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.     

Extraction of Lipids from Municipal Wastewater Plant Microorganisms for Production of Biodiesel

Municipal wastewater treatment plants in the USA produce over 6.2 × 10⁶ t of dried sewage sludge every year. This microorganism-rich sludge is often landfilled or used as fertilizer. Recent restrictions on the use of sewage sludge, however, have resulted in increased disposal problems. Extraction of lipids from sludge yields an untapped source of cheap feedstock for biodiesel production. Solvents used for extraction in this study include n-hexane, methanol, acetone, and supercritical CO₂. The gravimetric yield of oil was low for nonpolar solvents, but use of polar solvents gave a considerably increased yield; however, the percentage of saponifiable material was less. Extraction of lipids with a mixture of n-hexane, methanol, and acetone gave the largest conversion to biodiesel compared with other solvent systems, 4.41% based on total dry weight of sludge. In situ transesterification of dried sludge resulted in a yield of 6.23%. If a 10% dry weight yield of fatty acid methyl esters is assumed, the amount of biodiesel available for production in the USA is 1.4 × 10⁶ m³/year. Outfitting 50% of municipal wastewater plants for lipid extraction and transesterification could result in enough biodiesel production to replace 0.5% of the national petroleum diesel demand (0.7 × 10⁶ m³).     

Biodiesel Production from Soybean Oil Catalyzed by Li<Subscript>2</Subscript>CO<Subscript>3</Subscript>

In the present study, we synthesized biodiesel from soybean oil through a transesterification reaction catalyzed by lithium carbonate. Under the optimal reaction conditions of methanol/oil molar ratio 32:1, 12 % (wt/wt oil) catalyst amount, and a reaction temperature of 65 °C for 2 h, there was a 97.2 % conversion to biodiesel from soybean oil. The present study also evaluated the effects of methanol/oil ratio, catalyst amount, and reaction time on conversion. The catalytic activity of solid base catalysts was insensitive to exposure to air prior to use in the transesterification reaction. Results from ICP-OES exhibited non-significant leaching of the Li₂CO₃ active species into the reaction medium, and reusability of the catalyst was tested successfully in ten subsequent cycles. Free fatty acid in the feedstock for biodiesel production should not be higher than 0.12 % to afford a product that passes the EN biodiesel standard. Product quality, ester content, free glycerol, total glycerol, density, flash point, sulfur content, kinematic viscosity, copper corrosion, cetane number, iodine value, and acid value fulfilled ASTM and EN standards. Commercially available Li₂CO₃ is suitable for direct use in biodiesel production without further drying or thermal pretreatment, avoiding the usual solid catalyst need for activation at high temperature.     

Biodiesel Production Using a Carbon Solid Acid Catalyst Derived from β‐Cyclodextrin

A novel carbon solid acid catalyst was prepared by incomplete hydrothermal carbonization of β‐cyclodextrin into small polycyclic aromatic carbon sheets, followed by the introduction of –SO₃H groups via sulfonation with sulfuric acid. The physical and chemical properties of the catalyst were characterized in detail. The catalyst simultaneously catalyzed esterification and transesterification reactions to produce biodiesel from high free fatty acid (FFA) containing oils (55.2 %). For the as‐prepared catalyst, 90.82 % of the oleic acid was esterified after 8 h, while the total transesterification yield of high FFA containing oils reached 79.98 % after 12 h. By contrast, the obtained catalyst showed comparable activity to biomass (such as sugar, starch, etc.)‐based carbon solid acid catalyst while Amberlyst‐15 resulted in significantly lower levels of conversion, demonstrating its relatively high catalytic activity for simultaneous esterification and transesterification. Moreover, as the catalyst can be regenerated, it has the potential for use in biodiesel production from oils with a high FFA content.     

