黄连木籽油制备生物柴油副产物甘油的分离与精制

研究了黄连木籽油与甲醇酯交换反应的副产物甘油的分离与精制工艺。结果表明．反应下层液用水为稀释剂（加入量为其质量的50％）,用50％的硫酸调节pH值至4．0-5．0,离心分离,蒸馏除去溶剂得粗甘油;粗甘油经乙醇结晶脱盐、活性炭脱色后得半成品甘油：再减压蒸馏即可得无色透明、黏稠、纯度为96.19％的精制甘油。     

生物柴油的制备及其副产物粗甘油分离与精制工艺的研究

研究了生物柴油制备工艺条件的确定及其副产品粗甘油的分离与精制,对甘油精制中溶剂的选择、溶液的pH值和蒸馏温度对甘油得率的影响进行了研究。制备生物柴油的最佳条件为醇油摩尔比6:1,催化剂用量1%,反应温度60℃,反应时间90 m in,得率达到98.1%(以菜籽油质量100 g为基准)。粗甘油精制的最佳工艺为:用甲醇作溶剂,离心溶液的pH值在5~7之间,在此条件下甘油的得率可以达到31.2%(以粗甘油质量为基准,100 g菜籽油得16 g粗甘油),纯度达到97.52%,可以满足于各种化工生产。     

碱催化法生产生物柴油产品精制过程的优化

分别以麻疯树毛油、餐饮废油和食用玉米油为原料通过液体碱催化法制备生物柴油,对产品精制过程中涉及的分离甘油、去除过量甲醇和除皂等传统技术进行了评价、改善和优化。实验结果显示:采用离心法分离粗甲脂和甘油,所需时间比传统的重力沉降法大大缩短,从 6 h 缩短至 40 min,且分离效果与之相同,达到 88.0%,可以替代之;去除过量甲醇过程放在产品精制的第一步更有利于提高甲醇的回收率和减少工业应用时的设备投资;采用先加入质量分数 0.2% 的冰醋酸再用 60℃ 温水的水洗法,较好地解决了水洗过程中的油水乳化难题,使水洗次数、时间、耗水量大为减少,效率提高。对于餐饮废油,要获得高纯度生物柴油产品(甲脂含量大于或等于 96.5%),除了经过上述除杂步骤,还需通过精馏才能达到。     

生物柴油副产物甘油的分离提纯工艺进展

生物柴油产业的快速发展,使得副产物甘油的产量激增,而当前食品、化妆品、医药等行业对甘油都有着广泛的需求,但它们对甘油的纯度要求很较高。这就需要对生物柴油副产物甘油进行精制提纯。通常经酯交换反应得到的生物柴油,通过简单的离心或沉降过程即可得到粗甘油,其中含有催化剂、色素、盐、皂、脂肪酸等杂质,再加上甘油本身黏度大、沸点高,且是热敏性的物质,使得其分离精制过程变得很困难。本文介绍了现有文献中报道的从生物柴油中提纯精制甘油的各种工艺,主要有絮凝、乙醇结晶、草酸钠络合、离子交换、膜分离、减压蒸馏或分子蒸馏、生物吸附和反应络合等精制提纯工艺。并提出将两种或多种精制提纯技术相结合,将会是一种高效的甘油精制方案。     

生物柴油副产粗甘油的精制工艺研究

对生物柴油副产物粗甘油的分离精制工艺进行了研究。采用减压蒸馏结合活性炭吸附脱色的方法对粗甘油进行了精制提纯,并对操作条件进行了优化,同时,利用过程模拟软件AspenPlus进行了模拟计算,实验结果和计算结果吻合。实验所得的甘油产品的纯度为99.5%,甘油收率为91.8%,原料中的甲醇回收率为96.0%,纯度为99.5%。     

生物柴油副产物粗甘油的综合利用

生物柴油作为一种可替代化石燃料的可再生能源,得到了快速发展和规模化生产,使得其副产物甘油的产量过剩。通过简单工艺过程处理生物柴油,即可得到粗甘油,而粗甘油中除甘油外,还有其他的杂质组分,要想将其应用于食品、化妆品及医药等行业就必须对粗甘油进行精制。而当前,粗甘油精制工艺路线较为繁琐,成本较高,经济可行性比较低,故需开发粗甘油的应用空间,提高粗甘油的附加值。本文从生物柴油副产物粗甘油的综合应用入手,从生产化工产品,如1,2-丙二醇、1,3-丙二醇、DHA、PHA、丙烯醛等,用于制氢,用于制燃料添加剂,用于燃料电池,制甲醇或乙醇以及废物处理等领域概述了当前粗甘油的应用技术工艺现状。通过不断拓展粗甘油的应用前景,为生物柴油技术工艺的可持续发展提供技术支撑。     

