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91.
研制了固体超强酸催化剂S2O82-/聚乙二醇-TiO2-M2O3(M=Al,Cr), 并以赤砂糖为原料,催化水解法制备乙酰丙酸。通过单变量法考察了催化剂焙烧时间、催化剂用量、赤砂糖浓度、反应温度和反应时间等对乙酰丙酸收率的影响,并通过正交实验确定最佳工艺条件。结果表明,在催化剂焙烧时间120 min、赤砂糖浓度为10 g·L-1、催化剂用量为赤砂糖质量的15%、反应温度200 ℃和反应时间120 min条件下,乙酰丙酸收率达39.98%。 相似文献
92.
Anton A. Kiss Costin Sorin Bildea 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(7):861-879
Biodiesel is a biodegradable and renewable fuel, emerging as a viable alternative to petroleum diesel. Conventional biodiesel processes still suffer from problems associated with the use of homogeneous catalysts and the limitations imposed by the chemical reaction equilibrium, thus leading to severe economic and environmental penalties. This work provides a detailed review—illustrated with relevant examples—of novel reactive separation technologies used in biodiesel production: reactive distillation/absorption/extraction, and membrane reactors. Reactive separation offers new and exciting opportunities for manufacturing the fatty acid alkyl esters involved in the industrial production of biodiesel and specialty chemicals. The integration of reaction and separation into one operating unit overcomes equilibrium limitations and provides major benefits such as low capital investment and operating costs. These reactive separation processes can be further enhanced by heat‐integration and powered by heterogeneous catalysts, to eliminate all conventional catalyst related operations, using efficiently the raw materials and the reaction volume, while offering higher conversion and selectivity, as well as significant energy savings compared with conventional biodiesel processes. Remarkable, in spite of the high degree of integration, such integrated reactive‐separation processes are still very well controllable as illustrated by the included examples. Copyright © 2012 Society of Chemical Industry 相似文献
93.
Jiang Li Fenghui Sun Xiangzhen Li Zhiying Yan Yuexiang Yuan XiaoFeng Liu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(12):1687-1693
BACKGROUND: This work investigated the monokaryogenesis of dikaryon strains of Trametes hirsuta by protoplasts regeneration for extracellular ligninolytic enzyme production. Saccharification of corn straw was enhanced by alkali pretreatment combining crude ligninolytic enzymes. RESULTS: Effectiveness of alkali pretreatment of corn straw on delignification was evaluated under different concentrations. About 45% lignin loss was achieved at the concentration of 1.5% NaOH. In addition, 79.0% sugar yield was obtained after combined pretreatment with NaOH and crude ligninolytic enzyme produced from monokaryotic strains of Trametes hirsuta. Scanning electron microscopy (SEM) images showed that the porosity and surface area increased significantly after combined pretreatment. The FTIR spectra indicated that great intensity changes occurred at the 890–900 cm?1, 1509–1513 cm?1 and 1595 cm?1 bands. CONCLUSION: The proposed combined pretreatment removes lignin and enhances saccharification of corn straw effectively. Copyright © 2012 Society of Chemical Industry 相似文献
94.
有关邻苯二甲酸酯类增塑剂在食品包装材料中应用的法规 总被引:1,自引:0,他引:1
以台湾发生的"起云剂事件"为背景,简要讨论了邻苯二甲酸酯类增塑剂的危害、在食品包装过程中的迁移、国内外法规现状及发展前景等问题。 相似文献
95.
96.
《分离科学与技术》2012,47(6):802-810
This study was undertaken to check the possibility of using micellar enhanced ultrafiltration (MEUF) in the removal of chromium(III) ions from water systems. The influence of ion concentration in the feed, type of surfactant (SDS or Rofam 10), and the membrane material on separation efficiency were studied and discussed. The use of environmentally safer surfactants from renewable sources was proposed, that is, oxyethylated rape fatty acid methyl esters – trade name: Rofam 10. The results presented show the possibility of using MEUF as an effective method for removing chromium(III) ions from aqueous solutions, especially from solutions of low concentration. 相似文献
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98.
The NMR chemical shift, i.e., the π-electron density of the double bond, of acrylates and methacrylates is related to the reactivity of their monomers. We investigated quantitative structure-property relationships (QSPRs) between the base-catalyzed hydrolysis rate constants (k1) or the rate constant with glutathione (GSH) (log k(GSH)) for acrylates and methacrylates and the (13)C NMR chemical shifts of their α,β-unsaturated carbonyl groups (δC(α) and δC(β)) or heat of formation (Hf) calculated by the semi-empirical MO method. Reported data for the independent variables were employed. A significant linear relationship between k1 and δC(β), but not δC(α), was obtained for methacrylates (r(2) = 0.93), but not for acrylates. Also, a significant relationship between k1 and Hf was obtained for both acrylates and methacrylates (r(2) = 0.89). By contrast, log k(GSH) for acrylates and methacrylates was linearly related to their δC(β) (r(2) = 0.99), but not to Hf. These findings indicate that the (13)C NMR chemical shifts and calculated Hf values for acrylates and methacrylates could be valuable for estimating the hydrolysis rate constants and GSH reactivity of these compounds. Also, these data for monomers may be an important tool for examining mechanisms of reactivity. 相似文献
99.
100.