Evaluation of biodiesel obtained from cottonseed oil

Esters from vegetable oils have attracted a great deal of interest as substitutes for petrodiesel to reduce dependence on imported petroleum and provide a fuel with more benign environmental properties. In this work biodiesel was prepared from cottonseed oil by transesterification with methanol, using sodium hydroxide, potassium hydroxide, sodium methoxide and potassium methoxide as catalysts. A series of experiments were conducted in order to evaluate the effects of reaction variables such as methanol/oil molar ratio (3:1–15:1), catalyst concentration (0.25–1.50%), temperature (25–65 °C), and stirring intensity (180–600 rpm) to achieve the maximum yield and quality. The optimized variables of 6:1 methanol/oil molar ratio (mol/mol), 0.75% sodium methoxide concentration (wt.%), 65 °C reaction temperature, 600 rpm agitation speed and 90 min reaction time offered the maximum methyl ester yield (96.9%). The obtained fatty acid methyl esters (FAME) were analyzed by gas chromatography (GC) and ¹H NMR spectroscopy. The fuel properties of cottonseed oil methyl esters (COME), cetane number, kinematic viscosity, oxidative stability, lubricity, cloud point, pour point, cold filter plugging point, flash point, ash content, sulfur content, acid value, copper strip corrosion value, density, higher heating value, methanol content, free and bound glycerol were determined and are discussed in the light of biodiesel standards such as ASTM D6751 and EN 14214.     

Transesterification of soybean oil and analysis of bioproduct

Biodiesel produced by the transesterification reaction of soybean oil using potassium hydroxide (KOH) catalytic is a promising alternative fuel to diesel regarding the limited resources of fossil fuel and the environmental concerns. In order to decrease the operational temperature and increase the conversion efficiency of methanol, a novel idea was presented in which a co-solvent dichloromethane was added to the reactants. The results showed that the yield of methyl ester was improved when dichloromethane was coexistence. The effects of the co-solvent, molar ratio of methanol/oil, reaction temperature, and catalyst on the biodiesel conversion were investigated. With the optimal reaction temperature of 45 °C, methanol to oil ratio of 4.5:1, co-solvent dichloromethane of 4.0%, a 96% yield of methyl esters was observed in 2.0 h at the condition with 1.0 wt.% potassium hydroxide. The characterization and analysis of biodiesel were obtained by FT-IR, gas chromatograph and inductively coupled plasma atomic emission (ICP–OES) spectroscopy methods. The cetane number, flash point, cold filter plugging point, acid number, water content, ash content and total glycerol content were investigated.     

Optimization of transesterification for methyl ester production from chicken fat

In this study, low cost feedstock chicken fat was used to produce methyl ester. After reducing the free fatty acid level of the chicken fat less than 1%, the transesterification reaction was completed with alkaline catalyst. Potassium hydroxide, sodium hydroxide, potassium methoxide and sodium methoxide were used as catalyst and methanol was used as alcohol for transesterification reactions. The effects of catalyst type, reaction temperature and reaction time on the fuel properties of methyl esters were investigated. The produced chicken fat methyl esters were characterized by determining their viscosity, density, pour point, flash point, acid value, methanol content, heat of combustion value, total-free glycerin, mono-di-tri glycerides, copper strip corrosion and ester yield values. The measured fuel properties of the chicken fat methyl ester met EN 14214 and ASTM D6751 biodiesel specifications when using potassium hydroxide and sodium hydroxide catalysts with high ester yield.     

Production of biodiesel from waste fryer grease using mixed methanol/ethanol system

Transesterification of waste fryer grease (WFG) containing 5–6 wt.% free fatty acid (FFA) was carried out with methanol, ethanol, and mixtures of methanol/ethanol maintaining the oil to alcohol molar ratio of 1:6, and initially with KOH as a catalyst. Mixtures of methanol and ethanol were used for transesterification in order to use the better solvent property of ethanol and rapid equilibrium using methanol. Formation of soap by reaction of FFA present in WFG with KOH instigated difficulty in the separation of glycerol from biodiesel ester. To untangle this problem, two-stage (acid and alkali catalyzed) method was used for biodiesel synthesis. More than 90% ester was obtained when two-stage method was used compared to ∼ 50% ester in single stage alkaline catalyst. In the case of mixed alcohol, a relatively smaller amount of ethyl esters was formed along with methyl esters. Acid value, viscosity, and cetane number of all the esters prepared from WFG were within the range of the ASTM standard. Esters obtained from WFG showed good performance as a lubricity additive.     

