Biodiesel production from high FFA rubber seed oil

Currently, most of the biodiesel is produced from the refined/edible type oils using methanol and an alkaline catalyst. However, large amount of non-edible type oils and fats are available. The difficulty with alkaline-esterification of these oils is that they often contain large amounts of free fatty acids (FFA). These free fatty acids quickly react with the alkaline catalyst to produce soaps that inhibit the separation of the ester and glycerin. A two-step transesterification process is developed to convert the high FFA oils to its mono-esters. The first step, acid catalyzed esterification reduces the FFA content of the oil to less than 2%. The second step, alkaline catalyzed transesterification process converts the products of the first step to its mono-esters and glycerol. The major factors affect the conversion efficiency of the process such as molar ratio, amount of catalyst, reaction temperature and reaction duration is analyzed. The two-step esterification procedure converts rubber seed oil to its methyl esters. The viscosity of biodiesel oil is nearer to that of diesel and the calorific value is about 14% less than that of diesel. The important properties of biodiesel such as specific gravity, flash point, cloud point and pour point are found out and compared with that of diesel. This study supports the production of biodiesel from unrefined rubber seed oil as a viable alternative to the diesel fuel.     

Conventional and in situ transesterification of sunflower seed oil for the production of biodiesel

In the present work the alkaline transesterification of sunflower seed oil with methanol and ethanol, for the production of biodiesel fuel was studied. Both conventional and in situ transesterification were investigated using low frequency ultrasonication (24 kHz) and mechanical stirring (600 rpm). Use of ultrasonication in conventional transesterification with methanol gave high yields of methyl esters (95%) after a short reaction time (20 min) similar to those using mechanical stirring. Use of ultrasonication in conventional transesterification with ethanol gave similar yields to those using mechanical stirring but significantly lower than respective yields using methanol. In the in situ transesterification the use of ultrasonication and mechanical stirring led to similar high yields (95%) of methyl esters after approximately 20 min of reaction time. In the presence of ethanol use of ultrasonication led to high ester yields (98%) in only 40 min of reaction time while use of mechanical stirring gave lower yields (88%) even after 4 h of reaction time.

 In situ transesterification gave similar ester yields to those obtained by conventional transesterification being an alternative, efficient and economical process. In all cases a concentration of 2.0% NaOH gave higher ester yields.

 Reaction rate constants were calculated, using first order reaction kinetics, to be equal to 3.1 × 10^− 3 s^− 1 for conventional transesterification using methanol and 2.0% NaOH, and 9.5 × 10^− 4 s^− 1 using ethanol.     

Hydroprocessed rapeseed oil as a source of hydrocarbon-based biodiesel

This paper deals with the hydroprocessing of rapeseed oil representing a perspective technological way for production of biocomponents in diesel fuel range. Rapeseed oil was hydroprocessed at various temperatures (260-340 °C) under a pressure of 7 MPa in a laboratory flow reactor. Three Ni-Mo/alumina hydrorefining catalysts were used. Reaction products were analyzed using several gas-chromatographic methods. Reaction products contained water, hydrogen-rich gas and organic liquid product (OLP). The main components of OLP were identified as C₁₇ and C₁₈n-alkanes and i-alkanes. At a low reaction temperature, OLP contained also free fatty acids and triglycerides. At reaction temperatures higher than 310 °C, OLP contained only hydrocarbons of the same nature as hydrocarbons present in diesel fuel. Influence of reaction temperature and catalyst on the composition of reaction products is discussed.     

Preparation of KF/CaO nanocatalyst and its application in biodiesel production from Chinese tallow seed oil

KF/CaO nanocatalyst was prepared by using impregnation method and used to convert Chinese tallow seed oil to biodiesel. The effects of different preparation conditions on biodiesel yield were investigated and the structure of the catalyst was characterized. Transmission electron microscopy (TEM) photograph showed that the catalyst had porous structure with the particle size of 30-100 nm. Brunauer-Emmet-Teller (BET) analysis indicated that the catalyst specific surface area was 109 m² g⁻¹ and average pore size was 97 nm. X-ray diffractometer (XRD) analysis demonstrated that the new crystal KCaF₃ was formed in catalyst, which enhanced catalytic ability. Under the optimal conditions, the biodiesel yield was 96.8% in the presence of as-prepared KF/CaO catalyst, showing potential applications of catalyst in biodiesel industry.     