Fe3O4 nanoparticles impregnated eggshell as a novel catalyst for enhanced biodiesel production

Biodiesel is a green fuel which can replace diesel while addressing various issues such as scarcity of hydrocarbon fuels and environmental pollution to an extent. The high production cost of biodiesel and the recovery of the catalyst after the transesterification process are the major challenges to be addressed in biodiesel production. In the present work, a cheap and promising solid base oxide catalyst was synthesized from chicken eggshell by calcination at 900 °C forming catalyst eggshells (CES) and was impregnated with the nanomagnetic material (Fe₃O₄) to obtain Fe₃O₄ loaded catalytic eggshell (CES–Fe₃O₄). Fe₃O₄ nanomaterials were synthesized by co-precipitation method and were loaded in catalytic eggshell by sonication, for better recovery of the catalyst after transesterification process. CES–Fe₃O₄ material was characterized by Thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy, a vibrating-sample magnetometer, Brunauer-Emmett-Teller, Dynamic light scattering, and Scanning electron microscopy. Biodiesel was synthesized by transesterification of Pongamia pinnata raw oil with 1:12 oil to methanol molar ratio and 2 wt% catalyst loading for 2 h at a temperature of 65 °C and yields were compared. The reusability of the catalyst was studied by the transesterification of the raw oil and its catalytic activity was found to be retained up to 7 cycles with a yield of 98%.     

Optimization of process conditions using response surface methodology for the microwave-assisted transesterification of Jatropha oil with KOH impregnated CaO as catalyst

A transesterification reaction of Jatropha curcas oil with methanol in the presence of KOH impregnated CaO catalyst was performed in a simple continuous process. The process variables such as methanol/oil molar ratio (X₁), amount of catalyst (X₂) and total reaction time (X₃) were optimized through response surface methodology, using the Box–Behnken model. Within the range of the selected operating conditions, the optimal ratio of methanol to oil, amount of catalyst and total reaction time were found to be 8.42, 3.17% and 67.9 min, respectively. The results showed that the amount of catalyst and total reaction time have significant effects on the transesterification reaction. For the product to be accepted as a biodiesel fuel, its purity must be above 96.5% of alkyl esters. Based on the optimum condition, the predicted biodiesel conversion was 97.6% while the actual experimental value was 97.1%. The above mentioned results demonstrated that the response surface methodology (RSM) based on Box–Behnken model can well predict the optimum condition for the biodiesel production.     

RETRACTED ARTICLE: Optimization of Biodiesel Production Using a Magnetically Stabilized Fluidized Bed Reactor

A biodiesel production process using magnetically stabilized fluidized bed reactor (MSFBR) has been developed based on the refined cottonseed oil. The reactant flow rate and magnetic field intensity effects on the nanometer magnetic catalyst behavior in the column were investigated. Orthogonal experiments (L₄(2)³) were applied to optimize the best transesterification reaction conditions. Reaction temperature, methanol to oil molar ratio, and reactant flow rate were the main factors to influence transesterification conversion efficiency. These three factors chosen for the present investigation were based on the results of single-factor tests. The optimum transesterification reaction conditions of cottonseed oil were determined in MSFBR as follows: methanol to oil molar ratio 8:1, 40 cm³ min⁻¹ reactant flow rate, 225 Oe magnetic field intensity and reaction temperature of 65 °C, the conversion efficiency reached 97% in 100 min. The cold filter plugging point and kinematic viscosity of cottonseed oil biodiesel were higher than that described by Chinese specifications of biodiesel because of the special fatty acid profiles of cottonseed oil. The activity stability of the nanometer magnetic solid catalyst in MSFBR was much better than that in the autoclave stirred reactor (ASR).     

Catalytic and noncatalytic esterification and transesterification by subcritical methanol

The model reactions of benzoic acid (BA) esterification and ethyl benzoate (EB) transesterification by subcritical methanol were carried out for the first time at 220° C without catalysts in order to decrease the acid wastes from an industrially important reaction of the synthesis of biodiesel components. Methanol under these conditions is both a solvent and a catalyst. Benzoic acid is esterified in quantity even when the ratio of BA to methanol is 1: 3. Benzoic acid transesterification occurs with 82% conversion and a BA-to-methanol ratio of 1: 10. A process is proposed for biodiesel manufacturing from vegetable oil under the specified conditions and in the presence of a solid acid catalyst (sulfated TiO₂, SnO₂, or Al₂O₃). With the use of sulfated TiO₂, biodiesel fuel yields can reach 98% at 170 °C. Our results can be used in the large-scale production of biodiesel fuel components because they show a way to seriously decrease costs for recycling acid emissions and the load on the environment.     