Rape oil transesterification over heterogeneous catalysts

This work studies the application of KNO₃/CaO catalyst in the transesterification reaction of triglycerides with methanol. The objective of the work was characterizing the methyl esters for its use as biodiesel in compression ignition motors. The variables affecting the methyl ester yield during the transesterification reaction, such as, amount of KNO₃ impregnated in CaO, the total catalyst content, reaction temperature, agitation rate, and the methanol/oil molar ratio, were investigated to optimize the reaction conditions.The evolution of the process was followed by gas chromatography, determining the concentration of the methyl esters at different reaction times. The biodiesel was characterized by its density, viscosity, cetane index, saponification value, iodine value, acidity index, CFPP (cold filter plugging point), flash point and combustion point, according to ISO norms. The results showed that calcium oxide, impregnated with KNO₃, have a strong basicity and high catalytic activity as a heterogeneous solid base catalyst.The biodiesel with the best properties was obtained using an amount of KNO₃ of 10% impregnated in CaO, a methanol/oil molar ratio of 6:1, a reaction temperature of 65 °C, a reaction time of 3.0 h, and a catalyst total content of 1.0%. In these conditions, the oil conversion was 98% and the final product obtained had very similar characteristics to a no. 2 diesel, and therefore, these methyl esters might be used as an alternative to fossil fuels.     

Production of biodiesel through optimized alkaline-catalyzed transesterification of rapeseed oil

Present work reports an optimized protocol for the production of biodiesel through alkaline-catalyzed transesterification of rapeseed oil. The reaction variables used were methanol/oil molar ratio (3:1-21:1), catalyst concentration (0.25-1.50%), temperature (35-65 °C), mixing intensity (180-600 rpm) and catalyst type. The evaluation of the transesterification process was followed by gas chromatographic analysis of the rapeseed oil fatty acid methyl esters (biodiesel) at different reaction times. The biodiesel with best yield and quality was produced at methanol/oil molar ratio, 6:1; potassium hydroxide catalyst concentration, 1.0%; mixing intensity, 600 rpm and reaction temperature 65 °C. The yield of the biodiesel produced under optimal condition was 95-96%. It was noted that greater or lower the concentration of KOH or methanol than the optimal values, the reaction either did not fully occur or lead to soap formation.The quality of the biodiesel produced was evaluated by the determinations of important properties such as density, specific gravity, kinematic viscosity, higher heating value, acid value, flash point, pour point, cloud point, combustion point, cold filter plugging point, cetane index, ash content, sulphur content, water content, copper strip corrosion value, distillation temperature and fatty acid composition. The produced biodiesel was found to exhibit fuel properties within the limits prescribed by the latest American Standards for Testing Material (ASTM) and European EN standards.     

Pilot plant studies of biodiesel production using Brassica carinata as raw material

In recent years, the development of alternative fuels from renewable resources, like biomass, has received considerable attention. Biodiesel is defined as fatty acid methyl or ethyl esters from vegetable oils, when it is used as fuel in diesel engines and heating systems.

In this context, the cultivation of Brassica carinata as oilseed crop for biodiesel production in the south of Europe (Spain and Italy) and north of Africa has gained special interest, since it allows the use of set-aside lands, giving higher yields per hectare than the traditional Spanish crops.

Methyl or ethyl esters are the product of transesterification of vegetable oils with alcohol (methanol/ethanol) using an alkaline catalyst. In addition, the process yields glycerol, which has large applications in the pharmaceutical, food and plastics industries.

In the present work, the process of biodiesel production for pilot plant using B. Carinata oil as raw materials with methanol and using potassium hydroxide as catalyst has been studied.

The biodiesel quality meets European specifications defined by pr EN 14214:2002 (E). The obtained results have been used for industrial scale up of the process.     

