Acid-catalyzed production of biodiesel from waste frying oil

The reaction kinetics of acid-catalyzed transesterification of waste frying oil in excess methanol to form fatty acid methyl esters (FAME), for possible use as biodiesel, was studied. Rate of mixing, feed composition (molar ratio oil:methanol:acid) and temperature were independent variables. There was no significant difference in the yield of FAME when the rate of mixing was in the turbulent range 100 to 600 rpm. The oil:methanol:acid molar ratios and the temperature were the most significant factors affecting the yield of FAME. At 70 °C with oil:methanol:acid molar ratios of 1:245:3.8, and at 80 °C with oil:methanol:acid molar ratios in the range 1:74:1.9–1:245:3.8, the transesterification was essentially a pseudo-first-order reaction as a result of the large excess of methanol which drove the reaction to completion (99±1% at 4 h). In the presence of the large excess of methanol, free fatty acids present in the waste oil were very rapidly converted to methyl esters in the first few minutes under the above conditions. Little or no monoglycerides were detected during the course of the reaction, and diglycerides present in the initial waste oil were rapidly converted to FAME.     

Biodiesel production by esterification of palm fatty acid distillate

Production of fatty acid methyl ester (FAME) from palm fatty acid distillate (PFAD) having high free fatty acids (FFA) was investigated in this work. Batch esterifications of PFAD were carried out to study the influence of: including reaction temperatures of 70–100 °C, molar ratios of methanol to PFAD of 0.4:1–12:1, quantity of catalysts of 0–5.502% (wt of sulfuric acid/wt of PFAD) and reaction times of 15–240 min. The optimum condition for the continuous esterification process (CSTR) was molar ratio of methanol to PFAD at 8:1 with 1.834 wt% of H₂SO₄ at 70 °C under its own pressure with a retention time of 60 min. The amount of FFA was reduced from 93 wt% to less than 2 wt% at the end of the esterification process. The FAME was purified by neutralization with 3 M sodium hydroxide in water solution at a reaction temperature of 80 °C for 15 min followed by transesterification process with 0.396 M sodium hydroxide in methanol solution at a reaction temperature of 65 °C for 15 min. The final FAME product met with the Thai biodiesel quality standard, and ASTM D6751-02.     

Comparison of biodiesel production from crude Jatropha oil and Krating oil by supercritical methanol transesterification

This work compared the production of biodiesel from two different non-edible oils with relatively high acid values (Jatropha oil and Krating oil). Using non-catalytic supercritical methanol transesterification, high methyl ester yield (85–90%) can be obtained in a very short time (5–10 min). However, the dependence of fatty acid methyl ester yield on reaction conditions (i.e., temperature and pressure) and the optimum conditions were different by the source of oils and were correlated to the amount of free fatty acids (FFAs) and unsaturated fatty acid content in oils. Krating oil, which has higher FFAs and unsaturated fatty acid content, gave higher fatty acid methyl ester yield of 90.4% at 260 °C, 16 MPa, and 10 min whereas biodiesel from Jatropha oil gave fatty acid methyl ester yield of 84.6% at 320 °C, 15 MPa and 5 min using the same molar ratio of methanol to oil 40:1. The product quality from crude Krating oil met the biodiesel standard. Pre-processing steps such as degumming or oil purification are not necessary.     

Biodiesel production from jatropha oil (Jatropha curcas) with high free fatty acids: An optimized process

Response surface methodology (RSM) based on central composite rotatable design (CCRD) was used to optimize the three important reaction variables—methanol quantity (M), acid concentration (C) and reaction time (T) for reduction of free fatty acid (FFA) content of the oil to around 1% as compared to methanol quantity (M′) and reaction time (T′) and for carrying out transesterification of the pretreated oil. Using RSM, quadratic polynomial equations were obtained for predicting acid value and transesterification. Verification experiments confirmed the validity of both the predicted models. The optimum combination for reducing the FFA of Jatropha curcas oil from 14% to less than 1% was found to be 1.43% v/v H₂SO₄ acid catalyst, 0.28 v/v methanol-to-oil ratio and 88-min reaction time at a reaction temperature of 60 °C as compared to 0.16 v/v methanol-to-pretreated oil ratio and 24 min of reaction time at a reaction temperature of 60 °C for producing biodiesel. This process gave an average yield of biodiesel more than 99%. The fuel properties of jatropha biodiesel so obtained were found to be comparable to those of diesel and confirming to the American and European standards.     

