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Dependence of biodiesel fuel properties on the structure of fatty acid alkyl esters
Abstract
Biodiesel, defined as the mono-alkyl esters of vegetable oils or animal fats, is an “alternative” diesel fuel that is becoming accepted in a steadily growing number of countries around the world. Since the source of biodiesel varies with the location and other sources such as recycled oils are continuously gaining interest, it is important to possess data on how the various fatty acid profiles of the different sources can influence biodiesel fuel properties. The properties of the various individual fatty esters that comprise biodiesel determine the overall fuel properties of the biodiesel fuel. In turn, the properties of the various fatty esters are determined by the structural features of the fatty acid and the alcohol moieties that comprise a fatty ester. Structural features that influence the physical and fuel properties of a fatty ester molecule are chain length, degree of unsaturation, and branching of the chain. Important fuel properties of biodiesel that are influenced by the fatty acid profile and, in turn, by the structural features of the various fatty esters are cetane number and ultimately exhaust emissions, heat of combustion, cold flow, oxidative stability, viscosity, and lubricity.
... Refined vegetable oil and alkaline are used to conventionally utilize the transesterification process to produce biodiesel [2,4]. Since vegetable oil feedstock material can be replenished readily, Sunflower oil, Canola oil, palm oil, Moringa oleifera, jatropha curcas, soya beans, and macadamia nut are of high interest due to their high-fat content and they are available in the market in Republic of South Africa (RSA) and globally [5,9,10]. Everyone interested in the development of renewable biofuels, various feedstocks, macadamia nuts, and oil is best served and helped by this article. ...
... However, from Coatepec, Veracruz in Mexico, Macadamia integrifolia nut has a higher lipids content of 70.1g/100g DM, while Macadamia tetraphylla has a range of 69 to 78 g/100g DM, with insignificant percentage of SFA. Almost 80 % of its fatty acids (FAs) are Monounsaturated, mostly palmitoleic acids (C16:1; ~20 %) and oleic (C18:1; ~60 %) [22,10]. Compared to the other readily available edible nuts such as almonds and cashew nuts, macadamia nuts are high in total fat content. ...
... More biodiesel with a high concentration of saturated FFA esters is less susceptible to oxidation than biodiesel with a higher concentration of severely unsaturated FFA esters [41]. In comparison to gasoline-diesel, a 100% biofuel, has generally been shown to perform very badly in freezing conditions [10]. ...
Although fossil fuel continues to play a dominant role in global energy system unfortunately their life span is threatened as the fossil reserves are running out. Except for the fact that they are readily available, tried and tested, unfortunately they bring about a negative environmental and climate impact. When the fossil fuels are burned, they produce both carbon dioxide and carbon monoxide which is the largest driver of global climate change and air pollution. This has caused a need to explore and transition to a cleaner and renewable energy resource like biofuel. Biofuel is a combination of fatty acid alkyl esters achieved by the esterification and transterification of triglycerides that can either be animal fats and vegetable oil with methanol and ethanol. Biodiesel provides several positive benefits by helping in decreasing the country’s dependence on the importation of crude oils, it also reduces the greenhouse gas emissions and advances the lubricating property. Biodiesel is produced and deployed globally with China being the country with the highest biofuel capacity in the world, with nearly 29.8 gigawatts as of 2021. It is followed by Brazil which is ranked second, with a biofuel capacity of 16.3 gigawatts. The selection of a feedstock in biofuel production has a noticeable impact as it determines if a biofuel will be formed or not from the transesterification process performed. The fatty acid / triglyceride content especially the Mono-Unsaturated Fatty Acids (MUFA’s) are of interest. The higher the MUFA’s, the higher possibility of a successful transterification hence biofuel being the by-products/formation with less catalyst and alcohol used. Feedstocks with over 40% fatty acids, especially the MUFA’s are favorable for biodiesel formation. Almost 80% of Macadamia’s fatty acids (MFAs) are palmitoleic acids (C16:1; ~20%) and Monounsaturated, mostly oleic (C18:1; ~60%). This study reviews the preparation of biofuel utilizing Macadamia nut oil (MNO) as a feedstock for sustainable biodiesel Production.
... The variation of fatty acid ester in the composition of biodiesel will determine the biodiesel's physical and chemical characteristics, such as oxidative stability, clogging point, and cetane number, among others 25 . Using methanol or ethanol in biodiesel production ( Table 1) does not significantly differ in fatty acid ester content These facts corroborate the literature and confirm the relevance of environmental factors in the biodiesel composition of E. crassipes 8 . ...
... occurrence of the fatty acid esters oleic, linoleic, palmitic, linolenic, and stearic acid in the different biodiesel samples was 40, 32, 16, 7.5, and 6.5%, respectively 26 . The determinants properties of biodiesel, such as viscosity, the heat of combustion, oxidative stability, ignition quality, and lubricity, are influenced by the composition percentual of the fatty esters, the unsaturation of chains, and the ester moiety derived from the alcohol comprising biodiesel 25 . However, the dendrogram shows the diverse esters compositions of the commercial biodiesel samples described in the literature. ...
... In low temperatures, biodiesel has been causing clogging of filters or restricting the flow during ignition due to crystallization by excess saturated fatty acid esters (SFA). The high percent of SFA increases the melting point, giving the high biofuel values of Cloud Point (CP), Cold Filter Plugging Point (CFPP), and Pour Point (PP) 25 . The presence of one or more unsaturation in the monoalkyl esters of fatty acids with saturated hydrocarbon chains of C16 (palmitic) and C18 (stearic) reduces the tendency to solidify at low temperatures 31 , reduces the viscosity of the biodiesel and improves the filter-to-filter plugging point properties. ...
Renewable resources have stood out as raw materials in producing biofuels. This study aimed to evaluate the parameters of alcohol transesterification (ethanol and methanol) and localization of collection of aquatic macrophyte Eichhornia crassipes (Mart.) Solms in the production of biodiesel by in situ transesterification. E. crassipes was collected in Dourados and Corumbá (Brazil) municipalities. The fatty acid ester composition of the biodiesel was characterized and quantified by gas chromatography. The biodiesel properties were estimated using the BiodieselAnalyzer© program prediction. The ethyl transesterification resulted in higher yields, but the localization of collection was the most relevant parameter in biodiesel production according to the Permutation Multivariate Analysis of Variance. The simulation and comparison of the physical–chemical properties of E. crassipes biodiesel and BD 100 (commercial biodiesel) were promising for commercial application.
... The property of biodiesel was determined from FAME composition. The carbon chain sizes and the number and position of double bonds which determine the molecular structure of FAME, affect the quality of biodiesel [39,40]. These main parameters that greatly affect the biodiesel property are cetane number (CN), Iodine Value (IV), Cold Filter Plugging Point (CFPP), oxidation stability, Degree of Unsaturation (DU) and Long-Chain Saturated Factor (LCSF). ...
... Parameters such as other (CFPP), oxidation stability, DU and long chain saturated factor (LCSF) related to the quality of biodiesel used empirical equations as the other studies [39,41,42] that have been accurately before. ...
... High PUFA (≥ 2 double bonds) content in the fatty acid composition negatively impacts the oxidative stability of biodiesel making them more susceptible to oxidation and free radical attack [56]. Especially during storage high PUFA content of biodiesel undergoes oxidation reactions, resulting in the formation of peroxides, and other degradation products [39]. Therefore, to ensure good oxidative stability and improve the quality of biodiesel, it is generally preferred to have a higher proportion of saturated and monounsaturated fatty acids in the composition [56]. ...
Biodiesel production from microalgae is considered a sustainable alternative to fossil fuel sources. The economic feasibility of algae-based biodiesel is highly related to biomass, lipid and FAME yield of the species. Thus, optimization of the culture conditions plays an important role in biodiesel production. The aim of this study is to compare lipid and FAME yield and biodiesel quality of two green algae species, Chlorella vulgaris, and Botryococcus sudeticus, under nitrogen deficiency conditions. For this purpose, algae species were cultured under optimum conditions until the stationary phase, then in the second phase the effect of nitrogen stress on total lipid, FAME content, and biodiesel quality were assessed. Although nitrogen-deficiency had negative impact on the growth and survival of both species, complete nitrogen removal from the medium stimulated the total lipid and FAME yield and the level of enhancement varied among species. FAME yield increased by 21% in B. sudeticus and 28% in C. vulgaris cultures under nitrogen deficiency conditions. The biodiesel properties of both cultures met European standards, on the other hand the absence of nitrogen did not reveal a significant effect on the cetane number values of C. vulgaris. However, it caused a reduction in B. sudeticus cultures. Nitrogen deficiency had a negative impact on the oxidative stability of B. sudeticus, reducing its ability to resist oxidation. However, it enhanced the oxidative stability of C. vulgaris in long-term storage. The results highlighted the importance of species-specific approaches to maximize both lipid content and biodiesel quality.
Graphical Abstract
... However, the biggest challenge to the economic cost-effectiveness of the biofuel industry is related to dewatering microalgae culture, enhancing the microalgae growth rate, and product synthesis [13][14][15]. The quality of biodiesel depends on its lipid content, its fatty acid profile, and other indicators such as cetane number (CN), stability, and nitrous oxide (NO) emissions [16][17][18]. Another critical consideration in selecting microalgae strains used for lipid production is their capability to be maintained under high irradiance and temperature [19]; because of that, microalgae biomass production is usually carried out in outdoors massive cultures. ...