Nitration of biodiesel of waste oil: Nitrated biodiesel as a cetane number enhancer

Biodiesel has been produced by transesterification of waste frying oil with methanol catalysed by sodium methoxide. The unsaturated fatty acid methyl esters of the biodiesel produced have been nitrated by two alternative nitration methods, showing an incorporation of nitrogen between 3.43 and 5.10 wt.%, in the chemical form of nitro, nitrate and acetoxy functional groups. A detailed gas chromatography–mass spectrometry analysis has been carried out on the nitrated biodiesel samples in order to identify the nitration products of this complex mixture. The nitrated biodiesel has been added to a base diesel fuel in a 1000 mg L⁻¹ concentration resulting in an increase of the cetane number of the fuel by more than five points, from 54.7 to 60.5.     

Potassium hydroxide catalyst supported on palm shell activated carbon for transesterification of palm oil

In this study, potassium hydroxide catalyst supported on palm shell activated carbon was developed for transesterification of palm oil. The Central Composite Design (CCD) of the Response Surface Methodology (RSM) was employed to investigate the effects of reaction temperature, catalyst loading and methanol to oil molar ratio on the production of biodiesel using activated carbon supported catalyst. The highest yield was obtained at 64.1 °C reaction temperature, 30.3 wt.% catalyst loading and 24:1 methanol to oil molar ratio. The physical and chemical properties of the produced biodiesel met the standard specifications. This study proves that activated carbon supported potassium hydroxide is an effective catalyst for transesterification of palm oil.     

The production of fatty acid isopropyl esters and their use as a diesel engine fuel

Biodiesel is an alternative fuel for diesel engines that consists of the monoalkyl esters of vegetable oils or animal fats. Currently, most biodiesel consists of methyl esters, which have poor cold-flow properties. Methyl esters of soybean oil will crystallize and plug fuel filters and lines at about 0°C. However, isopropyl esters have better cold-flow properties than methyl esters. This paper describes the production of isopropyl esters and their evaluation in a diesel engine. The effects of the alcohol amount, the catalyst amount, and two different catalysts on producing quality biodiesel were studied. Both sodium isopropoxide and potassium isopropoxide were found to be suitable for use in the transesterification process. A 20∶1 alcohol/TG molar ratio and a catalyst amount equal to 1% by weight (based on the TG amount) of sodium metal was the most cost-effective way to produce biodiesel fuel. The emissions from a diesel engine running on isopropyl esters made from soybean oil and yellow grease were investigated by comparing them with No. 2 diesel fuel and methyl esters. For nitrogen oxide emission, the difference between the biodiesel produced from soybean oil and yellow grease was greater than the difference between the methyl and isopropyl esters of both feedstocks. The other emissions from using isopropyl esters were about 50% lower in hydrocarbons, 10–20% lower in carbon monoxide, and 40% lower in smoke number when compared with No. 2 diesel fuel.     

Low-temperature property and engine performance evaluation of ethyl and isopropyl esters of tallow and grease

Three monoalkyl fatty acid esters derived from tallow and grease were prepared by lipase-catalyzed transesterification and evaluated as prospective diesel engine fuels. The low-temperature properties of the esters, both neat and as 20% blends in No. 2 diesel fuel, were evaluated. Those properties included cloud point, pour point, cold filter plugging point, low-temperature flow test, and crystallization onset temperature. Other properties of the esters, such as kinematic viscosity, heating value, and calculated cetane number, also were determined. All three esters had acceptable physical and low-temperature properties, as well as acceptable fuel properties at the 20% level in diesel blends. Engine performance and emissions for the ester blends were determined in a direct-injection, matched two-cylinder diesel engine. Among the monoalkyl esters studied, ethyl greasate had better properties and engine performance characteristics than the two tallow esters. For the latter esters, isopropyl tallowate had better properties than ethyl tallowate. Presented in part at the 88th Annual Meeting of American Oil Chemists’ Society, Seattle, WA, May 1997.     

Evaluation of Methyl Esters of Mahua Oil (<Emphasis Type="Italic">Madhuca Indica</Emphasis>) as Diesel Fuel

There is increasing interest in India for suitable alternative fuels that are environment friendly. This search has led to mahua oil (MO) as one alternative for diesel fuel in India. Mahua oil methyl esters (MOME) were prepared by transesterification using potassium hydroxide (KOH) as catalyst and nuclear magnetic resonance (NMR) testing was done to determine the conversion of vegetable oil to biodiesel (MOME). The properties of MOME were close to those of diesel oil. Engine testing was conducted using a single-cylinder 4-stroke direct-injection, constant-speed compression-ignition diesel engine using MO, MOME and B20 as fuels. The engine ran smoothly with MOME and B20, but heavy smoke emissions were observed when MO was used as fuel.     

