共查询到20条相似文献,搜索用时 0 毫秒
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Lara-Isabel Rodríguez Oriol RossellMiquel Seco Arantxa OrejónAnna M. Masdeu-Bultó 《The Journal of Supercritical Fluids》2011,55(3):1023-1026
The palladocarbosilane dendrons 1 and 2, containing the P-stereogenic phosphine fragment at the focal point are soluble in supercritical CO2 medium and capable to catalyze the asymmetric hydrovinylation of styrene with good activity and enantiomeric excesses. 相似文献
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This review discusses the retention of organometallic catalysts in continuous flow processes utilizing supercritical carbon dioxide. Due to its innovative properties, supercritical carbon dioxide offers interesting possibilities for process intensification. As a result of safety and cost considerations, processes that use supercritical carbon dioxide are preferably done in continuous flow, as they require a pressure upwards of 74 bar. Many of the reactions that benefit from the application of supercritical carbon dioxide also involve the use of a homogeneous catalyst however, requiring efforts to recycle the catalyst when these are applied in continuous flow. Alternatively, the catalyst may be retained in the reactor by modifying the process or catalyst, such as by catalyst immobilization, membrane separation, or biphasic processing exploiting the properties of supercritical carbon dioxide. Each of these methods is discussed, including their advantages and drawbacks. Also discussed are milli- and micro-flow processes and their possibilities for integrated catalyst retention and handling supercritical carbon dioxide. 相似文献
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Over the past few years, supercritical fluids have received considerable interest as reaction media. Supercritical fluids combine properties of gases and liquids. Densities are lower than in the liquid phase, but significantly higher than in the gas phase. This makes supercritical fluids excellent solvents for a variety of substances. The good dissolution capacity exists only in or near the supercritical range. Reaction products can be separated, for instance, simply by decreasing temperature and pressure. This may be used to intensify the process as complex separation processes, like distillation, are avoided. 相似文献
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二氧化碳是有机物氧化的最终产物,如何将其转化为有用的化工资源,十分重要.综述了近年来二氧化碳在合成及制备高附加值化工原料等方面的进展. 相似文献
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介绍了超临界二氧化碳(scCO2)胶束催化技术的研究进展:scCO2胶束及其相特征、CO2表面活性剂及scCO2胶束催化技术的应用与工艺开发。scCO2胶束及其相特征对于设计高效的亲CO2表面活性剂及研究scCO2胶柬催化作用具有重要指导意义。scCO2胶束的相特征主要是温度、压力和胶束含水比的函数。指出了开发亲CO2表面活性剂的一些基本原则,其中降低表面活性剂在H2O/CO2表面的界面张力和提高活性剂的吸附能力要比提高溶解度更为重要。scCO2胶束催化技术可以明显提高催化反应活性,适合于开发原位分离反应工艺。建议加强scCO2胶束催化技术的研究及相关工艺开发。 相似文献
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天然香料植物的超临界CO2萃取及应用问题 总被引:1,自引:0,他引:1
本文结合我国天然香料植物资源的利用情况及超临界流体技术在天然香料植物提取方面的应用和存在的问题进行讨论。提出为加快我国天然香料资源的利用 ,发展边远地区的经济和香料经济作物的种植 ,应充分发挥联合的优势 ,应用新技术 ,开发新产品 ,提高资源的利用率和经济效益 相似文献
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在半连续式实验设备中分别测定了苯甲醇-2-苯乙醇和苯甲酸酯-苯甲醇的等摩尔混合物与超临界CO2三元系相平衡数据。实验温度分别为308.2K和318.2K,压力范围为8~20MPa。实验结果表明:对第一个三元系,两种液体在超临界CO2中的溶解度与CO2在液相中溶解行为密切相关;对第二个三元系,较高压力下,超临界流体相中苯甲酸甲酯浓度突然增大,而苯甲醇浓度变化不明显。通过引入考虑分子体积差别的二元作用参数,用Peng-Robinson方程对气液平衡数据进行了关联。 相似文献
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Sergey E. Lyubimov Ilya V. Kuchurov Eugenie A. Rastorguev Sergei G. Zlotin 《The Journal of Supercritical Fluids》2010,54(2):218-221
Pd-catalyzed amination of allylic carbonates with N-(ortho-carboran-3-yl)-N-methylamine was carried out in supercritical CO2. It has been demonstrated that complete conversion of allylic carbonates to the corresponding carborane amines with excellent regioselectivity may be achieved in scCO2 (170 atm, 60 °C) using NaHCO3 as the acceptor base. The reaction offers a selective method for the preparation of allylic amines and provides a useful approach to new terpenoids. 相似文献
