Biodiesel production by esterification of oleic acid over zeolite Y prepared from kaolin

Zeolite Y, with a Si/Al ratio 3.1, was prepared using Iraqi kaolin and tested as a catalyst in the liquid-phase esterification of oleic acid (a simulated free fatty acid frequently used as a model reaction for biodiesel production). XRD confirmed the presence of the characteristic faujasite structure of zeolite Y, and further analysis was conducted using BET adsorption, FTIR spectroscopy, XRF, DLS particle size and SEM. A range of experimental conditions were employed to study the reaction; alcohol/oleic acid molar ratio, temperature, and catalyst mass loading. The optimum conditions for the reaction were observed at 70 °C, 5 wt% catalyst loading and 6:1 ethanol to oleic acid molar ratio. The oleic acid conversion using the zeolite prepared from kaolin was 85% after 60 min, while the corresponding value for a commercial sample of HY zeolite was 76%. Our findings show that low Si/Al ratio zeolite Y is a suitable catalyst for esterification, which is in contrast to the widespread view of the unsuitability of zeolites, in general, for such applications.     

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.     

Biodiesel production from waste coconut oil by esterification with ethanol: The effect of water removal by adsorption

The production of biodiesel by esterification with ethanol using waste oil generated in the refining of coconut oil was investigated in this study. The reaction was performed with and without adsorption of water in order to verify the effect of removing water on the reaction conversion. Methanol was also evaluated as an esterification agent. For both ethanol and methanol, conversions over 99% mol were observed. Simultaneous water adsorption allowed the use of lower alcohol/oil molar ratios thus enabling better economics to a possible industrial process.     

Biodiesel production from Nerium oleander (Thevetia peruviana) oil through conventional and ultrasonic irradiation methods

In the present research work, Nerium oleander oil has been used as raw material for producing biodiesel using both ultrasonic transesterification and a magnetic stirrer method. A two-step transesterification process was carried out for optimum condition of 0.40% V/V methanol to oil ratio, 1% V/V H₂SO₄ catalyst, 55°C temperature, and 60 min reaction time followed by treatment with 0.2% V/V methanol to oil ratio, 1% V/W KOH alkaline catalyst, 55°C temperature, and 60 min reaction time. The process is repeated with an ultrasonic method at the frequency of 28 kHz using ultrasonic horn type reactor (50 W) for about 10–15 min. Biodiesel obtained from ultrasonic method and magnetic stirrer was then compared for their percentage yield and physiochemical properties. Ultrasonic transesterification process gave a maximum yield of 97% by weight of oleander biodiesel along with improved physiochemical characteristics. Therefore, it is concluded that ultrasonic method is the most effective method for converting crude oleander oil into biodiesel.     

Kinetic model for the esterification of oleic acid catalyzed by zinc acetate in subcritical methanol

The esterification of oleic acid in subcritical methanol catalyzed by zinc acetate was investigated in a batch-type autoclave. The effect of reaction conditions such as temperature, pressure, reaction time and molar ratio of oleic acid to methanol on the esterification was examined. The oleic acid conversion reached 95.0% under 220 °C and 6.0 MPa with the molar ratio of methanol to oleic acid being 4 and 1.0 wt% zinc acetate as catalyst. A kinetic model for the esterification was established. By fitting the kinetic model with the experimental results, the reaction order n = 2.2 and activation energy E_a = 32.62 KJ/mol were obtained.     

SO_4~(2-)/ZrO_2催化油酸和甘油酯化反应研究

以八水合氧氯化锆(Zr OCl2·8H2O)作为锆源,硫酸铵[(NH4)2SO4]作为硫化剂,通过沉淀浸渍法制得硫酸化氧化锆(SO42-/Zr O2)固体酸催化剂,通过XRD,Py-IR和SEM表征研究了催化剂的晶型,酸性和表面形貌,并测试了催化剂的硫含量及对油酸和甘油酯化反应的催化效果。研究结果表明:焙烧温度对催化剂的晶型有明显影响,并且随焙烧温度的升高,催化剂中SO42-含量流失加剧,500℃焙烧的催化剂催化效果最好;硫酸化氧化锆催化剂既有Br觟nsted酸位,也有Lewis酸位;水存在情况下硫酸化氧化锆催化剂易失活;在酯化反应中,升高反应温度、提高催化剂用量油酸转化率随之升高,回收的催化剂在重复使用前进行焙烧,其活性可得到恢复。     

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.     