Low-temperature property and engine performance evaluation of ethyl and isopropyl esters of tallow and grease

Three monoalkyl fatty acid esters derived from tallow and grease were prepared by lipase-catalyzed transesterification and evaluated as prospective diesel engine fuels. The low-temperature properties of the esters, both neat and as 20% blends in No. 2 diesel fuel, were evaluated. Those properties included cloud point, pour point, cold filter plugging point, low-temperature flow test, and crystallization onset temperature. Other properties of the esters, such as kinematic viscosity, heating value, and calculated cetane number, also were determined. All three esters had acceptable physical and low-temperature properties, as well as acceptable fuel properties at the 20% level in diesel blends. Engine performance and emissions for the ester blends were determined in a direct-injection, matched two-cylinder diesel engine. Among the monoalkyl esters studied, ethyl greasate had better properties and engine performance characteristics than the two tallow esters. For the latter esters, isopropyl tallowate had better properties than ethyl tallowate. Presented in part at the 88th Annual Meeting of American Oil Chemists’ Society, Seattle, WA, May 1997.     

Biodiesel production using tetramethyl- and benzyltrimethyl ammonium hydroxides as strong base catalysts

In recent years, the acceptance of fatty acid methyl esters (biodiesel) as an alternative fuel has rapidly grown in EU. The most common method for biodiesel production is based on triglyceride transesterification to methyl esters with dissolved sodium hydroxide in methanol as catalyst. In this study, cottonseed oil and used frying oil were subjected to the transesterification reaction with tetramethyl ammonium hydroxide and benzyltrimethyl ammonium hydroxide as strong base catalysts. This work investigates the optimum conditions for biodiesel production using amine-based liquid catalysts. Biodiesel ester content was strongly related with the type of feedstock and the reaction variables, such as those of the catalyst concentration, methanol to oil molar ratio, and reaction time. The overall results suggested that the transesterification of cottonseed oil achieved high conversion rates with both catalysts, while the use of waste oil resulted in lower yields of methyl esters due to the possible formation of amides.     

Production and characterization of biodiesel from trap grease

The feasibility of the production of biodiesel from trap grease containing 51.5% free fatty acids (FFAs) was investigated. The esterification of FFAs by an acid catalyst followed by the transesterification of triglycerides by an alkali catalyst was examined. The esterification of trap grease by sulfuric acid as a homogeneous catalyst or by Amberlyst-15 as a heterogeneous catalyst was optimized through a response surface methodology. After the two-step esterification of trap grease by sulfuric acid, the acid value decreased from 102.9 mg KOH/g to 2.75 mg KOH/g. Through the transesterification by potassium hydroxide, fatty acid methyl ester (FAME) content reached 92.4%. Following the esterification of trap grease by Amberlyst-15, the acid value decreased to 3.23 mg KOH/g. With the transesterification by potassium hydroxide, FAME content increased to 94.1%. After the distillation of the produced biodiesel, FAME content increased again, to 97.6%. The oxidation stability of the trap grease biodiesel was 0.17 h, and its cold filter plugging point was 4 °C. As the FAME content of the trap grease biodiesel satisfies the Korean Biodiesel Standard, the trap grease biodiesel seems to be applicable for use as an engine fuel after properties improvement.     

An ideal feedstock, kusum (Schleichera triguga) for preparation of biodiesel: Optimization of parameters