Solid superacid catalyzed glycerol esterification of free fatty acids in waste cooking oil for biodiesel production

The free fatty acids (FFAs) of waste cooking oil (WCO) are readily esterified with crude glycerol in the presence of the solid superacid SO/ZrO₂–Al₂O₃. This reaction lowers the acidity of WCO before biodiesel production. The solid superacid SO/ZrO₂–Al₂O₃ catalyzes both FFA esterification and TAG glycerolysis during the reaction. The conversion of FFA in the WCO with an acid value of 88.4 ± 0.5 mg KOH/g to acylglycerols was 98.4% under optimal conditions (mole ratio of glycerol to FFA = 1.4:1; reaction time = 4 h; reaction temperature = 200°C; catalyst loading = 0.3 wt%) obtained through an orthogonal experiment. The final FAME product with a FAME content of 96.9 ± 0.3 wt% yield was 94.8 wt%, after transesterification of the esterified WCO with methanol, catalyzed by potassium hydroxide. The FAME composition of the products produced by transesterification were identified and quantified by GC–MS. The results suggest that this new glycerol esterification process, using a solid superacid catalyst, affords a promising method to convert oils with high FFA levels, like WCO, to biodiesel. The process has the inherent advantage of easy separation steps for removing excess alcohol and significant savings in energy, when compared to acid catalyzed reactions with methanol to lower acidity. Practical applications : In this work, WCO with a high acid value was esterified with crude glycerol catalyzed by solid super acid, whose formula was expressed as SO/ZrO₂–Al₂O₃. There are distinct advantages to this new esterification process, which include easy separation of the excess crude glycerol by sedimentation or centrifugation, the use of the low cost reactant crude glycerol direct from the byproducts of transesterification, the potential to achieve a very low content of FFAs by post‐refining to improve the yield of the final product, and time and energy saving are found as compared to the traditional methanol esterification process. This new technology provides a promising alternative method for processing feedstocks of high acid value, such as WCO, for the production of biodiesel.     

Reduction of high content of free fatty acid in sludge palm oil via acid catalyst for biodiesel production

In this study, sulphuric acid (H₂SO₄) was used in the pretreatment of sludge palm oil for biodiesel production by an esterification process, followed by the basic catalyzed transesterification process. The purpose of the pretreatment process was to reduce the free fatty acids (FFA) content from high content FFA (> 23%) of sludge palm oil (SPO) to a minimum level for biodiesel production (> 2%). An acid catalyzed esterification process was carried out to evaluate the low content of FFA in the treated SPO with the effects of other parameters such as molar ratio of methanol to SPO (6:1-14:1), temperature (40-80 °C), reaction time (30-120 min) and stirrer speed (200-800 rpm). The results showed that the FFA of SPO was reduced from 23.2% to less than 2% FFA using 0.75% wt/wt of sulphuric acid with the molar ratio of methanol to oil of 8:1 for 60 min reaction time at 60 °C. The results on the transesterification with esterified SPO showed that the yield (ester) of biodiesel was 83.72% with the process conditions of molar ratio of methanol to SPO 10:1, reaction temperature 60 °C, reaction time 60 min, stirrer speed 400 rpm and KOH 1% (wt/wt). The biodiesel produced from the SPO was favorable as compared to the EN 14214 and ASTM D 6751 standard.     

