酸催化制备生物柴油的研究概况及发展

生物柴油生产过程中的催化剂是一个很关键的问题,目前实际生产中碱催化和酸催化应用较为广泛.相比之下酸催化应用受到了限制,然而酸催化制备生物柴油的优点也是显而易见的.本文简述了在酸催化作用下将高酸值原料油转化为生物柴油的原理,酸催化的主要工艺,重点介绍国外研究者从机理方面对酸催化剂的研究,涉及酯交换和酯化两个方面.对酸催化反应的影响因素以及存在解决的问题也稍加叙述.     

固体酸催化酯交换制备生物柴油的研究进展

制备生物柴油最常用的方法是植物油和动物脂肪的均相碱或酸催化酯交换.与石油基柴油相比,从植物油和动物脂肪生产生物柴油的主要瓶颈是生产价格,特别是原料价格.为降低生物柴油成本,应利用廉价原料(如废油脂)、采用连续酯交换工艺并从生物柴油副产品(甘油)中回收高纯度甘油.均相酸催化剂虽反应产率高,但废催化剂会带来环境问题,故固体酸催化剂已成为目前研究热点.简述了固体酸催化酯交换制备生物柴油的研究进展和发展趋势,最后提出了一些建议.     

炭基固体酸催化制备生物柴油研究进展

炭基固体酸是一种具有高催化活性和稳定性的催化剂.当以高酸值废油脂为反应原料制备生物柴油时,炭基固体酸可同时催化脂肪酸与甲醇的酯化反应和甘油三酯与甲醇的酯交换反应.对炭基固体酸的制备、结构及其分别在酯化反应或酯化与酯交换协同反应中的催化性能方面进行了详细阐述.指出了炭基固体酸存在的一些问题,并展望了其催化制备生物柴油今后的研究方向.     

固体酸催化制备生物柴油研究进展

生物柴油是一种绿色的可再生能源,主要通过酯交换反应生产。催化剂在酯交换反应中起重要作用,固体酸催化剂因污染少、效率高、易分离而成为研究热点。本文介绍了固体酸催化制备生物柴油的反应机理,综述了国内外近几年生物柴油制备中所用固体酸催化剂的研究进展,分为固体杂多酸、无机酸盐、金属氧化物及其复合物、沸石分子筛及阳离子交换树脂等,分析了催化剂的制备流程、反应操作条件和反应结果等,得出固体酸在催化含有大量水分和游离酸的油脂酯交换反应方面具有独特的优势,且符合生物柴油绿色生产的要求,是需要进一步研究和开发的方向。     

超临界流体制备生物柴油研究进展

生物柴油是一种环境友好的绿色能源。目前国内外的制备方法主要有酸催化法、碱催化法、生物酶催化法以及超临界流体法。文章主要阐述了各种超临界法制备生物柴油的国内外研究最新进展,介绍了其反应机理及反应动力学,并与传统的方法做了比较,指出其优点在于无需使用催化剂、反应速度快、提纯分离过程简单、对环境友好、无污染等。     

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。     

固体酸催化制备生物柴油研究进展

生物柴油是一种具有优良燃烧性能的石化替代燃料,开发可用于通过酯交换反应制备生物柴油的固体酸催化剂已成为国内外研究热点。本文综述了固体酸在催化合成生物柴油方面的研究进展,介绍了以纳米材料、磁性材料作为载体以及掺杂稀土元素等固体酸改性方法,并对固体酸催化制备生物柴油的发展前景进行了展望。     

高酸值油脂制备生物柴油的初步研究

以高酸值油脂为原料,采用酸碱不同的催化反应体系,制备生物柴油.初步研究了不同催化酯交换体系中醇油比、催化剂用量、反应时间等因素对收率的影响.结果表明碱催化酯交换的反应条件为:醇油物质的量比为6∶1、催化剂用量0.5%、反应时间0.5h,生物柴油的收率可达98%;酸催化采用两次酯交换,反应条件为:醇油物质的量比为10∶1,催化剂用量0.5%,反应时间2.0h,反应温度150℃,压力0.4～0.6MPa,生物柴油的收率可达98%.     

