共查询到20条相似文献,搜索用时 541 毫秒
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以L-天冬氨酸为原料,采用一步合成法制备了酸性离子液体[Asp]HSO_4,并用其催化油酸进行酯化反应合成油酸甲酯。考察了离子液体[Asp]HSO_4用量、醇酸物质的量比、反应温度和反应时间对油酸酯化反应的影响,同时考察了该离子液体的重复使用性能。结果表明:离子液体[Asp]HSO_4催化油酸酯化的最适条件为催化剂[Asp]HSO_4用量为油酸质量的20%、醇酸物质的量比7∶1、反应温度(85±2)℃、反应时间24 h,在此条件下酯化率可达97. 72%。反应结束后离子液体与酯化产物容易分离,离子液体[Asp]HSO_4重复使用4次,酯化率为96. 93%,仍有较高的催化活性。 相似文献
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为了开发环境友好型高效催化剂催化油酸酯化制备生物柴油,以L-谷氨酸与不同无机酸(硫酸、硝酸和磷酸)为原料合成了3种离子液体,对这3种离子液体催化油酸酯化反应制备油酸甲酯的酯化率进行了考察,筛选出催化效率较优的一种离子液体,对其进行傅里叶红外光谱表征,并进一步采用响应面法对其催化油酸酯化反应的工艺参数进行优化。结果表明:在3种离子液体中[L-Glu]HSO_(4)的催化效率最高;[L-Glu]HSO_(4)催化油酸酯化的最佳反应条件为离子液体用量15%、醇酸摩尔比11∶1、反应温度70℃、反应时间12 h,在此条件下酯化率为97.02%。因此,所合成的[L-Glu]HSO_(4)可以高效催化油酸酯化制备生物柴油。 相似文献
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离子液体催化合成食用香料乙酸辛酯的研究 总被引:2,自引:0,他引:2
乙酸辛酯是一种无色透明液体具有橙花、茉莉花和苹果香气的食用香料。实验利用微波辅助制备了离子液体1-丁基-3-甲基咪唑对甲苯磺酸盐([pmim]PTSA),并用红外光谱对其结构进行了分析表征。将[pmim]PTSA用于催化合成乙酸辛酯的反应中,考察了[pmim]PTSA的催化活性和离子液体用量、醇酸物质的量比、反应时间、离子液体重复使用等因素对酯化率的影响。结果表明:离子液体对该酯化反应有较好的催化活性。乙酸辛酯最佳合成条件为:离子液体用量15mL,n(辛醇):n(乙酸)=1.5:1.0,反应时间2.5h,酯化率达91.5%。反应结束后,产物乙酸辛酯与离子液体分层,倾倒即可分离。分离后的[pmim]PTSA蒸馏除水能重复使用,连续使用6次,催化活性不变。[pmim]PTSA是合成乙酸辛酯的良好催化剂。 相似文献
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离子液体为催化剂.以顺丁烯二酸酐与仲辛醇为原料催化合成渗透剂T。研究了催化剂的用量、酯化、磺化反应时间、酸醇摩尔比对反应的影响。催化剂能使用多次且催化效果较好。 相似文献
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氨基酸离子液体(AAILs)作为一种兼有溶剂和催化剂双重功能的新型功能化离子液体,在催化制备生物柴油的过程中具有较大的应用潜力。在AAILs中,氨基酸可以为阴离子,也可以为阳离子。综述了AAILs的类型、性质与结构的关系以及近年来利用AAILs作为催化剂催化制备生物柴油的研究进展,分析了AAILs催化酯化和酯交换反应制备生物柴油的机理,旨在为AAILs在生物柴油制备过程中的应用提供依据。 相似文献
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探讨了固定化Camdoda antarctica脂肪酶催化胆固醇与油酸合成胆固醇油酸酯,通过脂肪酶催化酯化反应的工艺路线进行研究,系统考察了反应溶剂、醇油比、催化剂用量、反应温度等对酯化反应的影响.结果表明,以环己烷为溶剂,30℃,物质的量比(胆固醇:油酸)为1:1,2%(质量分数)脂肪酶,反应时间48 h,反应的最高酯化率可达到88%以上,产品经HPLC和LC-MS分析的纯度可达98%以上,固定化Candida ant-arctica脂肪酶具有较高的催化的催化稳定性,其半衰期至少达100 d. 相似文献
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Soo EL Salleh AB Basri M Zaliha Raja Abdul Rahman RN Kamaruddin K 《Journal of Bioscience and Bioengineering》2003,95(4):361-367
The feasibility of using palm oil fractions as cheap and abundant sources of raw material for the synthesis of amino acid surfactants was investigated. Of a number of enzymes screened, the best results were obtained with the immobilized enzyme, Lipozyme. The effects of temperature, solvent, incubation period, fatty substrate/amino acid molar ratio, enzyme amount, and water removal on the reactions were analyzed and compared to those on reactions with free fatty acids and pure triglycerides as fatty substrates. All reactions were most efficient when carried out at high temperatures (70-80 degrees C) in hexane as a solvent. However, while reactions with free fatty acids proceeded better when a slight excess of the free fatty acids over the amino acids was used, reactions with triglycerides and palm oil fractions were best performed at equimolar ratios. Also, the addition of molecular sieves slightly enhanced reactions with free fatty acids but adversely affected reactions with triglycerides and palm oil fractions. Although reactions with palm oil fractions took longer (6 d) to reach equilibrium compared to reactions with free fatty acids (4 d) and pure triglycerides (4 d), better yields were obtained. Such lipase-catalyzed transacylation of palm oil fractions with amino acids is potentially useful in the production of mixed medium- to long-chain surfactants for specific applications. 相似文献
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Beckman EJ 《Environmental science & technology》2003,37(23):5289-5296
