Ultrasonic-assisted biodiesel production process from palm oil using alkaline earth metal oxides as the heterogeneous catalysts

The ultrasonic-assisted transesterification of palm oil in the presence of alkaline earth metal oxide catalysts (CaO, SrO and BaO) was investigated. Batch process assisted by 20 kHz ultrasonic cavitation was carried out to study the effect of reaction time (10-60 min), alcohol to palm oil molar ratio (3:1-15:1), catalysts loading (0.5-3%) and varying of ultrasonic amplitudes (25-100%). The activities of the catalysts were mainly related to their basic strength. The catalytic activity was in the sequence of CaO < SrO < BaO. At optimum conditions, 60 min was required to achieve 95% yield compared to 2-4 h with conventional stirring. Also, the yields achieved in 60 min increased from 5.5% to 77.3% (CaO), 48.2% to 95.2% (SrO), and 67.3% to 95.2 (BaO). Fifty percentage amplitude of ultrasonic irradiation was deemed the most suitable value and physical changes on the catalysts after the ultrasonic-assisted reaction were successfully elucidated. BaO catalyst underwent relatively more severe activity drop in the catalyst reusability test. Catalysts dissolution was found to be mainly responsible for activity drop of the reused catalysts, especially with BaO catalyst.     

Intensification of biodiesel production from vegetable oils using ultrasonic-assisted process: Optimization and kinetic

Intensification of biodiesel production process using low frequency ultrasonic irradiation (20 kHz, 200 W) is elucidated in this study. Effects of five process variables in an ultrasonic-assisted reactor catalyzed by SrO through transesterification of vegetable oils are investigated. RSM was employed and the optimum conditions were at an ultrasonic pulse on of 9 s followed by 2 s of pulse off within a reaction time of 30.7 min. The optimum ultrasonic power was found to be 130 W using an oil amount of 52 g (R² = 0.97). The model was applicable to different types of oil with errors less than 10%. FFA content was responsible for the different yields obtained with different oils. Three steps of the transesterification process were measured to obtain the kinetic study. The results revealed that the reaction followed a second-order kinetic. The activation energies varied between 70.63 kJ/mol and 136.93 kJ/mol showing relatively high coefficient of determinations.     

纳米催化剂在生物柴油合成中的应用

生物柴油作为一种可再生的绿色能源,是化石燃料理想的替代品.该文聚焦于纳米催化剂在生物柴油合成中的应用,对常见的纳米催化剂的设计、制备、物化性质、催化行为及重复使用性等方面进行了综述.提出了纳米催化剂在生物柴油合成中所面临的问题并展望其应用前景.     

纳米催化剂在生物柴油合成中的应用

生物柴油作为一种可再生的绿色能源,是化石燃料理想的替代品。本文聚焦于纳米催化剂在生物柴油合成中的应用,就常见的纳米催化剂的设计制备、物化性质、催化行为及重复使用性等方面进行了综述,最后提出了纳米催化在生物柴油合成中所面临的问题并展望其应用前景。     

Synthesis of biodiesel fuel using an electrolysis method

The paper details the first use of a simple electrolysis method to produce biodiesel fuel (BDF) from corn oil and waste cooking oil at room temperature. This novel process exhibited a high fatty acid methyl ester (FAME) yield (>97%) even in the presence of a relatively high water content (as high as 2 wt.% of the total reaction mixture) when using a low concentration of sodium chloride (<1.2 wt.% based on oil weight). FAME yield was influenced by methanol/oil molar ratio, the amount of cosolvent addition, water content, NaCl concentration and electrolysis voltage. With the proceeding of electrolysis, the pH value of the electrolyte rapidly increased from 7 to 12, but the conductivity of the reaction mixture decreased. When the electrolysis was stopped on the way, the transesterification reaction was still continued, but the reaction rate became lower than that when continuing the electrolysis in the case of high water content. During the electrolysis process, no chlorine molecule in the evolved gas was detected (<0.5 ppm).     

