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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。 相似文献
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Biodiesel from an alkaline transesterification reaction of soybean oil using ultrasonic mixing 总被引:6,自引:1,他引:6
The feasibility of using ultrasonic mixing to obtain biodiesel from soybean oil was established. The alkaline transesterification
reaction was studied at three levels of temperature and four alcohol-to-oil ratios. Excellent yields were obtained for all
conditions. For example, at 40°C with ultrasonic agitation and a molar ratio of 6∶1 methanol/oil, the conversion to FAME was
greater than 99.4% after about 15 min. For a 6∶1 methanol/oil ratio and a 25 to 60°C temperature range, a pseudo second-order
kinetic model was confirmed for the hydrolysis of DG and TG. Reaction rate constants were three to five times higher than
those reported in the literature for, mechanical agitation. We suspect that the observed mass transfer and kinetic rate enhancements
were due to the increase in interfacial area and activity of the microscopic and macroscopic bubbles formed when ultrasonic
waves of 20 kHz were applied to a two-phase reaction system. 相似文献
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超声波辅助制备生物柴油的新方法研究 总被引:12,自引:0,他引:12
以大豆油和甲醇为原料制备生物柴油,酯交换反应在超声波条件下以碱作为催化剂进行,讨论了超声波对反应的影响.研究结果表明,与机械搅拌增强反应比较,低频超声波可以大大强化酯交换反应过程,缩短反应时间. 相似文献
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Ultrasonic Pretreatment Transesterification for Solid Basic-Catalyzed Synthesis of Fatty Acid Methyl Esters 下载免费PDF全文
Pingmei Guo Suhuan Ma Fenghong Huang 《Journal of the American Oil Chemists' Society》2017,94(5):733-740
Generally, ultrasound irradiation is required throughout the reaction for fatty acid methyl esters (FAME, namely, biodiesel) production, which is energy-consuming and difficult to scale-up. In order to improve the industrial application of ultrasonic technology, a systematic study of ultrasonic pretreatment solid basic (Na2SiO3)-catalyzed transesterification for FAME production from cottonseed oil was carried out, and the effect of ultrasonic waves on the properties of Na2SiO3 catalyst was assessed by X-ray diffraction (XRD), Fourier transform Infrared (FTIR) and scanning electron microscopy (SEM) characterization of fresh and collected catalysts. An ultrasonic frequency of 30 kHz, ultrasonic power of 200 W and ultrasonic pretreatment irradiation time of 30 min was determined to guarantee a satisfactory degree of transesterification. The optimum production was achieved in the reaction system at 45 °C with methanol/cottonseed oil molar ratio 5:1, catalyst dosage 3% and stirring speed 350 rpm resulting in a FAME yield of above 97% after 60 min of reaction under mechanical stirring with the ultrasonic pretreatment process. The new process has a shorter reaction time, a more moderate reaction temperature, a less amount of methanol and catalyst than only the mechanical stirring process without essential damage to activity and the structure of catalyst. These results are of great significance for applying the ultrasonic pretreatment method to produce FAME. 相似文献
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以NaOH、正硅酸乙酯和乙醇为原料,经溶胶-凝胶法制备新型固体碱催化剂(Na/SiO2),用于催化大豆油与甲醇的酯交换反应制备生物柴油,研究催化剂焙烧温度、n(NaOH)∶n(SiO2)、n(甲醇)∶n(大豆油)、催化剂用量和反应时间对产率的影响以及催化剂的稳定性。结果表明,固体碱催化剂Na/SiO2在大豆油与甲醇的酯交换反应中具有较高的催化活性,在催化剂焙烧温度600 ℃、n(NaOH)∶n(SiO2)=2∶1、n(甲醇)∶n(大豆油)=15∶1、催化剂用量为大豆油质量的7%和反应时间3 h的条件下,脂肪酸甲酯产率可达97.42%,催化剂在稳定性试验中呈现出优良的稳定性。 相似文献
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Ultrasonic mixing and closed microwave irradiation-assisted transesterification of soybean oil 总被引:1,自引:0,他引:1
The present study employed ultrasonic mixing and closed microwave irradiation to assist transesterification of soybean oil. The purpose was to obtain the optimal ultrasonic mixing and closed microwave irradiation procedure. The optimal reaction conditions including amount of catalyst used, reaction temperature and methanol/oil molar ratio were also investigated to achieve the highest possible conversion rate of biodiesel. Results showed that the optimal procedure involved 1-min ultrasonic mixing and 2-min closed microwave irradiation. The optimal reaction conditions that can reach 97.7% of conversion rate were amount of catalyst used, 1.0 wt%; reaction temperature, 333 K; and methanol/oil molar ratio, 6:1. 相似文献
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《Catalysis communications》2007,8(7):1107-1111
