共查询到18条相似文献,搜索用时 593 毫秒
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分子筛固体碱是一种环境友好型固体碱催化剂,催化剂表现出很好的催化活性并且分离后可重复使用。本文综述了用于催化油脂酯交换反应制备生物柴油的分子筛固体碱催化剂的研究进展,并分析了各种分子筛固体碱催化剂的特性。 相似文献
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分子筛固体碱催化剂在有机合成中的应用 总被引:1,自引:1,他引:0
综述了近年来以分子筛制备固体碱催化剂的研究进展,包括X型、Y型、L型等微孔分子筛和MCM-41、SBA-15等介孔分子筛经改性得到的固体碱,以及分子筛固体碱催化剂在双键异构化、酯化、酯交换、Knoevenagel缩合、Aldol缩合和Michael加成等有机反应中的应用。 相似文献
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以固体碱催化剂中典型的负载型固体碱催化剂(K2CO3/人造沸石、KF/Al2O3催化剂和CaO/人造沸石催化剂)作为酯交换反应的催化剂,利用地沟油经过酯交换反应制取生物柴油,对比不同催化剂的催化效率以及重复使用效率,从中选择最优固体碱催化剂,并选择最优催化剂研究其最佳工艺条件。最终产物通过GC-MS进行表征。 相似文献
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以介孔分子筛SBA-15为载体,负载KNO3后焙烧制得K2O/SBA-15固体碱催化剂,以合成丙烯酸正丁酯的酯交换反应为探针反应,在间歇式反应釜中对K2O/SBA-15催化剂进行催化活性评价。结果表明,当K2O负载量为2%,K2O/SBA-15催化剂对此酯交换反应的催化活性最高。 相似文献
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负载型膨润土固体碱催化剂的制备及在生物柴油合成中的应用 总被引:1,自引:0,他引:1
提出了一种负载型膨润土固体碱催化剂的制备方法,并将此催化剂用于生物柴油合成的酯交换反应。该催化剂通过碱性钙基膨润土在半干条件下负载氢氧化钠制得。催化剂制备的单因素实验结果表明:当氢氧化钠与碱性钙基膨润土的质量配比为0.6、负载时间为18 h、温度为60 ℃及碱性钙基膨润土中OH8722;含量为1.5 mmol/g时,催化剂中氢氧化钠负载量达到4.10 mmol/g。将该催化剂用于生物柴油酯交换反应,反应转化率可达97.4%,反应完成后生物柴油无需洗涤,避免了三废的大量排放,减少了对环境的污染。 相似文献
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Heterogeneous catalysts are promising for the transesterification reaction of vegetable oils to produce biodiesel. Unlike homogeneous, heterogeneous catalysts are environmentally benign and could be operated in continuous processes. Moreover they can be reused and regenerated. However a high molar ratio of alcohol to oil, large amount of catalyst and high temperature and pressure are required when utilizing heterogeneous catalyst to produce biodiesel. In this paper, the catalytic activity of several solid base and acid catalysts, particularly metal oxides and supported metal oxides, was reviewed. Solid acid catalysts were able to do transesterification and esterification reactions simultaneously and convert oils with high amount of FFA (Free Fatty Acids). However, the reaction rate in the presence of solid base catalysts was faster. The catalyst efficiency depended on several factors such as specific surface area, pore size, pore volume and active site concentration. 相似文献
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新型固体碱铝酸钙催化剂用于生物柴油的制备研究 总被引:1,自引:0,他引:1
采用化学合成法制备了铝酸钙固体催化剂,并将其用于菜籽油与甲醇酯交换反应的研究.考察了酯交换反应的条件,实验结果表明,当醇/油摩尔比为15:1,催化剂质茸分数6%,反应温度65℃,搅拌速率270 r/min,反应时间3 h,甲酯的收率为89.05%.产物和催化剂固液分离简单容易,铝酸钙固体催化剂具有较好的稳定性,连续使用7次,甲酯的收率均在87.00%以上.同时采用Hammett指示剂法、XRD、BET等手段对铝酸钙同体催化剂进行了表征. 相似文献
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非均相固体碱催化剂(CaO体系)用于生物柴油的制备 总被引:19,自引:1,他引:18
为解决生物柴油酯交换过程中的产物与催化剂分离问题,制备了负载型固体碱催化剂(CaO/SiO2、CaO/Al2O3和CaO/MgO体系),考察该系列催化剂在生物柴油制备中的不同反应特点,对制备的催化剂进行XRD表征,研究了反应条件对反应的影响。结果表明,CaO可以很好地分散在催化剂载体上,该体系催化剂是制备生物柴油的良好非均相催化剂。催化剂的最佳制备条件为:焙烧温度700 ℃,催化剂质量分数为原料油的1%,m(醇)∶m(油)=18∶1,反应温度60~65 ℃,反应时间10 h。 相似文献
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Heterogeneous Catalyst of Mixed K Compounds/Ca‐Al‐Graphite Oxide for the Transesterification of Soybean Oil to Biodiesel
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A novel heterogeneous solid base catalyst was prepared by loading of Ca‐Al‐graphite oxide with mixed potassium salts and applied in the transesterification of soybean oil with methanol to produce biodiesel. The catalysts were characterized by Hammett indicators, X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X‐ray spectrometry, and transmission electron microscopy. The effects of the methanol‐to‐oil molar ratio, catalyst amount, reaction temperature, stirring rate, and reaction time were investigated to optimize the transesterification reaction conditions. Moreover, the prepared catalyst retains its activity after being used for four cycles. In particular, the solid base catalyst can be effectively and easily separated from the reaction system, which may provide significant benefits for the development of an environmentally benign and continuous process for preparing biodiesel. 相似文献
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固体碱催化剂用于酯交换反应制备生物柴油有易分离、流程简单的优点。通过金属氧化物活性筛选,发现氧化钙具有很好的酯交换反应活性。将乙酸钙溶液等体积浸渍负载于碱性载体MgO上,并煅烧得到了氧化钙负载量为16.5%(质量)的CaO/MgO混合氧化物催化剂,其在油脂甲醇酯交换反应制备生物柴油的过程中具有高的反应活性。在64.5℃、醇油比18∶1 、催化剂用量2%、反应3.5 h条件下,油脂转化率为92%,接近传统的液体强碱NaOH的催化能力。用XRD、AAS、XPS、CO2 -TPD等对制得的系列催化剂进行了表征,发现催化剂的碱强度对酯交换反应有着重要的影响。通过选择合适的载体、含钙前驱体和氧化钙负载量可以增加负载型氧化钙催化剂的强碱性位,提高催化剂的反应活性。 相似文献
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The hydrogenation of naphthalene in hexane was carried out over the catalyst Pd-Pt supported on alumina mixed with different molecular sieves including ZSM-5, Beta, USY and SAPO-11. The catalyst was characterized by N2 sorption, NH3-TPD, TPR, and H2-O2 titration. The results indicated that the catalyst performance for naphthalene hydrogenation is related to its acid property, pore structure, Pd-Pt dispersion, and metal-support interaction, which may be well regulated by mixing proper molecular sieves in the alumina support. The catalyst Pd-Pt supported on a two-component support of Al2O3-SAPO-11 is provided with proper acidity, large pores and moderate metal dispersion; it exhibits excellent performance in the saturated hydrogenation of naphthalene to decalin (over it a complete conversion of naphthalene is observed and the selectivity to decalin exceeds 90% at 260-300 °C). 相似文献