共查询到19条相似文献,搜索用时 312 毫秒
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以氢氧化钠水溶液为水相,采用液-液相转移催化方法,通过Wittig-Horner反应合成二苯乙烯。考察了催化剂种类、催化剂用量、水相碱液质量分数、反应温度、有机相溶剂种类对转化率的影响,并比较不同种类的醛在液液相转移催化体系中的反应性。结果表明,以四辛基溴化铵为相转移催化剂、n(相转移催化剂)∶n(磷酸酯)=1∶10、水相碱液质量分数为50%、反应温度45℃、甲苯为有机相溶剂,二苯乙烯的收率可达94%;不同种类的醛为原料时,相转催化Wittig-Horner反应均有较高的收率并且产物结构以E式为主。 相似文献
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醇类选择性氧化制备相应羰基(醛或酮)化合物是有机合成中的重要反应。综述醇类选择性催化氧化的研究现状,主要有液均相氧化、液多相氧化和水/有机两相催化氧化,对所用催化剂发展状况和反应机理分别进行阐述。均相催化氧化催化剂难于从反应体系分离,造成成本过高,而且污染环境。大部分多相催化剂来自均相催化剂的负载,活性中心分布不均匀,结构不明确,存在活性组分易从载体上脱落和流失的现象,导致催化剂活性下降。以水作溶剂,不仅清洁无污染,且产物和催化剂容易分离,催化剂可以循环使用,从经济和环保角度值得大力推广,但该体系价格昂贵,反应条件不够温和,还需进一步改进。因此,多相催化氧化和水/有机两相催化氧化相对于均相催化剂有更广阔的发展和应用空间,是今后的研究方向。 相似文献
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烯烃氢甲酰化反应催化剂的研究进展 总被引:2,自引:0,他引:2
综述了烯烃氢甲酰化反应的催化剂体系 ,通过对发展较成熟的烯烃氢甲酰化均相催化体系缺点的分析 ,引入近 2 0年来发展起来的水溶性膦配体和过渡性金属配位生成的水 /有机两相催化体系 ,对其催化机理、优点和最新发展动态进行了评述 ;最后重点介绍了负载水相催化体系的组成、优点、水溶性配体和已报道的此类催化剂。 相似文献
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本文研究了相转移催化条件下的1,2,4-三唑烷茯化反应。评价了几种相转移催化剂,结果表明PEG是适合的固-液相转移催化剂,并对实验结果进行了讨论。 相似文献
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综述了多相操作均相催化技术的研究进展,分成水相-有机相、有机相-有机相、全氟相溶剂对、超临界流体相、非水离子液体溶剂相和可溶态聚合物相等组成的两相操作均相催化体系。重点评述了水相/有机相两相体系。水相-有机相两相体系率先使得多相操作均相催化技术获得突破,并且取得工业化应用成就,也是目前最受工业界和学术界关注的领域。 相似文献
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用1:12钨磷杂多酸(PW12)和硅酸钠通过凝胶法制备了固载杂多酸催化剂PW12/SiO2并以其为固相催化剂,用对苯二甲酸(TPA)和2-乙基己醇(2-EH)复相催化酯化合成了增塑剂-对苯二甲酸二辛酯(DOTP),该方法具有催化活性和选择性高,合成工艺简单,催化剂容易回收率重复使用以及无废酸液排放等优点。 相似文献
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逆向相转移催化(IPTC) 总被引:1,自引:0,他引:1
相转移催化宜加速各种介面间的反应,包括小分子反应、聚合物合成和聚合物修饰等。迄今所用的相转移催化剂都是将水溶性或固体的反应物转入有机相。Mathias等提出了一新型的反应,它是将溶于有机相的反应物转入水 相似文献
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通过1-n-丁基-3-甲基咪唑六氟磷酸盐离子液体([BMIM][PF6])/环己烷构建了液/液两相体系。研究了两相体系内反应温度、Al/Cr摩尔比、离子液体浓度等因素对异丙基双膦胺配体(PNP)/Cr(Ⅲ)/甲基铝氧烷(MAO)催化乙烯齐聚性能的影响。研究结果表明:与均相催化体系相比,两相体系内PNP/Cr(Ⅲ)/MAO催化乙烯由四聚变为三聚, 的选择性最高达到97.40%。齐聚产物存在于有机溶剂相,催化剂溶解在离子液体相,便于产物与催化剂的分离及催化剂的循环使用。 相似文献
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综述了近年来离子液体/有机两相均相催化的研究进展,重点介绍了基于氟硼酸根(BF4-)或氟磷酸根(PF6-)的咪唑类离子液体在均相催化加氢、氢甲酰化、齐聚、Heck反应中的应用,并对离子液体/有机两相催化工业应用的前景进行了探讨。 相似文献
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Liquid–liquid–liquid phase transfer catalysis (L–L–L PTC) offers orders of magnitude intensification of rates of reaction and better selectivities than the biphasic PTC. The catalyst-rich middle phase is the main reaction phase. The etherification or alkoxylation of p-chloronitrobenzene (PCNB) was conducted by using alkanol and alkali instead of the metal alkoxide. A kinetic model is presented and validated. 相似文献
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Wet oxidation of phenol by hydrogen peroxide using heterogeneous catalysis Fe-ZSM-5: a promising catalyst 总被引:8,自引:0,他引:8