制备生物柴油的固体酸催化剂研究进展

生物柴油是一种绿色可再生能源。目前,大多采用高活性的固体酸催化酯化、酯交换反应进行制备,该工艺具有产品与催化剂易分离、催化剂可回收再生且环保等优点。本文综述了固体超强酸、负载型固体酸、金属氧化物及复合物、沸石分子筛、阳离子交换树脂、离子液体及杂多酸等不同类型固体酸催化剂催化制备生物柴油的最新研究进展,包括催化剂的制备、活性、催化行为。最后,对制备生物柴油的固体酸在物理化学性质、成本等方面的研究进行展望。     

固体酸催化剂制备生物柴油研究进展

生物柴油是一种可再生的生物能源,近年来得到广泛关注.固体酸催化剂可同时催化油脂和脂肪酸制备生物柴油,同时还具有环境友好、易于和产物分离等优点.本文综述了沸石分子筛、杂多酸、离子交换树脂、固体超强酸等同体酸在催化合成生物柴油方面的研究进展.     

Physical-chemical properties of waste cooking oil biodiesel and castor oil biodiesel blends

This work presents the physical-chemical properties of fuel blends of waste cooking oil biodiesel or castor oil biodiesel with diesel oil. The properties evaluated were fuel density, kinematic viscosity, cetane index, distillation temperatures, and sulfur content, measured according to standard test methods. The results were analyzed based on present specifications for biodiesel fuel in Brazil, Europe, and USA. Fuel density and viscosity were increased with increasing biodiesel concentration, while fuel sulfur content was reduced. Cetane index is decreased with high biodiesel content in diesel oil. The biodiesel blends distillation temperatures T₁₀ and T₅₀ are higher than those of diesel oil, while the distillation temperature T₉₀ is lower. A brief discussion on the possible effects of fuel property variation with biodiesel concentration on engine performance and exhaust emissions is presented. The maximum biodiesel concentration in diesel oil that meets the required characteristics for internal combustion engine application is evaluated, based on the results obtained.     

A New Method of Dealcoholization of Crude Biodiesel Fuel

In the production of biodiesel fuel from natural oils and fats via transesterification with a surplus of low molecular alcohols biodiesel and glycerol phases are obtained with alcohol residues. The utilization of the dealcoholized glycerol phase for dealcoholization of crude biodiesel phase is discussed. Theoretical relations for the calculation of the optimum conditions of this operation are derived and their validity is experimentally tested on the reaction between rapeseed oil and methanol catalyzed by KOH.     

生物柴油原料资源开发及深加工技术研究进展

生物柴油（脂肪酸甲酯）是一种绿色清洁的再生能源。我国生物柴油产业发展速度很快,但受原料价格高及产品多元化程度低等因素的影响,生物柴油价格高,产业缺乏竞争力。开发多样化的原料资源,进行产品深加工,对于生物柴油产业的发展具有重要的意义。本文综述了国内外生物柴油原料开发利用进展,介绍了国外生物柴油原料资源分布、资源特点及不同原料生物柴油的特点。简述了我国生物柴油原料资源现状及发展策略。介绍了生物柴油深加工技术研究进展,重点阐述了在制备第二代生物柴油、生物降解润滑油基础油、脂肪醇、烷醇酰胺、脂肪酸甲酯磺酸盐及绿色增塑剂等方面的研究进展及面临的问题,指出开发高效催化剂是发展生物柴油深加工技术的关键。     

添加剂对橡胶籽油生物柴油氧化稳定性的改进

测定了橡胶籽油的物化性能及组成. 加入6种抗氧化剂,采用Rancimat法研究了其添加量及复配、温度、0#柴油添加量、金属铜、铁等对橡胶籽油生物柴油氧化稳定性能的影响. 结果表明,橡胶籽油所制生物柴油不饱和脂肪酸含量达82.1%,诱导期为0.81 h,达不到国家标准(6 h). 6种抗氧化剂在添加量为4000′10-6(w)时对橡胶籽油生物柴油的氧化稳定性能均有提升,其中TBHQ效果最好,使其氧化稳定性诱导期达13.09 h,6种抗氧化剂的抗氧化效果为TBHQ>BHT>D-TBHQ>OG>PG>BHA. PG与其他抗氧化剂复配后效果较好,而TBHQ与其他抗氧化剂复配后效果降低. 温度和0#轻柴油添加量对橡胶籽油生物柴油的氧化稳定性能影响很大,随温度升高,诱导期明显缩短,而随0#柴油添加量增大,诱导期增加,添加量较大时诱导期增幅很大. 铁、铜对其氧化稳定性能也有一定影响.     