... The length of the carbon chain and the degree of unsaturation of the fatty acids are important characteristics of biodiesel properties such as cetane number [16]. The SFAs produce an increase in CN, low emissions, and stability. ...
... The SFAs produce an increase in CN, low emissions, and stability. MUFAs produce moderate CN and stability but high emissions; meanwhile, PUFAs produce low CN and greater emissions [16,52]. In several microalgae groups, lipid contents are mainly polyunsaturated fatty acids and, when used for biodiesel production, are prone to oxidation with problems of biodiesel storage [46]. ...
The aim of this work was to measure the growth rate, biomass production, proximate composition, and fatty acid content of eleven microalgae strains to evaluate their potential for biofuel production. The growth rate (p < 0.05), total dry weight (p < 0.05), organic dry weight (p < 0.05), ash content (p < 0.05), and biomass productivity (p < 0.05) differed among eleven microalgae strains. The proximate composition differed (p < 0.05) among the eleven microalgae strains. The lipid contents were higher in Cymbella sp. (strain 2) (42.46 ± 1.06%) (p < 0.05). The carbohydrate content was higher (p < 0.05) in Aphanocapsa marina (42.40 ± 1.18 %). The protein content was significantly higher (p < 0.05) in Chlamydomonas mexicana (52.83 ± 0.60%). The contents of saturated (SFAs) (p < 0.05), monounsaturated (MUFAs), and polyunsaturated (PUFAs) (p < 0.05) fatty acids among the eleven microalgae strains were different. The most important indicators of biodiesel properties are the cetane number (CN), iodine value (IV), and saponification value (SV). It was concluded that Chlorella vulgaris was an adequate strain to be used in the production of biodiesel due to their high amount of palmitic acid, oleic acid, and alpha-linolenic acid, by high values of IV (147.27 g I2/100 g), SV (210.96 mg KOH/g), and CN (48.88). The diatom Cymbella sp. is a promising strain for biodiesel production due to its high values of lipid content (42.46%), lipid productivity (1.24 g/L/day), growth rate (0.67 divisions/day), and IV (197.93 g I2/100 g), and by the lowest values of generation time (35.60 h) and SV (208.85 mg KOH/g). Another promising strain for biodiesel production is Porphyridium cruentum due to its high values of biomass productivity (0.038 g/L/day), lipid productivity (0.80 g/L/day), CN (45.60), and IV (220.15 g I2/100 g), and by the low generation time and SV (199.25 mg KOH/g).
... According to biodiesel standard EN 14214 methods, the concentration of linolenic acid and acid containing four double bonds in FAMEs should not exceed the limit of 12% and 1%, respectively. Higher oleic acid content increases the oxidative stability for longer storage (Knothe, 2005) and decreases the cold filter plugging point (CFPP) for use in cold regions (Stournas et al., 1995). The pour and cloud points of feedstock decrease with increasing chain length and branching of the alcohol moiety (Foglia et al., 1997). ...
... The pour and cloud points of feedstock decrease with increasing chain length and branching of the alcohol moiety (Foglia et al., 1997). Biodiesel feedstock with a high degree of saturation is more resistant to oxidation and more stable in presence of light, oxygen, high temperatures, and metals (Canakci and Sanli, 2008;Knothe, 2005). The determination of fatty acid composition of algae oil is essential for assessing the fuel quality of biodiesel. ...
... Knothe et al. [16] noticed that the fatty esters in biodiesel have a direct impact on its properties. A combination of fat and alcohol moieties can affect the cetane number, cold flow rate, stability, viscosity, and lubricity. ...
... This study aims to establish a benchmark by promoting the larger-scale production of neem biodiesel for lower blends, aligning with government policies such as India's guidelines on biodiesel blending up to (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)% in the future. The study involved the production of neem oil biodiesel from neem seeds and experimental evaluation of various blends on a single-cylinder diesel engine to assess the performance and emissions. ...
Biodiesel has attracted a lot of attention as a possible replacement for traditional fuels due to the limited supply of fossil fuels and the growing concern about emissions of greenhouse gases. It is renewable and produces less hazardous emissions when burned. Enhancing biodiesel production is imperative to meet the escalating demand for eco-friendly fuels, serving as a remedy for the rising costs and dwindling accessibility of petroleum. This study aims in boosting neem biodiesel production specially in dry and unproductive soil regions and improving engine power using neem oil biodiesel, especially using lower blends. This study is in line with the initiatives that promote sustainable energy growth by gradually increase biodiesel blending from 15% to 30% in the near future. This research delves into the manufacturing of biodiesel from neem seeds and impact of its blends on the efficiency and emissions of compression ignition engines when combined with regular fuel. The biodiesel was produced using the transesterification method.Three distinct blends, B10, B15, and B20, were prepared by blending neem biodiesel with regular diesel. When testing engine performance, these mixtures were compared against pure diesel fuel. The specific fuel consumption and brake thermal efficiency of all blend combinations improved with increasing load. In comparison to pure diesel, there were also decreased percentages of hydrocarbons (HC), carbon monoxide (CO), and smoke opacity. There was an increase in nitrogen oxides with increasing load for all mixes as compared to pure diesel. The research results highlight neem biodiesel as a practical and efficient alternative to conventional diesel fuel due to its ability to enhance engine efficiency and lowering emissions.
... Particularly, it was higher that rice seed which has been reported around 2 or 3% (Ju & Vali, 2005;Zubair et al., 2012). S. latifolia leaves, P. sagittata seeds and T. domingensis seeds presented values near of the half recorded for the Glycine max seeds and a fourth of the Elaeis guineensis (Knothe, 2005). The leaves and seeds of P. sagittata, S. latifolia and T. domingensis reported around seventeen FA in length carbon atoms of 14 to 24 (Table 1). ...
... Similar to other aquatic macrophytes, it is possible to diversify lipids of the three macrophytes into non-conventional food and bioproducts nutraceutical, pharmacological and oleochemical, and simultaneous use as raw material for bioethanol and biogas sources (Ju & Vali, 2005;Hatti-Kaul et al., 2007). Moreover, the S. latifolia leaf, as well as the leaf and seed of P. sagittata and T. domingensis, presented averages of 95.1% to 96.5% according to ideal composition for biodiesel (C8:0, C10:0, C12:0, C14:0, C16:0, C18:0 and IFA , C16:1, C18:1, C18:2, C18:3 and C22:1) (Knothe, 2005). The above becomes relevant because the rice (Oryza sativa) bran currently intends to use into biodiesel (Binod et al., 2010;Ri-chmond, 2004). ...
... The palm oil feedstock has an average molecular weight of 774.4 g/mol. After the transesterification reaction, the average value of molecular weight of biodiesel is between 269.6 and 271.2 g/mol, which is reduced by approximately three times in comparison with that of the main component tripalmitin, indicating that the conversion of the triglycerides to the corresponding ester is rather complete [51][52][53]. The value of the refractive index decreased as the temperature increased and varied in a narrow range between 1.452 and 1.463 in the temperature range between 20 and 70 • C (not all shown). ...
... Inorganics 2024, 12,51 ...
This work investigates biodiesel production via transesterification of Mexican palm oil with methanol catalyzed by binary solid base core–shell catalysts with improved catalytic stability. A series of CaO–ZnO mixed solids were prepared using an inexpensive co–precipitation method by varying ZnO content from 5 to 20 mol%. Several factors, such as surface basicity, ZnO content, phase compositions, and thermal treatment of the catalysts, were all proven to be crucial for the production of biodiesel with good quality. Thermal treatment could effectively remove the surface adsorbed water and impurities and improved the catalytic activity. The addition of ZnO to CaO significantly enhanced the catalysts’ stability; however, it led to lower surface basicity and slightly diminished catalytic activity. ZnO doping inhibited the formation of surface Ca(OH)2 and promoted the formation of Ca–Zn–O or CaZn2(OH)6 phase as the core and a surface CaCO3 shell, which effectively decreased Ca2+ leaching by approximately 74% in methanol and 65% in a methanol–glycerol (4:1) mixture. A combined method of separation and purification for obtaining clean biodiesel with high quality was proposed. The biodiesel obtained under the control conditions exhibited properties which satisfied the corresponding standards well.
... In order to use FAAE as biodiesel or fuel blends certain characteristics such as degree of saturation, fatty acid moiety, hydrocarbon chain length and its branching are to be considered [54]. The properties are dependent on the solvent used for transesterification of oil wherein the chain length (C1-C5) and the branching of alcohol moiety could significantly affect the cloud point and pour point as evident from this study [55]. ...
... The properties are dependent on the solvent used for transesterification of oil wherein the chain length (C1-C5) and the branching of alcohol moiety could significantly affect the cloud point and pour point as evident from this study [55]. Though higher chain esters (butyl and propyl) seems to have superior fuel properties, considering the cost and techno-economic feasibility low chain alcohols are employed in large scale [54]. Therefore, in our study methanol and ethanol only employed than other solvents. ...