Cerbera odollam (sea mango) oil as a promising non-edible feedstock for biodiesel production

This paper explores the feasibility of converting Cerbera odollam (sea mango) oil into biodiesel. The first part of this study focused on the extraction of oil from the seeds of C. odollam fruits, whereas the second part focused on the transesterification of the extracted oil to fatty acid methyl esters (FAME). The transesterification reactions were carried out using three different catalysts; sodium hydroxide (NaOH) as a homogenous catalyst, sulfated zirconia alumina and montmorillonite KSF as heterogeneous catalysts. The seeds were found to contain high percentage of oil up to 54% while the yield of FAME can reach up to 83.8% using sulfated zirconia catalyst.     

Biodiesel production from tobacco (Nicotiana tabacum L.) seed oil with a high content of free fatty acids

The production of fatty acid methyl esters (FAME) from crude tobacco seed oil (TSO) having high free fatty acids (FFA) was investigated. Due to its high FFA, the TSO was processed in two steps: the acid-catalyzed esterification (ACE) followed by the base-catalyzed methanolysis (BCM). The first step reduced the FFA level to less than 2% in 25 min for the molar ratio of 18:1. The second step converted the product of the first step into FAME and glycerol. The maximum yield of FAME was about 91% in about 30 min. The tobacco biodiesel obtained had the fuel properties within the limits prescribed by the latest American (ASTM D 6751-02) and European (DIN EN 14214) standards, except a somewhat higher acid value than that prescribed by the latter standard (<0.5). Thus, tobacco seeds (TS), as agricultural wastes, might be a valuable renewable raw material for the biodiesel production.     

Graphical method to select vegetable oils as potential feedstock for biodiesel production

Chemical compositions of 80 vegetable oils were collected from literature and the properties of the obtainable biodiesel (methyl esters) have been predicted by empirical relationships. The purpose has been to check the viability of predicting if a biodiesel could meet the EN 14214 standards knowing only the fatty acid profile (FAP) of the parent oil. Two parameters were used in this investigation: (i) average number of carbon atoms in the fatty acid chains, (ii) average number of double bonds (C?C) per molecule. Two new empirical relationships have been proposed to predict the viscosity and the cetane number of biodiesel from the two parameters. The range of values of the two parameters leading to biodiesel meeting the EN 14214 standard for viscosity, cetane number, iodine value, and cold filter plugging point have been graphically obtained by overlapping the corresponding level surfaces. Practical applications: This work provides biodiesel producers with indications of the quality of biodiesel without the need for analytical testing of the product (indeed, of the product itself). Only the fatty acid profile of the starting vegetable oil is required. The quality of biodiesel can be estimated by using a chart developed in this work, allowing to estimate, e.g. if the biodiesel meets the European standards. The work can be useful to rapidly screen oil seed crops in studies of genetic engineering that require high throughput.     

Utilization of green seed canola oil for biodiesel production

Increasing percentage of green canola seed every year is a serious problem for canola growers. Chlorophyll content of this oil is very high, which makes it more susceptible to photo‐oxidation and ultimately the oxidation stability of the oil is very reduced. Hence green seed canola oil is underutilized for edible purposes. The present work is an attempt to produce high‐quality biodiesel from green seed canola oil and methanol, ethanol and various mixtures of methanol and ethanol using KOH as a catalyst. A mixture of alcohols improved the rate of reaction. After transesterification of green seed canola oil using KOH, the chlorophyll content of the oil was decreased substantially (from 22.1 ppm to 10.3 ppm). Characteristics of the esters prepared from green seed canola oil were well within the limits of ASTM standards. Lubricity of the green seed oil esters was excellent (20% decrease in wear scar area) when added at 1 vol% to the base fuel. Oxidation stability is crucial for long‐term storage of the fuel. Oxidation stability index (OSI) of green seed esters was 4.9 h at 110 °C, which is much less than the European Standard (6 h at 100 °C). The low oxidation stability of green seed esters is attributed to its higher chlorophyll (10.3 ppm) content. An attempt was also made to reduce the chlorophyll content of the oil before transesterification using activated carbon treatment, and it was observed that chlorophyll content was reduced from 22.1 to 2.2 ppm. Copyright © 2006 Society of Chemical Industry     

Conventional and in situ transesterification of castor seed oil for biodiesel production

In the present study, biodiesel production from Ricinus communis L. red and BRS-149 nordestina varieties seed oil is reported. Reactions were made through conventional and in situ processes using ethanol and evaluating the addition of n-hexane as co-solvent. The content of ethyl esters was quantified by ¹H NMR. The highest conversions were obtained from crude oil (conventional reaction) after pre-esterification, using ethanol and a molar ratio of alcohol to oil of 60; furthermore, the addition of n-hexane was not significant on yield. Under these conditions, best conversion was around 95% for both varieties.     