酯交换法制备生物柴油的研究进展

综述了酯交换制备生物柴油的方法,详细介绍了酯交换法中各种酯交换过程制备生物柴油的研究进展,并对各种酯交换法进行了比较。     

Protection of biodiesel against oxidation

The importance of using synthetic antioxidants to improve oxidation stability and shelf life of biodiesel is today generally accepted. In our investigations which started early with the development of biodiesel we have looked at the course of stability, ageing of biodiesel, and the use of synthetic antioxidants. We have shown for the first time that oxidative stability of biodiesel is lower than that of the rape seed oil from which it was produced. The natural stability of biodiesel relates mainly to the content of tocopherols which survive the transesterification process. Biodiesel freed from tocopherols has no stability and will be destroyed immediately in air. Synthetic antioxidants like BHT and the newly developed stronger “Bis‐BHT” dramatically improve oxidative stability and prolong shelf life. Biodiesel rich in polyunsaturated fatty acid methyl ester needs strong antioxidants to be sufficiently protected. The class of hindered phenolic antioxidants from which the BHT and “Bis‐BHT” derive are well suited as industrial biodiesel stabilizer because of their ready availability, sufficient effectiveness and proven safety in diesel fuel. Surprisingly, none of the approved international biodiesel and biodiesel blend specifications refer to shelf life as a quality parameter. There is no definition of shelf life available, although it is well understood that biodiesel ages and loses its oxidative stability over time. We propose to consider the time span from production until the biodiesel reaches zero oxidative stability and becomes rancid and detrimental for the engine as the “shelf life” of biodiesel. From the perspective of a customer running their car on biodiesel blends, shelf life should become a more important issue.     

Sensitivity of Diesel Particulate Material Emissions and Composition to Blends of Petroleum Diesel and Biodiesel Fuel

A number of investigations have examined the impact of the use of biodiesel on the emissions of carbon dioxide and regulated emissions, but limited information exists on the chemical composition of particulate matter from diesel engines burning biodiesel blends. This study examines the composition of diesel particulate matter (DPM) emissions from a commercial agriculture tractor burning a range of biodiesel blends operating under a load that is controlled by a power take off (PTO) dynamometer. Ultra-low sulfur diesel (ULSD) fuel was blended with soybean and beef tallow based biodiesel to examine fuels containing 0% (B0), 25% (B25), 50% (B50), 75% (B75), and 100% (B100) biodiesel. Samples were then collected using a dilution source sampler to simulate atmospheric dilution. Diluted and aged exhaust was analyzed for particle mass and size distribution, PM_2.5 particle mass, PM_2.5 organic and elemental carbon, and speciated organic compounds. PM_2.5 mass emissions rates for the B25, B50, and B75 soybean oil biodiesel mixtures had 20%–30% lower emissions than the petroleum diesel, but B100 emissions were about 40% higher than the petroleum diesel. The trends in mass emission rates with the increasing biodiesel content can be explained by a significant decrease in elemental carbon (EC) emissions across all blending ranges and increasing organic carbon (OC) emissions with pure biodiesel. Beef tallow biodiesel blends showed similar trends. Nevertheless, it is important to note that the study measurements are based on low dilution rates and the OC emissions changes may be affected by ambient temperature and different dilution conditions spanning micro-environments and atmospheric conditions. The results show that the use of biodiesel fuel for economic or climate change mitigation purposes can lead to reductions in PM emissions and a co-benefit of EC emission reductions. Detailed speciation of the OC emissions were also examined and are presented to understand the sensitivity of OC emissions with respect to biodiesel fuel blends.

