CaO/KIT-6固体碱催化剂的制备及其在酯交换反应中的催化性能

采用浸渍法将活性氧化钙颗粒负载在介孔二氧化硅(KIT-6)表面,制备了酯交换反应催化剂CaO/KIT-6,并研究了其在大豆油与甲醇酯交换制备生物柴油反应中的催化性能。通过X射线衍射(XRD)、X射线光电子能谱(XPS)、CO_2程序升温脱附(CO_2-TPD)等测试手段对催化剂进行表征。在酯交换反应中,当醇油物质的量比为12、反应温度为65°C、催化剂用量为8%、Ca/Si原子比为0.4、反应时间为2 h时,生物柴油转化率达到99.9%,CaO/KIT-6重复使用五次后催化活性仍保持在90%以上。与CaO及其他负载型催化剂相比,CaO/KIT-6催化剂在较低醇油物质的量之比、较短反应时间展现出更高的催化性能和良好的重复使用性。     

固体碱KF/Sm2O3催化菜籽油制备生物柴油

以菜籽油为原料,研究了负载型固体碱催化剂KF/Sm2O3在酯交换制备生物柴油过程中的催化活性.用气相色谱法对酯交换产物进行分析,并用CO2-TPD,XRD,Ramaa等技术对催化剂进行了表征.当催化剂焙烧温度为873 K,KF负载量为15%,甲醇跟菜籽油的计量比为12:1,催化剂用量为菜籽油质量的3%,反应温度为338 K,反应时间为1 h时,生物柴油产率达到95.1%.     

多频超声反应槽连续强化酸化油酯交换制备生物柴油研究

以平均酸值高达33.07 mgKOH/g不可食用的廉价酸化油为原料,利用自行设计的多频超声溢流槽连续强化酯交换反应生物柴油生产装置,先后经预酯化、酯交换两步反应,高效、低耗的制备生物柴油。主要考察了室温下物料流量(停留时间)、超声功率、超声频率及组合、KOH用量、醇油物质的量比对酯交换反应的影响及单位产品能耗。结果表明,多频组合超声辐射比单频更有利于生物柴油的制备;预酯化后的油料在流量为25 L/h(物料停留时间为54 min),催化剂(KOH)用量为1.2%(质量分数),醇油物质的量比为6∶1和各反应槽功率为200 W的条件下,甲酯产率达96.83%。50 L废弃酸化油能制得符合国标GB19147—2009的生物柴油48L,整个生物柴油制备过程总耗时和总耗电量仅为8.667 h、5.42 kWh。     

CaO-MgO@CoFe_2O_4磁性固体碱的制备及其大豆油酯交换反应催化性能

以草酸盐为前驱体采用两步法制备了一种以CaO-MgO作为活性组分,以CoFe_2O_4作为磁核的磁性固体碱催化剂,并用于大豆油与甲醇的酯交换反应合成生物柴油。对制备的磁性固体碱催化剂进行了磁滞回线、X-射线衍射(XRD)、CO_2-TPD及透射电镜(TEM)表征。考察了不同核壳物质的量比、焙烧温度、反应温度、反应时间、醇油物质的量比以及催化剂用量等因素对大豆油转化为生物柴油产率的影响。结果表明,采用核壳物质的量比为1∶6、焙烧温度为700℃所制备的CaO-MgO@CoFe_2O_4催化剂,当醇油物质的量比为12、催化剂用量为大豆油质量的1.0%时,在65℃下反应时间3 h,生物柴油收率高达97.1%。该催化剂具有较好的重复利用性能,重复利用四次后生物柴油的收率仍可达90%。     

