棉籽油间歇式酯交换反应动力学的研究

生物柴油(棉籽油甲酯)可以由棉籽油与甲醇在催化剂KOH存在下通过酯交换反应制得。故对棉籽油间歇式酯交换反应动力学进行了研究,并考察了反应温度和催化剂浓度对产物棉籽油甲酯浓度的影响。用液相色谱法分析棉籽油的组成;用气相色谱法分析产物中棉籽油甲酯的含量。由实验数据绘制的动力学曲线得到酯交换反应在开始阶段为准二级反应,以后紧接转为一级反应和零级反应,与文献报导的棕榈油酯交换反应动力学结果一致。由实验数据求出酯交换反应在开始阶段的动力学参数,35℃、45℃时的反应速率常数分别为0.9179Lmol-1min-1和1.049Lmol-1min-1,酯交换反应的活化能为10.88kJmol-1。根据实验结果得到棉籽油酯交换反应的最佳反应温度为45℃,最佳催化剂为1.1%KOH。     

酯交换法制备生物柴油的反应动力学研究进展

掌握制备生物柴油的反应动力学对优化生物柴油的生产工艺、降低成本有重要作用。主要论述了目前国内酯交换反应制取生物柴油的反应动力学研究的现状,分析并总结了各自的特点。     

棕榈油酯交换制备生物柴油的反应动力学

在甲醇与棕榈油的摩尔比为6∶1和催化剂KOH用量为棕榈油质量1.0%的条件下,研究不同温度下棕榈油制备生物柴油的酯交换反应动力学,采用Origin软件拟合曲线方程,建立棕榈油酯交换反应的宏观动力学模型。研究结果表明:棕榈油制备生物柴油的酯交换反应遵循1.40级动力学方程,反应速率随温度的升高而加快,二者符合Arrhenius方程,该反应的活化能为27.23 kJ/mol,频率因子为1.4×103。文中研究建立的反应动力学模型将对扩大试验研究提供理论依据和基础数据支持。     

酯交换反应体系混合物料的介电特性

近几年来,微波在制备生物柴油的化学工艺中被广泛应用。而微波强化化学反应的实验研究和工程应用中存在很多限制因素,物料介电特性是其中一个重要因素。针对甲醇和菜籽油加入自制催化剂的酯交换反应体系,采用矢量网络分析仪测量不同反应条件下甲醇和菜籽油酯交换反应系统的介电系数,考察反应温度、醇油摩尔比、催化剂用量等因素对介电特性的影响规律。结合酯交换反应动力学,讨论反应温度变化对介电特性的影响,从而为微波加热酯交换反应过程的多物理仿真提供物料介电信息。     

固体碱催化酯交换反应制备生物柴油研究进展

介绍了非负载型和负载型2类固体碱催化剂用于制备生物柴油的研究进展,采用酯交换法因其无需消耗大量能量、操作方法简单,成为制备生物柴油的主要方法,并随着负载型固体碱催化剂载体的纳米化、介孔化,纳米级以及以分子筛作为载体的固体碱催化剂将成为一个主要的研究方向。认为开发更加稳定、耐水、耐酸的固体碱催化将是今后固体碱催化剂的研究重点。     

酯交换反应制备生物柴油催化剂的研究进展

生物柴油是一种环境友好型的可再生资源,本文介绍了生物柴油的制备技术,并综述了采用酯交换反应制备生物柴油所使用的催化剂的研究进展,简述了各种催化剂的优缺点。     

催化酯交换制备生物柴油的研究进展

催化酯交换是制备生物柴油的一个重要方法。本文综述了均相催化和非均相催化、酸性催化和碱性催化、固体酸和固体碱催化的研究进展,并针对每类催化剂的特性和应用范围进行比较,得出固体酸和固体碱催化符合绿色生产生物柴油的要求,是未来发展的方向。特别是固体酸在催化含有水分和游离酸的油脂酯交换方面具有独特的优势,需要进一步研究和开发。     

酯交换法制备生物柴油的催化剂研究进展

在酯交换反应制备生物柴油的工艺过程中,可以选用的催化剂有酸/碱均相催化剂、生物酶催化剂和固体催化剂3大类.本文对这几类催化剂在该工艺过程中的应用情况进行介绍,并就各自的成本、活性、稳定性和可回收性等相关因素进行了对比分析,指出利用固体催化剂是该领域的发展方向,对固体催化剂的研究前景做出了展望.     

