原料配比对生物柴油合成反应转化率的影响

用化学平衡原理导出了油脂与甲醇酯交换合成生物柴油反应中标准平衡常数、活度因子商、摩尔分数商之间的关系式。讨论了摩尔分数商不变的理想生物柴油反应和摩尔分数商变化的非理想生物柴油反应中,醇油物质的量比和油脂平衡转化率之间的关系。其共同点:低醇油比时,增加醇油物质的量比,油脂平衡转化率增幅明显;高醇油比时,增加醇油物质的量比,油脂平衡转化率增幅不甚明显。其不同点:醇油物质的量比增大引起油脂平衡转化率增大的幅度,表现为非理想生物柴油反应小于理想生物柴油反应。     

废油脂制取生物柴油的工艺优化及其品质提升

在碱性催化剂作用下,对废油脂制取生物柴油的工艺优化及品质提升方法进行了研究.考察了原料油水分含量、醇油物质的量比、催化剂浓度、反应温度、反应时间等对转酯化反应的影响,以及水洗、酸洗、萃取、减压蒸馏等不同后处理方法对产品品质的影响.在醇油物质的量比为9:1、催化剂质量分数为1.3%、反应温度为50℃及反应时间为90 min的条件下,所得样品通过常压、减压蒸馏相结合的后处理方法,可以获得品质良好的生物柴油样品.     

麻疯树油制备生物柴油的试验研究

试验研究了麻疯树油在季铵碱催化剂(四甲基氢氧化铵)的作用下与甲醇发生转酯化反应生成脂肪酸甲酯(生物柴油)的反应条件.试验结果表明,该转酯化反应的最佳操作条件:四甲基氢氧化铵用量为麻疯树油质量的0.5%、油醇物质的量比为1:6、搅拌时间为30min、反应温度为65℃.     

季铵碱催化剂在合成生物柴油中的应用

对合成生物柴油的几种方法进行了比较,讨论了以季铵碱作催化剂,以大豆油为原料合成生物柴油的工艺条件,并研究了原料油的酸值和含水量对脂肪酸甲酯转化率的影响.试验结果表明,该酯化及转酯化反应的最佳反应条件:催化剂的投入量为油重的0.5%,油醇的物质的量比为1∶6,反应温度为60℃,搅拌时间为30min;原料油的酸值小于2,原料水分质量分数在1%以下.     

响应曲面法优化固体碱催化制备生物柴油的工艺

以固体碱硅酸钠为催化剂进行酯交换反应制备生物柴油,采用响应曲面法中的Box-Behnken模式对影响生物柴油转化率的4个主要因素(温度、催化剂用量、反应时间、醇油物质的量比)进行优化.建立生物柴油转化率的二次多项回归模型方程,并对回归方程系数进行显著性检验和方差分析.试验结果表明:当反应温度为66℃、催化剂用量为大豆油质量的2.1%、反应时间为7h、醇油物质的量比为8.6:1时,生物柴油的转化率最高,最高转化率预测值为75.78%,与实测值基本相符,优化模型有效可靠.     

对甲苯磺酸催化麻疯树油甲酯化的实验研究

实验研究了麻疯树油在对甲苯磺酸催化剂的作用下与甲醇发生转酯化反应生成脂肪酸甲酯(生物柴油)的情况.实验结果表明,该转酯化反应的最佳操作条件为催化剂用量为麻疯树油量的5% 、油醇摩尔比为1∶ 3、反应时间为30 min、反应温度为70℃.     

酸碱树脂两步催化含酸油脂制备生物柴油

设计催化酯化脂肪酸和催化转酯化甘油三酯连续制备生物柴油过程,分别考察NKC-9催化酯化脂肪酸的能力及D261催化转酯化甘油三酯的能力,并利用模型化合物在固定床中依次进行酯化、转酯化,实现连续反应。实验表明:酯化与转酯化反应在理想条件下,转化率均高于95%,应用于连续制备效果较好,且可多次再生并重复利用。     

大豆酸化油制备生物柴油的研究

试验研究了大豆酸化油在复合酸催化剂的作用下与甲醇发生转酯化和酯化反应生成脂肪酸甲酯(生物柴油)的最佳反应条件.试验结果表明,该酯化及转酯化反应的最佳操作条件:复合酸催化剂的用量为大豆油质量的5%、油醇摩尔比为1:6、反应时间为6h、反应温度为65℃.     

菜籽油皂脚制备生物柴油工艺的研究

探讨以菜籽油皂脚为原料经过酸化.两次酯化.转酯化过程获得生物柴油的工艺,研究了如何降低酸化油中游离脂肪酸含量的方法以及转酯化反应的条件.结果表明:两次甲酯化使得酸价降到1.67mgKOH/g样品,效果明显;转酯化反应的最佳条件为:催化剂用量0.5%,甲醇用量25.0%(25mL/100g油脂),反应时间30min,反应温度65℃,转化率达到95.84%.经分子蒸馏后脂肪酸甲酯的含量达到98.0%以上.     