Palm kernel oil (PKO) is a non-edible oil which is enriched with saturated fatty acids that can be used as a raw material for many industrial applications. Indian PKO (IPKO) was chosen in this study which has been explored sporadically in industries. IPKO was characterized and utilized for the synthesis of fatty acid alkyl esters through transesterification (solvolysis) using methanol and ethanol solvents coupled with alkali catalysts such as sodium hydroxide (NaOH) and potassium hydroxide (KOH). Upon comparison, methanol and NaOH resulted in the maximum biodiesel (esters) yield of 67.77% as compared to ethanol-based solvolysis. Compositional analysis of fatty acid methyl esters (FAMEs) through GC–MS elucidated the presence of long chain (C12:0 to C18:1) esters, which can be utilized as biodiesel. Therefore, IPKO FAME has been tested as diesel blend in engines without any modification, where, B5 (5% v/v) blend showed at-par fuel characteristics and engine efficiency as compared to non-blended diesel with minimal emissions. To induct a waste circular reprocessing startegy, crude glycerol resulted from transesterification of IPKO was supplemented to Candida tropicalis NCIM3118 for xylitol (a sweetener) synthesis. The results indicated that upon supplemention of IPKO crude glycerol as co-substrate, enhancement in xylitol production of about 0.93 gxylitol/gtotal organic carbon as compared to only xylose as ‘C’ source (0.81 gxylitol/gtotal organic carbon) was observed with efficiency improvement in overall growth kinetic behavior. This study demonstrates the circular economy approach in which that the IPKO can be utilized for biodiesel production, while, the by-product (crude glycerol) generated could be deployed for xylitol production.
Graphical Abstract
... F02 has the highest percentage at 4.19%. The SFAs identified in this study are favourable since biodiesel with a high saturation degree is highly stable to oxidation in the presence of oxygen, light, and high temperature (Canakci and Sanli, 2008;Knothe, 2005). Further, SFA content in biodiesel improves the cetane number, better ignition, and combustion quality (Patel et al., 2017). ...
... C16:1 (palmitoleic acid) was also detected, but its percentages were lower compared to C18:1 in all the strains. Higher oleic acid (MUFA) content increases the oxidative stability for longer storage and decreases the cold filter plugging point for use in cold regions (Knothe, 2005;Kumar, 2017). As per EN 14214 standard, linolenic acid content and fatty acid with 4 double bonds should not be higher than 12 and 1%, respectively in biodiesel (Mutanda et al., 2011). ...
In this study, phycoremediation of textile wastewater (TWW) by freshwater cyanobacterial strains such as sp., Oscillatoria sp. F01 and Oscillatoria sp. F02 was evaluated, and lipids were simultaneously extracted from biomass for biodiesel production. Onset of the study, Phormidium sp. and Oscillatoria sp. F01 has better growth rates, increased biomass production, high chlorophyll content, and efficient nutrient utilization in TWW compared to Oscillatoria sp. F02. Phormidium sp. showed 1.41 g/L dry weight, followed by Oscillatoria sp. F01 with 1.39 g/L and Oscillatoria sp. F02 with 1.02 g/L biomass. Both strains demonstrated their capability to elevate the pH level while reducing TDS and eliminating/reducing several nutrients such as nitrates, nitrites, phosphates, sulphates, sulphides, chlorides, calcium, sodium, and magnesium. Further, the total lipids extracted from the TWW-grown Phormidium sp., Oscillatoria sp. F01 and Oscillatoria sp. F02 was estimated to be 8.20, 13.70 and 11.20 %, respectively, on day 21, which was higher than the lipid content obtained from control cultures. Further, biodiesel produced from the lipids of all strains showed higher levels of C12:0, C16:0, C16:1, C18:1, C18:2, and C18:3 among all the fatty acids. Therefore, they can potentially offer a valuable source of lipids and diverse fatty acids for high-quality biodiesel production. This integrated system not only offers a solution for TWW treatment but also provides a feedstock for renewable fuel production simultaneously.
... Higher cetane fuels have been found to have shorter igniting delay times than lower cetane fuels in some diesel engines. As a result, it's critical to confirm that biodiesel's cetane number matches the engine's cetane rating [91]. In light of these factors, the "ideal mix" of fatty acids has been proposed to be 16:1, 18:1, and 14:0 in a 5:4:1 ratio. ...
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... Olefin-ester copolymers and dispersants are two more additives that are utilized. Additionally, the two varieties may be combined [75,76]. ...
The extensive consumption of petroleum fuel directly correlates with both hazardous exhaust emissions affecting human health and contributing to global warming. Initially, biodiesel fuels were proposed as a viable alternative to address these issues. This perspective finds support in numerous published studies that highlight how the significant catalytic effect of nanoparticles allows for their integration into biodiesel blends, resulting in improved combustion characteristics, reduced exhaust emissions, and enhanced performance. This study investigates the impact of additives on biodiesel fuel properties and its effects on engine performance metrics such as brake power, brake thermal efficiency, exhaust gas concentration, engine vibration, and noise levels. In this work, we extracted the majority of previous research findings from specific studies. The inclusion of additives leads to increased concentrations of carbon dioxide (CO2) and NOx, as well as enhanced brake power and brake thermal efficiency. It also reduces the amount of gasoline consumed during braking, exhaust gas temperature, vibration, noise, hydrocarbons, carbon monoxide (CO), and smoke emissions. The comprehensive review concludes definitively that the compromised engine performance, combustion, and emission characteristics of biodiesel-diesel blends can be effectively restored through the addition of nanoparticles.
... Based on the result of the previous researches, physicochemical properties of the biodiesel completely depend on Monoesters of fatty acid (Palmitic, Stearic, Oleic and Linoleic), which is available in oil [27]. Table 4 shows the fatty acid composition of P. glabra. ...
... Las propiedades de los diversos ésteres grasos individuales que comprenden los aceites determinan las propiedades globales del biodiesel final (Knothe G., 2005). ...
Resumen En la búsqueda de la implementación de biocombustibles tales como el biodiesel, la principal limitante es un precio competitivo con el petrodiésel, una alternativa a la reducción de los costos de producción de dicho biocombustible es la recuperación del catalizador alcalino KOH utilizado en el proceso por su alto rendimiento de conversión, la desventaja de esta catálisis homogénea, es su arrastre en los productos al término de la conversión, es necesaria la etapa de purificación para evitar la corrosión de los vehículos automotores, generalmente se hace mediante lavados con agua destilada, el método propuesto es la destilación solar como alternativa al tratamiento del efluente, mediante un prototipo de doble vertiente se demuestra que es posible la recuperación diaria de 0.95 gr del álcali y 1.13 L del agua destilada, significando un doble ahorro económico en los costos de las materias primas requeridas en el proceso de producción del biodiesel. Biodiesel, Recuperación, Destilación Abstract In the search for the implementation of biofuels such as biodiesel, the main limitation is a competitive price with the petrodiésel; An alternative to reducing the production costs of this biofuel is the recovery of the alkaline KO H catalyst used in the process due to its high conversion efficiency, the disadvantage of this homogeneous catalysis, is its drag on the products at the end of conversion. The stage of purification is necessary to avoid the corrosion of the automotive vehicles, generally it is done by means of distilled water washes, the proposed method is the solar distillation as an alternative to the treatment of the effluent, by means of a prototype of double slope it is demonstrated that it is possible the daily recovery of 0.95 gr of the alkali and 1.13 L of the distilled water, meaning a double economic saving in the costs of the raw materials required in the biodiesel production process.
... CN for B100 increased from 58.5 to 62.4; that of B30 increased from 53.6 to 56.3; CN for B20 increased from 52.5 to 54.5 while CN for B10 increased from 51.9 to 53.4. Knothe (2005) established that cetane number decreases with increasing unsaturation and increases with increasing chain length. Hence the slight increase in the cetane number of the www.wjir.org ...
-A lot of research work has proven that Nigerian Jatropha curcas is a potential feedstock for biodiesel production. However, the major drawback is its susceptibility to oxidation due to the presence of unsaturated fatty acids in the parent oil which adversely affects the quality of the biodiesel produced. This work investigated the effect of the oxidation on the quality of the biodiesel produced. Two important oxidation parameters: the acid value and the induction period were measured and correlated with biodiesel quality indices such as viscosity and cetane number. The results show that the Nigerian Jatropha curcas biodiesel (NJCB) fails to meet the minimum oxidation stability limit (IP of 6 hours) without antioxidant. Blending with petro-diesel as well as the addition of antioxidants leads to a composition having efficient and improved oxidation stability. The viscosity of all the samples are found to increase during the 24 weeks period of storage indicating an increase in the formation of oxidized products which lead to the formation of sediments and gum. The slight increase in the cetane number of the pure biodiesel and its blends can be attributed to the gradual saturation of the unsaturated methyl esters which are being oxidized into aldehydes and carboxylic acids.
... Many types of alternative fuels have some other disadvantages such as higher viscosity with lower volatility and lower heating value when compared to pure diesel. This can lead to the low atomization and mixture concentrations with air that result in slower combustion, lower thermal efficiency and higher emissions [4][5]. Natural gas contains large amount of methane with less percentages ethane, propane, and butane. ...
