Gerhard Knothe

The biodiesel handbook

The second edition of this invaluable handbook covers converting vegetable oils, animal fats, and used oils into biodiesel fuel. The Biodiesel Handbook delivers solutions to issues associated with biodiesel feedstocks, production issues, quality control, viscosity, stability, applications, emissions, and other environmental impacts, as well as the status of the biodiesel industry worldwide. * Incorporates the major research and other developments in the world of biodiesel in a comprehensive and practical format* Includes reference materials and tables on biodiesel standards, unit conversions, and technical details in four appendices* Presents details on other uses of biodiesel and other alternative diesel fuels from oils and fats

Cetane numbers of branched and straight-chain fatty esters determined in an ignition quality tester☆☆

The cetane number, a widely used diesel fuel quality parameter related to the ignition delay time (and combustion quality) of a fuel, has been applied to alternative diesel fuels such as biodiesel and its components. In this work, the cetane numbers of 29 samples of straight-chain and branched C1 –C 4 esters as well as 2-ethylhexyl esters of various common fatty acids were determined. The cetane numbers of these esters are not significantly affected by branching in the alcohol moiety. Therefore, branched esters, which improve the cold-flow properties of biodiesel, can be employed without greatly influencing ignition properties compared to the more common methyl esters. Unsaturation in the fatty acid chain was again the most significant factor causing lower cetane numbers. Cetane numbers were determined in an ignition quality tester (IQT) which is a newly developed, automated rapid method using only small amounts of material. The IQT is as applicable to biodiesel and its components as previous cetane-testing methods. Published by Elsevier Science Ltd.

Moringa oleifera oil: a possible source of biodiesel.

Biodiesel is an alternative to petroleum-based conventional diesel fuel and is defined as the mono-alkyl esters of vegetable oils and animal fats. Biodiesel has been prepared from numerous vegetable oils, such as canola (rapeseed), cottonseed, palm, peanut, soybean and sunflower oils as well as a variety of less common oils. In this work, Moringa oleifera oil is evaluated for the first time as potential feedstock for biodiesel. After acid pre-treatment to reduce the acid value of the M. oleifera oil, biodiesel was obtained by a standard transesterification procedure with methanol and an alkali catalyst at 60 degrees C and alcohol/oil ratio of 6:1. M. oleifera oil has a high content of oleic acid (>70%) with saturated fatty acids comprising most of the remaining fatty acid profile. As a result, the methyl esters (biodiesel) obtained from this oil exhibit a high cetane number of approximately 67, one of the highest found for a biodiesel fuel. Other fuel properties of biodiesel derived from M. oleifera such as cloud point, kinematic viscosity and oxidative stability were also determined and are discussed in light of biodiesel standards such as ASTM D6751 and EN 14214. The 1H NMR spectrum of M. oleifera methyl esters is reported. Overall, M. oleifera oil appears to be an acceptable feedstock for biodiesel.

Improving biodiesel fuel properties by modifying fatty ester composition

Biodiesel is an alternative to petroleum-derived diesel fuel composed of alkyl esters of vegetable oils, animal fats or other feedstocks such as used cooking oils. The fatty acid profile of biodiesel corresponds to that of its feedstock. Most common feedstocks possess fatty acid profiles consisting mainly of five C16 and C18 fatty acids, namely, palmitic (hexadecanoic), stearic (octadecanoic), oleic (9(Z)-octadecenoic), linoleic (9(Z),12(Z)-octadecadienoic) and linolenic (9(Z),12(Z),15(Z)-octadecatrienoic) acids, with the exception of a few oils such as coconut oil, which contains high amounts of saturated acids in the C12–C16 range or others. While in many respects biodiesel possesses advantages or is competitive with petroleum-derived diesel fuel, virtually all biodiesel fuels, typically the methyl esters, produced from these oils have performance problems such as poor low-temperature properties or insufficient oxidative stability. Considerable research has focused on solving or alleviating these problems and five approaches have been developed. Besides the approach of using additives, changing the fatty ester composition by either varying the alcohol or the fatty acid profile of the oil have been studied. Changing the fatty acid profile can be achieved by physical means, genetic modification of the feedstock or use of alternative feedstocks with different fatty acid profiles. In some cases approaches may overlap. This article briefly summarizes the five approaches currently used with an emphasis on those dealing with changing the fatty ester composition of a biodiesel fuel.

A technical evaluation of biodiesel from vegetable oils vs. algae. Will algae-derived biodiesel perform?

Biodiesel, one of the most prominent renewable alternative fuels, can be derived from a variety of sources including vegetable oils, animal fats and used cooking oils, as well as alternative sources such as algae. While issues such as land-use change, foodvs.fuel, feedstock availability, and production potential have influenced the search for the “best” feedstocks, an issue that will ultimately determine the usability of any biodiesel fuel is that of fuel properties. Issues such as cold flow and oxidative stability have been problematic for biodiesel. The fatty acid profile of a biodiesel fuel is largely identical to that of the feedstock and significantly influences these properties. This article compares biodiesel derived from vegetable oils and biodiesel obtained from algae in light of fuel properties. While the properties of biodiesel fuels derived from vegetable oils are well-known, the properties of biodiesel obtained from algal oils have usually not been reported. The fatty acid profiles of many algal oils possess high amounts of saturated and polyunsaturated fatty acids. Thus, biodiesel fuels derived from algae in many cases likely possess poor fuel properties, i.e., both poor cold flow and low oxidative stability simultaneously. This observation shows that production potential alone does not suffice to judge the suitability of a feedstock for biodiesel use. This article also summarizes how the fuel properties of biodiesel can be improved through modification of the fatty ester content. Algal oils for biodiesel production are probably best produced under tightly controlled conditions since the fatty acid profile of algal oils is very susceptible to changes in these conditions. Algal oils likely yielding biodiesel with the least problematic properties as determined by reported fatty acid profiles are discussed.