双核碱性离子液体催化棉籽油酯交换制备生物柴油

采用两步法制备了五种新型咪唑类碱性双核功能化离子液体化合物,并考察了对棉籽油酯交换制备生物柴油的催化性能。结果表明,咪唑类碱性双核功能化离子液体具有很好的催化活性,其催化活性与阳离子中碳链长度有关。其中,双-(3-甲基-1-咪唑)亚乙基双氢氧化物离子液体的催化活性最好。催化剂量、反应时间、反应温度及醇油比对生物柴油中脂肪酸甲酯含量及选择性影响的研究发现,在催化剂用量为0.4%(质量分数),醇油摩尔比为12,反应温度为55℃,反应时间为4 h时,脂肪酸甲酯的含量和选择性分别达98.5%和99.9%。催化剂7次循环后,产物中脂肪酸甲酯含量仍达到96.2%,单甘酯和双甘酯的含量很少,表明该催化剂重复使用良好。     

固体碱催化剂K_2CO_3/Al_2O_3的制备及其催化餐饮废油制生物柴油的性能

采用浸渍法制备了K2CO3/Al2O3固体碱催化剂,考察了活性组分负载量、焙烧温度、焙烧时间等制备条件对催化剂在催化餐饮废油合成生物柴油的酯交换反应中催化活性的影响,并对其进行了FT-IR、XRD、TG-DTG、SEM和BET表征分析。实验结果表明,所制备的催化剂在催化餐饮废油合成生物柴油的酯交换反应中表现出良好的活性,在活性组分K2CO3负载量为50%、焙烧温度500℃、焙烧时间3 h的条件下制备的催化剂催化酯交换反应时,生物柴油产率可达86.70%。催化剂表征结果显示,K2CO3/Al2O3催化活性是因K2CO3与Al2O3经高温焙烧产生新的晶相有关。催化剂重复使用4次,生物柴油产率仍在75%以上。制得的生物柴油产品质量达到国家生物柴油B100标准。     

酯交换制生物柴油的CaO固体碱催化剂

用不同的前驱物合成了三种CaO催化剂, 并以X射线衍射(XRD)、扫描电子显微镜(SEM) 、程序升温脱附(TPD)等方法加以表征. 这些CaO被用作大豆油(SBO)经酯交换制取脂肪酸甲酯(FAME), 即生物柴油的催化剂, 由方解石制备的氧化钙(Cal(N))表现了最好的SBO酯交换活性. 检测发现CaO的酯交换活性与它们的碱性强度密切相关, 当暴露于CO2气氛下, 显著降低了CaO的酯交换催化活性(Raman光谱测试显示当置CaO于常温空气中, 其表面形成的CaCO3和Ca(OH)2将阻止CaO继续参与SBO的酯交换反应). CO2的毒化颇受制于CaO前驱体种类, Cal(N)比来自文石的CaO(即Ara(N))有更好的抗CO2毒化能力; 这些受损的CaO催化活性可部分复原. 提出了CaO催化剂受CO2毒化及其再生的机理, 同时讨论了SBO酯交换活性相到底是CaO固体表面, 拟或溶解了的CaO的问题.     

新型碱性离子液体催化酯交换合成生物柴油

两步法合成了吗啉阴离子型碱性离子液体1-丁基-3-甲基吗啉盐Im,经 ¹H-NMR和FT-IR分析确认了离子液体中间体的结构,并通过阴离子交换得到碱性离子液体,对该离子液体在酯交换制备生物柴油反应中的催化性能进行了研究。结果表明,该碱性离子液体Im具有较高的酯交换催化活性,在60 ℃、催化剂用量为3%、醇油物质的量比为6.5：1.0、反应2 h的条件下,产物脂肪酸甲酯（FAME）含量可达95.80%。而且该离子液体的催化稳定性较好,重复使用5次后仍有较高的催化活性。     

原位共沉淀法制备NiMg(Al)O/γ-Al2O3催化剂及其酯交换性能

以γ-Al₂O₃为载体通过原位共沉淀法制备NiMgAl-LDHs/γ-Al₂O₃,经焙烧后得到NiMg（Al）O/γ-Al₂O₃催化剂,通过TG-DTG、XRD、SEM、BET、FT-IR、CO₂-TPD等手段对催化剂进行了表征,并对其在酯交换制备生物柴油反应中的催化性能进行了研究。结果表明,NiMgAl-LDHs和NiMg（Al）O成功在γ-Al₂O₃内孔表面生长,并有良好的结合度。催化剂对酯交换具有很高的催化活性;在醇油物质的量比为12：1的条件下反应3 h,生物柴油产率为95%,重复使用七次后,生物柴油产率仍然在82%以上。     