Optimization of transesterification conditions for the production of fatty acid methyl ester (FAME) from Chinese tallow kernel oil with surfactant-coated lipase

Surfactant-coated lipase was used as a catalyst in preparing fatty acid methyl ester (FAME) from Chinese tallow kernel oil from Sapium sebiferum (L.) Roxb. syn. Triadica sebifera (L.) small. FAME transesterification was analyzed using response surface methodology to find out the effect of the process variables on the esterification rate and to establish prediction models. Reaction temperature and time were found to be the main factors affecting the esterification rate with the presence of surfactant-coated lipase. Developed prediction models satisfactorily described the esterification rate as a function of reaction temperature, time, dosage of surfactant-coated lipase, ratio of methanol to oil, and water content. The FAME mainly contained fatty acid esters of C16:0, C18:0, C18:1, C18:2, and C18:3, determined by a gas chromatograph. The optimal esterification rate was 93.86%. The optimal conditions for the above esterification ratio were found to be a reaction time of 9.2 h, a reaction temperature of 49 °C, dosage of surfactant-coated lipase of 18.5%, a ratio of methanol to oil of 3:1, and water content of 15.6%. Thus, by using the central composite design, it is possible to determine accurate values of the transesterification parameters where maximum production of FAME occurs using the surfactant-coated lipase as a transesterification catalyst.     

Production of FAME by palm oil transesterification via supercritical methanol technology

The present study employed non-catalytic supercritical methanol technology to produce biodiesel from palm oil. The research was carried out in a batch-type tube reactor and heated beyond supercritical temperature and pressure of methanol, which are at 239 °C and 8.1 MPa respectively. The effects of temperature, reaction time and molar ratio of methanol to palm oil on the yield of fatty acid methyl esters (FAME) or biodiesel were investigated. The results obtained showed that non-catalytic supercritical methanol technology only required a mere 20 min reaction time to produce more than 70% yield of FAME. Compared to conventional catalytic methods, which required at least 1 h reaction time to obtain similar yield, supercritical methanol technology has been shown to be superior in terms of time and energy consumption. Apart from the shorter reaction time, it was found that separation and purification of the products were simpler since no catalyst is involved in the process. Hence, formation of side products such as soap in catalytic reactions does not occur in the supercritical methanol method.     

Biodiesel production from palm oil via heterogeneous transesterification

This paper presents the study of the transesterification of palm oil via heterogeneous process using montmorillonite KSF as heterogeneous catalyst. This study was carried out using a design of experiment (DOE), specifically response surface methodology (RSM) based on four-variable central composite design (CCD) with α (alpha) = 2. The transesterification process variables were reaction temperature, x₁ (50–190 °C), reaction period, x₂ (60–300 min), methanol/oil ratio, x₃ (4–12 mol mol^?1) and amount of catalyst, x₄ (1–5 wt%). It was found that the yield of palm oil fatty acid methyl esters (FAME) could reach up to 79.6% using the following reaction conditions: reaction temperature of 190 °C, reaction period at 180 min, ratio of methanol/oil at 8:1 mol mol^?1 and amount of catalyst at 3%.     

Coriander seed oil methyl esters as biodiesel fuel: Unique fatty acid composition and excellent oxidative stability

Coriander (Coriandrum sativum L.) seed oil methyl esters were prepared and evaluated as an alternative biodiesel fuel and contained an unusual fatty acid hitherto unreported as the principle component in biodiesel fuels: petroselinic (6Z-octadecenoic; 68.5 wt%) acid. Most of the remaining fatty acid profile consisted of common 18 carbon constituents such as linoleic (9Z,12Z-octadeca-dienoic; 13.0 wt%), oleic (9Z-octadecenoic; 7.6 wt%) and stearic (octadecanoic; 3.1 wt%) acids. A standard transesterification procedure with methanol and sodium methoxide catalyst was used to provide C. sativum oil methyl esters (CSME). Acid-catalyzed pretreatment was necessary beforehand to reduce the acid value of the oil from 2.66 to 0.47 mg g^?1. The derived cetane number, kinematic viscosity, and oxidative stability (Rancimat method) of CSME was 53.3, 4.21 mm² s^?1 (40 °C), and 14.6 h (110 °C). The cold filter plugging and pour points were ?15 °C and ?19 °C, respectively. Other properties such as acid value, free and total glycerol content, iodine value, as well as sulfur and phosphorous contents were acceptable according to the biodiesel standards ASTM D6751 and EN 14214. Also reported are lubricity, heat of combustion, and Gardner color, along with a comparison of CSME to soybean oil methyl esters (SME). CSME exhibited higher oxidative stability, superior low temperature properties, and lower iodine value than SME. In summary, CSME has excellent fuel properties as a result of its unique fatty acid composition.     