In the development of alternative, biodegradable, and renewable fuels used for internal combustion (IC)engines to obtain the power. Therefore, in this present study, influence of fuel injection timing on the exhaustemission of a single cylinder, four stroke, and direct injection(DI) diesel engine was considered. It has beenexperimentally investigated using rubber seed and jatropha seed oil blended diesel fuel from 20%(B20)to40%(B40) with an increment of 10%. The engine was tested at different loads from no load to full loadconditions with diesel fuel at normal injection pressure of 220 bar and fuel injection timing of 240CA BTDC.The experimental tests were performed at 210CA BTDC injection timings by changing the thickness ofadvance shim. The experimental results obtained show that CO and UHC emissions were decreasedfor theproportion of B20,NOx and exhaust gas temperatureincreased with increasing amount of biodieselconcentration in the fuel mixture.Keywords: Performance, Biodiesel, Injection Timing, Diesel fuel, Emission, Diesel engine
(PDF) Effect of injection timing on emission analysis of a constant speed diesel engine running on biodiesel fuelled with pure diesel fuel. Available from: https://www.researchgate.net/publication/377768235_Effect_of_injection_timing_on_emission_analysis_of_a_constant_speed_diesel_engine_running_on_biodiesel_fuelled_with_pure_diesel_fuel [accessed Jan 29 2024].
... Many types of alternative fuels have some other disadvantages such as higher viscosity with lower volatility and lower heating value when compared to pure diesel. This can lead to the low atomization and mixture concentrations with air that result in slower combustion, lower thermal efficiency and higher emissions [4][5]. Natural gas contains large amount of methane with less percentages ethane, propane, and butane. ...
In the development of alternative, biodegradable, and renewable fuels used for internal combustion (IC)engines to obtain the power. Therefore, in this present study, influence of fuel injection timing on the exhaustemission of a single cylinder, four stroke, and direct injection(DI) diesel engine was considered. It has beenexperimentally investigated using rubber seed and jatropha seed oil blended diesel fuel from 20%(B20)to40%(B40) with an increment of 10%. The engine was tested at different loads from no load to full loadconditions with diesel fuel at normal injection pressure of 220 bar and fuel injection timing of 240CA BTDC.The experimental tests were performed at 210CA BTDC injection timings by changing the thickness ofadvance shim. The experimental results obtained show that CO and UHC emissions were decreasedfor theproportion of B20,NOx and exhaust gas temperatureincreased with increasing amount of biodieselconcentration in the fuel mixture.Keywords: Performance, Biodiesel, Injection Timing, Diesel fuel, Emission, Diesel engine
(PDF) Effect of injection timing on emission analysis of a constant speed diesel engine running on biodiesel fuelled with pure diesel fuel. Available from: https://www.researchgate.net/publication/377768056_Effect_of_injection_timing_on_emission_analysis_of_a_constant_speed_diesel_engine_running_on_biodiesel_fuelled_with_pure_diesel_fuel [accessed Jan 29 2024].
... Biodiesel is an easy-to-use, nontoxic fuel, biodegradable, and ultimately free of sulfur and aromatics. Furthermore, it considerably decreases the number of hazardous pollutants and greenhouse gases (3). ...
Developing alternatives to fossil fuels has become increasingly essential due to the ongoing depletion of non-renewable energy sources worldwide. Biodiesel, a promising substitute for fossil fuels, is not only environmentally friendly but also compatible with diesel engines. The process of converting used vegetable oils or animal fats into biodiesel is known as transesterification. In order to increase Palestine's potential for renewable energy and attain energy independence, biodiesel could be used as a renewable resource. This study focuses on the viability of developing a home appliance that can transform used cooking oil into biodiesel appropriate for domestic usage. Currently, used cooking oil is disposed of inappropriately in Palestine, causing serious environmental harm. Palestine stands to gain by addressing this environmental problem and making it simpler to use used cooking oil as a renewable energy source. Therefore, the main objective of this study is to create a machine that is simple to operate, affordable in comparison to other devices on the market, and needs minimal maintenance. An in-house prototype was built at An-Najah National University's workshop for 4,500 NIS (or roughly $1,320). In addition, a number of lab tests were performed to assess the characteristics of the cooking oil and the required reaction conditions, such as temperature, mixing rate, and the right catalyst. According to the findings, the created machine has a production cost that is 25% lower than that of conventional diesel while maintaining a comparable level of performance in diesel engines. This study opens the door for a long-term solution to Palestine's energy problems and environmental problems
... Fuel properties such as cetane number, heat of combustion, kinematic viscosity, melting point, and oxidative stability are assessed through fatty acid compositional analysis [56][57][58]. The presence of high levels of monounsaturated fatty acids is desirable for a biodiesel substrate because of the favorable balance they conferred on these parameters [5,59]. In assessing biodiesel feedstocks, a mixture of high amounts of monounsaturated fatty acids and a balanced level of saturated and polyunsaturated fatty acids is preferable for biodiesel production [60]. ...
... The successful introduction and commercialization of biodiesel in many countries around the world has been accompanied by the development of standards to ensure high product quality and user confidence. Some biodiesel standards are ASTM D6751 (American Society for Testing and Materials) and EN 14214 (European norm) [13]. ...
Biofuel’s production is a topical domain for researchers due to the relevance that it is winning every day. This, because of the increase in the petroleum price and the environmental advantages. Biodiesel is a promising way to reduce the environmental degradation by increasing pollutants including greenhouse gas emissions (fossil CO2, nitrogen and sulfur oxides). Biodiesel price is directly related to the cost of the used raw materials (70-95 % of the total biodiesel cost). In this context, the purpose of this paper is to study the different renewable resources which can be used as raw material for biodiesel production to emphasize the possibility of the use of edible used oils. The special attention is paid to optimization of biodiesel production from used edible oil by trans esterification reaction.
... The kinematic viscosity (KV) increases with fatty acid chain length and with increasing degree of saturation of either fatty acid or alcohol moiety in the FAMEs ( Knothe G 2005). ASTM specified KV range for biodiesel is 3.3-5.2 ...
The non-renewable energy sources such as coal, petrol decreasing day by day and their price also increasing. In this fast depleting era of fossil fuels biodiesel produced from nonedible seed oils plays an important role. In the present work the biodiesel is produced from nonedible seed oil Salvia farinacea. In this work from Salvia farinacea seeds oil is extracted and fatty acid components are analysed by GC-FID. Physicochemical properties of the oil are determined by AOAC standard methods. The oil is transesterified in presence of KOH catalyst. Fuel parameters like iodine number, cetane number, heating values, kinematic viscosity, flash point, cold flow properties are determined and are compared with already existing biodiesels and petrodiesel. The emission components like CO, CO2, NOx, HC and Smoke opacity are analysed using four stroke one cylinder engine. This work reveals that Salvia farinacea seed oil is a potential renewable feedstock for the production of biodiesel.
Biodiesel was obtained by transesterification of chicken fat and methanol using CaO from eggshells, through a factorial 24 experiment design to evaluate the influence of reaction variables. The fat was characterized through the: refractive index, saponification index, free fatty acids, density, and viscosity, giving as results 1.465, 183.166 mg KOH g−1, 1.623%, 0.919 g cm−1 and 63.337 cSt. The temperature was the variable with the greatest impact on biodiesel production. The optimal variables to achieve a viscosity of 5.918 cSt were: temperature 65°C, chicken fat (CF): methanol molar ratio 1:6, catalyst percentage 5% w/w and reaction time of 5 h.
Microalgae-derived biodiesel is commonly studied and recently gained attention as a possible substitute feed- stock for production of biodiesel. In this study, the potential of marine diatoms, Cylindrotheca sp. (FPU 0031) and T. chinensis (FPU 0030), for production of biodiesel was evaluated by investigating the effect of nutrient limi- tation (100, 75, 50, and 25 % Roschin medium) on growth behavior response, lipid productivity, and FAME profiles of the diatom strains. The total lipid yield increased under nutrient-limited culture condition. When the concentration of the nutrient was restricted to 50 %, the average lipid yield of Cylindrotheca sp. and T. chinensis were 19.32 and 21.72 % with lipid productivity of 73.46 and 68.19 mg L− 1 day− 1, respectively. Nutrient limi- tation resulted in a decrease in biomass yield and an increase in the lipid yield of the diatom strains. The properties of biodiesel generated by the two diatoms were assessed based on FAME profiles using empirical equations. Results showed that Cylindrotheca sp. and T. chinensis conforms to the biodiesel standards specifica- tions set by EN 14214 and ASTM D6751. The predicted properties of biodiesel observed for Cylindrotheca sp. and T. chinensis were both ideal, e.g. good cold filter plugging points (− 6.94 ◦C and − 2.16 ◦C), cetane numbers (65.57 and 75.29), cloud points (1.81 ◦C and 7.75 ◦C), pour points (1.60 ◦C and − 4.86 ◦C), and low kinematic viscosities (2.89 and 2.16 mm2 s− 1), respectively. Thus, suggesting the potential use of these diatoms as feedstock for producing biodiesel with high-grade fuel characteristics.