Transesterification of Pistacia chinensis oil for biodiesel catalyzed by CaO-CeO2 mixed oxides

This study investigates the use of CaO-CeO₂ mixed oxides as solid base catalysts for the transesterification of Pistacia chinensis oil with methanol to produce biodiesel. These CaO-CeO₂ mixed-oxide catalysts were prepared by an incipient wetness impregnation method and characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. The cerium improved the heterogeneous catalytic stability remarkably due to the defects induced by the substitution of Ca ions for Ce ions on the surface. The best catalyst was determined to be C0.15-973 (with a Ce/Ca molar ratio of 0.15 and having been calcined at 973 K), considering its catalytic and anti-leaching abilities. The effects of reaction parameters such as the methanol/oil molar ratio, the amount of catalyst amount and the reaction temperature were also investigated. For the C0.15-973 regenerated after five reuses, the biodiesel yield was 91%, which is slightly less than that of the fresh sample. The test results revealed that the CaO-CeO₂ mixed oxides have good potential for use in the large-scale biodiesel production.     

Feasibility of Palm Oil as the Feedstock for Biodiesel Production via Heterogeneous Transesterification

The production of biodiesel has become popular recently as a result of increasing demand for a clean, safe and renewable energy. Biodiesel is made from natural renewable sources such as vegetable oils and animal fats. The conventional method of producing biodiesel is by reacting vegetable oil with alcohol in the presence of a homogenous catalyst (NaOH). However, this conventional method has some limitations such as the formation of soap, usage of significant quantities of wash water and complicated separation processes. Heterogeneous processes using solid catalysts have significant advantages over homogenous methods. Currently, more than 90 % of world biodiesel is produced using rapeseed oil. The production of biodiesel from rapeseed oil is considered uneconomical, considering the fact that palm oil is currently the world's cheapest vegetable oil. Therefore, the focus of this study is to show the feasibility of producing biodiesel from palm oil using montmorillonite KSF as a heterogeneous catalyst. The heterogeneous transesterification process was studied using design of experiment (DOE), specifically response surface methodology (RSM) based on a four‐variable central composite design (CCD) with α = 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 the amount of catalyst, x₄ (1–5 wt %). It was found that the conversion of palm oil to biodiesel can reach up to 78.7 % using the following reaction conditions: reaction temperature of 155 °C, reaction period of 120 min, ratio of methanol/oil at 10:1 mol mol^–1 and amount of catalyst at 4 wt %. From this study, it was shown that montmorillonite KSF catalyst can be used as a solid catalyst for biodiesel production from palm oil.     

Biodiesel production from vegetable oil using heterogenous acid and alkali catalyst

Zanthoxylum bungeanum seed oil (ZSO) with high free fatty acids (FFA) can be used for biodiesel production by ferric sulfate-catalyzed esterification followed by transesterification using calcium oxide (CaO) as an alkaline catalyst. Acid value of ZSO with high FFA can be reduced to less than 2 mg KOH/g by one-step esterification with methanol-to-FFA molar ratio 40.91:1, ferric sulfate 9.75% (based on the weight of FFA), reaction temperature 95 °C and reaction time 2 h, which satisfies transesterification using an alkaline catalyst. The response surface methodology (RSM) was used to optimize the conditions for ZSO biodiesel production using CaO as a catalyst. A quadratic polynomial equation was obtained for biodiesel conversion by multiple regression analysis and verification experiments confirmed the validity of the predicted model. The optimum combination for transesterification was methanol-to-oil molar ratio 11.69:1, catalyst amount 2.52%, and reaction time 2.45 h. At this optimum condition, the conversion to biodiesel reached above 96%. This study provided a practical method to biodiesel production from raw feedstocks with high FFA with high reaction rate, less corrosion, less toxicity, and less environmental problems.     

Analysis of parameters and interaction between parameters of the microwave-assisted continuous transesterification process of Jatropha oil using response surface methodology

A simple continuous process was designed for the transesterification of Jatropha curcas (J. curcas) oil to alkyl esters using microwave-assisted method. The product with purity above 96.5% of alkyl ester is called the biodiesel fuel. Using response surface methodology, a series of experiments with three reaction factors at three levels were carried out to investigate the transesterification reaction in a microwave and conversion of alkyl ester from J. curcas oil with NaOH as the catalyst. The results showed that the ratio of methanol to oil, amount of catalyst and flow rate have significant effects on the transesterification and conversion of alkyl ester. Based on the response surface methodology using the selected operating conditions, the optimal ratio of methanol to oil, amount of catalyst and flow rate of transesterification process were 10.74, 1.26 wt% and 1.62 mL/min, respectively. The largest predicted and experimental conversions of alkyl esters (biodiesel) under the optimal conditions are 99.63% and 99.36%, respectively. Our findings confirmed the successful development of a two-step process for the transesterification reaction of Jatropha oil by microwave-assisted heating, which is effective and time-saving for alkyl ester production.     