膨润土吸附精制粗生物柴油的工艺过程研究

为了提高碱催化酯交换工艺中粗生物柴油的精制效果,研究提出了膨润土吸附精制粗生物柴油的优化工艺。实验考察了膨润土用量、吸附温度和吸附时间对游离甘油和总甘油脱除效果的影响,测定了膨润土吸附游离甘油、单甘酯及二甘酯过程的动力学,并探讨了吸附精制过程的机理。结果表明,在膨润土用量为粗生物柴油质量的4%、吸附温度为60℃、吸附时间为40 min条件下,精制得到的生物柴油质量达到欧洲标准(EN 14214)要求,收率达到97.6%,效果明显优于传统的水洗精制法;膨润土吸附游离甘油、单甘酯及二甘酯过程动力学均符合拟二级动力学方程,其吸附活化能分别为27.1、28.2和31.8 k J·mol-1,为物理吸附;膨润土的吸附动力是其亲水性,亲水性强及分子小的游离甘油和皂先吸附,而亲水性较弱、分子较大的单甘酯及二甘酯后吸附,吸附剂分两批加入对精制过程有利。     

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.     

生物柴油副产物甘油的高附加值利用

生物柴油的生产过程中都会产生副产物甘油,随着生物柴油的规模化发展,副产物甘油的合理利用成为生物柴油产业发展的关键问题之一. 粗甘油的有效再利用有利于降低生物柴油的生产成本和解决环境污染问题. 粗甘油可以通过各种工艺路线转化为1,3-丙二醇、环氧氯丙烷、乳酸、聚羟基脂肪酸酯、氢、二羟基丙酮和1,2-丙二醇等具有市场前景的高附加值产品. 目前技术比较成熟并进入产业化阶段的粗甘油利用工艺路线是生物法生产1,3-丙二醇和化学法生产环氧氯丙烷,其他工艺路线多数还处在实验室研究阶段. 本文以粗甘油综合利用为中心对目前研究进展和产业现状进行了综述.     

固体催化剂催化酯交换反应制备生物柴油研究进展

酯交换法由于无需消耗大量的能量即可制备出低黏度的生物柴油,是制备生物柴油的主要方法,发展前景较好。固体催化剂催化酯交换反应产物易分离,废弃催化剂无环境污染。综述了酯交换反应制备生物柴油过程中固体催化剂的研究概况,包括固体酸和碱催化剂的研究进展,认为采用负载型固体碱催化剂催化油脂酯交换反应合成生物柴油将成为主要的研究方向。     

A novel technique for separating glycerine from palm oil-based biodiesel using ionic liquids

Biodiesel production from abundant bio-sources has drawn the attention of the academic as well as the industrial communities in recent years. However, one of the most serious obstacles for using biodiesel as an alternative fuel is the complicated and costly purification processes involved in its production. The difficulties involved in the separation of glycerine and other un-reacted reactants and by-products necessitate the development of new competent low cost separation processes for this purpose. In this work, a low cost quaternary ammonium salt-glycerine-based ionic liquid is proposed as a solvent for extracting glycerine from the transesterification biodiesel product. The separation technique was tested on palm oil-based produced biodiesel with KOH as a reaction catalyst. The study investigated the effect of DES:biodiesel ratio and the DES composition on the efficiency of the extraction process. The lab scale purification experiments proved the viability of the separation technique with a best DES:biodiesel molar ratio of 1:1 and a DES molar composition of 1:1 (salt:glycerine). The purified biodiesel fulfilled the EN 14214 and ASTM D 6751 standard specifications for biodiesel fuel in terms of glycerine content. A continuous separation process is suggested for industrial scale application.     

Novel applications of dividing‐wall column technology to biofuel production processes

Biofuels enjoy nowadays increased public and scientific attention, driven by key factors such as volatile oil price, the need for increased energy security, and concerns over greenhouse gas emissions from fossil fuels. However, in order to make biofuels a competitive alternative, the cost of production has to be significantly reduced by using enhanced process technologies. Distillation is heavily involved in the production processes of biofuels—taking the blame for the high energy requirements that have a negative impact on the operating costs. Dividing‐wall column (DWC) is one of the best examples of proven industrial process intensification technology in distillation, as it allows significantly lower investment and operating costs while also reducing the number of equipment units and the carbon footprint. This work presents an overview of novel applications using the DWC technology in the production of the most important biofuels, by employing multi‐component separations, azeotropic, extractive or reactive distillation in a DWC: enhanced methanol recovery and glycerol separation in biodiesel production, synthesis of fatty acid methyl esters and dimethyl ether (DME) by reactive distillation, integrated DME purification and methanol or CO₂ recovery in the dimethyl ether process, as well as bioethanol concentration and dehydration. The industrially relevant case studies presented here show that significant energy savings are possible (ranging from ∼20 to 60%) while simplifying the processes by using less equipment that requires a lower plant footprint. Remarkably, in most cases there is also the possibility of revamping existing plants producing biofuels, and thus reusing the already available equipment. © 2013 Society of Chemical Industry     

