sodium hydroxide (1.0 wt%), sodium methoxide (1.35 wt%), and potassium hydroxide (1.4 wt%) gave similar results, presumably because the same number of moles was used. The ASTM biodiesel specification for chemically bound glycerol was achieved after only 3 min when 2.0 wt% sodium hydroxide was used. However, the standard was not achieved after 4 h when 1.0 wt% sodium hydroxide was used, the MG content being 1.1–1.6 wt%. The use of 2.0 wt% catalyst is commercially impractical.     

氨基甲酸酯基丙烯酸酯的合成及其光固化性能

利用碳酸亚乙酯与1,6-己二胺、异佛尔酮二胺反应，制备出两种含氨基甲酸酯基的二元醇，基于氨基甲酸酯二元醇与1,6-己二醇二丙烯酸酯（HDDA）、新戊二醇二丙烯酸酯（NPGDA）及三羟甲基丙烷三丙烯酸酯（TMPTA）本体条件下的Oxa-Michael加成反应及酯交换反应，合成出6种含氨基甲酸酯基的丙烯酸酯混合物。利用FTIR及高分辨质谱分析了产物结构，用FTIR考察了所合成氨基甲酸酯基丙烯酸酯光固化过程的动力学,测定了光固化膜的性能。结果表明，在含占总质量分数3% 的2-羟基-2-甲基-1-苯基-1-丙酮（1173）光引发剂的引发下，氨基甲酸酯基丙烯酸酯能在30s内固化形成表面平整、柔韧性（0.5~2.5mm）良好、透明或半透明的膜；固化膜的凝胶率及铅笔硬度分别为92%~96%、4~5H，对玻璃的附着力为0~1级。     

棉籽油间歇式酯交换反应动力学的研究

生物柴油(棉籽油甲酯)可以由棉籽油与甲醇在催化剂KOH存在下通过酯交换反应制得。故对棉籽油间歇式酯交换反应动力学进行了研究,并考察了反应温度和催化剂浓度对产物棉籽油甲酯浓度的影响。用液相色谱法分析棉籽油的组成;用气相色谱法分析产物中棉籽油甲酯的含量。由实验数据绘制的动力学曲线得到酯交换反应在开始阶段为准二级反应,以后紧接转为一级反应和零级反应,与文献报导的棕榈油酯交换反应动力学结果一致。由实验数据求出酯交换反应在开始阶段的动力学参数,35℃、45℃时的反应速率常数分别为0.9179Lmol-1min-1和1.049Lmol-1min-1,酯交换反应的活化能为10.88kJmol-1。根据实验结果得到棉籽油酯交换反应的最佳反应温度为45℃,最佳催化剂为1.1%KOH。