Kusum (Schleichera triguga), a non-edible oil bearing plant has been used as an ideal feedstock for biodiesel development in the present study. Various physical and chemical parameters of the raw oil and the fatty acid methyl esters derived have been tested to confirm its suitability as a biodiesel fuel. The fatty acid component of the oil was tested by gas chromatography. The acid value of the oil was determined by titration and was found to 21.30 mg KOH/g which required two step transesterification. Acid value was brought down by esterification using sulfuric acid (H₂SO₄) as a catalyst. Thereafter, alkaline transesterification was carried out using potassium hydroxide (KOH) as catalyst for conversion of kusum oil to its methyl esters. Various parameters such as molar ratio, amount of catalyst and reaction time were optimized and a high yield (95%) of biodiesel was achieved. The high conversion of the feedstock into esters was confirmed by analysis of the product on gas chromatograph-mass spectrometer (GC-MS). Viscosity and acid value of the product biodiesel were determined and found to be within the limits of ASTM D 6751 specifications. Elemental analysis of biodiesel showed presence of carbon, hydrogen, oxygen and absence of nitrogen and sulfur after purification. Molar ratio of methanol to oil was optimized and found to be 10:1 for acid esterification, and 8:1 for alkaline transesterification. The amounts of H₂SO₄ and KOH, 1% (v/v) and 0.7% (w/w), respectively, were found to be optimum for the reactions. The time duration of 1 h for acid esterification followed by another 1 h for alkaline transesterification at 50 ± 0.5 °C was optimum for synthesis of biodiesel.     

Characterization of <Emphasis Type="Italic">Annona cherimola</Emphasis> Mill. Seed Oil from Madeira Island: a Possible Biodiesel Feedstock

The possibility of using Annona seed oil as an added value product, namely as a source of biodiesel, is explored. Milled Annona seeds were extracted with hexane at room temperature (72 h) and at solvent boiling point (6 h). Oil content was found to be 25 and 22.4% respectively. The oil was characterized in terms of lipid composition (HPLC–APCI–MS and ¹³C NMR), resistance to oxidation and acidity index. FAME composition was determined by GC–MS and five major peaks were identified. Production of biodiesel from Annona’s seed oil was achieved by base-catalyzed transesterification. Density, viscosity, refraction coefficient, acid value, cold filter plugging point, cloud point and oxidation stability were measured. The iodine value and the “apparent cetane number” were calculated. Density, viscosity, acid value, iodine value, cold filter plugging point and cloud point were within EN14214 specifications and the calculated “apparent cetane number” was also indicative of a suitable product.     

Application of response surface methodology for optimization of biodiesel production by transesterification of soybean oil with ethanol

In this paper, the transesterification of soybean oil with ethanol is studied. The transesterification process can be affected by differing parameters. The biodiesel production process was optimized by the application of factorial design 2⁴ and response surface methodology. The combined effects of temperature, catalyst concentration, reaction time and molar ratio of alcohol in relation to oil were investigated and optimized using response surface methodology. Optimum conditions for the production of ethyl esters were the following: mild temperature at 56.7 °C, reaction time in 80 min, molar ratio at 9:1 and catalyst concentration of 1.3 M.     

Alkali catalyzed transesterification of safflower seed oil assisted by microwave irradiation

The safflower (Carthamus tinctorius L.) oil was extracted from the seeds of the safflower that grows in Diyarbakir, SE Anatolia of Turkey. Biodiesel has been prepared from safflower seed by transesterification of the crude oil under microwave irradiation, with methanol to oil molar ratio of 10:1, in the presence of 1.0% NaOH as catalyst. The conversion of C. tinctorius oil to methyl ester was over 98.4% at 6 min. The important fuel properties of safflower oil and its methyl ester (biodiesel) such as density, kinematic viscosity, flash point, iodine number, neutralization number, pour point, cloud point, cetane number are found out and compared to those of no. 2 petroleum diesel, ASTM and EN biodiesel standards. Compared with conventional heating methods, the process using microwaves irradiation proved to be a faster method for alcoholysis of triglycerides with methanol, leading to high yields of biodiesel.     

Transesterification of neat and used frying oil: Optimization for biodiesel production

In this study, the characteristics and performance of three commonly used catalysts used for alkaline-catalyzed transesterification i.e. sodium hydroxide, potassium hydroxide and sodium methoxide, were evaluated using edible Canola oil and used frying oil. The fuel properties of biodiesel produced from these catalysts, such as ester content, kinematic viscosity and acid value, were measured and compared. With intermediate catalytic activity and a much lower cost sodium hydroxide was found to be more superior than the other two catalysts. The process variables that influence the transesterification of triglycerides, such as catalyst concentration, molar ratio of methanol to raw oil, reaction time, reaction temperature, and free fatty acids content of raw oil in the reaction system, were investigated and optimized. This paper also studied the influence of the physical and chemical properties of the feedstock oils on the alkaline-catalyzed transesterification process and determined the optimal transesterification reaction conditions that produce the maximum ester content and yield.