Biodiesel production from two stage esterification of simarouba glauca seed oil and its characterization

In this work, biodiesel was produced from simarouba glauca seed oil through a two-stage acid-alkali esterification process. Concentrated sulphuric acid and sodium hydroxide were used as catalysts for acid and alkaline catalyzed esterification process, respectively. The free fatty acid content of the oil was reduced from 3.5 to 0.2%. The major properties of oil and its biodiesel were studied. Upon two-stage esterification, kinematic viscosity was reduced from 45.75 to 3.1 cSt and the acid value was reduced from 6.9348 to 0.4 mg KOH/g. The measured physio-chemical properties are within the limits set by ASTM biodiesel standards.     

Hydrogen production by laser irradiation of metals in water under an ultrasonic field: A novel approach

An alternative method for hydrogen production by laser irradiation of metals in water is proposed. Metals such as Ti, Al, Mg an Al–Mg alloy and Si, were laser ablated and subjected to an ultrasonic field simultaneously to promote a displacement chemical reaction of hydrogen from water. The produced gas was characterized by gas chromatography and mass spectrometry. Molecular hydrogen was found suggesting that this procedure allows the production of H₂ of high purity. All the studied metals under laser irradiation produced H₂ and the volume rise as the laser fluence was increased following a no-linear monotonic behavior with a similar tendency. Without ultrasound the amount of hydrogen was significantly reduced. An important advantage of the proposed H₂ production method is the low amount of mass consumed which lead to maximum hydrogen production rates close to 1300 ml/min per gr of aluminum.     

Thermodynamic analysis of fatty acid esterification for fatty acid alkyl esters production

The development of renewable energy source alternatives has become a planet need because of the unavoidable fossil fuel scarcity and for that reason biodiesel production has attracted growing interest over the last decade. The reaction yield for obtaining fatty acid alkyl esters varies significantly according to the operating conditions such as temperature and the feed reactants ratio and thus investigation of the thermodynamics involved in such reactional systems may afford important knowledge on the effects of process variables on biodiesel production. The present work reports a thermodynamic analysis of fatty acid esterification reaction at low pressure. For this purpose, Gibbs free energy minimization was employed with UNIFAC and modified Wilson thermodynamic models through a nonlinear programming model implementation. The methodology employed is shown to reproduce the most relevant investigations involving experimental studies and thermodynamic analysis.     

Homogeneous borotungstic acid and heterogeneous micellar borotungstic acid catalysts for biodiesel production by esterification of free fatty acid

A highly negatively charged borotungstic acid H₅BW₁₂O₄₀ had been tested as homogeneous catalyst in esterification. Compared with common used H₃PW₁₂O₄₀, it displayed a higher conversion (98.7%) and excellent efficiency (96.2%) due to its high amount of protons in methanol. In order to overcome the drawbacks of homogeneous heteropolyacid H₅BW₁₂O₄₀, a Brønsted-surfactant-combined (C₁₆TA)H₄BW₁₂O₄₀ (C₁₆TA = cetyltrimethyl ammonium) had been fabricated with strong acidity and nano-size micellar structure resulting in enhanced activity and stability during the reaction, which exhibited consistent activity during recycling in esterification reaction.     

Biodiesel production from Cedrus deodara oil in different types of ultrasonic reactors and energy analysis

This paper deals with the production of biodiesel using vegetable oil, extracted from Deodar (Cedrus deodara) in various types of ultrasonic reactors. The biodiesel so produced is tested for its property and stability. Biodiesel yield is optimized as a function of reaction time for various ultrasonic reactors. The biodiesel production through the triple-frequency flow cell ultrasonic reactor is found the most energy efficient when compared to other types of ultrasonic reactors. Biodiesel so produced from deodar oil is stable under atmospheric conditions with its various physicochemical properties within the range of acceptable limits of the diesel engine.     

Biodiesel production by transesterification of duck tallow with methanol on alkali catalysts

Duck tallow was employed as a feedstock for the production of biodiesel by transesterification with methanol. The content of fatty acid methyl ester (FAME) was evaluated on various alkali catalysts during transesterification. The composition and chemical properties of the FAME were investigated in the raw duck tallow and the biodiesel products. The major constituent in the biodiesel product was oleic acid. The FAME content was 97% on KOH catalyst in the reaction. It was acceptable for the limit of European biodiesel qualities for BD100. Acid value, density, and kinematic viscosity of the biodiesel products also came up to the biodiesel qualities.     

