酯交换制油酸甲酯的基团贡献法热力学分析

采用基团贡献法和赵氏经验公式(ΔS? v = A s lgT b + B s )计算了三油酸甘油酯与甲醇之间发生的三步连续可逆酯交换反应的标准摩尔反应焓、标准摩尔熵、标准摩尔反应Gibbs函数和标准平衡常数,并分析了酯交换反应转化率的影响因素。结果表明,酯交换反应是放热反应,低温和高压有利于反应的进行。酯交换反应的转化率在甲醇液相时受温度和压力的影响较小,醇油比增大可以提高反应的转化率,当醇油比为20:1时转化率达到98.8%。酯交换反应的转化率在甲醇气相时,随着压力的增大而增大,随着温度的增大而减小。通过计算结果与实验数据进行比较,表明本文提出的分析方法是可行的。     

三油酸甘油酯的合成研究

详细论述了催化酯化合成三油酸甘油酯的方法，此合成分两步完成，避免了酯化反应的可逆性，高质量的产品符合医药用标准。     

对甲苯磺酸季铵盐离子液体催化酯交换反应制备生物柴油

合成了4种不同阳离子的-SO3H功能化对甲苯磺酸季铵盐离子液体,并用FT-IR和NMR表征结构,结果表明,合成的离子液体符合其理论结构特征。热重分析实验表明离子液体的分解温度都在200℃以上,可以作为合成生物柴油的催化剂;采用吡啶红外探针法测定其酸性大小,实验结果表明其酸性受阳离子烷基侧链影响,烷基侧链越短或越少,酸性越强,但相差不大。以它们为催化剂进行了三油酸甘油酯酯交换反应制备生物柴油的研究,实验表明,这些-SO3H功能化对甲苯磺酸季铵盐离子液体的催化活性都较高,油酸甲酯的产率与离子液体的酸性顺序一致,正-丙基磺酸-三乙基对甲苯磺酸铵的催化活性最高。考察了正-丙基磺酸-三乙基对甲苯磺酸铵离子液体用量、醇油摩尔比、反应时间、反应温度对生物柴油产率的影响规律。实验结果表明,在甲醇、油脂和离子液体的摩尔比为12:1:0.167,反应温度130℃下反应4 h,油酸甲酯的产率可达到92.16%;将反应后离子液体相中的甲醇蒸出,再用乙酸乙酯将其中的甘油萃取出来,剩余的离子液体直接用于下次的酯交换反应,油酸甲酯的产率无明显降低,表明离子液体的稳定性好,回收的离子液体可循环使用。     

油酸甘油酯的制备

介绍了油酸甘油酯的制备及原理,讨论了各种因素对反应效果的影响,提出了最佳的反应条件。     

酯交换法合成三羟甲基丙烷油酸酯的研究

以油酸及甲醇为原料,经过酯化反应先生成油酸甲酯,油酸甲酯进一步与三羟甲基丙烷反应生成三羟甲基丙烷油酸酯。通过实验确定最佳反应条件为:反应温度为160℃,油酸甲酯与三羟甲基丙烷物质的量比为6.5∶1,甲醇钠的用量为总质量的0.5%,反应8h,收率为95.5%。目的产物的结构经红外光谱和核磁氢谱证实。     

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。     

甲醇与碳酸乙烯酯反应体系热力学分析

用基团贡献法计算了碳酸乙烯酯及部分碳酸二甲酯的热力学数据。通过对甲醇和碳酸乙烯酯酯交换反应合成碳酸二甲酯理想状态下气一液反应平衡常数的计算，可以得出：副反应的反应热力学推动力极小，在反应竞争中没有优势；主反应是吸热反应，温度高有利于反应向正方向进行；副反应是放热反应，低温有利于副反应进行。     

微藻超临界甲醇直接酯交换法制备生物柴油

以规模化养殖的小球藻为原料,采用超临界甲醇酯交换法开展了制备生物柴油的实验研究。通过对原料藻粉的主要组成和实验产物的元素、化合物组成及基本理化特性进行分析,考察了不同工艺条件对产率的影响。结果表明,在甲醇与湿藻（50%含水量）配比为8∶1（mL∶g）、反应温度260℃、反应压力8 MPa和停留时间10 min的条件下,微藻生物柴油产率高达9%以上,具有与石化柴油接近的理化性质和成分组成。     

