Transesterification of waste cooking palm oil by MnZr with supported alumina as a potential heterogeneous catalyst

The transesterification of waste cooking palm oil (WCPO) with methanol into fatty acid methyl esters (FAMEs) was investigated using solid acidic mixed oxide catalysts Mn_3.5xZr_0.5yAl_xO₃ prepared via coprecipitation. The effects of reaction temperature, time, molar methanol-to-oil ratio, and catalyst loading were investigated. The stability of the catalytic activity was examined via leaching and reusability tests through five consecutive batch runs. The catalyst achieved a FAME content of more than 93%, and the optimal reaction conditions are as follows: reaction temperature of 150 °C, reaction time of 5 h, molar methanol-to-WCPO ratio of 14:1, and catalyst loading of 2.5 wt.%.     

Optimization of the reaction parameters for fast pseudo single-phase transesterification of sunflower oil

Transesterification of sunflower oil with methanol was carried out using potassium hydroxide and methoxide as catalysts and MTBE as cosolvent. The aim of this work was to study and optimize the reaction parameters. Chosen parameters were reaction time, catalyst amount and methanol amount (expressed as catalyst-to-oil and methanol-to-oil molar ratios, respectively). The response variables were methyl ester content (ME) and acid value (AV) due to their relationship with the completion and yield reaction, respectively. A factorial plus composite design was developed to carry out the optimization. From this design, several quadratic models have been used to fit the experimental data. All the factors studied had a positive influence on methyl ester content and acid value, except the methanol amount on acid value. For methoxide catalyst, optimum values were 0.235 catalyst to oil molar ratio, 12 methanol to oil molar ratio and 5 min reaching 99 wt.% ME and 0.20 mg KOH/g of AV.     

Transesterification kinetics of palm olein oil using supercritical methanol

Continuous transesterification of palm olein oil using supercritical methanol was investigated in the absence of a catalyst. The variables studied were reaction temperature (270–350 °C), pressure (20–40 MPa), and residence time (5–25 min), with a methanol-to-oil molar ratio of 40. Preheating at 245 °C was used to form a homogeneous phase in the absence of thermal decomposition of palm olein oil. The activation energies and reaction activation volumes of the fatty acid methyl ester (FAME), and those of the individual components (C16:0, C18:0, C18:1, and C18:2 methyl esters), were calculated. The entropies of activation (ΔS^‡) of the transesterification reactions were also obtained. As the transesterification of vegetable oil in supercritical methanol included a strongly negative (−175 J/mol K) entropy of activation, transesterification required harsh conditions.     

Transesterification of rapeseed oil in the presence of basic zeolites and related solid catalysts

The transesterification of rapeseed oil with methanol was performed by reflux of methanol over cesium-exchanged NaX faujasites, mixed magnesium-aluminum oxides, magnesium oxide, and barium hydroxide for different methanol-to-oil ratios. Over cesium-exchanged NaX faujasites and mixed magnesium-aluminum oxides, a long reaction time and a high methanol-to-oil ratio are required to achieve both high oil conversion and high yields in methyl esters. However, over a 300 m²/g magnesium oxide, methanol-to-oil ratios and reaction times are significantly reduced to obtain both high oil conversion and high yield in the methyl esters, particularly when the hydroxide precursor is calcined at 823 K. Finally, preliminary results with other basic solids such as barium hydroxide have shown a very high activity and a very high yield in esters. This catalyst is particularly effective since, for a methanol-to-oil ratio of 6, at reflux of methanol and after a reaction time of only 1 h, the oil conversion is about 80% with a nearly quantitative ester molar fraction. Part of this work was presented at the 91st AOCS Annual Meeting, San Diego, California, April 2000.     

Optimization of biodiesel production from trap grease via acid catalysis

As a kind of waste collected from restaurants, trap grease is a chemically challenging feedstock for biodiesel production for its high free fatty acid (FFA) content. A central composite design was used to evaluate the effect of methanol quantity, acid concentration and reaction time on the synthesis of biodiesel from the trap grease with 50% free fatty acid, while the reaction temperature was selected at 95 °C. Using response surface methodology, a quadratic polynomial equation was obtained for ester content by multiple regression analysis. Verification experiments confirmed the validity of the predicted model. To achieve the highest ester content of crude biodiesel (89.67%), the critical values of the three variables were 35.00 (methanol-to-oil molar ratio), 11.27 wt% (catalyst concentration based on trap grease) and 4.59 h (reaction time). The crude biodiesel could be purified by a second distillation to meet the requirement of biodiesel specification of Korea.     