Research on photocatalytic H2 production from acetic acid solution by Pt/TiO2 nanoparticles under UV irradiation

The Pt/TiO₂ particles have been prepared by the photodeposition of Pt on TiO₂ surface and characterized by X-ray diffraction. Photocatalytic H₂ production from acetic acid (HAc) over Pt/TiO₂ in aqueous solution has been studied at ambient temperature under UV irradiation. The effects of operational variables such as Pt loading, photocatalyst concentration, HAc concentration, and solution pH, have been systematically investigated. The optimum conditions for H₂ production from HAc by Pt/TiO₂ were Pt loading 1.0 wt.%, Pt/TiO₂ concentration 0.22 g/L, HAc concentration 6.52 g/L and pH 1.0. The H₂ yield is 0.27 mol-H₂/mol-HAc obtained under prolonged time irradiation. Experimental results showed that the photocatalytic H₂ production activity could be enhanced remarkably by depositing a suitable amount Pt on TiO₂ surface. Based on our results, a new process for H₂ production from biomass can be achieved by coupling fermentative H₂ production with photocatalytic H₂ production. The process also provides a method for degradation of organic pollutants with simultaneous H₂ production. A possible mechanism for photocatalytic decomposition of HAc over Pt/TiO₂ was also proposed.     

Hydrogen-rich syngas production by catalytic cracking of tar in wastewater under supercritical condition

This paper presents the results from experimental study of syngas production by catalytic cracking of tar in wastewater under supercritical condition. Ni/Al₂O₃ catalysts were prepared via the ultrasonic assisted incipient wetness impregnation on activated alumina, and calcined at 600 °C for 4 h. All catalysts showed mesoporous structure with specific surface area in a range of 146.6–215.3 m²/g. The effect of Ni loading (5–30 wt%), reaction temperature (400–500 °C), and tar concentration (0.5–7 wt%) were systematically investigated. The overall reaction efficiency and the gas yields, especially for H₂, were significantly enhanced with an addition of Ni/Al₂O₃ catalysts. With 20%Ni/Al₂O₃, the H₂ yield increased by 146% compared to the non-catalytic experiment. It is noteworthy that the reaction at 450 °C with the addition of 20%Ni/Al₂O₃ had a comparable efficiency to the reaction without catalyst at 500 °C. The maximum H₂ yield of 46.8 mol/kg_tar was achieved with 20%Ni/Al₂O₃ at 500 °C and 0.5 wt% tar concentration. The catalytic performance of the catalysts gradually decreased as the reuse cycle increased, and could be recovered to 88% of the fresh catalyst after regeneration. 20%Ni/Al₂O₃ has a potential to improve H₂ production, as well as a good reusability. Thus, it is considered a promising catalyst for energy conversion of tar in wastewater.     

Response surface optimization of poly (3-hydroxyalkanoic acid) production using oleic acid as an alternative carbon source by Pseudomonas aeruginosa

This study aims at optimizing medium-chain-length Polyhydroxyalkanoate (MCL-PHA) production from Pseudomonas aeruginosa 13003 culture using the statistical design techniques of 2-level factorial design and RSM. Two-level factorial design with eight variables viz. oleic acid, (NH₄)₂PO₄, incubation time, trace metal solution, MgCl₂, K₂HPO₄, KH₂PO₄ and inoculum was performed to screen for nutrients that were significantly affecting MCL-PHA production. After the values for the less-influential variables were fixed, oleic acid, (NH₄)₂PO₄, K₂HPO₄ and KH₂PO₄ having high t-values were selected to study their optimal relationship for maximal PHA production using 2⁴ Central Composite Design. The optimal composition of the medium was found to be at 7.5 g L⁻¹ oleic acid, 0.4 g L⁻¹ (NH₄)₂PO₄, 3.0 g L⁻¹ K₂HPO₄ and 1.5 g L⁻¹ KH₂PO₄ which gave 60% of CDW as MCL-PHA. This optimization resulted in a 1.6 times increase in the PHA content (60% mass fraction in contrast to 36%). On analysis carbon to nitrogen ratio of 19 was found to be optimum for PHA production. This is the first report on the use of CCD to improve MCL-PHA production from P. aeruginosa.     