Highly efficient procedure for the synthesis of biodiesel from soybean oil

The novel efficient procedure has been developed for the synthesis of biodiesel from soybean oil and methanol. K₂CO₃ supported on MgO has been selected as the most efficient catalyst for the reaction with the yield of 99%. Operational simplicity, low cost of the catalyst used, high yields, short reaction time and reusability are the key features of this methodology.     

镍镁铝复合金属氧化物催化剂制备生物柴油

采用共沉淀法先制备镍镁铝类水滑石化合物,以其为前驱体经400℃煅烧后制得镍镁铝复合金属氧化物催化剂。研究了过渡金属含量、n(甲醇)∶n(大豆油)和反应温度对生物柴油转化率的影响。当n(Ni 2+)∶n(Mg2+)∶n(Al 3+)=0.64∶2.36∶1时,转化率最高,可达到92.8%。而n(甲醇)∶n(大豆油)=10∶1,w(催化剂)=4%,反应温度为65℃,反应时间4h是所得的最佳操作条件。研究出的镍镁铝复合金属氧化物可作为多相催化剂,具有生产生物柴油的潜力。     

Small scale biodiesel synthesis from waste frying oil and crude methanol in Morocco

Biodiesel was produced at small scale by transesterification of used frying oil(UFO) recovered from Moroccan pastry shops and fish frying restaurants. Biodiesel was first synthesised at laboratory scale in order to optimize the transesterification parameters. The cost of the final product was also optimized using low-cost raw materials.The UFO and the produced biodiesel were characterized with several techniques including gas chromatography,1H NMR,13 C NMR, FTIR, and TGA–TDA techniques.1H NMR gas chromatographic analyses of the final product confirmed that the transesterification in the chosen experimental conditions was completed. These results were confirmed by TGA–TDA analysis used as new techniques to monitoring triglyceride conversion. The biodiesel did not contain any trace of glycerol, and it did meet the international standards. The transesterification at low cost in small scale conditions was performed at 60 °C using 1.2% of KOH and a methanol/oil molar ratio of 6:1. A yield of 80.8% was achieved. The properties of the produced biodiesel were found to be as good as those of biodiesels obeying to European standards. The biodiesel production was also performed at small-scale for individual utilisation. Thus, the product was tested in a kerosene stove for heating and non-modified commercial diesel engine producing electricity.     

Transesterification of soybean frying oil to biodiesel using heterogeneous catalysts

In the present work, the transesterification reaction of soybean frying oil with methanol, in the presence of different heterogeneous catalysts (Mg MCM-41, Mg-Al Hydrotalcite, and K⁺ impregnated zirconia), using low frequency ultrasonication (24 KHz) and mechanical stirring (600 rpm) for the production of biodiesel fuel was studied. Selection of catalysts was based on a combination of porosity and surface basicity. Their characterization was carried out using X-ray diffraction, Nitrogen adsorption-desorption porosimetry and scanning electron microscopy (SEM) with energy dispersive spectra (EDS). The activities of the catalysts were related to their basic strength. Mg-Al hydrotalcite showed particularly the highest activity (conversion 97%). It is important to mention that the catalyst activity of ZrO₂ in the transesterification reaction increased as the catalyst was enriched with more potassium cations becoming more basic. Use of ultrasonication significantly accelerated the transesterification reaction compared to the use of mechanical stirring (5 h versus 24 h).     

Intensified production of biodiesel using a spinning disk reactor

This work achieves continuous transesterification of soybean oil and methanol in a spinning disk reactor. The effects of the methanol-to-oil molar ratio, catalyst type, catalyst concentration, reaction temperature, flow rate, and rotational speed were investigated. Optimal yield of 96.9% was obtained with a residence time of 2–3 s at a molar ratio of 6, potassium hydroxide concentration of 1.5 wt%, temperature of 60 °C, flow rate of 773 mL/min, and rotational speed of 2400 rpm. The production rate of 1.86 mol/min was high compared to that of other reactors for continuous transesterification process, indicating that a spinning disk reactor is a promising alternative method for continuous biodiesel production.     