Process optimization for methyl ester production from waste cooking oil using activated carbon supported potassium fluoride

This paper presents the transesterification of waste cooking palm oil (WCO) using activated carbon supported potassium fluoride catalyst. A central composite rotatable design was used to optimize the effect of molar ratio of methanol to oil, reaction period, catalyst loading and reaction temperature on the transesterification process. The reactor was pressurized up to 10 bar using nitrogen gas. All the variables were found to affect significantly the methyl ester yield where the most effective factors being the amount of catalyst and reaction temperature, followed by methanol to oil ratio. A quadratic polynomial equation was obtained for methyl ester yield by multiple regression analysis using response surface methodology (RSM). The optimum condition for transesterification of WCO to methyl ester was obtained at 3 wt.% amount of catalyst, 175 °C temperature, 8.85 methanol to oil molar ratio and 1 h reaction time. At the optimum condition, the predicted methyl ester yield was 83.00 wt.%. The experimental value was well within the estimated value of the model. The catalyst showed good performance with a high yield of methyl ester and the separation of the catalyst from the liquid mixture is easy.     

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.     

Na/SiO2新型固体碱催化制备生物柴油的研究

以NaOH、正硅酸乙酯和乙醇为原料,经溶胶-凝胶法制备新型固体碱催化剂（Na/SiO₂）,用于催化大豆油与甲醇的酯交换反应制备生物柴油,研究催化剂焙烧温度、n(NaOH)∶n(SiO₂)、n(甲醇)∶n(大豆油)、催化剂用量和反应时间对产率的影响以及催化剂的稳定性。结果表明,固体碱催化剂Na/SiO₂在大豆油与甲醇的酯交换反应中具有较高的催化活性,在催化剂焙烧温度600 ℃、n(NaOH)∶n(SiO₂)=2∶1、n(甲醇)∶n(大豆油)=15∶1、催化剂用量为大豆油质量的7%和反应时间3 h的条件下,脂肪酸甲酯产率可达97.42%,催化剂在稳定性试验中呈现出优良的稳定性。     

Conversion of biomass to fuel: Transesterification of vegetable oil to biodiesel using KF loaded nano-γ-Al2O3 as catalyst

KF-impregnated nanoparticles of γ-Al₂O₃ were calcinated and used as heterogeneous catalysts for the transesterification of vegetable oil with methanol for the synthesis of biodiesel (fatty acid methyl esters, FAME). The ratio of KF to nano-γ-Al₂O₃, calcination temperature, molar ratio of methanol/oil, transesterification reaction temperature and time, and the concentration of the catalyst were used as the parameters of the study. A methyl ester yield of 97.7 ± 2.14% was obtained under the catalyst preparation and transesterification conditions of KF loading of 15 wt%, calcination temperature of 773 K, 8 h of reaction time at 338 K, and using 3 wt% catalysts and molar ratio of methanol/oil of 15:1. This relatively high conversion of vegetable oil to biodiesel is considered to be associated with the achieved relatively high basicity of the catalyst surface (1.68 mmol/g) and the high surface to volume ratio of the nanoparticles of γ-Al₂O₃.     

Biodiesel production from waste cooking palm oil using calcium oxide supported on activated carbon as catalyst in a fixed bed reactor

A reactor has been developed to produce high quality fatty acid methyl esters (FAME) from waste cooking palm oil (WCO). Continuous transesterification of free fatty acids (FFA) from acidified oil with methanol was carried out using a calcium oxide supported on activated carbon (CaO/AC) as a heterogeneous solid-base catalyst. CaO/AC was prepared according to the conventional incipient-wetness impregnation of aqueous solutions of calcium nitrate (Ca(NO₃)₂·4H₂O) precursors on an activated carbon support from palm shell in a fixed bed reactor with an external diameter of 60 mm and a height of 345 mm. Methanol/oil molar ratio, feed flow rate, catalyst bed height and reaction temperature were evaluated to obtain optimum reaction conditions. The results showed that the FFA conversion increased with increases in alcohol/oil molar ratio, catalyst bed height and temperature, whereas decreased with flow rate and initial water content in feedstock increase. The yield of FAME achieved 94% at the reaction temperature 60 °C, methanol/oil molar ratio of 25: 1 and residence time of 8 h. The physical and chemical properties of the produced methyl ester were determined and compared with the standard specifications. The characteristics of the product under the optimum condition were within the ASTM standard. High quality waste cooking palm oil methyl ester was produced by combination of heterogeneous alkali transesterification and separation processes in a fixed bed reactor. In sum, activated carbon shows potential for transesterification of FFA.     