Biodiesel from palm oil via loading KF/Ca–Al hydrotalcite catalyst

The solid base catalyst KF/Ca–Al hydrotalcite was obtained from Ca–Al layered double hydroxides and successfully used in the transesterification of methanol with palm oil to produce biodiesel. With the load of KF, the activity of Ca–Al mixed-oxides had been improved much. For the mass ratio 80 wt.%(KF·6H₂O to Ca–Al mixed-oxides) catalyst, under the optimal condition: 338 K, catalyst amount 5%(wt./wt. oil) and methanol/oil molar ratio 12:1, after 5 h reaction, the fatty acid methyl esters yield could reach 97.98%; for the mass ratio 100 wt.%(KF·6H₂O to Ca–Al mixed-oxides) ones, under the same reaction condition, only needed 3 h to get the FAME yield of 99.74%, and even only reacted 1 h, the FAME yield could obtain 97.14%.     

Effects of water on the esterification of free fatty acids by acid catalysts

To maximize the production of biodiesel from soybean soapstock, the effects of water on the esterification of high-FFA (free fatty acid) oils were investigated. Oleic acid and high acid acid oil (HAAO) were esterified by reaction with methanol in the presence of Amberlyst-15 as a heterogeneous catalyst or sulfuric acid as a homogeneous catalyst. The yield of fatty acid methyl ester (FAME) was studied at oil to methanol molar ratios of 1:3 and 1:6 and reaction temperatures of 60 and 80 °C. The rate of esterification of oleic acid significantly decreased as the initial water content increased to 20% of the oil. The activity of Amberlyst-15 decreased more rapidly than that of sulfuric acid, due to the direct poisoning of acid sites by water. Esterification using sulfuric acid was not affected by water until there was a 5% water addition at a 1:6 molar ratio of oil to methanol. FAME content of HAAO prepared from soapstock rapidly increased for the first 30 min of esterification. Following the 30-min mark, the rate of FAME production decreased significantly due to the accumulation of water. When methanol and Amberlyst-15 were removed from the HAAO after 30 min of esterification and fresh methanol and a catalyst were added, the time required to reach 85% FAME content was reduced from 6 h to 1.8 h.     

Biodiesel fuel production with solid amorphous-zirconia catalysis in fixed bed reactor

Amorphous zirconia catalysts, titanium-, aluminum-, and potassium-doped zirconias, were prepared and evaluated in the transesterification of soybean oil with methanol at 250 °C, and the esterification of n-octanoic acid with methanol at 175–200 °C. Titanium- and aluminum-doped zirconias are promising solid catalysts for the production of biodiesel fuels from soybean oil because of their high performance, with over 95% conversion in both of the esterifications.     

Continuous esterification for biodiesel production from palm fatty acid distillate using economical process

An overflow system for continuous esterification of palm fatty acid distillate (PFAD) using an economical process was developed using a continuous stirred tank reactor (CSTR). Continuous production compared to batch production at the same condition had higher product purity. The optimum condition for the esterification process was a 8.8:1:0.05 molar ratio of methanol to PFAD to sulfuric acid catalyst, 60 min of residence time at 75 °C under its own pressure. The free fatty acid (FFA) content in the PFAD was reduced from 93 to less than 1.5%wt by optimum esterification. The esterified product had to be neutralized with 10.24%wt of 3 M sodium hydroxide in water solution at a reaction temperature of 80 °C for 20 min to reduce the residual FFA and glycerides. The components and properties of fatty acid methyl ester (FAME) could meet the standard requirements for biodiesel fuel. Eventually the production costs were calculated to disclose its commercialization.     

Optimization of conditions for the extraction of phorbol esters from Jatropha oil

The production of Jatropha curcas seeds as a biodiesel feedstock is expected to reach 160 Mt by 2017. The present study aims at extracting phorbol esters (PEs) as a co-product from Jatropha oil before processing it to biodiesel. The conditions were optimized for extraction of PEs in organic solvents by using a magnetic stirrer and an Ultra turrax. The extent of reduction in PEs was >99.4% in methanol using any of the stirring tools. However, the extraction using Ultra turrax affected considerably the colour of the remaining oil. Therefore, further solvent:oil ratio, time and temperature were optimized using a magnetic stirrer to get PE rich fraction-I (48.4 mg PEs g^?1) and virtually PE-free oil. PEs were 14 fold higher in this fraction than the control oil. PEs, extracted in methanol from the untreated Jatropha oil, at 1 mg L^?1 produced 100% mortality in snails (Physa fontinalis). The methanol extract from virtually PE-free oil when concentrated 20 and 25 time the untreated Jatropha oil (equivalent of 20 mg L^?1 and 25 mg L^?1 PEs in the control oil) was nontoxic to snails. PE rich fraction-I, obtained as a co-product, can be used in agricultural, medicinal and pharmaceutical applications and the remaining oil can be used for biodiesel preparation. The remaining oil will be friendly to the environment and workers.     