A novel solid superbase of Eu2O3/Al2O3 and its catalytic performance for the transesterification of soybean oil to biodiesel

A novel solid superbase catalyst of Eu₂O₃/Al₂O₃ was prepared and its basic strength reached 26.5 measured by indicators according to Hammett scale. The catalytic activity of Eu₂O₃/Al₂O₃ was evaluated for the transesterification of soybean oil with methanol to biodiesel in the fixed bed reactor and under atmospheric pressure. The results show that Eu₂O₃/Al₂O₃ is an excellent catalyst for the transesterification of soybean oil, and the conversion of soybean oil can reach 63.2% at 70 °C for 8 h.     

Soybean oil transesterification over zinc oxide modified with alkali earth metals

Fatty acid methyl esters, derived from vegetable oils or animal fats and better known as biodiesel, have received considerable attention because of their environmental benefits and the limited resources of fossil fuels. Most biodiesel is usually produced by the transesterification of vegetable oils with methanol in the presence of a catalyst. This study reports on the preliminary results of using alkaline earth metal-doped zinc oxide as a heterogeneous catalyst for transesterification of soybean oil. The highest catalytic activity was obtained with ZnO loaded with 2.5 mmol Sr(NO₃)₂/g, followed by calcination at 873 K for 5 h. When the transesterification reaction was carried out at reflux of methanol (338 K), with a 12:1 molar ratio of methanol to soybean oil and a catalyst amount of 5 wt.%, the conversion of soybean oil was 94.7%. Besides, tetrahydrofuran (THF), when used as a co-solvent, could increase the conversion up to 96.8%. However, the recovered catalyst exhibited the lower catalytic activity with a conversion of soybean oil of 15.4%. Furthermore, DTA-TG, IR and the Hammett indicator method were employed for the catalyst characterizations.     

The Optimization of the Production of Methyl Esters from Corn Oil Using Barium Hydroxide as a Heterogeneous Catalyst

In recent years, vegetable oils, as renewable raw materials, became a promising feedstock for chemicals and biodiesel production. The main products derived from oils are esters of fatty acids, especially methyl esters, obtained by their transesterification with methanol, in presence of acid or alkaline catalysts. The use of such catalysts implies the need for washing operations, which leads to environmental pollution. In the present paper, the response surface methodology based on a central composite design, has been developed to optimize the process of transesterification of corn oil. Ba(OH)₂ in presence of diethyl ether was used as catalyst. A quadratic polynomial equation was obtained. It correlates the reaction parameters [methanol/oil molar ratio (x _r), reaction time (x _t) and catalyst concentration (x _c)] with methyl esters yield. Analysis of variance analysis showed that only methanol/oil molar ratio and catalyst concentration have had the most significant influences on the conversion. The maximum methyl esters yield was obtained using the following optimum parameters: methanol/corn oil ratio of 11.32, reaction time of 118 min and catalyst concentration of 3.6 wt%.     

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.     

Simplifying the Process of Microalgal Biodiesel Production Through In Situ Transesterification Technology

Crop-based biofuels, including biodiesel, has sparked international concerns during recent years. Microalgae have been strongly advocated as the most promising substitute for oil crops. However, the commercialization of microalgal biodiesel is hindered by the high costs of feedstock and conventional production processes. This paper elucidates a simplified, scalable production process under conditions of least energetic demand, which integrates oil extraction and conversion into one step through in situ transesterification. Introducing a co-solvent is the key to success. Criteria for co-solvents applicable to the microalgal biodiesel industry are proposed. The overall biodiesel yield (OBY) of Spirulina was determined for benchmarking purposes, using the Bligh and Dyer protocol for oil extraction, and transesterification with potassium hydroxide. The performance in in situ transesterification of the selected co-solvents toluene, dichloromethane and diethyl ether, as well as the solvent combinations petroleum ether/toluene, toluene/methanol and dichloromethane/methanol, was evaluated by OBY. Among all the co-solvents tested, the toluene/methanol system, 2:1 by volume ratio, demonstrated the highest efficiency, achieving a biodiesel yield of 76% of the OBY for the first in situ transesterification cycle and 10% for the second in situ transesterification cycle.     