Conducting oxidation reactions using CO2 as the solvent is a promising strategy for creation of greener chemical processes that are also economical, as CO2 and water are probably the only solvents that can be used in oxidation reactions without the formation of any solvent byproducts. However, it must be noted that the promise of CO2-based oxidation still dwarfs the actual realization of CO2-based oxidation processes. Nevertheless, there is extensive literature on the use of CO2 as the solvent for the oxidation of cyclohexane (adipic acid synthesis), cumene oxidation (phenol synthesis), and epoxidation (propylene oxide synthesis). In all of these studies, knowledge of the phase behavior is crucial toward understanding the effects of pressure and temperature on reaction outcomes. To date, much of the research in this field has involved simply using CO2 as a "drop-in" replacement for a conventional organic solvent; it will be interesting in the future to see if the use of CO2 can be combined with innovations in catalyst and reactor design to create truly green oxidation processes where the use of CO2 is not merely tolerated but truly supports process and chemistry innovation. 相似文献
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Bateman AP Walser ML Desyaterik Y Laskin J Laskin A Nizkorodov SA 《Environmental science & technology》2008,42(19):7341-7346
This study examined the effect of solvent on the analysis of organic aerosol extracts using electrospray ionization mass spectrometry (ESI-MS). Secondary organic aerosol (SOA) produced by ozonation of d-limonene, as well as several organic molecules with functional groups typical for OA constituents, were extracted in methanol, d3-methanol, acetonitrile, and d3-acetonitrile to investigate the extent and relative rates of reactions between analyte and solvent. High resolution ESI-MS showed that reactions of carbonyls with methanol produce significant amounts of hemiacetals and acetals on time scales ranging from several minutes to several days, with the reaction rates increasing in acidified solutions. Carboxylic acid groups were observed to react with methanol resulting in the formation of esters. In contrast acetonitrile extracts showed no evidence of reactions with analyte molecules, suggesting that acetonitrile is the preferred solvent for SOA extraction. The use of solvent-analyte reactivity as a tool for the improved characterization of functional groups in complex organic mixtures was demonstrated. Direct comparison between mass spectra of the same SOA samples extracted in methanol versus acetonitrile was used to estimate the lower limits for the relative fractions of carbonyls (> or = 42%) and carboxylic acids (> or = 55%) in d-limonene SOA. 相似文献
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酶是能够进行复杂化学反应的生物催化剂,具有活性高、选择性好和环境友好等优良特性。然而用于催化反应的酶来源较窄,空间结构相对柔性易失活,以及催化稳定性差等不足,客观上限制了其应用的进一步扩大,强化酶催化性能包括提高酶活性和增加酶催化稳定性是近年生物工程领域的研究热点。不同的糖类物质对酶的活性均有不同程度的保护作用,葡聚糖是一种以葡萄糖为单元通过糖苷键连接而成的同型多糖,在酶催化性能强化的过程中得到了越来越多的关注。近几年来有关葡聚糖在酶催化性能强化中的研究报道相对较多,本文主要综述了葡聚糖作为交联剂、修饰剂和添加剂在酶固定化过程中的研究进展,介绍了葡聚糖在有机溶剂和无溶剂酶催化体系中的应用实例,分析了葡聚糖对酶催化性能的影响,为葡聚糖在酶催化中的进一步应用奠定基础。 相似文献
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对浸出毛油闪点与其残溶量关系的探讨 总被引:1,自引:0,他引:1
在油脂浸出生产中,定期检测浸出毛油的残溶对保证生产效果是十分必要的。采用气相色谱仪可以较准确地检测浸出毛油的残溶量,但由于检测仪器费用较高使之在浸出油厂得不到普遍应用。浸出毛油残溶量与其闪点之间呈负相关性,通过测定浸出毛油闪点可以判断浸出毛油残溶量。通过测定不同浸出毛油油样的闪点,再利用气相色谱仪测定对应浸出毛油油样的残溶,对浸出毛油闪点与其残溶量之间的对应关系进行了初步分析和探讨,提出了浸出生产中毛油闪点指标的控制范围,以利于浸出生产中采用闪点法简便快捷地检测浸出毛油中残溶,正确指导生产。 相似文献