Oxygenated compounds derived from glycerol for biodiesel formulation: Influence on EN 14214 quality parameters

The methyl esters of fatty acids (biodiesel) obtained via transesterification of vegetable oils or animal fats are an alternative to current fossil fuels. A large amount of glycerol as a by-product is generated in this process and new applications for this surplus need to be found. Thus, the transformation of glycerol into branched oxygen-containing compounds could be an interesting solution to provide an outlet for increasing glycerol stocks. In this work, several oxygenated compounds, obtained by transformation of glycerol via etherification, esterification and acetalisation, have been assessed as components for biodiesel formulation. Different quality parameters have been evaluated following the procedures listed in the EN 14214 European Standard for biodiesel specifications. These parameters have been correlated with the amount and chemical nature of oxygenated derivate present in the biodiesel. The best performance as component for biodiesel formulation has been achieved by the mixture of ethers produced via etherification of glycerol with isobutylene. The addition of these compounds has not only improved the low-temperature properties of biodiesel (i.e. pour point and cold filter plugging point) and viscosity, but also did not impair other important biodiesel quality parameters analyzed. Although most of the studied oxygenated derivates do not significantly improve any biodiesel property, they do not exert a significant negative effect either. Furthermore, all of them allow an enhancement of overall yield in the biodiesel production. Nevertheless, further improvement could be addressed with a better purification to reduce the presence of non-desired impurities such as di-isobutylenes and unreacted acetic acid, which have a negative influence especially in acid number and oxidation stability.     

Purification of crude glycerol derived from waste used-oil methyl ester plant

The purification of crude glycerol from a biodiesel plant using waste used-oil as a raw material was carried out on a laboratory scale by using the combined chemical and physical treatments based upon repeated cycles of acidification to the desired pH within the range of 1–6 using 1.19 M H₂SO₄, allowing phase separation and harvesting of the glycerol-rich middle phase followed by neutralization of the harvested glycerol phase with 12.5M NaOH. Subsequently, the glycerol-enriched fraction was extracted by ethanol. The results indicated that increasing the pH of the acidification step led to an increased yield of the glycerol-rich layer and decreased amount of inorganic salt and free fatty acids phase. Under strong acid conditions, large quantities of fatty acid and salt in the glycerol-enriched fraction were eliminated and, at pH 1, high purity glycerol (∼93.34%) with relatively low contaminant levels (0.00045% (w/w) ash and 5.16% (w/w) MONG) was obtained.     

Revalorization of glycerol: Comestible oil from biodiesel synthesis

High dependence on fossil fuel has caused increase of carbon dioxide concentration in the atmosphere. The actual political trends are towards an increased use of renewable fuels from agricultural origin. One of the main products of the European biorefineries is biodiesel. The main reaction involved in biodiesel synthesis produces a large amount of glycerol as by-product. Two aspects are arising in this respect: the glycerol obtained as residue and the food conversion to fuel. This paper deals with the revalorization of the residual glycerol stream to obtain triacetin (glyceryl triacetate), the lightest comestible oil. The application of glycerol as raw material to produce triacetin is not new. The goal of this paper is to check the feasibility of this transformation in an efficient integrated continuous process which is suitable for processing high quantities of glycerol. A kinetic model was determined experimentally for the production of triacetin from glycerol and acetic acid in the absence of catalyst. The results showed that by process integration of the reaction and distillation in the same unit (reactive distillation), a more sustainable process can be developed. The proposed configuration output is checked by rigorous simulation.     