Flow-mode synthesis of biodiesel under simultaneous microwave-magnetic irradiation

In this study, aiming at optimization of a novel continuous biodiesel production system was developed by combining technologies based on microwaves and magnetic fields. Factors affecting microwave-assisted biodiesel (alkyl esters) production reaction were analyzed in this investigation. Studied factors included magnetic field intensity (0, 0.225 and 0.450 T), microwave power (400, 821, and 1181 W), percentages of KOH and NaOH catalysts at constant concentrations of 1 wt% (0, 50% and 100%), and percentages of ethanol and methanol at a constant molar ratio of 6:1 (0, 50% and 100%). Response Surface Methodology (RSM) was used to optimize the reaction conditions. RSM-based analysis indicated that, all independent parameters had significant effects on the reaction efficiency. Results of the investigations reveal that the largest effects on the conversion efficiency were due to type of alcohol and magnetic field intensity. The optimized conditions were found to be a magnetic field intensity of 0.331 T, a microwave power of 677.77 W, catalyst percentages of 30.35% and 69.65% for KOH and NaOH, respectively, and alcohol percentages of 80.47% and 19.53% for methanol and ethanol, respectively. Under the optimal conditions, yield of the reaction was 96.2%.     

Mass transfer simulation of biodiesel synthesis in microreactors

A coupled nonlinear mathematical model for the mass transfer of the species involved in the transesterification reaction between soybean oil and methanol in a parallel plates geometry microreactor is presented. The set of partial differential equations that governs the concentration profile of these species were obtained from the general mass balance equation for the case of isothermal flow and steady state with constant physical properties. The velocity profile was obtained from the Navier-Stokes equations assuming fully developed stratified laminar flow for two immiscible Newtonian fluids, with a plane interface between them, based on experimental observation of this flow pattern. The second order kinetic equations for the species were developed assuming homogeneous and reversible chemical reactions and these equations were written as source terms in the main equations. The mathematical model was solved using the hybrid method known as Generalized Integral Transform Technique (GITT). The simulation results were critically compared with those obtained by using the COMSOL multiphysics platform, showing a good agreement between the hybrid and fully numerical simulations. The effects of governing parameters such as residence time, temperature and microreactor dimensions were investigated. It was observed that higher triglycerides conversion rates occurred at higher temperatures and residence times and lower microreactor depths.     

Transesterification of vegetable oil to biodiesel fuel using acid catalysts in the presence of dimethyl ether

The immiscibility of methanol and vegetable oil leads to a mass-transfer resistance in the transesterification of vegetable oil. To overcome this problem, dimethyl ether (DME) was used as an environmentally friendly cosolvent to produce a homogeneous solution. Methylesterifications of corn oil in both the presence and the absence of DME were performed using p-toluenesulfonic acid (PTSA), benzenesulfonic acid and sulfuric acid. PTSA showed highest catalytic activity. The yield of FAME reached 97.1% when 4 wt% of PTSA based on the oil weight was used at 80 °C with a reaction time of 2 h in the presence of DME. The obtained biodiesel was composed of methyl palmitate (9.1 wt%), methyl oleate (33.9 wt%), methyl linoleate (53.5 wt%), methyl linolenate (3.0 wt%) and methyl arachidate (0.5 wt%), and it was similar to the biodiesel compositions from corn oil as reported. The effects of concentrations of FFA and water on FAME yields were also investigated. All results suggested that the reaction rate was greatly improved by the addition of DME to the reaction system.     

Intensification of production of O/W emulsions using oscillatory woven metal micro-screen (WMMS)

Using high porosity woven metal micro-screen (WMMS), a novel design oscillatory emulsifier had been used for intensification of production of relatively narrow size distribution oil in water (O/W) emulsions. The average droplet size increased with increasing the dispersed phase flow and decreased with increasing both the oscillation frequency and amplitude. The emulsion polydispersity decreased with increasing both oscillation intensities as well as dispersed phase flux. Although the change in droplet size with oscillation was reasonably predicted using a simple torque balance model based on Stokes oscillatory flow, both the flow patterns and the surface phenomena are more complex, and the final droplet size is affected by interactions between different operating and physical parameters.     