微波强化酯交换反应制备生物柴油研究进展

在碳达峰、碳中和的目标背景下,生物柴油被认为是替代化石燃料最有前途的新型能源之一。作为新型的加热方式,微波强化技术克服了传统加热方式下受热不均等缺点,在与不同催化体系偶联的过程中显著促进了酯交换反应的效率,较大幅度地提高了生物柴油的产率。本文归纳了微波技术强化酯交换反应制备生物柴油的优势,介绍了微波强化技术偶联均相催化、非均相催化、离子液体催化以及酶催化技术在生物柴油制备领域的研究进展,阐述了微波强化技术偶联各催化体系的利弊。从催化效率和环保等方面考虑,微波强化偶联非均相催化和酶催化具有更优的研究前景。最后,就该领域的研究方向提出几点展望与建议。     

分子筛型固体碱催化剂用于酯交换反应制备生物柴油

采用等体积浸渍法制备了NaOH/NaX固体碱催化剂,用于催化大豆油与甲醇酯交换反应制备甲酯生物柴油。考察了NaOH负载量、焙烧温度、反应时间、反应温度、催化剂用量和醇油摩尔比对转化率的影响。结果表明,在NaOH负载量25%,焙烧温度500℃,反应时间4 h,反应温度65℃,催化剂用量3%和醇油摩尔比12条件下,转化率达95.3%。     

酯化-酯交换两步法制备生物柴油的动力学

以潲水油（WCO）为原料,探讨了酯化-酯交换两步法制备生物柴油的反应动力学。以活性炭负载硫酸铁［Fe₂(SO₄)₃/AC］为负载型催化剂,通过测定不同反应温度、不同甲醇/脂肪酸（FFA）摩尔比条件下WCO中游离脂肪酸的转化率,以此确定酯化反应的动力学控制步骤及动力学方程中的待定参数,从而建立了在实验温度范围内酯化反应的动力学方程,并根据碱催化酯交换反应机理,在简化的动力学模型基础上,推导出了WCO中甘油三酯（TG）与甲醇发生酯交换反应的宏观动力学方程。结果表明,酯化反应和酯交换反应的动力学方程在实验条件范围内都能较好地描述各自的反应过程。     

酯交换法在生物柴油制备中的研究进展

介绍了国内外生物柴油制备方法的研究进展,主要阐述了非均相催化、均相催化、生物催化和超临界催化技术等酯交换法的研究进展。阐明了各种催化法的优缺点,指出了目前酯交换法研究的热点和未来发展的方向。     

Production of mixed methyl/ethyl esters from waste fish oil through transesterification with mixed methanol/ethanol system

Biodiesel (mixed fatty acid methyl/ethyl esters) was prepared from waste fish oil through base-catalyzed transesterification with mixed methanol/ethanol system. Effect of methanol/ethanol (% v/v), type and concentration of the catalyst, mixed alcohols to oil molar ratio, the reaction temperature, and the reaction time on the biodiesel yield was optimized. Maximum biodiesel yield (97.30?wt%) was produced by implementing 1:1 methanol/ethanol (v/v), 1.0?wt% KOH, 6:1 mixed alcohols to oil molar ratio, 40°C reaction temperature, and 30?min of reaction time. Conversion of the waste fish oil to mixed methyl/ethyl esters was confirmed by ¹H NMR spectroscopy. Fuel properties of the resulting biodiesel in addition to its blends with petrodiesel were in good agreement with specifications of ASTM D6751 and ASTM D7467, respectively. Therefore, it was concluded that using mixed alcohol system for biodiesel production could reduce the production cost through reducing conditions required for maximum conversion.     

Synthesis and properties of bisphenol-Z polycarbonate via melt transesterification

Polycarbonate (PC) is a thermoplastic engineering plastic with excellent properties, and its excellent dielectric properties have broad application prospects in the field of electronics. In this paper, bisphenol Z (BPZ) and diphenyl carbonate (DPC) are used as raw materials to synthesize special polycarbonate (BPZ-PC) by melt transesterification. The effects of catalyst type, catalyst dosage, molar ratio of raw materials, transesterification reaction time and vacuum degree, polycondensation reaction temperature and time on the molecular weight of the product are investigated, and the optimal reaction conditions are obtained. The chemical structure of the product is verified by FTIR, ¹H-NMR and ¹³C-NMR spectra tests. The thermal properties, mechanical properties, optical properties and dielectric properties of BPZ-PC are evaluated. Therefore, due to its excellent performance, BPZ-PC, a high-performance low-dielectric polycarbonate, can be widely used in high-frequency communication, microelectronics, and aerospace industries.     