新型碱性离子液体催化酯交换合成生物柴油

两步法合成了吗啉阴离子型碱性离子液体1-丁基-3-甲基吗啉盐[Hnmm]Im,经1 H-NMR和FT-IR分析确认了离子液体中间体的结构,并通过阴离子交换得到碱性离子液体,对该离子液体在酯交换制备生物柴油反应中的催化性能进行了研究。结果表明,该碱性离子液体[Hnmm]Im具有较高的酯交换催化活性,在60℃、催化剂用量为3%、醇油物质的量比为6.5∶1.0、反应2 h的条件下,产物脂肪酸甲酯(FAME)含量可达95.80%。而且该离子液体的催化稳定性较好,重复使用5次后仍有较高的催化活性。     

CaO@SiO_2纳米固体碱的制备、表征及其大豆油酯交换反应催化性能

采用溶胶-凝胶法合成Ca O@Si O_2固体碱催化剂,以聚苯乙烯有机聚合物为硬模板剂和以P123为软模板剂对Ca O的微观形貌进行调控。并将其应用于大豆油与甲醇的酯交换制备生物柴油的反应体系中。通过对Ca O@Si O_2纳米固体碱催化剂进行X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电镜(TEM)、CO_2-TPD及N_2的吸附-脱附(BET)表征发现,不仅制备得到了形貌归整的纳米固体颗粒,而且得到了Ca O包裹在Si O_2表面的核壳结构。进一步考察了不同的硅钙质量比、反应温度、催化剂的用量以及油醇物质的量比对生物柴油收率的影响,生物柴油的收率最高可以达到95.6%。     

HPLC method for rapidly following biodiesel fuel transesterification reaction progress using a core-shell column

There are a wide and growing variety of feedstocks for biodiesel fuel. Most commonly, these feedstocks contain triglycerides which are transesterified into the fatty acid alkyl esters (FAAEs) which comprise biodiesel fuel. While the tranesterification reaction itself is simple, monitoring the reaction progress and reaction products is not. Gas chromatography-mass spectrometry is useful for assessing the FAAE products, but does not directly address either the tri-, di-, or monoglycerides present from incomplete transesterification or the free fatty acids which may also be present. Analysis of the biodiesel reaction mixture is complicated by the solubility and physical property differences among the components of the tranesterification reaction mixture. In this contribution, we present a simple, rapid HPLC method which allows for monitoring all of the main components in a biodiesel fuel transesterification reaction, with specific emphasis on the ability to monitor the reaction as a function of time. The utilization of a relatively new, core-shell stationary phase for the HPLC column allows for efficient separation of peaks with short elution times, saving both time and solvent.     

Stainless Steel Electrodes to Determine Biodiesel Content in Petroleum Diesel Fuel by Electrochemical Impedance Spectroscopy

The blending ratio of biodiesel in petroleum diesel has become one of the most important parameters to ensure the quality of diesel/biodiesel blend. This paper presents a fast and simple method based on electrochemical impedance spectroscopy to determine the biodiesel content in diesel fuel. Different from the method reported in the literature, using a pair of two identical screen printed carbon paste electrodes, in the present work we used two electrodes made from 304 stainless steel with dimensions of 0.8×0.3 cm for the EIS measurements. Improved results were obtained in terms of sensitivity, stability of measurements, electrode reuse, and cost. In this procedure the charge transfer resistance is proportionally related to the biodiesel content, which is used to construct a calibration curve for the analysis of biodiesel content. The procedure was validated by an official method, using two samples, being one of them, certified through an official interlaboratory program of the Brazilian government (Interlaboratory Program for Biodiesel of National Agency of Petroleum, Natural Gas and Biofuels (PIB)/ANP). Good results were obtained in terms of recovery (102.6 %‐102.8 %), precision (coefficient of variation lower than 2.3 %), limit of detection (0.24 %) and limit of quantification (0.80 %). These results indicate that this method is sufficiently suitable as an alternative method to the official method for determining biodiesel content in commercial diesel fuel.     