Biodiesel production through transesterification of triolein with various alcohols in an ultrasonic field

The biodiesel production through transesterification of triolein with various alcohols such as methanol, ethanol, propanol, butanol, hexanol, octanol and decanol was investigated at molar ratio 6:1 (alcohol:triolein) and 25 °C in the presence of base catalysts (NaOH and KOH) under ultrasonic irradiation (40 kHz) and mechanical stirring (1800 rot/min) conditions. It was found that the rate of the alkyl ester formation under the ultrasonic irradiation condition was higher than that under the stirring condition. In addition, it was confirmed that the rate depended upon the kind of alcohols; as the number of carbon in alcohol increased, the rate of the ester formation tended to decrease. On the other hand, the secondary alcohols such as 2-propanol, 2-butanol, 2-hexanol, and 2-octanol showed little ester conversion, suggesting that the steric hindrance strongly affected the transesterification of triolein.     

An experimental comparison of transesterification process with different alcohols using acid catalysts

Vegetable oils and animal fats in their raw form have high viscosities that makes them unsuitable as fuels for diesel engines. Transesterification is one of the well-known processes by which fats and oils are converted into biodiesel. The reaction often makes use of acid/base catalyst. If the material possesses high free fatty acid then acid catalyst gives better results. In the present investigation, Mahua oil having 14% free fatty acid was transesterifed to obtain biodiesel using acid catalysts with different alcohols. The alcohols used were Methanol, Ethanol and Butanol. The objective of using higher alcohol is to find their effect on ester yield. The process optimization was made based on the maximum ester yield. The results show that transesterification with butanol gives a better yield compared to methanol and ethanol. The transesterification results show that higher catalyst concentration by 6–10% Vol. produces biodiesel with lower viscosity, lower specific gravity with a higher yield (short reaction time of 5 hours). The best process condition with butanol was found to be 6% Vol. of sulfuric acid with 150% excess butanol, which gave an yield of around 95.4% in a reaction time of 5 hours. The prepared biodiesels were tested as per the standard and were found to be satisfactory.     

Biodiesel production from Jatropha curcas oil

In view of the fast depletion of fossil fuel, the search for alternative fuels has become inevitable, looking at huge demand of diesel for transportation sector, captive power generation and agricultural sector, the biodiesel is being viewed a substitute of diesel. The vegetable oils, fats, grease are the source of feedstocks for the production of biodiesel. Significant work has been reported on the kinetics of transesterification of edible vegetable oils but little work is reported on non-edible oils. Out of various non-edible oil resources, Jatropha curcas oil (JCO) is considered as future feedstocks for biodiesel production in India and limited work is reported on the kinetics of transesterification of high FFA containing oil. The present study reports a review of kinetics of biodiesel production. The paper also reveals the results of kinetics study of two-step acid–base catalyzed transesterification process carried out at pre-determined optimum temperature of 65 and 50 °C for esterification and transesterification process, respectively, under the optimum condition of methanol to oil ratio of 3:7 (v/v), catalyst concentration 1% (w/w) for H₂SO₄ and NaOH and 400 rpm of stirring. The yield of methyl ester (ME) has been used to study the effect of different parameters. The maximum yield of 21.2% of ME during esterification and 90.1% from transesterification of pretreated JCO has been obtained. This is the first study of its kind dealing with simplified kinetics of two-step acid–base catalyzed transesterification process carried at optimum temperature of both the steps which took about 6 h for complete conversion of TG to ME.     

Application of response surface methodology for optimizing transesterification of Moringa oleifera oil: Biodiesel production

Response surface methodology (RSM), with central composite rotatable design (CCRD), was used to explore optimum conditions for the transesterification of Moringa oleifera oil. Effects of four variables, reaction temperature (25–65 °C), reaction time (20–90 min), methanol/oil molar ratio (3:1–12:1) and catalyst concentration (0.25–1.25 wt.% KOH) were appraised. The quadratic term of methanol/oil molar ratio, catalyst concentration and reaction time while the interaction terms of methanol/oil molar ratio with reaction temperature and catalyst concentration, reaction time with catalyst concentration exhibited significant effects on the yield of Moringa oil methyl esters (MOMEs)/biodiesel, p < 0.0001 and p < 0.05, respectively. Transesterification under the optimum conditions ascertained presently by RSM: 6.4:1 methanol/oil molar ratio, 0.80% catalyst concentration, 55 °C reaction temperature and 71.08 min reaction time offered 94.30% MOMEs yield. The observed and predicted values of MOMEs yield showed a linear relationship. GLC analysis of MOMEs revealed oleic acid methyl ester, with contribution of 73.22%, as the principal component. Other methyl esters detected were of palmitic, stearic, behenic and arachidic acids. Thermal stability of MOMEs produced was evaluated by thermogravimetric curve. The fuel properties such as density, kinematic viscosity, lubricity, oxidative stability, higher heating value, cetane number and cloud point etc., of MOMEs were found to be within the ASTM D6751 and EN 14214 biodiesel standards.     