Copyright 2012 American Association for Aerosol Research     

酵母油脂及用于生物柴油制备研究进展

油脂酵母具有高产油能力,并且所积累油脂的主要成分与植物油脂相似,可作为生物柴油制备的原料。本文对影响酵母油脂合成的关键酶、基因、碳源以及酵母油脂在生物柴油制备中的研究进展进行了综述,认为ATP∶柠檬酸裂解酶和苹果酸酶是酵母油脂合成代谢途径中的关键酶,另外,LRO1、DGA1和ARE基因也被认为同油脂合成有着紧密联系。对酵母油脂用于生物柴油生产的前景进行了展望：利用廉价碳源如甘油、能源作物以及木质纤维素水解液等培养酵母,可有效降低生产成本。在不同催化方法下,酵母油脂均可用于制备生物柴油,这对进一步研究生物柴油的生产应用有着重要意义。     

Influence of waste cooking oil biodiesel on the nanostructure and volatility of particles emitted by a direct-injection diesel engine

To reduce air pollution and the reliance on fossil fuel, biodiesel has been widely investigated as an alternative fuel for diesel engines. The purpose of this study is to investigate the influence of waste cooking oil (WCO) biodiesel on the physical properties and the oxidation reactivity of the particles emitted by a diesel engine operating on WCO biodiesel as the main fuel. Experiments were conducted on a direct-injection diesel engine fueled with biodiesel, B75 (75% biodiesel and 25% diesel on volume basis, v/v), B50, B20, and diesel fuel, at five engine loads and at an engine speed of 1920 rev/min. Particulate samples were collected to analyze the particulate nanostructure, volatility, and oxidation characteristics. Biodiesel or low-load operation leads to smaller primary particles and more disordered nanostructures having shorter and more curved graphene layers. It can be found that particles from biodiesel, blended fuels, or low-load operation have higher volatile mass fractions and faster oxidation reaction rates than particles from diesel or heavy-load operation. The higher oxidation reaction rates are due mainly to the smaller particle size, the more disordered nanostructure, and the higher volatile mass fraction. It is also found that changes in primary particle size and particulate nanostructure are not directly proportional to the biodiesel content, while changes in particulate volatility and particulate oxidation reactivity are proportional to the biodiesel content. The use of biodiesel can enhance particulate oxidation reactivity and the regeneration of soot particles in an after-treatment device.

Copyright © 2016 American Association for Aerosol Research     

A comparison of injector flow and spray characteristics of biodiesel with petrodiesel

Performance and emission characteristics of compression ignition engines depend strongly on inner nozzle flow and spray behavior. These processes control the fuel air mixing, which in turn is critical for the combustion process. The differences in the physical properties of petrodiesel and biodiesel are expected to significantly alter the inner nozzle flow and spray structure and, thus, the performance and emission characteristics of the engine. In this study, the inner nozzle flow dynamics of these fuels are characterized by using the mixture-based cavitation model in FLUENT v6.3. Because of its lower vapor pressure, biodiesel was observed to cavitate less than petrodiesel. Higher viscosity of biodiesel resulted in loss of flow efficiency and reduction in injection velocity. Turbulence levels at the nozzle orifice exit were also lower for biodiesel. Using the recently developed KH-ACT model, which incorporates the effects of cavitation and turbulence in addition to aerodynamic breakup, the inner nozzle flow simulations are coupled with the spray simulations in a “quasi-dynamic” fashion. Thus, the influence of inner nozzle flow differences on spray development of these fuels could be captured, in addition to the effects of their physical properties. Spray penetration was marginally higher for biodiesel, while cone angle was lower, which was attributed to its poor atomization characteristics. The computed liquid lengths of petrodiesel and biodiesel were compared with data from Sandia National Laboratories. Liquid lengths were higher for biodiesel due to its higher boiling temperature and heat of vaporization. Though the simulations captured this trend well, the liquid lengths were underpredicted, which was attributed to uncertainty about the properties of biodiesel used in the experiments. Parametric studies were performed to determine a single parameter that could be used to account for the observed differences in the fuel injection and spray behavior of petrodiesel and biodiesel; fuel temperature seems to be the best parameter to tune.