Production of biodiesel fuel by transesterification of rapeseed oil

Fatty acid methyl esters (FAMEs) show large potential applications as diesel substitutes, also known as biodiesel fuel. Biodiesel fuel as renewable energy is an alternative that can reduce energy dependence on petroleum as well as air pollution. Several processes for the production of biodiesel fuel have been developed. Transesterification processes under alkali catalysis with short-chain alcohols give high yields of methyl esters in short reaction times. We investigated transesterification of rapeseed oil to produce the FAMEs. Experimental reaction conditions were molar ratio of oil to alcohol, concentration of catalyst, type of catalyst, reaction time, and temperature. The conversion ratio of rapeseed oil was enhanced by the alcohol:oil mixing ratio and the reaction temperature.     

KF/La2O2CO3固体碱的制备、表征及催化酯交换反应的性能——一个综合创新实验

固体碱催化剂具有易分离、可循环使用、对设备无腐蚀、可使反应工艺过程连续化等优点。它被认为是催化酯交换反应制备可再生能源生物柴油的一种优异催化剂。本实验是在科研成果的基础上创新设计了一个综合实验。通过浸渍法制备了KF/La2O2CO3固体碱催化剂;利用X射线衍射测定了其物相,使用CO2程序升温脱附技术测定了催化剂的表面碱性;并以三丁酸甘油酯与甲醇进行酯交换反应作为模型反应,考查其催化活性。     

Critical review on analytical methods for biodiesel characterization

Biodiesel is an alternative fuel composed of mono-alkyl esters and obtained mainly from the base-catalyzed transesterification reaction of oils or fats. Its use (pure or blended) does not demand any modification in the diesel engine and in the existing fuel distribution and storage infrastructure. Moreover, biodiesel has a high energetic yield, fixes the solar energy and contains insignificant amounts of sulphur. Therefore, biodiesel is currently the best substitute for fossil diesel fuel.Besides mono-alkyl esters, glycerol (main co-product), alcohol, catalyst, free fatty acids, tri-, di- and monoglycerides compose the final mixture of biodiesel production process. These and other kinds of contaminants can lead to severe operational and environmental problems. Therefore, the quality control of biodiesel is greatly significant to the success of its commercialization and market acceptance. Some important issues on the biodiesel quality control involve the monitoring of transesterification reaction, the quantification of mono-alkyl esters and free- and bonded glycerol as well as determination of residual catalysts and alcohol. Moreover, the determination of blend levels is another key aspect of biodiesel analyses. Chromatography and spectroscopy are the analytical methods most used for the biodiesel characterization, but procedures based on physical properties are also available.Previously, a review on analytical methods used to evaluate biodiesel quality was written by Knothe. Due to the importance of this field, we made an update of Knothes’ review. Therefore, in this paper, we will describe new developments in biodiesel analyses and some references showed in Knothes’ paper. Specially, we will describe analytical methods used for quantification of glycerol, mono-, di-, triglycerides, methanol, water, Na, K, P, and steroids in biodiesel or along the transesterification reaction. Also, the determination of biodiesel content in blends and some physicochemical parameters are discussed. At the end, we will assess the available techniques and point out some improvements on analytical methods for biodiesel characterization.     

Thermal investigation of oil and biodiesel from <Emphasis Type="Italic">Jatropha curcas</Emphasis> L.

Biodiesel is susceptible to autoxidation if exposed to air, light and temperature, during its storage. Physic nut (Jatropha curcas L.) seeds show potential application for biodiesel production since its oil yields high quality biodiesel. This work aims to evaluate the thermal behavior of the physic nut oil and biodiesel, from several Brazilian crops, by means of thermoanalytical techniques. Thermogravimetry (TG) and pressurized-differential scanning calorimetry (PDSC) were used in order to determine the applicability of physic nut biodiesel as fuel. Results suggest that physic nut biodiesel is a practical alternative as renewable and biodegradable fuel able to be used in diesel motors.     