This letter presents an original approach to the treatment of phenolic aqueous wastes using H2O2 with heterogeneous catalysts. The experimental results indicate that the system using Fe-ZSM-5 zeolite with MFI structure is promising since it allows total elimination of phenol and significant total organic carbon (TOC) removal under mild working conditions. Moreover, Fe-ZSM-5 remains active after after successive runs. Compared with processes using homogeneous catalysis, the possibility of induced pollution caused by the metal ions in the solution is avoided. 相似文献
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非均相催化法生产生物柴油的研究进展 总被引:1,自引:0,他引:1
综述了国内外非均相催化法生产生物柴油的现状,介绍了非均相固体酸催化剂、固体碱催化剂和固定化生物酶的最新研究进展,展望了未来生物柴油生产技术的发展趋势。 相似文献
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Metal nanoparticles in ionic liquid‐cosolvent biphasic systems as active catalysts for acetylene hydrochlorination 下载免费PDF全文
Lifeng Yang Qiwei Yang Jingyi Hu Zongbi Bao Baogen Su Zhiguo Zhang Qilong Ren Huabin Xing 《American Institute of Chemical Engineers》2018,64(7):2536-2544
Ionic liquid (IL)‐stabilized metal nanoparticles (NPs) have attracted increased attention as novel catalysts for various reactions due to their excellent stability and high activity. However, the high viscosity of ILs limits their applications. Here, for the first time, we reported an NPs@IL‐cosolvent liquid–liquid biphasic system for metal NPs catalysis. The NPs were successfully confined to IL phase, and abundant IL droplets containing NPs were generated under the reactant flow. The NPs@IL droplets served as microreactors for the catalysis; while the low viscosity organic phase enabled the rapid mass transfer of substances. The biphasic system exhibited improved performance for acetylene hydrochlorination than that of the pure IL system. An acetylene conversion of 98% and a selectivity of 99.5% were achieved along with a 90% decrease on IL usage. The tolerable gas hourly space velocity in the biphasic system for a satisfactory conversion was almost double that of the pure IL system. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2536–2544, 2018 相似文献
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《分离科学与技术》2012,47(1-3):765-780
Abstract Aqueous biphase systems are heterogeneous liquid/liquid systems that result from appropriate combinations of inorganic salts and water-soluble polymers such as polyethylene glycol. Colloid-size particles that are suspended in an aqueous biphase system will partition to one of the phases, depending on a complex balancing of particle interactions with the surrounding solvent. With regard to waste treatment applications, aqueous biphase systems are similar to conventional solvent extraction but do not utilize an organic diluent, which may itself become a source of pollution. In addition, the water-soluble polymers that have been used in biphase formation are inexpensive, nontoxic, and biodegradable. The application of aqueous biphasic extraction to the beneficiation of plutonium residues will be discussed. 相似文献