Organic carbon may be obtained sustainably from lignocellulosic biomass; however, the majority of microorganisms, including microalgae, find it difficult to convert it through bioconversion due to its refractory nature. As a result, a significant challenge lies in the bioprospecting and metabolic engineering of microalgae to use lignocellulosic carbohydrates including cellulose, hemicellulose, and lignin with minimal pretreatment. Diatoms that are heterotrophic epiphytic are capable of consuming organic matter as they can naturally produce cellulolytic and hydrolytic enzymes, allowing them to effectively use lignocellulose for growth. They have a unique carbon metabolism which, due to the presence of enzymes, is exclusively involved in the breakdown of lignin via the β-ketoadipate pathway. This chapter focuses on how diatoms convert lignocellulose to produce biofuels and other value-added products that can help to achieve a sustainable environment in the near future.
In recent years, biofuel has gained popularity as a feasible substitute for conventional fuels like gasoline and diesel and as a renewable energy source. Depending on the complexity of their production procedures and the energy content of the fuel they create, the various types of biofuel are divided into generations. Fuels from the first generation include ethanol and biodiesel, which are produced by transforming organic material like sugarcane, corn, or soybeans into fuel. The second generation creates more sophisticated fuels like renewable diesel and drop-in aviation fuels that use cellulose and lignin as feedstocks to make a fuel that is comparable to those used in conventional transportation. The third generation is concentrated on utilising waste products to produce fuels, such as landfill gas and syngas, which are produced by transforming organic matter into a gas that may be used as fuel. Finally, the fourth generation is concentrated on the creation of advanced biofuels, such as hydrogen-based and algae biofuels. The current book chapter gives an overall idea about the various generations of biofuel and their source. The prospect for a larger-scale deployment of biofuel is becoming increasingly more enticing as the technology develops and the production costs become more affordable.
The excessive reliance on fossil fuels has resulted in an energy crisis, environmental pollution, and health problems, calling for alternative fuels such as biodiesel. Here, we review computational chemistry and machine learning for optimizing biodiesel production from waste. This article presents computational and machine learning techniques, biodiesel characteristics, transesterification, waste materials, and policies encouraging biodiesel production from waste. Computational techniques are applied to catalyst design and deactivation, reaction and reactor optimization, stability assessment, waste feedstock analysis, process scale-up, reaction mechanims, and molecular dynamics simulation. Waste feedstock comprise cooking oil, animal fat, vegetable oil, algae, fish waste, municipal solid waste and sewage sludge. Waste cooking oil represents about 10% of global biodiesel production, and restaurants alone produce over 1,000,000 m3 of waste vegetable oil annual. Microalgae produces 250 times more oil per acre than soybeans and 7–31 times more oil than palm oil. Transesterification of food waste lipids can produce biodiesel with a 100% yield. Sewage sludge represents a significant biomass waste that can contribute to renewable energy production.
Biodiesel is a material serving as a promising energy alternative to cover the demand of clean sustainable energy sources. Conventional biodiesel production is done by transesterification method using stirred tank reactor and homogeneous base or acid catalyst then followed by purification process. However, there are some disavantages related with this method. They include soap formation, sensitivity to free fatty acid (FFA) content and purification difficulties.Transesterifica-tion process depends upon a number of process parameters which are required to be optimized in order to maximize the biodiesel yield. In this paper we have worked for flow sheet constructions of Biodiesel small plant using computer simulating software. All the conclusion results will be shown in simulation part of paper. The core objective of this paper would to design and develop a profitable biodiesel production plantby examining all models.
Because of its low environmental impact and high production, microalgae bio-oil has quickly become a popular renewable fuel option. The process utilizes microalgae which are readily available in nature to produce an alternative to fossil fuel. Although microalgal bio-oil production mechanisms have been previously reviewed in recent studies, comparatively few of them emphasize the significance of algal bio-oil production through all available bio-oil conversion mechanisms from microalgae. Here we review the available and common bio-oil conversion processes from microalgae, bio-oil upgrading, and the commercial aspects of its utilization. The most efficient route to bio-oil production can be identified by analysing both the biomass feedstock and the final product. For example, pyrolysis can produce high-energy bio-oil, but it also produces large amounts of char and gas. Although hydrothermal liquefaction and gasification are more complex and costly, they have the potential to produce bio-oil with greater consistency. However, the expense of using bio-oil in a commercial context is a major concern. The cost of producing bio-oil from microalgae is typically higher than that of producing conventional fossil fuels. Several factors, including cost, availability, and necessary infrastructure, contribute to the uncertainty of bio-oil’s commercial feasibility. With the constant improvements in technology and government
support, however, bio-oil has the potential to emerge as a viable alternative to conventional fossil fuels.
This chapter reviews competing technologies for converting vegetable oils and animal fats into diesel fuel besides biodiesel. Aside from transesterification to produce biodiesel, microemulsion/co-solvent blending and hydroprocessing (deoxygenation) appear to be the two most promising approaches for converting vegetable oils and fats into alternative diesel fuels. Microemulsion or co-solvent blend hybrid fuels is a relatively low-cost conversion process since it requires little more than the mixing of individual components at ambient temperature. Transesterification generally requires a slightly elevated temperature; a minimum reaction time, depending on catalyst; and several product separation and washing steps to prepare the biodiesel for distribution. Similarly, hydroprocessing generally requires elevated temperature and hydrogen pressure; a minimum reaction time, depending on catalyst; condensation; and the fractionation of liquid products. Although hydroprocessing and transesterification may be economically competitive with each other, it is unlikely either approach will compare favorably with hybrid fuel formulation. Other advantages favoring hybrid fuel formulation over transesterification or hydroprocessing include adaptability to large-scale continuous flow processing equipment, no catalysts to recover or re-generate, no excess alcohol, no by- or co-products, and no product separation/fractionation steps. All compounds, including amphiphiles used in hybrid fuel formulations, may be derived from renewable agricultural feedstocks. Another disadvantage for hydroprocessing is the likelihood that it has an unfavorable energy balance. Life cycle analyses for biodiesel generally indicate that it gives back more than three times the energy required to produce it resulting in a net positive energy balance.
The combustion related properties of vegetable oils are somewhat similar to diesel oil. Neat vegetable oils or their blends with diesel, however, pose various long-term problems in compression ignition engines, e.g., poor atomization characteristics, ring-sticking, injector coking, injector deposits, injector pump failure, and lube oil dilution by crank-case polymerization, These undesirable features of vegetable oils are because of their inherent properties like high viscosity, low volatility, and polyunsaturated character. Linseed oil methyl ester (LOME) was prepared using methanol for long-term engine operations. The physical and combustion-related properties of the fuels thus developed were found to be closer to that of the diesel oil. A blend of 20 percent was selected as optimum biodiesel blend. Two similar new engines were completely disassembled and subjected to dimensioning of various vital moving parts and then subjected to long-term endurance tests on 20 percent biodiesel blend and diesel oil, respectively. After completion of the test, both the engines were again disassembled for physical inspection and wear measurement of various vital parts. The physical wear of various vital parts, injector coking, carbon deposits on piston, and ring sticking were found to be substantially lower in case of 20 percent biodiesel-fuelled engine. The lubricating oil samples drawn from both engines were subjected to atomic absorption spectroscopy for measurement of various wear metal traces present. AAS tests confirmed substantially lower wear and thus improved life for biodiesel operated engines.
A wide-ranging study of the effect of free-radical initiators, especially i-octyl nitrate and di-t-butyl peroxide, on the spontaneous ignition of diesel fuel is reported. The important kinetic processes induced by these additives occur in the gas phase, and not in the liquid droplets. Di-t-butyl and i-octyl nitrate peroxide work in different ways: the nitrate is involved in the ignition process itself, whereas the peroxide competes for sulfur-containing inhibitors in the fuel.
This paper assesses the impact of esters of monocarboxylic fatty acids, on the lubrication properties of ultra-low-sulfur diesel fuels. Seven esters were used as lubricating additives on a matrix of eight fuels, at five different concentrations of 50, 100, 500, 750, and 1000 ppm. Tribological experiments carried out on the high-frequency reciprocating test rig (HFRR) showed that the effective concentration of the additives was 500 ppm or higher.
This paper presents the impact of the addition of specific types of fatty acid derivatives on the lubrication properties of low sulfur diesel fuels. It discusses the most recent results, concerning the influence of adding low amounts of four specific types of biodiesel and two tertiary amides on the tribological behavior of the steel-on-steel systems, lubricated with low-sulfur automotive diesel. Experiments were carried out on the HFRR test rig. The obtained wear results have clearly shown a specific behavior of the components tested, which dissolved in selected base fuels at the concentration range of 0.05−10%. It is concluded that a very small amount of the selected biodiesel types and tertiary amides dramatically improves the low-sulfur diesel lubricity.