Preparation of a CaO Nanocatalyst and Its Application for Biodiesel Production Using Butea monosperma Oil: An Optimization Study

CaO nanoparticles (NP) were synthesized through solution combustion using crude glycerin (biodiesel by‐product) as the combustion fuel. The synthesized CaO NP were characterized using Fourier transform infrared spectrometer (FTIR), X‐ray diffractometer (XRD), temperature programmed desorption of carbon dioxide (CO₂‐TPD), scanning electron microscope (SEM), and transmission electron microscope (TEM). The CaO NP were successfully used as a catalyst for biodiesel synthesis. Response surface methodology was used to determine the optimal conditions for biodiesel production from Butea monosperma oil (BMO) using central composite design. A total of 20 experiments were designed and conducted to study the effects of the methanol to BMO molar ratio, reaction time, and catalyst loading conditions on the biodiesel yield. A yield of 96.2% of Butea monosperma methyl ester (BMME or biodiesel) was obtained under optimum conditions, namely a molar ratio (methanol to BMO) of 9:1, a reaction time of 70 min, a catalyst loading of 1.60 wt%, a constant temperature of 65 °C, and an agitation speed of 600 rpm. The fatty‐acid composition of BMO was characterized through gas chromatography. Finally, BMME was characterized using FTIR, ¹H NMR, and ¹³C NMR, and the fuel properties of BMME were determined using the test methods of the American Society for Testing and Materials.     

Biodiesel synthesis via homogeneous Lewis acid-catalyzed transesterification

Lewis acids (AlCl₃ or ZnCl₂) were used to catalyze the transesterification of canola oil with methanol in the presence of terahydrofuran (THF) as co-solvent. The conversion of canola oil into fatty acid methyl esters was monitored by ¹H NMR. NMR analysis demonstrated that AlCl₃ catalyzes both the esterification of long chain fatty acid and the transesterification of vegetable oil with methanol suggesting that the catalyst is suitable for the preparation of biodiesel from vegetable oil containing high amounts of free fatty acids. Optimization by statistical analysis showed that the conversion of triglycerides into fatty acid methyl esters using AlCl₃ as catalyst was affected by reaction time, methanol to oil molar ratio, temperature and the presence of THF as co-solvent. The optimum conditions with AlCl₃ that achieved 98% conversion were 24:1 molar ratio at 110 °C and 18 h reaction time with THF as co-solvent. The presence of THF minimized the mass transfer problem normally encountered in heterogeneous systems. ZnCl₂ was far less effective as a catalyst compared to AlCl₃, which was attributed to its lesser acidity. Nevertheless, statistical analysis showed that the conversion with the use of ZnCl₂ differs only with reaction time but not with molar ratio.     

Synthesis of biodiesel from soybean oil using supercritical methanol in a one-step catalyst-free process in batch reactor

The transesterification of soybean oil with supercritical methanol in a batch reactor with no added catalyst was investigated, studying the evolution of intermediate products (monoglycerides and diglycerides) as well as the conversion of triglycerides and the yield of fatty acid methyl esters and glycerol. Experiments were carried out in a temperature range of 250–350 °C (12–43 MPa) at reaction times of between 15 and 90 min for a methanol-to-oil molar ratio of 43:1. The best reaction conditions in this one-step supercritical process (325 °C/35 MPa and 60 min), in which triglyceride conversion was practically total, led to a maximum yield of fatty acid methyl esters of 84%. In these conditions an 8.1 wt% of monoglycerides and diglycerides remained in the medium. Although the use of more severe reaction conditions (longer reaction times and higher temperatures) reduced the content of these glycerides, the yield of methyl esters decreased due to their thermal decomposition.     