A review of biodiesel production by integrated reactive separation technologies

Biodiesel is a biodegradable and renewable fuel, emerging as a viable alternative to petroleum diesel. Conventional biodiesel processes still suffer from problems associated with the use of homogeneous catalysts and the limitations imposed by the chemical reaction equilibrium, thus leading to severe economic and environmental penalties. This work provides a detailed review—illustrated with relevant examples—of novel reactive separation technologies used in biodiesel production: reactive distillation/absorption/extraction, and membrane reactors. Reactive separation offers new and exciting opportunities for manufacturing the fatty acid alkyl esters involved in the industrial production of biodiesel and specialty chemicals. The integration of reaction and separation into one operating unit overcomes equilibrium limitations and provides major benefits such as low capital investment and operating costs. These reactive separation processes can be further enhanced by heat‐integration and powered by heterogeneous catalysts, to eliminate all conventional catalyst related operations, using efficiently the raw materials and the reaction volume, while offering higher conversion and selectivity, as well as significant energy savings compared with conventional biodiesel processes. Remarkable, in spite of the high degree of integration, such integrated reactive‐separation processes are still very well controllable as illustrated by the included examples. Copyright © 2012 Society of Chemical Industry     

Separation of glycerol from FAME using ceramic membranes

International standards (e.g., ASTM D6751 and EN14214) limit the presence of free glycerol in biodiesel. The traditional water wash method for removing glycerol from crude fatty acid methyl esters (FAME) obtained in the production of biodiesel results in waste waters that cannot be readily discharged. To circumvent the water wash purification method, a membrane separation system using ceramic membranes was designed, constructed and tested for the removal of glycerol from crude FAME from a biodiesel production process. Ceramic membranes in the ultrafiltration (0.05 μm) and microfiltration (0.2 μm) ranges were tested at three different operating temperatures: 0, 5 and 25 °C. All runs separated glycerol from the crude FAME. International standards for glycerol content in biodiesel were met after 3 h when utilizing the ultrafiltration membrane setup at 25 °C with a concentration factor greater than 1.6.     

基于MVR热泵精馏的粗甘油脱水提纯工艺模拟研究

利用Aspen Plus流程模拟软件,选用NRTL-RK物性模型和精馏模型格及压缩机模块对粗甘油脱水过程进行了模拟计算,分别计算了塔顶汽相出料直接压缩热泵精馏、塔底产物闪蒸压缩热泵精馏以及常规精馏,结果表明:对于粗甘油脱水提出过程来说,在相同的原料处理量、产品质量、操作压力及回流比、产品纯度(≥99%)时,两种热泵精馏工艺均比常规精馏工艺的能耗有所降低,分别节能56.5%和54.5%,总能耗(标油/吨产品)比常规精馏工艺分别节能58.75%和56.67%,具有十分显著的节能效果。     

乙酸甲酯体系酶催化法生产生物柴油的后处理精制工艺

乙酸甲酯代替甲醇作为酯交换的酰基受体,可避免甲醇和甘油对酶催化剂的损害. 本工作根据乙酸甲酯体系制备生物柴油的特点,提出了相应的生物柴油后处理精制工艺,并根据实验研究给出了可行的操作工艺参数及物料衡算,所得成品精生物柴油符合DINE 51606质量标准. 应用化工模拟软件Pro/II模拟计算了粗生物柴油精馏的影响因素. 结果表明,精馏塔理论板数7~11块、塔顶绝对压力133~1333 Pa、回流比1.5~3.0是较优的减压精馏操作范围.     

Glycerol removal from biodiesel using membrane separation technology

Membrane separation technology was used to remove free glycerol from biodiesel in order to meet the ASTM D6751 and EN 14214 standards. Fatty acid methyl esters (FAME) produced from canola oil and methanol were purified using ultra-filtration. The effect of different materials present in the transesterification reaction, such as water, soap, and methanol, on the final free glycerol separation was studied. A modified polyacrylonitrile (PAN) membrane, with 100 kD molecular weight cut-off was used in all runs. Tests were performed at 25 °C and 552 kPa operating pressure. The free glycerol content in the feed, retentate and permeate of the membrane system was analyzed using gas chromatography according to ASTM D6584. Results showed low concentrations of water had a considerable effect in removing glycerol from the FAME even at approx. 0.08 mass%. This is four orders of magnitude less than the amount of water required in a conventional biodiesel purification process using water washing. It is suggested that the mechanism of separation of free glycerol from FAME was due to the removal of an ultrafine dispersed glycerol-rich phase present in the untreated FAME. This was confirmed by the presence of particulates in the untreated FAME. The size of the particles and the free glycerol separation both increased with increasing water content of the FAME. The trends of separation and particle size vs. water content in the FAME phase were very similar and exhibited a sudden increase at 0.08 mass% water in the untreated FAME. This supports the conclusion that water increased the size of the distributed glycerol phase in the untreated FAME leading to its separation by the ultra-filtration membrane. The technology for the removal of free glycerol from biodiesel was found to use 2.0 g of water per L of treated FAME (0.225 mass% water) vs. the current 10 L of water per L of treated FAME.