A COMPARISON OF USED COOKING OILS: A VERY HETEROGENEOUS FEEDSTOCK FOR BIODIESEL

Used cooking or frying oils are of increasing interest as inexpensive feedstock for biodiesel production. In this work, used frying oils obtained from 16 local restaurants were investigated regarding their fatty acid profile vs. the fatty acid profile of the oil or fat prior to use. The fatty acid profiles were analyzed by gas chromatography and proton nuclear magnetic resonance spectroscopy. Besides the fatty acid profile, the acid value and dynamic viscosity of the samples were determined. Dynamic viscosity was determined because of non-Newtonian behavior of some samples. The results indicate that oils and fats experience various degrees of increase in saturation during cooking/frying use, with the magnitude of these changes varying from sample to sample, i.e., a high degree of randomness of composition is found in used frying oil samples. Properties of the samples that were investigated were acid value and viscosity which consistently increased with use, also in a random fashion. Multiple independent samples obtained from the same restaurants indicate that there is little consistency of used cooking oil obtained from the same source. These results are discussed with regards to the potential fuel properties of biodiesel derived from these used frying oils.

History of Vegetable Oil-Based Diesel Fuels

Publisher Summary This chapter presents a history of vegetable oil-based diesel fuels. Vegetable oils and animal fats were investigated as diesel fuels well before the energy crises of the 1970s and early 1980s sparked renewed interest in alternative fuels. Palm oil was often considered as a source of diesel fuel in the “historic” studies, although the diversity of oils and fats as sources of diesel fuel, an important aspect again today, and striving for energy independence were reflected in other “historic” investigations. Most major European countries with African colonies—Belgium, France, Italy and the UK with Portugal apparently making an exception—at the time, had varying interest in vegetable oil fuels. Vegetable oils were also used as emergency fuels and for other purposes during World War II. The kinematic viscosity of vegetable oils is about an order of magnitude greater than that of conventional, petroleum-derived diesel fuel. High viscosity causes poor atomization of the fuel in the engines combustion chambers and ultimately results in operational problems, such as engine deposits. As a result of the energy crises of the 1970s, vegetable oils were remembered as alternatives to petrodiesel fuel, with work commencing in countries such as Austria, Germany, South Africa, and the United States. The use of methyl esters of sunflower oil to reduce the viscosity of vegetable oil was reported at several technical conferences in 1980 by South African researchers and marked the beginning of the rediscovery and eventual commercialization of vegetable oil esters as biodiesel fuel.

Biodiesel Production Technology: August 2002--January 2004

Biodiesel is an alternative fuel for diesel engines that is gaining attention in the United States after reaching a considerable level of success in Europe. The purpose of this book is to describe and explain the process and issues involved in producing this fuel.

Hydroxy fatty acids through hydroxylation of oleic acid with selenium dioxide/tert.-butylhydroperoxide

Oleic acid was hydroxylated in the allylic positions with the selenium dioxide/tert.-butylhydroperoxide system to give 8-hydroxy-9(E)-octadecenoic acid, 11-hydroxy-9(E)-octadecenoic acid and the novel 8,11-dihydroxy-9(E)-octadecenoic acid. This is a viable method for obtaining hydroxy fatty acids. The unsaturated hydroxy acids were hydrogenated with the hydrazine/air system to give the cor-responding saturated products. 8,11-Dihydroxyoctadecanoic acid thus obtained is also a novel compound. The saturated and unsaturated dihydroxy products were obtained aserythro/threo isomers as determined by nuclear magnetic resonance.

NMR characterization of dihydrosterculic acid and its methyl ester

Cyclopropane FA occur in nature in the phosphoplipids of bacterial membranes, in oils containing cyclopropene FA, and in Litchi sinensis oil. Dihydrosterculic acid (2-octyl cyclopropaneoctanoic acid) and its methyl ester were selected for 1H and 13C NMR analysis as compounds representative of cyclopropane FA. The 500 MHz 1H NMR spectra acquired with CDCl3 as solvent show two individual peaks at −0.30 and 0.60 ppm for the methylene protons of the cyclopropane ring. Assignments were made with the aid of 2D correlations. In accordance with previous literature, the upfield signal is assigned to the cis proton and the downfield signal to the trans proton. This signal of the trans proton is resolved from the peak of the two methine protons of the cyclopropane ring, which is located at 0.68 ppm. The four protons attached to the two methylene carbons α to the cyclopropane ring also show a split signal. Two of these protons, one from each methylene moiety, display a distinct shift at 1.17 ppm, and the signal of the other two protons is observed at 1.40 ppm, within the broad methylene peak. The characteristic peaks in the 13C spectra are also assigned.