Single‐step ultrasonic synthesis of biodiesel from crude Jatropha curcas oil

A novel single‐step process with chlorosulfonic acid catalyst for ultrasonic biodiesel synthesis using feedstock with high free fatty acid content is investigated.Jatropha curcas oil has been used as the model feedstock with methanol as alcohol. The distinct merit of chlorosulfonic acid is that it catalyzes both esterification and transesterification reactions. Moreover, chlorosulfonic acid also counteracts inhibition caused by water formed during esterification, which is the cause for very slow kinetics of acid catalyzed transesterification. In addition, sonication of the reaction mixture also causes strong micromixing and emulsification that enhances the transesterification kinetics. Statistical optimization of the process shows 93% yield for 8.5 wt % catalyst, 20:1 alcohol to oil molar ratio and temperature of 333 K. Peculiar feature of this process is that high yield is seen at moderate temperature and molar ratio, which are much smaller than that for conventional sulfuric acid catalyzed processes. The activation energy for the process (57 kJ/mol) is at least 3× lower than the energy for sulfuric acid catalyzed transesterification. The thermodynamic analysis reveals that the net Gibbs energy change for the single‐step process is almost same as that for sulfuric acid catalyzed process. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1572–1581, 2014     

Ionic liquids in supercritical methanol greatly enhance transesterification reaction for high‐yield biodiesel production

Biodiesel production is one of the most promising future alternatives to replacing fossil fuels. This work studies the use of ionic liquids (ILs) as potential catalysts in supercritical methanol for biodiesel production from non‐edible oil. The transesterification reaction of karanja oil was investigated in supercritical methanol in the presence of two respective ILs, [BMIM⁺][ ] and [Chol⁺][H₂ ]. The reaction was performed in a one‐step batch process at several temperatures and percentages by weight of catalyst (w/w_oil). The results obtained show that the IL [Chol⁺][H₂ ] allows a high yield of fatty acid methyl esters to be achieved in a short reaction time (above 95% in 45 min). A catalytic mechanism is also proposed for the IL that offered significant catalytic activity. This work investigates the effects of the use of ionic liquids as potential catalysts in supercritical methanol for the transesterification reaction of non‐edible oil. The reported reaction times to obtain biodiesel yields above 90% through the transesterification reaction of karanja oil range between 90 min and 8 h. ILs as catalysts in supercritical methanol drastically reduce reaction time (45 min) to obtain high fatty acid methyl ester yield (95.6%). © 2016 American Institute of Chemical Engineers AIChE J, 62: 3842–3846, 2016     

大豆油与甲醇酯交换反应体系的相平衡研究

生物柴油是一类清洁的可再生液体燃料,精炼植物油与甲醇酯交换是制备生物柴油的重要反应。针对目前难以准确获得酯交换反应体系的多组分相平衡组成等方面存在的问题,研究了间歇反应和连续逆流分离甘油等不同反应方式下大豆油与甲醇酯交换反应体系的多组分相平衡行为,并以三油酸甘油酯与甲醇酯交换为模型反应,采用UNIFAC和Modified UNIFAC模型进行了模拟计算。结果表明,在常压、60^oC反应条件下,在总组成偏离甲醇-甲酯二元组成的区域,UNIFAC和Modified UNIFAC模型准确计算了生物柴油酯交换反应体系的三元和四元相平衡组成。在甘油含量大于2.2%(质量)或转化率小于90%(质量)的酯交换反应中,计算值与实验值的平均偏差约为2%。酯交换反应相平衡的实验值和模型计算值表明,采用连续逆流方式分离甘油可以提高酯相中的甲醇含量,有利于传质和酯交换反应。这些结果为生物柴油工艺过程模拟、设备优化以及新技术开发提供了理论参考。     

Study on the kinetics of transesterification reaction between poly(ethylene terephthalate) and its copolyesters

Polyethylene terephthalate (PET) was blended with two kinds of co[poly(ethylene terephthalate-p-oxybenzoate)] (POB–PET) copolyester, designated as P46 and P64, respectively. The PET and POB–PET copolyester were combined in the ratios of 85/15, 70/30, and 50/50. The blends were melt mixed in a Brabender Plasticorder at 275, 285, and 293°C for different amounts of time. The transesterification reactions during the melt mixing processes of PET with POB–PET copolyester blends were detected by proton nuclear magnetic resonance analysis. The values of the rate constants are a function of temperature and the composition of blends. The transesterification reactions that may occur during the melt mixing processes have been discussed also. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2727–2732, 1999     

CaO/MgO混合催化剂的制备及催化合成生物柴油

采用溶胶-凝胶法制备纳米CaO,采用溶胶-凝胶自蔓延燃烧法制备纳米MgO,并通过TG-DSC、XRD和SEM对制备的CaO和MgO晶体结构、形貌特性及热稳定性等进行表征。采用固体研磨法将纳米CaO和纳米MgO混合制备催化剂,并应用于大豆油与甲醇的酯交换反应中制备生物柴油。结果表明,纳米CaO和纳米MgO按质量比0.7∶0.5混合的催化剂具有良好的催化活性,在催化剂用量为大豆油质量的3%、甲醇与大豆油物质的量比为12∶1和回流状态下反应4h条件下,大豆油酯化率可达88.58%。