生物柴油的超声波辅助固体碱催化制备研究

以精制的山桐子油为原料,固体碱CaO-ZrO为催化剂,在超声波辅助下制备生物柴油。通过单因素实验探讨催化剂用量、醇油物质的量之比、反应温度、超声功率、超声频率、反应时间等因素对生物柴油得率的影响。在此基础上,选取超声功率、催化剂用量、醇油物质的量之比、反应时间4个因素通过正交试验确定最佳工艺条件,即超声功率500 W,催化剂用量3%,醇油物质的量之比10∶1,反应时间60 min。在最佳工艺条件下,生物柴油得率为98.2%,该催化剂具有较好的重复利用性能。     

固定化脂肪酶在离子液体中催化合成生物柴油

通过硅胶载体涂布法对细菌Burkholderia cepacia GX-35所产的脂肪酶进行固定化。比较了自制固定化脂肪酶在4种离子液体中催化合成生物柴油的效果,其中文章研究新设计并合成的一种离子液体溴代1-乙基-2-甲基咪唑[EMIM]Br对催化反应起促进作用。通过对转酯率的测定,研究了固定化脂肪酶在[EMIM]Br中的最适反应条件:最适反应温度为35℃,[EMIM]Br加入量为花生油质量分数的60%,最佳醇类为乙醇,加水量为花生油质量分数的5%,乙醇与花生油之比为9∶1,固定化脂肪酶加入量为花生油的20%,反应时间为6 h。固定化脂肪酶在[EMIM]Br中稳定性好,使用6次之后转酯率下降不明显。试验结果表明,与不加[EMIM]Br相比,加[EMIM]Br能有效提高生物柴油的转化率。     

Biodiesel from corn germ oil catalytic and non-catalytic supercritical methanol transesterification

Transesterifications of grain of corn oil samples in KOH catalytic and in supercritical methanol were studied without using any catalyst. Biodiesel, an alternative biodegradable diesel fuel, is derived from triglycerides by transesterification with methanol and ethanol. The transesterification reaction is affected by the molar ratio of glycerides to alcohol, catalysts, reaction temperature, reaction time and free fatty acids and water content of oils or fats. It was observed that increasing the reaction temperature, especially to supercritical temperatures, had a favorable influence on methyl ester (biodiesel) conversion. The molar ratio of methanol to corn germ oil is also one of the most important variables affecting the yield of methyl esters. Higher molar ratios result in greater ester production in a shorter time. In the transesterification, free fatty acids and water always produce negative effects, since the presence of free fatty acids and water causes soap formation, consumes catalysts, and reduces catalyst effectiveness, all of which result in a low conversion.     

Optimisation of base-catalysed transesterification of Simarouba glauca oil for biodiesel production

Biodiesel was prepared from the crude oil of Simarouba glauca by transesterification with methanol in the presence of KOH as a catalyst. The reaction parameters such as catalyst concentration, alcohol to oil molar ratio, temperature and rate of mixing were optimised for the production of Simarouba oil methyl ester. The yield of methyl esters from Simarouba oil under the optimal condition was 94–95%. Important fuel properties of methyl esters of Simarouba oil (biodiesel) was compared with ASTM and DIN EN 14214. The viscosity was found to be 4.68 Cst at 40°C and the flashpoint was 165°C.     

Calcium-based mixed oxide catalysts for methanolysis of Jatropha curcas oil to biodiesel

Calcium-based mixed oxides catalysts (CaMgO and CaZnO) have been investigated for the transesterification of Jatropha curcas oil (JCO) with methanol, in order to evaluate their potential as heterogeneous catalysts for biodiesel production. Both CaMgO and CaZnO catalysts were prepared by coprecipitation method of the corresponding mixed metal nitrate solution in the presence of a soluble carbonate salt at ∼ pH 8-9. The catalysts were characterized by X-ray diffraction (XRD), temperature programmed desorption of CO₂ (CO₂-TPD), scanning electron microscopy (SEM) and N₂ adsorption (BET). The conversion of JCO by CaMgO and CaZnO were studied and compared with calcium oxide (CaO), magnesium oxide (MgO) and zinc oxide (ZnO) catalysts. Both CaMgO and CaZnO catalysts showed high activity as CaO and were easily separated from the product. CaMgO was found more active than CaZnO in the transesterification of JCO with methanol. Under the suitable transesterification conditions at 338 K (catalyst amount = 4 wt. %, methanol/oil molar ratio = 15, reaction time = 6 h), the JCO conversion of more than 80% can be achieved over CaMgO and CaZnO catalysts. Even though CaO gave the highest activity, the conversion of JCO decreased significantly after reused for forth run whereas the conversion was only slightly lowered for CaMgO and CaZnO after sixth run.     