Lithium ion impregnated calcium oxide as nano catalyst for the biodiesel production from karanja and jatropha oils

Lithium impregnated calcium oxide has been prepared by wet impregnation method in nano particle form as supported by powder X-ray diffraction and transmission electron microscopy. Basic strength of the same was measured by Hammett indicators. Calcium oxide impregnated with 1.75 wt% of lithium was used as solid catalyst for the transesterification karanja and jatropha oil, containing 3.4 and 8.3 wt% of free fatty acids, respectively. The reaction parameters, viz., reaction temperature, alcohol to oil molar ratio, free fatty acid contents, amount of catalyst and amount of impregnated lithium ion in calcium oxide support, have been studied to establish the most suitable condition for the transesterification reaction. The complete transesterification of karanja and jatropha oils was achieved in 1 and 2 h, respectively, at 65 °C, utilizing 12:1 molar ratio of methanol to oil and 5 wt% (catalyst/oil, w/w) of catalyst. Few physicochemical properties of the prepared biodiesel samples have been studied and compared with standard values.     

Biomass estimates,characteristics, biochemical methane potential,kinetics and energy flow from Jatropha curcus on dry lands

In this study, we examined the production of Jatropha curcus plants on 1 ha of rain fed dry lands. All of the plant components that would result from plantation tending, fruit harvesting and processing were sampled for their yield and chemical composition, and then subjected to the biochemical methane potential (BMP) assay. The component parts exhibited significant variation in BMP which was reflected in their ultimate methane yield which ranged from 0.08 to 0.97 L g^?1 VS added, and their first order kinetics which ranged from 0.07 to 0.14 d^?1. We examined two integrated utilization schemes: the first which converted plant prunings, fruit hulls and de-oiled seed cake to methane, and the oil to fatty acid methyl-ester (FAME); the second was to convert the seeds, plant prunings and fruit hulls entirely to methane. The basis for the plantation was, a density of 4444 plant ha^?1 (1.5 m × 1.5 m spacing), with a seed yield of 0.911 kg TS plant^?1 (1 kg total weight) with an oil content of 35% providing an annual oil yield of 1.42 t y^?1. The corresponding yields of pruned leaves, fruit hulls and de-oiled cake are 0.97, 1.0, and 2.35 t VS ha y^?1, respectively. An integrated scheme of producing biogas by means of anaerobic digestion of the latter components and oil for biodiesel would produce 90 GJ ha^?1 y^?1 in total with the oil being 54 GJ. The alternative biogas only option which would convert the seed oil into methane instead of biodiesel would produce 97 GJ ha^?1 y^?1.     

Pool boiling of R-123/oil mixtures on enhanced tubes having different pore sizes

The effect of enhanced geometry (pore diameter, gap width) is investigated on the pool boiling of R-123/oil mixture for the enhanced tubes having pores with connecting gaps. Tubes having different pore diameters (and corresponding gap widths) are specially made. Significant heat transfer degradation by oil is observed for the present enhanced tubes. At 5% oil concentration, the degradation is 26–49% for T_sat = 4.4 °C. The degradation increases 50–67% for T_sat = 26.7 °C. The heat transfer degradation is significant even with small amount of oil (20–38% degradation at 1% oil concentration for T_sat = 4.4 °C), probably due to the accumulation of oil in sub-tunnels. The pore size (or gap width) has a significant effect on the heat transfer degradation. The maximum degradation is observed for d_p = 0.20 mm tube at T_sat = 4.4 °C, and d_p = 0.23 mm tube at T_sat = 26.7 °C. The minimum degradation is observed for d_p = 0.27 mm tube for both saturation temperatures. It appears that the oil removal is facilitated for the larger pore diameter (along with larger gap) tube. The highest heat transfer coefficient with oil is obtained for d_p = 0.23 mm tube, which yielded the highest heat transfer coefficient for pure R-123. The optimum tube significantly (more than 3 times) outperforms the smooth tube even with oil. The heat transfer degradation increases as the heat flux decreases.