During storage and use, vegetable oil-derived industrial products such as biodiesel and biodegradable lubricants can be subjected
to conditions that promote oxidation of their unsaturated components. The materials arising during oxidation and subsequent
degradation can seriously impair the quality and performance of such products. Therefore, oxidative stability is a significant
issue facing these vegetable oil-derived products, and enhanced understanding of the influence of various components of vegetable
oils and storage parameters is necessary. In this work, the oil stability index (OSI) was used for assessing oxidation of
monoalkyl esters of FA by varying several parameters. Neat fatty compounds and prepared mixtures thereof were studied for
assessing the influence of compound structure and concentration. Small amounts of more highly unsaturated compounds had a
disproportionately strong effect on oxidative stability. The recently developed concept of bis-allylic equivalents correlated
more closely than the iodine value with the OSI times of mixtures of fatty esters. The OSI times of free acids were shorter
than those of the corresponding alkyl esters. The presence of copper, iron, and nickel also reduced oxidative stability, but
their effect was less than the presence of more highly unsaturated fatty compounds. Of these metals, copper had the strongest
catalytic effect on OSI time. OSI may be an alternative to long-term storage tests for determining the influence of extraneous
materials such as metals on oxidative stability.
Renewable vegetable fuels are spreading rapidly throughout Europe and North America. Because biodiesel fuel has now acquired
an important market share, it is necessary to thoroughly examine aspects of its use not previously considered either at the
research stage or when overhauling the production technology. One of these aspects is its medium-term storage. The object
of the present work is to study the behavior of biodiesel under controlled storage conditions that simulate those found in
reality. Samples of biodiesel were kept in the dark, at two different temperatures (20°C and 40°C), in both glass and iron
containers. They were controlled by the parameters that indicate their state of oxidation. Another group of samples was stored
in glass and kept under the conditions described above in the presence of increasing quantities of water to determine its
influence on the formation of acidity.
The low-temperature properties of mono-alkyl esters derived from tallow and recycled greases were determined for neat esters
and 20% ester blends in No. 2 low-sulfur diesel fuel. Properties studied included cloud point, pour point, cold filter plugging
point, low-temperature flow test, crystallization onset temperature, and kinematic viscosity. Compositional properties of
the alkyl esters determined included water, residual free fatty acids, and free glycerol content. In general, the secondary
alkyl esters of tallow showed significantly improved cold-temperature properties over the normal tallow alkyl ester derivatives.
The low-temperature flow test did not show a 1:1 correlation with cloud point as previously observed with methyl soyate and
methyl tallowate. For the homologous series methyl to n-butyl tallowate, ethyl tallowate had the best broad-spectrum low-temperature properties, both neat and when blended in diesel
fuel. For the greases studied, both the normal and branched alkyl ester derivatives showed improved properties over corresponding
tallow esters, especially with neat esters.
One of the main problems in the study or industrial application of transesterification processes for vegetable oils is how
to measure the methyl ester content. In this work, a quick analytical method was developed for assessing the methyl ester
content of purified “fuel grade” transesterification products by applying a simple correlation with viscosity. The correlation
was tested on a wide range of samples with various methyl ester contents; the results were in agreement with the values measured
by gas-chromatographic analysis. In a defined range of weight fractions the correlation allows for the determination of the
methyl ester content of purified transesterification products by a single viscosity measurement. This method is especially
suitable for process control purposes as it determines the methyl ester content quickly and simply.
Biodiesel derived from transesterification of soybean oil and methanol is an attractive alternative fuel for combustion in
direct-injection compression ignition (diesel) engines. During long-term storage, oxidation due to contact with air (autoxidation)
presents a legitimate concern with respect to maintaining fuel quality of biodiesel. This work examines the effects of oxidation
under controlled accelerated conditions on fuel properties of methyl soyate (SME). SME samples from four separate sources
with varying storage histories were oxidized at elevated temperature under a 0.5 standard cm3/min air purge and with continuous stirring. Results showed that reaction time significantly affects kinematic viscosity (ν).
With respect to increasing reaction temperature, ν, acid value (AV), PV, and specific gravity (SG) increased significantly,
whereas cold flow properties were minimally affected for temperatures up to 150°C. Antioxidants TBHQ and α-tocopherol showed
beneficial effects on retarding oxidative degradation of SME under conditions of this study. Results indicated that ν and
AV have the best potential as parameters for timely and easy monitoring of biodiesel fuel quality during storage.
This work examines low-temperature properties of triglyceride-based alternate fuels for direct-injection compression-ignition
engines. Methyl esters from transesterified soybean oil were studied as neat fuels and in blends with petroleum middle distillates
(No. 1 or No. 2 diesel fuel). Admixed methyl esters composed of 5–30 vol% tallowate methyl esters in soyate methyl esters
were also examined. Pour points, cloud points, and kinematic viscosities were measured; viscosities at cooler temperatures
were studied to evaluate effects of sustained exposure. Low-temperature filterability studies were conducted in accordance
with two standard methodologies. The North American standard was the low-temperature flow test (LTFT), and its European equivalent
was the cold-filter plugging point (CFPP). With respect to cold-flow properties, blending methyl esters with middle distillates
is limited to relatively low ester contents before the properties become preclusive. Under most conditions, cold-flow properties
were not greatly affected by admixing the methyl esters with up to 30 vol% tallowate (before blending). Least squares analysis
showed that both LTFT and CFPP of formulations containing at least 10 vol% methyl esters are linear functions of cloud point.
In addition, statistical analysis of the LTFT data showed a strong 1:1 correlation between LTFT and CP. This result may prove
crucial in efforts to improve low-temperature flow properties of alternate diesel fuels that contain methyl esters derived
from triglycerides.
This work explores near-term approaches for improving the low-temperature properties of triglyceride oil-derived fuels for
direct-injection compression-ignition (diesel) engines. Methyl esters from transesterified soybean oil were evaluated as a
neat fuel and in blends with petroleum middle distillates. Winterization showed that the cloud point (CP) of methyl soyate
may be reduced to −16°C. Twelve cold-flow additives marketed for distillates were tested by standard petroleum methodologies,
including CP, pour point (PP), kinematic viscosity, cold filter plugging point (CFPP), and low-temperature flow test (LTFT).
Results showed that additive treatment significantly improves the PP of distillate/methyl ester blends; however, additives
do not greatly affect CP or viscosity. Both CFPP and LTFT were nearly linear functions of CP, a result that compares well
with earlier studies with untreated distillate/methyl ester blends. In particular, additives proved capable of reducing LTFT
of neart methyl esters by 5–6°C. This work supports earlier research on the low-temperature properties; that is, approaches
for improving the cold flow of methyl ester-based diesel fuels should continue to focus on reducing CP.
Several novel fatty diesters with bulky moieties were synthesized by esterification of mono- or bifunctional fatty acids or
with mono- or bifunctional alcohols using p-toluenesulfonic acid as catalyst. They were characterized by 1H and 13C nuclear magnetic resonance as well as positive chemical ionization (PCl) mass spectrometry. The PCl mass spectra of the
resulting diol diesters and diacid diesters are discussed and compared. The compounds were investigated as potential additives
for improving the cold flow properties of vegetable oil esters used as biodiesel.
Methyl and ethyl monoalkyl esters of various vegetable oils were produced for determining the effects of type of alcohol and
fatty acid profile of the vegetable oil on the lubricity of the ester. Four methyl esters and six ethyl esters were analyzed
for wear properties using the American Society for Testing and Materials method D 6079, Evaluating Lubricity of Diesel Fuels
by the High-Frequency Reciprocating Rig. Ethyl esters showed noticeable improvement compared to methyl esters in the wear
properties of each ester tested. No correlation was found between lubricity improvement and fatty acid profile of the ester,
except that esters of castor oil had improved lubricity over other oils with similar carbon chain-length (C18) fatty acids.
Biodiesel, an alternative diesel fuel that may be derived from soybean oil, is composed of long-chain saturated and unsaturated fatty acid alkyl esters. Extensive oxidative degradation can compromise viscosity, acid value, peroxide value, and other parameters in the current ASTM biodiesel fuel guideline. This work examines pressurized-differential scanning calorimetry (P-DSC) for analysis of oxidative stability of biodiesel. Heating scans were conducted under static air-atmosphere with 5°C/min ramping. Increasing pressure from 1000 to 5000 kPa did not significantly affect results and 2000 kPa was selected for the remainder of this study. Curves were analyzed for oxidation temperature (OT) of methyl soyate samples from four separate sources. With respect to unmodified methyl soyate, addition of antioxidants increased OT from 108.4-127.2°C to 137.2-163.4°C. Mixtures with added tert.-butylhydroquinone consistently gave higher OT values than those with ±α-tocopherol; therefore, P-DSC may be useful for screening antioxidants. Although P-DSC results were consistent with corresponding oil stability index (OSI) data measured at 50°C, no correlation for predicting OSI directly from OT results was evident, with the possible exception of unmodified methyl soyate. This work establishes P-DSC as an analytical tool in evaluating the oxidative stability of biodiesel with and without antioxidants.
In this investigation the identity characteristics of the pure plant oils were compiled from literature sources and our own experimental results. The quality characteristics were determined and the results compared to those given in the literature data. Lastly, an attempt was made to evaluate the oils according to their oxidative stability. Accelerated storage tests were done on the pure oils and the plant oil-diesel mixtures. Literature sources contained information on the stability and composition of pure refined oils but very little on degummed and crude oils and none on the characteristics of plant oil-diesel mixtures.