Tri-potassium phosphate as a solid catalyst for biodiesel production from waste cooking oil

Transesterification of waste cooking oil with methanol, using tri-potassium phosphate as a solid catalyst, was investigated. Tri-potassium phosphate shows high catalytic properties for the transesterification reaction, compared to CaO and tri-sodium phosphate. Transesterification of waste cooking oil required approximately two times more solid catalyst than transesterification of sunflower oil. The fatty acid methyl ester (FAME) yield reached 97.3% when the transesterification was performed with a catalyst concentration of 4 wt.% at 60 °C for 120 min. After regeneration of the used catalyst with aqueous KOH solution, the FAME yield recovered to 88%. Addition of a co-solvent changed the reaction state from three-phase to two-phase, but reduced the FAME yield, contrary to the results with homogeneous catalysts. The catalyst particles were easily agglomerated by the glycerol drops derived from the homogeneous liquid in the presence of co-solvents, reducing the catalytic activity.     

Current scenario and potential of biodiesel production from waste cooking oil in Pakistan: An overview

Biodiesel utilization has been rapidly growing worldwide as the prime alternative to petrodiesel due to a global rise in diesel fuel demand along with hazardous emissions during its thermochemical conversion. Although, several debatable issues including feedstock availability and price, fuel and food competition, changes in land use and greenhouse gas emission have been raised by using edible as well as inedible feedstocks for the production of biodiesel. However, non-crop feedstocks could be a promising alternative. In this article, waste cooking oils have been recommended as a suitable option for biodiesel production bearing in mind the current national situation. The important factors such as the quantity of waste cooking oil produced, crude oil and vegetable oil import expenses, high-speed diesel imports, waste management issues and environmental hazards are considered. Moreover, process simulation and operating cost evaluation of an acid catalyzed biodiesel production unit are also conducted. The simulation results show that the production cost of waste cooking oil-based biodiesel is about 0.66USD·L^-1. We believe that the present overview would open new pathways and ideas for the development of biofuels from waste to energy approach in Pakistan.     

Biodiesel development from high acid value polanga seed oil and performance evaluation in a CI engine

Non-edible filtered high viscous (72 cSt at 40 °C) and high acid value (44 mg KOH/gm) polanga (Calophyllum inophyllum L.) oil based mono esters (biodiesel) produced by triple stage transesterification process and blended with high speed diesel (HSD) were tested for their use as a substitute fuel of diesel in a single cylinder diesel engine. HSD and polanga oil methyl ester (POME) fuel blends (20%, 40%, 60%, 80%, and 100%) were used for conducting the short-term engine performance tests at varying loads (0%, 20%, 40%, 60%, 80%, and 100%). Tests were carried out over entire range of engine operation at varying conditions of speed and load. The brake specific fuel consumption (BSFC) and brake thermal efficiency (BTE) were calculated from the recorded data. The engine performance parameters such as fuel consumption, thermal efficiency, exhaust gas temperature and exhaust emissions (CO, CO₂, HC, NO_x, and O₂) were recorded. The optimum engine operating condition based on lower brake specific fuel consumption and higher brake thermal efficiency was observed at 100% load for neat biodiesel. From emission point of view the neat POME was found to be the best fuel as it showed lesser exhaust emission as compared to HSD.     