Hydrogen production by Chlamydomonas reinhardtii under light driven sulfur deprived condition

This article explores the possibility of demonstrating sustainable photohydrogen production using Chlamydomonas reinhardtii when grown in sulfur deprived photoautotrophic condition. The hydrogen evolving capability of the algal species was monitored based on alternating light and dark period. Investigation was carried out during the day time in order to exploit the solar energy for meeting the demand of the light period. The results showed that when the reactor was operated at varying photoperiod namely 2, 3 and 4 h of alternating light and dark period, the gas generation was found to be 32 ± 4, 63 ± 7 and 52 ± 5 mL/h, while the corresponding hydrogen content was 47, 86 and 87% respectively. Functional components of hydrogen generation reaction centers were also analyzed, which showed that the PS(I) reaction centers were involved in hydrogen production pathway, as the light absorption by PS(I) was prerequisite for hydrogen generation under sulfur deprived photoautotrophic condition. The findings showed a higher gas yield and hydrogen content under dark period, whereas under light period the gas content was below detectable level for hydrogen due to the reversible hydrogenase reaction.     

Production of microbial oil with high oleic acid content by Trichosporon capitatum

Microbial oils with high unsaturated fatty acids content, especially oleic acid content, are good feedstock for high quality biodiesel production. Trichosporon capitatum was found to accumulate lipid with around 80% oleic acid and 89% total unsaturated fatty acids content on nitrogen-limited medium. In order to improve its lipid yield, effects of medium components and culture conditions on cell growth and lipid accumulation were investigated. Optimization of media resulted in a 61% increase in the lipid yield of T. capitatum after cultivation at 28 °C and 160 rpm for 6 days. In addition, T. capitatum could grow well on cane molasses and afford a lipid yield comparable to that on synthetic nitrogen-limited medium. The biodiesel from the microbial oil produced by T. capitatum on cane molasses displayed a low cold filter plugging point (−15 °C), and so T. capitatum might be a promising strain to provide lipid suitable for high quality biodiesel production.     

Synthesis of magnetic carbonaceous acid derived from waste garlic peel for biodiesel production via esterification

Waste biomass-supported magnetic solid acids have particular advantages in catalyst separation. First, a novel magnetic carbonaceous catalyst was synthesized from waste garlic peel (GP) via in situ impregnation before conducting carbonization at 450–600°C and sulfonation at 105°C. The physical and chemical properties of the synthesized catalysts were characterized. It was found that the magnetism of the catalyst increased with the carbonization temperature. The optimized catalyst, carbonized at 600°C (C600-S), possessed an excellent magnetization value of 12.5 emu/g, with a specific surface area of 175.1 m²/g, a pore volume of 0.16 cm³/g, and an acidic property of 0.74 mmol/g -SO₃H density. By optimizing the esterification conditions to produce biodiesel, an oleic acid conversion of 94.5% was achieved at w(catalyst dosage) = 10% (w is mass fraction), a molar ratio of n(methanol): n(oleic acid) = 10: 1 (n is the amount of substance), and a reaction for 4 h at 90°C. Further, for catalyst regeneration, it was found that sulfuric acid treatment was more effective for improving the esterification activity than solvent washing, with which a conversion of more than 76% was achieved after the third run.     

Biohydrogen production from autoclaved fruit and vegetable wastes by dry fermentation under thermophilic condition

Dark fermentative hydrogen production from organic waste is an attractive technique that simultaneously treats waste along with generation of renewable fuel. In this study, a relative new technology named dark dry fermentation was tested in a 55-L reactor to treat fruit and vegetable waste (FVW) along with simultaneous generation of biohydrogen. To understand the effect of autoclaving as a pretreatment method on FVW for subsequent biohydrogen production, two independent experiments were performed; one with autoclaved waste (experiment I) and another by using non autoclaved waste (experiment II). From the analyses, it was found that maximum hydrogen % obtained for experiment I was 41% (v/v%) whereas, for experiment II was 21%. In terms of total hydrogen produced, around 30% higher production was observed with experiment I compared to experiment II. The hydrogen yields for experiment I and experiment II were respectively, 27.19 and 20.81 NmL H₂/gVS (VS = volatile solid added), and the metabolites (VFAs) preferentially produced were acetic acid and iso-butyric acid.