In this study, transesterification of soybean oil to biodiesel using SrO as a solid base catalyst was studied. The reaction mechanism was proposed and the separate effects of reaction temperature, molar ratio of methanol to oil, mass ratio of catalyst to oil and repeated experiments were investigated. The results showed that the yield of biodiesel produced with SrO as a catalyst was in excess of 95% at temperatures below 70 °C within 30 min. SrO had a long catalyst lifetime and could maintain sustained activity even after being repeatedly used for 10 cycles. The results proved that transesterification of soybean oil to biodiesel using SrO as a catalyst is a commercially viable way to decrease the costs of biodiesel production. 相似文献
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Optimization of the production of biodiesel from soybean oil by ultrasound assisted methanolysis 总被引:1,自引:0,他引:1
This paper evaluates and optimizes the production of biodiesel from soybean oil and methanol using sodium hydroxide as catalyst. The study and optimization was carried out at low catalyst concentration (0.2 to 0.6 w/w). The reaction was carried out with application of low-frequency high-intensity ultrasound under atmospheric pressure and ambient temperature in a batch reactor. Response surface methodology (RSM) was used to evaluate the influence of methanol to oil ratio and catalyst concentration on soybean oil conversion into biodiesel. Analysis of the operating conditions by RSM showed that the most important operating condition affecting the reaction was the methanol to oil ratio, while catalyst amount showed little significance in the transesterification reaction. Total consumption of oil was obtained when alcohol to oil ratio of 9:1 and catalyst concentration of 0.2 w/w were applied. 相似文献
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以介孔分子筛SBA-15为载体,通过浸渍法制备固体碱催化剂K2O-SBA-15、CaO-SBA-15和K2O/CaO-SBA-15,并对其进行XRD表征。将制备的催化剂用于催化大豆油和无水甲醇制备生物柴油。按四因素三水平的正交实验设计方案进行实验,表明各因素影响程度依次为:反应时间反应温度油醇物质的量比催化剂用量。最佳反应条件:在温度为60℃时加入n(原料油)∶n(甲醇)=12∶1的反应物,加入m(催化剂)∶m(原料油)=3%的催化剂,反应3h,产率达86.97%。 相似文献
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Calcium methoxide as a solid base catalyst for the transesterification of soybean oil to biodiesel with methanol 总被引:1,自引:0,他引:1
In this study, physical and chemical characterizations of calcium methoxide were investigated to assess its performance as an excellent solid base catalyst using some instrumental methods, such as BET surface area measurement, scanning electron micrographs and particle size distribution. Then, it was used to catalyze transesterification of soybean oil to biodiesel with methanol. The effects of various factors such as mass ratio of catalyst to oil, reaction temperature and volume ratio of methanol to oil were studied to optimize the reaction conditions. The results showed that calcium methoxide has strong basicity and high catalytic activity as a heterogeneous solid base catalyst and it was obtained a 98% biodiesel yield within 2 h in this reaction. Besides, the recycling experiment results showed it had a long catalyst lifetime and could maintain activity even after being reused for 20 cycles. 相似文献
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Effect of Ultrasonication on Droplet Size in Biodiesel Mixtures 总被引:1,自引:0,他引:1
Peng Wu Ying Yang José A. Colucci Eric A. Grulke 《Journal of the American Oil Chemists' Society》2007,84(9):877-884
Biodiesel fuels have become more attractive recently because of their environmental benefits and cost competitiveness compared
to diesel fuel. Many processing improvements have been proposed to increase the conversion rates and the yields of vegetable
oil in order to lower production costs and improve biodiesel product quality. In conventional biodiesel production chemistries,
alkaline transesterifications of alcohol/oil dispersions should occur primarily near the interface. Ultrasonic mixing has
already been shown to increase overall conversion rates for alcohol/vegetable oil mixtures. Our data show that ultrasonic
mixing produced smaller droplet sizes than conventional agitation, leading to more interfacial area for the reaction to occur.
Droplet size distributions have been measured for conventional impeller and ultrasonic mixing systems using methanol/soybean
oil as a model system. The dispersions were stabilized by surfactant in order to obtain droplet size distribution for mixture
samples. Ultrasonic mixing produced dispersions with average droplet sizes 42% smaller than those generated using standard
impellers. 相似文献