Roselle (Hibiscus sabdariffa L.) oil as an alternative feedstock for biodiesel production in Thailand

The production of biodiesel fuel from crude roselle oil was evaluated in this study. The process of alkali-catalyzed transesterification with methanol was carried out to examine the effects of reaction variables on the formation of methyl ester: variables which included methanol-to-oil molar ratios of 4:1-10:1, catalyst concentrations of 0.25-2.0% w/w of oil, reaction temperatures of 32-60 °C, and reaction times of 5-80 min. The methyl ester content from each reaction condition was analyzed by gas chromatography (GC), the optimum condition having been achieved at a methanol-to-oil molar ratio of 8:1, a catalyst concentration of 1.5% w/w of oil, a reaction temperature of 60 °C, and a reaction time of 60 min. The resultant methyl ester content of 99.4% w/w, plus all of the other measured properties of the roselle biodiesel, met the Thai biodiesel (B100) specifications and international standards EN 14214:2008 (E) and ASTM D 6751-07b, with the exception of a higher carbon residue and lower oxidation stability.     

Physical-chemical properties of waste cooking oil biodiesel and castor oil biodiesel blends

This work presents the physical-chemical properties of fuel blends of waste cooking oil biodiesel or castor oil biodiesel with diesel oil. The properties evaluated were fuel density, kinematic viscosity, cetane index, distillation temperatures, and sulfur content, measured according to standard test methods. The results were analyzed based on present specifications for biodiesel fuel in Brazil, Europe, and USA. Fuel density and viscosity were increased with increasing biodiesel concentration, while fuel sulfur content was reduced. Cetane index is decreased with high biodiesel content in diesel oil. The biodiesel blends distillation temperatures T₁₀ and T₅₀ are higher than those of diesel oil, while the distillation temperature T₉₀ is lower. A brief discussion on the possible effects of fuel property variation with biodiesel concentration on engine performance and exhaust emissions is presented. The maximum biodiesel concentration in diesel oil that meets the required characteristics for internal combustion engine application is evaluated, based on the results obtained.     

Kinetics of the pre-treatment of used cooking oil using Novozyme 435 for biodiesel production

The pre-treatment of used cooking oil (UCO) for the preparation of biodiesel has been investigated using Novozyme 435, Candida antarctica Lipase B immobilised on acrylic resin, as the catalyst. The reactions in UCO were carried out using a jacketed batch reactor with a reflux condenser. The liquid chromatography–mass spectrometry (LC–MS) method was developed to monitor the mono-, di- and triglyceride concentrations and it was found that the method was sensitive enough to separate isomers, including diglyceride isomers. It was found that the 1,3 diglyceride isomer reacted more readily than the 1,2 isomer indicating stereoselectivity of the catalyst. This work showed that Novozyme 435 will catalyse the esterification of free fatty acids (FFAs) and the transesterification of mono- and diglycerides typically found in UCO when Novozyme 435 is used to catalyse the pre-treatment of UCO for the formation of biodiesel. A kinetic model was used to investigate the mechanism and indicated that the reaction progressed with the sequential hydrolysis esterification reactions in parallel with transesterification.     

生物技术法生产生物柴油的研究进展

介绍了化学酯交换法、酶催化法、全细胞催化法等生产生物柴油的方法。指出了这一领域难以实现商业化的原因,并针对这些问题提出了相应的建议,分析了生物柴油的现状及发展趋势。     

Optimization of the production of biodiesel from soybean oil by ultrasound assisted methanolysis

This paper evaluates and optimizes the production of biodiesel from soybean oil and methanol using sodium hydroxide as catalyst. The study and optimization was carried out at low catalyst concentration (0.2 to 0.6 w/w). The reaction was carried out with application of low-frequency high-intensity ultrasound under atmospheric pressure and ambient temperature in a batch reactor. Response surface methodology (RSM) was used to evaluate the influence of methanol to oil ratio and catalyst concentration on soybean oil conversion into biodiesel. Analysis of the operating conditions by RSM showed that the most important operating condition affecting the reaction was the methanol to oil ratio, while catalyst amount showed little significance in the transesterification reaction. Total consumption of oil was obtained when alcohol to oil ratio of 9:1 and catalyst concentration of 0.2 w/w were applied.