Lipase immobilization and production of fatty acid methyl esters from canola oil using immobilized lipase

Lipase enzyme from Aspergillus oryzae (EC 3.1.1.3) was immobilized onto a micro porous polymeric matrix which contains aldehyde functional groups and methyl esters of long chain fatty acids (biodiesel) were synthesized by transesterification of crude canola oil using immobilized lipase. Micro porous polymeric matrix was synthesized from styrene-divinylbenzene (STY-DVB) copolymers by using high internal phase emulsion technique and two different lipases, Lipozyme TL-100L^® and Novozym 388^®, were used for immobilization by both physical adsorption and covalent attachment. Biodiesel production was carried out with semi-continuous operation. Methanol was added into the reactor by three successive additions of 1:4 M equivalent of methanol to avoid enzyme inhibition. The transesterification reaction conditions were as follows: oil/alcohol molar ratio 1:4; temperature 40 °C and total reaction time 6 h. Lipozyme TL-100L^® lipase provided the highest yield of fatty acid methyl esters as 92%. Operational stability was determined with immobilized lipase and it indicated that a small enzyme deactivation occurred after used repeatedly for 10 consecutive batches with each of 24 h. Since the process is yet effective and enzyme does not leak out from the polymer, the method can be proposed for industrial applications.     

Preparation of Polymeric Pour Point Depressants for Shale Oil

The melt esterification of acrylic acid and higher alcohols without solvent is carried out and the effects of factors on the production efficiency of acrylic higher alcohol ester are investigated. Optimum reaction conditions are obtained at molar ratio of acrylic acid to higher alcohol 1.2:1.0 and reflux time 7 h at 110–140°C in stepwise heating. At this point the acrylic higher alcohol ester will be polymerized with maleic anhydride, phenylethylene, and vinyl acetate, and formed into four components. Copolymer shale oil pour point depressant and the polymerization condition are also studied by orthogonal method. The effect of pour point depressants is best when the monomer molar ratio is 8:1:1:1 at 80°C for 8 h for reflux and the benzoyl peroxide is added. The pour point of Fushun shale oil reduces by 9°C when only 0.5% copolymer is added.     

Enzymatic transesterification of soybean oil by using immobilized lipase on magnetic nano-particles

Lipase was covalently immobilized onto magnetic Fe₃O₄ nano-particles by using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) as an activating agent, and the bound lipase was used to catalyze the transesterification of vegetable oils with methanol to produce fatty acid methyl esters. The binding of lipase to magnetic particles was confirmed by enzyme assays, transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) spectra. It was determined that the immobilized lipase exhibited better resistance to temperature and pH inactivation in comparison to free lipase. Using the immobilized lipase, the major parameters affecting the transesterification reaction, such as the alcohol/oil molar ratio, enzyme loading and free fatty acid present in reactants were investigated to obtain the optimum reaction condition. The conversion of soybean oil to methyl esters reached over 90% in the three-step transesterification when 40% immobilized lipase was used. Moreover, the lipase catalyst could be used for 3 times without significant decrease of the activity.     

Esterification of fatty acids using acid-activated Brazilian smectite natural clay as a catalyst

This work reports the use of an acid-activated Brazilian smectite natural clay-based catalyst in the esterification of fatty acids at atmospheric pressure and without a co-solvent. Conversion levels of 99%, 98%, 93% and 80% were reached for caprylic, lauric, stearic and oleic methyl esters, respectively, using 1:3 fatty acid/methanol molar ratio, heating bath at 100 °C after 4 h. A conversion level of 89% was achieved for methyl esters from a fatty acid residue of the palm oil refining industry in the same reaction condition. The acid-activated clay provided better performance than the commercial catalyst K-10. The effects of catalyst amount, temperature, fatty acid/alcohol molar ratio and time were investigated. The heating activation of the catalyst immediately before the catalytic test increased the conversion from 94% to 99% using 1:1.5 stearic acid/methanol molar ratio, heating bath at 100 °C after 4 h. The catalyst was reused five times. The conversion decreases less than 5% in the first three reuses. The smectite natural clay and the catalyst were characterized by X-ray fluorescence, X-ray diffraction, n-butylamine thermodesorption, nitrogen adsorption analysis, thermogravimetric analysis and differential thermal analysis.     

Effect of reaction parameters on the catalytic transesterification of cottonseed oil using silica sulfuric acid

Transesterification of refined cottonseed oil was studied in the presence of silica sulfuric acid as a new heterogeneous solid acid catalyst to overcome the drawbacks of homogeneous alkali and acid catalysts. The effect of various reaction parameters, such as oil to methanol ratio, reaction temperature, reaction time, and catalyst amount, was investigated. The highest methyl ester conversion was obtained at 373 K using 5% catalyst amount and 1:20 methanol ratio within 8 h. Silica sulfuric acid was found to be a promising catalyst for cleaner biodiesel production without tedious post treatments for the product purification.