Montmorillonite-supported KF/CaO: a new solid base catalyst for biodiesel production

Biodiesel is an alternative to petroleum-derived diesel fuel; development of a high-efficiency base catalyst to be used in heterogeneous biodiesel production is still a challenge. In this paper, a novel solid base catalyst, KF- and CaO-supported montmorillonite (KCa/MMT) was successfully synthesized by a facile impregnation method, and used for producing biodiesel in transesterification of commercial soybean oil with methanol. The catalysts were characterized by X-ray diffraction, carbon dioxide temperature-programmed desorption and scanning electron microscopy. Effects of the parameters, such as the loading amount of KF, the amount of KCa/MMT, and the methanol to oil molar ratios, on the yield of biodiesel were investigated. A maximum biodiesel yield of 98 % was obtained under the optimal reaction conditions. The separated catalyst can be directly used in the next round of reactions and gave a satisfactory yield. Furthermore, analysis of the catalyst's tolerance to oil-containing water or free fatty acids, and a kinetic study were also carried out. Koros–Nowak tests were designed and conducted, and it was proven that the heat and mass transfer were not limited by the reaction rate.     

Thermal behaviors of soy biodiesel

Biodiesel is a prospective and promising fuel for diesel engines. However, some aspects need improvement, to develop into an ideal fuel, such as flow properties at low temperatures and storage stability at high temperatures with exposure to the air. Thermal analysis is an efficient tool for measuring properties, such as crystallization temperature, and thermal and oxidative stabilities. In this study, the thermal behaviors of biodiesel at low and high temperatures were investigated by using thermogravimetric analyzer, differential scanning calorimetry, pressurized differential scanning calorimetry (PDSC), and sorption analyzer (SA). The soy biodiesel was obtained through a transesterification reaction with a homogeneous catalyst. The constituents of the soy biodiesel as determined by gas chromatography show that methyl esters content was 99?% and of these 84?% were unsaturated fatty acids. TG results illustrate that the total weight loss of the biodiesel was 99?% below 300?°C under nitrogen flow, indicating a high purity biodiesel. The onset decomposition temperature and the peak temperatrue of the soy biodiesel were 193 and 225?°C, respectively, implying the biodiesel has good thermal stability. PDSC results show that the oxidation onset temperature of the soy biodiesel was 152?°C, and the oxidative induction time was 24?min. DSC results demonstrate that the onset crystallization temperature of the soy biodiesel was 1.0?°C. The SA results point out that with increasing temperature and humidity, the soy biodiesel absorbed more water, and in which humidity was the dominant factor. The water absorption and desorption of the soy biodiesel is a non-reversible process. The preferable storage conditions for soy biodiesel occur when humidity is less than 30?% and the temperature is less than 30?°C. In summary, thermal analysis is a faster alternative for thermal behavior studies as compared with conventional standard methods.     

The Obtaining Biodiesel from Used Vegetable Oil and Animal Waste Oil by Two Stages Transesterification Reaction

The biodiesel was obtained from used vegetable oil (UVO) and animal waste oil (AWO) by the two stages transesterification reaction. Also chemical and technical properties of feed and products were determined. Conditions of transesterification reaction for each of the oil samples were determined as a result of several sets of experiments. The suitable conditions of transesterification reaction were the following. Hereto a molar ratio of oil: methanol: catalyst was 1: 6: 1/40, for 30 min, at temperature of 600°C. To obtain biodiesel directly by the one stage transesterification, in case of using UVO sample, when the acidity number of feed oil had to less than 3 mg KOH/g. The biodiesel from UVO and AWO was prepared by mixing 5, 10, 20% of volume in the summer and winter diesel fuel. However, the product from mixture of UVO and winter diesel fuel met the technique requirements both of winter and summer diesel fuel, but the product from mixture of AWO and summer diesel fuel did not satisfy technical requirements of diesel fuel.