Preparation of Biodiesel by Transesterification of Rapeseed Oil with Methanol Using Solid Base Catalyst Calcined K<Subscript>2</Subscript>CO<Subscript>3</Subscript>/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>

We report here the preparation of biodiesel by transesterification of rapeseed oil with methanol using calcined K₂CO₃/γ-Al₂O₃ as a solid base catalyst. The prepared catalysts were characterized using SEM, IR and BET, and their catalytic activities were evaluated. The reaction conditions were optimized, and in particular, the conversion can be as high as 98.62% under the optimal reaction conditions. In addition, the effect of the presence of water in the reaction system on the catalytic activity was also studied.     

Two Stages of N‐Deficient Cultivation Enhance the Lipid Content of Microalga Scenedesmus sp.

Scenedesmus sp. 14‐3 was identified as a suitable candidate for producing biodiesel. The present work studied the effects of nitrogen concentration on the biomass and lipid productivity of algae, the consumption of sodium nitrate, and the two‐stage N‐deficient cultivation that could enhance dramatically the accumulation of biomass and lipids of Scenedesmus sp. 14‐3. The two‐stage N‐deficient cultivation was described as follows: microalga Scenedesmus sp. 14‐3 was cultured under low light intensity (LL) for 10 days in an N‐deficient medium by 20 % inoculum concentration, and transferred to complete N‐depletion BG11 under high light intensity (HL) for 8 days. The highest lipid content of Scenedesmus sp. 14‐3 was 53.05 ± 0.08 % (10 % inoculum concentration) following the second stage of N‐deficient cultivation after 8 days. For the second stage of N‐deficient cultivation, the lipid content of Scenedesmus sp. 14‐3 was 49.85 ± 0.22 %, which was 1.8 times higher than that under low light intensity (LL) (46–48 μmol m^?2 s^?1 ) in 10 days. Meanwhile, the high algal biomass productivity was around 0.10 g L^?1 day^?1 after the first stage of N‐deficient cultivation (10 days) and the biomass productivity was around 0.037 g L^?1 day^?1 under the second stage of N‐deficient cultivation (8 days). The comparison under different culture conditions showed a significant effect of the two‐stage of N‐deficient cultivation on lipid accumulation of Scenedesmus sp. 14‐3. The two‐stage N‐deficient cultivation without centrifugation achieved a complete N‐depletion condition, but the two‐stage process required centrifugation which is unsuitable for commercialization and large‐scale utilization. In summary, two‐stage N‐deficient cultivation is a more suitable and effective culture method for commercial applications and dramatic accumulation of lipids than the two‐stage process.     

Magnetic Solid Base Catalysts for the Production of Biodiesel

Magnetic solid base catalysts were prepared by loading Na₂SiO₃ on Fe₃O₄ nano-particles with Na₂O·3SiO₂ and NaOH as precipitator. The catalysts were used to catalyze the transesterification reactions for the production of fatty acid methyl esters (FAME, namely biodiesel) from cottonseed oil. The optimum conditions of the catalysts' preparation and transesterification reactions were investigated by orthogonal experiments. The catalyst with the highest catalytic activity was obtained when Si/Fe molar ratio of 2.5, aging time of 2 h, calcination temperature of 350 °C, calcination time of 2.5 h. Magnetic of the catalyst was characterized with Vibrating Sample Magnetometer (VSM) and transmission electron microscopy photograph (TEM), and the results showed the catalyst Na₂SiO₃/Fe₃O₄ had good specific saturation magnetization and paramagnetism, and its water resistance was better than the traditional homogeneous base catalysts; under the transesterification conditions of methanol/oil molar ratio of 7:1, catalyst dosage of 5%, reaction temperature of 60 °C, reaction time of 100 min and stirring speed of 400 rpm, yield of biodiesel was 99.6%. The lifetime and recovery rate of the magnetic solid base catalyst were much better than those of Na₂SiO₃.