The oxidative stability of two samples of rapeseed oil methyl esters from different production sites was determined. The effect of various antioxidants on the induction period at 120°C was studied. As the additives did not show a positive effect on the stability of the rapeseed oil methyl ester under the test conditions, the temperature was varied and the effect of a random antioxidant in comparison to the pure ester was determined. The antioxidant HITEC did show a negative effect at 120°C and positive effects both at 100°C and 90°C. However, the difference in induction period was very low. The test method used was an automated version of the active oxygen method (AOM) at ambient temperature.
The oxidative stability of different plant oil based fatty acid methyl esters can be estimated by determining the induction period with the active oxygen method. Measuring the volatile and oil soluble acids for a long period preceding the induction period shows that the alues are approaching a certain limit. Even if the esters do not differ dramatically in the composition of fatty acids it is a fact that the different production processes influence the amount of tocopherols significantly. The exclusion of light is more crucial than the exclusion of air when storing plant oil based fatty acid esters.
In the recent years the sulfur content of diesel fuel was reduced gradually. As a result of the severe hydrotreating it became necessary to add additives to diesel fuel in order to meet the required lubricity standard. Oxygen containing substances show a high suitability for this purpose. Serveral substance classes were examined by HFRR in order to investigate their influence on the lubricity of diesel fuel.
Methyl and ethyl esters, prepared from various vegetable oils by the process of transesterification, have shown much promise as fuels for all types of diesel engines. Very limited information is available on possible deterioration of biodiesel in storage. This project was designed to determine the extent of deterioration of Rape Methyl Ester (RME) and Rape Ethyl Ester (REE) in storage. The study involved triplicate samples of RME and REE stored in glass and steel containers at room temperature (inside) and at the local ambient outdoor temperatures (outside). The study was conducted for 24 months. At the beginning of the study and at three-month intervals, samples were taken for measurement of peroxide value, acid value, density, viscosity, and heat of combustion. At the conclusion of the study, engine performance tests were conducted with the two year stored REE and RME, new REE and RME, and low sulfur diesel reference fuel. On the average, the esters increased over time in all of the previously mentioned properties with the exception of heat of combustion, which decreased. Regression models are presented to predict the deterioration with time. Engine power varied less than 2% for both Biodiesel fuels compared to the stored counterparts while smoke density decreased 3.2% for the stored RME and increased 17.5% for stored REE.
Biodiesel is an alternative fuel for diesel engines that can be produced from renewable feedstocks such as vegetable oil and animal fats. These feedstocks are reacted with an alcohol to produce alkyl monoesters that can be used in conventional diesel engines with little or no modification. Biodiesel, especially if produced from highly unsaturated oils, oxidizes more rapidly than diesel fuel. This article reports the results of experiments to track the chemical and physical changes that occur in biodiesel as it oxidizes. These results show the impact of time, oxygen flow rate, temperature, metals, and feedstock type on the rate of oxidation. Blending with diesel fuel and the addition of antioxidants are explored also. The data indicate that without antioxidants, biodiesel will oxidize very quickly at temperatures typical of diesel engines. This oxidation results in increases in peroxide value, acid value, and viscosity. While the peroxide value generally reaches a plateau of about 350 meq/kg ester, the acid value and viscosity increase monotonically as oxidation proceeds.
The first edition of this best-selling, widely-used book was published as the Automotive Fuels Handbook in 1990. Since that time, significant progress has been made in fuels technology, and major changes in the industry have occurred. Some of these changes include the wider introduction of reformulated fuels, the introduction of new additives for primary and secondary treatment of diesel fuels, and the increase in legislation related to exhaust emissions control. This second edition covers these changes and provides the most thorough single resource of fuels technology currently available. The book has been extensively updated to reflect current technology on automotive fuels and fuel quality. Information has been included on the health and environmental effects of fuels, the alternative fuels LPG, LNG, and CNG, and tables of conversions and heating values. Written from a global viewpoint, the Automotive Fuels Reference Book covers fuels and procedures used on a worldwide basis. The book is an excellent reference for automotive engineers, fuel technologists, commercial and academic researchers, fuel additive manufacturers, environmentalists, and government personnel in energy-related positions. The book also features an extensive appendix section, including a glossary of terms, fuel consumption and quality regulations, worldwide survey of emissions legislation, and more.
The compositional changes a diesel fuel undergoes during hydrotreating were investigated, specifically in relation to the changes in natural lubricity components. A unique set of six diesel fuels from the United States, England, Israel, and Spain were hydrotreated to four different levels of sulfur and aromatic content. Three different ASTM methods were used to determine the lubricity of these samples. These tests showed that the lubricity of the fuels was severely impacted by the hydrotreating process. A chemical test was developed that employed a base extraction followed by GC analysis that positively correlated with the ASTM tests. Additionally, GC/MS was employed to determine the major classes of compounds that are responsible for a fuel's inherent lubricity. The samples were aged at ambient conditions for two years as well as undergoing accelerated aging experiments. There appears to be a fuel dependent relationship between aging and compositional changes that affords a fuel its lubricity.
As the use of biodiesel becomes more wide-spread, engine manufacturers have expressed concern about biodiesel’s higher viscosity.
In particular, they are concerned that biodiesel may exhibit different viscosity-temperature characteristics that could result
in higher fuel injection pressures at low engine operating temperatures. This study presents data for the kinematic viscosity
of biodiesel and its blends with No. 1 and No. 2 diesel fuels at 75, 50, and 20% biodiesel, from close to their melting point
to 100°C. The results indicate that while their viscosity is higher, biodiesel and its blends demonstrate temperature-dependent
behavior similar to that of No. 1 and No. 2 diesel fuels. Equations of the same general form are shown to correlate viscosity
data for both biodiesel and diesel fuel, and for their blends. A blending equation is presented that allows the kinematic
viscosity to be calculated as a function of the biodiesel fraction.
Methyl soyate, made from typical soybean varieties, has a crystallization onset temperature (T
co) of 3.7°C and, as a biodiesel fuel, is prone to crystallization of its high-melting saturated methyl esters at cold operating
temperatures. Removal of saturated esters by winterization was assessed as a means of reducing theT
co of methyl soyate. Winterizing neat methyl esters of typical soybean oil produced aT
co of −7.1°C, but this was not an efficient way of removing saturated methyl esters because of the low yield (26%) of the separated
liquid fraction. However, aT
co of −6.5°C with 86% yield was obtained by winterizing the neat methyl esters of a low-palmitate soybean oil; aT
co of −5.8°C with 77% yield was obtained by winterizing methyl esters of normal soybean oil diluted with hexane.
Kinematic viscosities at 20C, 40C and at 70C have been measured for methyl oleate, linoleate, linolenate, erucate, and for
the saturated fatty acid methyl esters acetate through nonadecanoate. Using a recently developed dynamic viscosity-temperature
criterion, log (1.200+log η)=A−S log (1+t/135), the viscosity-temperature behavior of the saturated compounds could be characterized
by one single parameter.
Gross heats of combustion (HG) have been measured for three classes of fatty esters and two classes of triglycerides (TGs).
The esters included saturated methyl esters, Me 6:0–22:0; saturated ethyl esters, Et 8:0–22:0; and unsaturated methyl esters,
Me 12:1–22:1, Me 18:2 and Me 18:3. The TGs included the saturated TGs, C 8:0–22:0, and unsaturated TGs, C 11:1, C 16:1, C
18:1, C 18:2, C 18:3, C 20:1 and C 22:1. HG were measured in a Parr adiabatic calorimeter according to a modification of ASTM
D240 and D2015. Linear regression analysis (LINREG) yielded equations that related HG to carbon number (CN) or chain length,
electron number (EN) or number of valence electrons and molecular weight (MW). Calculated HG values from CN, EN, or MW were
nearly identical. Thus, any one of these three variables can be used to predict HG satisfactorily. R squared values for all
equations were 0.99. Equations for correlating HG of saturated or unsaturated TGs with molecular characteristics of these
molecules have not been reported. With LINREG, we developed equations that permitted predictions of HG from structures of
the saturated and unsaturated TGs. Equations for predicting HG of methyl and ethyl esters were compared to those in the literature
and were found to be more accurate and precise.
The biodiesel that is considered as a possible substitute or extender of conventional automotive diesel fuel is commonly composed
of fatty acid methyl esters that are prepared from the glycerides in vegetable oils by transesterification with methanol.
This form of biodiesel is compatible with diesel fuel but offers no improvement in its ignition quality. This work describes
the results of a series of experiments aimed at assessing other common fatty acid derivatives that could provide the desired
biofuel component and, at the same time, improve the performance of the fuel. It was found that tertiary fatty amines and
amides are significantly more effective than methyl esters in enhancing the ignition quality of the finished diesel fuel without
having any negative effect on its cold flow properties.