甲醇合成反应热力学分析及实验研究

比较了近年来文献中甲醇合成反应平衡常数的各种计算方法,采用固定反应器在反应温度为230－270℃和反应压力为5－8MPa的条件下对甲醇合成反应热力进行了实验研究。结果表明,不同计算方法的预测结果存在较大的差异,而采用Reid的热容 数据及SRK方程得到的计算结果与实验结果吻合很好,具有良好的预测能力。     

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。     

Ca-Mg-Al类水滑石催化大豆油甲醇酯交换制备生物柴油

采用不同前驱体,用过饱和共沉淀法制备了两种Ca-Mg-Al类水滑石,并考察了其用于催化大豆油甲醇酯交换制备生物柴油的性能。结果表明,由草酸钙为前驱体制备的Ca-Mg-Al类水滑石表现出更高的催化活性,在反应温度65℃、醇油物质的量比12:1、催化剂用量为大豆油质量的4%和反应时间180min的最佳条件下,酯化率可达84.71%。催化剂重复利用3次,仍保持较高活性。     

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     

甲醇乙烯烷基化反应体系热力学分析

考察了甲醇乙烯烷基化反应体系各独立反应吉布斯自由能随温度变化情况,采用吉布斯自由能最小法计算得到不同反应条件下体系平衡组成。结果表明:该反应体系主要受动力学控制;适当升高温度有利于烯烃生成,且乙烯和丁烯的生成是丙烯生成反应的阻碍点;在只生成丙烯的极端情况下,单独考察生成丙烯的反应,为了提高丙烯产率,需要适当降低反应温度,若综合考虑设备和能耗等因素,体系存在最佳反应压力和进料比(乙烯与甲醇摩尔比)。     

响应面法优化羊毛脂甲酯化工艺研究

以羊毛脂为原料,采用甲醇钠、氢氧化钠2种催化剂,考察了反应温度、时间、催化剂用量、醇用量等因素对甲酯化的影响。结果表明:甲醇钠为催化剂时,在反应温度60℃、甲醇与羊毛脂质量比1.6、反应时间60 min、催化剂质量分数4%的条件下,酯转化率达到94.3%。用响应面法优化氢氧化钠为催化剂的羊毛脂甲酯化工艺,得到最佳工艺条件为:反应温度65.3℃、甲醇与羊毛脂质量比1.85、催化剂质量分数6%、反应时间90 min,在此条件下酯转化率可达94.2%。     

Phase behavior of the base-catalyzed transesterification of soybean oil

Biodiesel is made by the transesterification of vegetable oils to form alkyl FA esters. High levels of conversion (>99%) are required to lower the total concentration of free and chemically bound glycerol to that allowed by the ASTM standard (0.240 wt%) for biodiesel. A polar dye was used to visualize the phase behaviors in methanolysis, ethanolysis, and butanolysis. The dye was more strongly colored in more polar phases. Methanolysis and ethanolysis reactions commenced as two phases (alcohol and oil), then formed emulsions, and ended as two phases as glycerol-rich phases separated. Ethanolysis was more easily initiated by mixing than was methanolysis. Ethanolysis also exhibited a much longer emulsion period and slower glycerol separation. The glycerol-rich phase was smaller in volume in ethanolysis than in methanolysis. Butanolysis remained one phase throughout, and no polar phase existed at any time. The results are consistent with the known phase compositions in these reactions. The concentrations of MG, DG, and TG in the products with time in stirred reactions were consistent with the observed phase behavior in the dye experiments.     

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.     

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。     

Phase distributions of alcohol, glycerol, and catalyst in the transesterification of soybean oil

Two-phase base-catalyzed transesterification of vegetable oils is the most common method for making biodiesel. The reaction starts as separate oil and alcohol phases. At the end of the reaction, the mixture, if allowed to settle, consists of an upper ester-rich layer and a lower glycerol-rich layer. The compositions of these layers from the methanolysis and ethanolysis of soybean oil were measured. Synthetic mixtures and actual reaction mixtures were used either to represent or generate steadystate reaction mixtures resulting from the initial condition of 6∶1 alcohol/oil molar ratio and catalyst concentration (1.0 wt% sodium methoxide or 1.26 wt% sodium ethoxide). At 23°C, for methanolysis, 42.0% of the alcohol, 2.3% of the glycerol, and 5.9% of the catalyst were in the ester-rich phase at steady state. In ethanolysis, 75.4% of the ethanol, 19.3% of the glycerol, and 7.5% of the catalyst were in the ester-rich phase. The volume of the glycerol-rich phase decreased from methanolysis to ethanolysis to propanolysis; butanolysis remained monophasic throughout. The results explain some of the general kinetic behavior observed in transesterifications and provide useful information for alcohol recovery and product purification.