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In this article, new perfluorinated binaphthyl Mn(III) complexes have been synthesized by template effect. The synthesized complexes were characterized by elemental analysis, FT-IR, LC/MS, UV–vis spectroscopy. After the solubility of the catalysts in scCO2 was observed through the high pressure reactor, catalytic activities of the catalysts have been tested in homogeneous asymmetric epoxidation of styrene in both dichloromethane (organic solvent) and supercritical carbon dioxide (scCO2). In order to determine and compare to complexes, the effect of synthesized catalysts to conversion and selectivity was investigated. Reaction parameters such as; reaction time, solvent type and position of substituents were also assessed during the analysis. 相似文献
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超临界二氧化碳萃取器萃取分离香茅油 总被引:1,自引:0,他引:1
本文介绍了利用现有150L高压釜(压力20MPa)改造的超临界二氧化碳萃取器萃取分离香茅油,探讨了压力、温度、时间对萃取分离效果的影响。结果表明,采用超临界二氧化碳萃取器萃取分离香茅油时应选择一个适宜的压力、温度和萃取时间,产品的色、香味、纯度均优于常规的减压蒸馏法。 相似文献
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A new process was used to foam homogeneous polypropylene (HPP) and ethylene-polypropylene block copolymer (CPP). Many different foaming behaviors of these two kinds of PP were observed. The HPP and CPP were characterized by Differential Scanning Calorimetry (DSC), and Capillary Rheometry. We find that the melt shear viscosity of CPP is more sensitive to the temperature variation than that of HPP, thus leading to larger change of cell diameter of CPP with foaming temperature. Cell size of CPP is the result of competition between cell nucleation and cell growth. When the saturation pressure is lower or higher than 25 MPa, cell nucleation or cell growth plays a dominant role, which leads to the increase or decrease of cell size, respectively. Because of its low melting temperature and crystallinity, cell diameter of CPP increases with the infiltration temperature increasing, which is opposite to those of HPP. And at the foaming temperature of 152°C or 158°C, cell diameter of CPP increases or decreases with an increase in foaming time, while that of HPP decreases with foaming time increasing at both foaming temperatures. 相似文献
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Dilek Büyükbeşe Emine Elçin Emre Ahmet Kaya 《Journal of the American Oil Chemists' Society》2014,91(1):169-177
Supercritical carbon dioxide was used to fractionate anhydrous milk fat. Six fractions were produced at 40, 50 and 60 °C using pressure values of 10, 20, 25, 30, 33 and 36 MPa. The fractions were analyzed for fatty acids, thermal behavior, iodine and color values. Composition and yield of fatty acid methyl esters were evaluated at different fractionation conditions in relation to the original milk fat values. Short chain fatty acids (C4–C8), medium chain fatty acids (C10–C14) and total saturated fatty acids were decreased from fraction obtained in the order of 10–36 MPa, while long chain fatty acids (C16–C18:2) and total unsaturated fatty acids were increased. Fractions obtained in the raffinate stage of the fractionation exhibited higher melting behavior that obtained at the low CO2 pressures. The higher iodine value of raffinate fraction indicated that fraction was richer in oleic acid. Fractions produced at low pressures had lower melting behavior than those obtained at high pressures. Yellowness Index and b* values increased in raffinate fraction due to concentration of carotenoids. 相似文献
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The accurate experimental determination of pharmaceutical compound solubilities at various temperature and pressure ranges in supercritical carbon dioxide (ScCO2) is a challenging and time‐consuming task. Therefore, prediction or correlations of solute solubilities are essential for implementation of ScCO2 technologies to pharmaceutical industries. Solubilities of 41 pharmaceutical compounds in ScCO2 are correlated by an empirical model, which is developed based on the degree of freedom analysis. Its correlating ability is compared with existing solubility models elaborated by other authors and evaluated in terms of global mean absolute relative deviation, sum of squares due to error, root mean square deviation, R2, and Adj. R2. The proposed model is found to correlate better than existing models. 相似文献