Gross heats of combustion (Hg) for the homologous series of saturated fatty alcohols C10–C22 were measured in a Parr adiabatic calorimeter according to ASTM D240 and D2015. The measured values for these alcohols ranged
from 1582 to 3453 kg-cal/mole. We developed equations that related carbon number (CN) or chain length, electron number (EN)
or number of valence electrons and molecular weight (MW) to calculated Hg by linear regression analysis (LINREG). These equations
are: Hg=26.00+155.60 CN; Hg=26.00+25.94 EN; and Hg=−172.2+11.00 MW. R squared values for all three equations were 0.99. The
results obtained with LINREG were compared to a literature method. Comparisons were made for both the fatty alcohols above
and C1–C5, C7, C8 and C16 alcohols of the literature method. For the former alcohols there was no difference in accuracy or precision between the two
methods. For the latter alcohols LINREG was both more accurate and precise. Measured Hg vs. chain length for C1–C22 alcohols showed a perfect linear relationship. Thus, knowing chain length, Hg can be predicted accurately for alcohols in
this range.
Cetane numbers for various esters of the saturated fatty acids from C8 to C18 have been determined according to ASTM D-613.
For the methyl esters the cetane numbers were found to increase in a non-linear relationship with the chain length of the
fatty acid. Cetane numbers of esters in which the fatty acid is kept constant while the alcohol esterified is altered also
increased with the molecular weight of the ester. However, increases in the molecular weight of the fatty acid portion of
the ester produce greater increases in cetane number than the same change in molecular weight in the alcohol portion of the
ester. Except for the esters of octanoic acid, all of the esters tested had cetane numbers above the value of 40, which is
specified as the minimum cetane number for commercial diesel fuel.
To reduce the tendency of biodiesel to crystallize at low temperatures, branched-chain alcohols were used to esterify various
fats and oils, and the crystallization properties of the branched esters were compared with those of methyl esters by using
differential scanning calorimetry (DSC), cloud point, and pour point. Compared with the methyl esters that are commonly used
in biodiesel, branched-chain esters greatly reduced the crystallization onset temperature (TCO) of neat esters and their corresponding ester diesel fuel blends. Isopropyl and 2-butyl esters of normal (∼10 wt% palmitate)
soybean oil (SBO) crystallized 7–11 and 12–14°C lower, respectively, than the corresponding methyl esters. The benefit of
the branched-chain esters in lowering TCO increased when the esters were blended with diesel fuel. Esters made from a low-palmitate (3.8%) SBO crystallized 5–6°C lower
than those of normal SBO. Isopropyl esters of lard and tallow had TCO values similar to that of methyl esters of SBO. DSC provided an accurate means of monitoring crystallization, and the DSC
results correlated with cloud and pour point measurements.
Cetane numbers (C#) for the homologous series of straight-chain, saturated n-alcohols, C5−C12 and C14, were determined according to ASTM D 613. Measured C# ranged from 18.2–80.8 and increased linearly with carbon number (CN).
Regression analyses developed equations that related various physical properties or molecular characteristics of these alcohols
to calculated C#. The degree of relationship between measured and calculated C# was expressed as R2. The decreasing order of the precision with which these properties correlated with C# was: boiling point (bp)>melting point
(mp)>CN>heat of combustion (HG)>refractive index (n20
D)>density (d). This ranking was based upon R2 (0.99–0.96) and the Average % error (2.8–7.2%). C# were also determined for straight-chain homologs of saturated methyl esters
with CN of 6, 10, 12, 14, 16 and 18. C# ranged from 18.0–75.6 and increased curvilinearly with CN. Equations were also developed
that related physical properties of these esters to C#. The precision with which these properties correlated with C# was:
bp>viscosity (V)>heat of vaporization (HV)>HG>CN>surface tension (ST)>mp>n20
D>d. R2 ranged from 0.99 for bp to 0.98 for d. Equations for the alcohols were linear or quadratic, while equations for the esters
were linear, quadratic or cubic based upon statistical considerations that included a Student’s t-test. With related physical
properties and these equations, accurate predictions of C# can be made for saturated n-alcohols and methyl esters.
Fatty acid esters, high in linoleic acid, were prepared and stored for long-term engine tests. Storage tests with these esters were undertaken to obtain more information on optimal storage requirements and general stability characteristics.
Samples were kept at three temperature levels (20 C, 30 C and fluctuating around 50 C) for a 90-day period and were removed at regular intervals for chemical and physical analysis. The influence of air, temperature, light, TBHQ and contact with mild steel was evaluated by comparing the free fatty acid, peroxide, anisidine, ultraviolet absorption, viscosity and induction periods. A statistical model was used to evaluate the data and to reduce the large number of data points to comparable curves.
Storage of esters in contact with air, especially at a temperature above 30 C, resulted in significant increases in peroxide, ultraviolet absorption, free fatty acid, viscosity and anisidine values. Exclusion of air retarded oxidation at all temperature levels.
A direct relationship between viscosity increases and oxidation parameters was evident. Exposure to light caused a small increase in the oxidation parameters of esters stored at the highest temperature level. Addition of TBHQ prevented oxidation of samples stored under moderate conditions. Under unfavorable storage conditions the anti-oxidant was no longer effective. Mild steel had very little effect on the oxidation parameters. Only the anisidine values of samples stored at the highest temperature level were slightly increased. Methyl esters performed slightly better than ethyl esters during the storage test.
The following practical guidelines for storage of fatty acid ester fuels are: (i) airtight containers should be used; (ii) the storage temperature should be <30 C; (iii) mild steel (rust free) containers may be used, and (iv) TBHQ has a beneficial effect on oxidation stability.
Chemical and physical characteristics of some compression-ignition fuels derived from vegetable oils are recorded and some relationships between them established. From consideration of the literature relating to spark-ignition engine performance and its dependence upon hydrocarbon fuel structure, guidelines are proposed for the chemical structure requirements of compression-ignition engine fuels derived from plant seed oils.The guidelines have proved successful in predicting the ignition quality of a range of vegetable oil fuels evaluated by means of a rapid ranking engine test method and have been further supported by cetane index calculations (carried out according to ASTM standard method D976) and by other recently published data.
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–C4 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.
Viscosity is one of the most significant properties to affect the utilization of biodiesel fuels. This paper presents a method, which has been verified experimentally, for predicting the viscosities of biodiesel fuels from the knowledge of their fatty acid composition. The applicability of a logarithmic mixture equation was verified using controlled mixtures of standard fatty acid esters and natural biodiesels. Several binary, ternary and quaternary mixtures of fatty acid ethyl ester (FAEE) gas chromatography (GC) standards were formulated. Their viscosities were predicted from their component values and were within ±3.7% of their measured values. The fatty acid compositions of six typical oils were simulated by mixing fatty acid methyl ester (FAME) standards in appropriate amounts. Viscosities of these mixtures were also predicted within ±2.1% of their measured values. Five biodiesel types were produced from natural oils and the logarithmic equation was applied to predict their viscosities. An average prediction error of ±3% was obtained for these samples. The viscosities of fifteen biodiesel types were then predicted based on their fatty acid composition as published in the literature and were found to vary as much as 100% This is most likely a principal contributing factor to the variation in performance of some biodiesel fuel types. The viscosity of biodiesel fuels reduce considerably with increase in unsaturation. Contamination with small amounts of glycerides significantly affects the viscosity of biodiesel fuels.
A base fuel having a cetane number of 40.2 was split into nine batches. To eight of these batches, varying quantities of ignition improver were added, resulting in cetane numbers up to 62. The base fuel and each of the blends with ignition improver were used in a co-operative fuel research (CFR) diesel engine, and the exhaust emissions of NOx unburnt hydrocarbons (UHC) and smoke were measured, to ascertain the effect of varying cetane number on emissions when the basic chemical structure and physical properties of the fuel were almost unaltered. The results showed that the exhaust NOx progressively decreased with increasing cetane number, due to the reduction in ignition delay and amount of premixed fuel burnt. Similarly, the UHC decreased. However, the smoke increased due to the reduction in the amount of relatively smoke-free premixed fuel burnt.
Biodiesel is an oxygenated diesel fuel made from vegetable oils and animal fats by conversion of the triglyceride fats to esters via transesterification. In this study we examined biodiesels produced from a variety of real-world feedstocks as well as pure (technical grade) fatty acid methyl and ethyl esters for emissions performance in a heavy-duty truck engine. The objective was to understand the impact of biodiesel chemical structure, specifically fatty acid chain length and number of double bonds, on emissions of NOx and particulate matter (PM). A group of seven biodiesels produced from real-world feedstocks and 14 produced from pure fatty acids were tested in a heavy-duty truck engine using the U.S. heavy-duty federal test procedure (transient test). It was found that the molecular structure of biodiesel can have a substantial impact on emissions. The properties of density, cetane number, and iodine number were found to be highly correlated with one another. For neat biodiesels, PM emissions were essentially constant at about 0.07 g/bhp-h for all biodiesels as long as density was less than 0.89 g/cm3 or cetane number was greater than about 45. NOx emissions increased with increasing fuel density or decreasing fuel cetane number. Increasing the number of double bonds, quantified as iodine number, correlated with increasing emissions of NOx. Thus the increased NOx observed for some fuels cannot be explained by the NOx/PM tradeoff and is therefore not driven by thermal NO formation. For fully saturated fatty acid chains the NOx emission increased with decreasing chain length for tests using 18, 16, and 12 carbon chain molecules. Additionally, there was no significant difference in NOx or PM emissions for the methyl and ethyl esters of identical fatty acids.
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