Theoretical study of the transesterification of triglycerides to biodiesel fuel

The transesterification of various triglycerides was considered in terms of the activation energy obtained from quantum computational chemistry. According to these values, the effect upon the reactivity of the structure of the triglyceride is not particularly large. Moreover, the transesterification reaction is completed via a transition state, in which ring formation consisting of the carbon of the carboxyl and alkoxy groups appears, even if a long-chain alcohol is used as a reactant. Finally, an ideal reaction pathway, in which the ester bond at the center of the triglyceride is transesterified before peripheral ester bonds, was shown by an activation energy analysis and electrostatic potential (ESP) distribution.     

Kinetics of biodiesel synthesis from sunflower oil over CaO heterogeneous catalyst

Calcium oxide as a heterogeneous catalyst was investigated for its effect on the biodiesel synthesis from refined sunflower oil. Experiments were carried out using a commercial bench stirred tank reactor of 2 dm³ volume, at 200 rpm, with a methanol to oil ratio 6 to 1 and 1 mas.% catalyst loading as constant parameters. Ester yields were followed as a function of temperature (60-120 °C), pressure (1-15 bars) and reaction time (1.5-5.5 h). The temperature of 100 °C was found to be optimal for the maximum (91%) conversion to methyl esters, while pressure had a positive impact up to 10 bars at 80 °C. The catalyst activation in air leading to the formation of strong basic sites was found to occur at 900 °C. Catalyst particle coalescence took place during the reaction, giving a gum-like structure, and resulted in a significant catalyst deactivation. The pseudo-first order reaction was established, with a “knee” at 80 °C in the Arrhenius plot separating the kinetic and diffusion regimes. During the reaction progress, an activation energy decrease from 161 to 101 kJ/mol, and from 32 to (−3) kJ/mol, was found for the kinetic and diffusion regimes, respectively.     

生物柴油合成催化剂的研究进展

生物柴油是典型的"绿色能源",是优质的石油柴油代用品。综述了酯交换方法生产生物柴油过程中催化剂的研究进展,并重点介绍了固体碱催化剂的研究状况。     

Optimization of the transesterification reaction in biodiesel production

In this paper response surface methodology (RSM) was used to study the transesterification reaction of rapeseed oil for biodiesel production. The three main factors that drive the conversion of triglycerides into fatty acid methyl esters (FAME) were studied according to a full factorial design at two levels. These factors were catalyst concentration (KOH), temperature and reaction time. The range investigated for each factor was selected taking into account the process of Fox Petroli S.p.A. Analysis of variance (ANOVA) was used to determine the significance of the factors and their interactions which primarily affect the first of the two transesterification stages. This analysis evidenced the best operating conditions of the first transesterification reaction performed at Fox’s plant: KOH concentration 0.6% w/w, temperature 50 °C and reaction time 90 min with a CH₃OH to KOH ratio equal to 60. Three empirical models were derived to correlate the experimental results, suitable to predict the behavior of triglyceride, diglyceride and monoglyceride concentration. These models showed a good agreement with the experimental results, demonstrating that this methodology may be useful for industrial process optimization.     

Kalsilite based heterogeneous catalyst for biodiesel production

Kalsilite (KAlSiO₄) was used as a heterogeneous catalyst for transesterification of soybean oil with methanol to biodiesel. Kalsilite showed relatively low catalytic activity for transesterification reaction. The catalytic activity of this catalyst was significantly enhanced by introducing a small amount of lithium nitrate by the impregnation method. A biodiesel yield of 100% and a kinematic viscosity of 3.84 cSt were achieved at a mild temperature of only 120 °C over this lithium modified kalsilite catalyst (2.3 wt.% Li).