Ni/NiAl2O4用于脂肪酸甲酯加氢制备液体石蜡

分别以γ-Al₂O₃和NiAl₂O₄为载体制备了用于脂肪酸甲酯加氢制备液体石蜡的催化剂,考察了载体酸性和工艺条件对脂肪酸甲酯加氢制备液体石蜡的影响。结果表明,载体酸性影响催化剂生成液体石蜡的选择性,适宜工艺条件为：反应温度400 ℃,反应氢压5.0 MPa,空速1.0 h^-1,氢油物质的量比15.56∶1。以Ni/NiAl₂O₄为催化剂,脂肪酸甲酯转化率达98.9%,正构烷烃选择性达100%。     

固体碱催化黄连木籽油制备生物柴油

制备了K2CO3/Mg(A l)O固体碱催化剂,适宜制备条件为:K2CO3负载量30%、在700℃下焙烧4 h。用比表面积测定仪、X射线衍射仪、红外光谱仪对其进行了表征。以黄连木籽油为原料,开展了酯交换法制备生物柴油的研究,考察了主要影响因素:醇油摩尔比、催化剂用量、反应时间和反应温度对酯交换反应的影响,得到的酯交换反应适宜条件为:以黄连木籽油0.01 mol计,醇油摩尔比12∶1、催化剂用量为黄连木籽油质量的4.0%、反应时间2.5 h、反应温度68℃。在该条件下生物柴油的收率可达99%以上。催化剂经4次循环使用,生物柴油收率仍可保持在96%以上。用FTIR1、HNMR对所制备的产品进行了表征,证明产品中含有饱和脂肪酸甲酯和不饱和脂肪酸甲酯。     

Continuous production of palm methyl esters

A system for continuous transesterification of palm oil was developed using a continuous stirred-tank reactor (CSTR) and pumps for continuous delivery of oil and catalyst and for continuous removal of product. Potassium hydroxide was used as the catalyst, the methanol-to-oil molar ratio was 6∶1, and reaction temperature was 60°C. The yield of methyl esters increased from 58.8% of theoretical yield at a residence time of 40 min to 97.3% at a residence time of 60 min. However, higher residence times decreased the production rate. During long-term continuous operation, the CSTR displayed steady state conditions in terms of product profile and methyl ester concentration. This process has good potential in the manufacture of biodiesel.     

Biolubricant Production of 2‐Ethylhexyl Palmitate by Transesterification Over Unsupported Potassium Carbonate

Owing to the decrease of global oil price, development of downstream value‐added products is important to biodiesel industry. In this study, we used palmitic acid methyl ester (PAME) as a starting material to produce 2‐ethylhexyl palmitate (2‐EHP), an environmentally friendly biolubricant product, which was derived from the transesterification of fatty acid methyl esters and long chain fatty alcohols. Conventional synthetic routes of 2‐EHP have disadvantages, including high catalyst price, low conversion efficiency, and pollution issues. To solve these problems, in situ transesterification of PAME with 2‐ethylhexanol (2‐EH) was conducted over unsupported potassium carbonate as heterogeneous catalyst. The optimal reaction temperature, 2‐EH to PAME molar ratio, and catalyst to PAME mass ratio were 180 °C, 3:1, and 3.0 wt%, respectively. The PAME conversion reached up to 100% within 1 hour under the optimal conditions. In addition, a kinetic model describing the experimental data over a temperature range of 160–180 °C was developed. The dependence of kinetic rate constant (k) on temperature was evaluated, and the activation energy (E_a) for the transesterification of PAME with 2‐EH was calculated to be 57.04 kJ mol^?1.     

Oil transesterification over calcium oxides modified with lanthanum

Investigations were conducted on a series of calcium and lanthanum oxides catalyst for biodiesel production. Mixed oxides catalyst showed a superior transesterification activity over pure calcium or pure lanthanum oxide catalysts. The catalyst activity was correlated with surface basicity and specific surface areas. The effects of water and free fatty acids (FFA) levels in oil feedstock, water and CO₂ in air, mass ratio of catalyst, molar ratio of oil to methanol, and reaction temperature on fatty acid methyl ester (FAME) yield were investigated. Under optimal conditions, FAME yields reached 94.3% within 60 min at 58 °C. Mixed CaO-La₂O₃ catalyst showed a high tolerance to water and FFA, and could be used for converting pure or diluted unrefined/waste oils to biodiesel.     

In-situ synthesis of MCM-41 on ceramic membranes and its application in transesterification as catalyst support for p-toluenesulfonic acid

In this study, a new kind of solid acid catalyst p-toluenesulfonic acid/MCM-41/ceramic membrane was synthesized by in situ synthesis and impregnation method, which has shown its favorable catalytic activity, as verified in the transesterification and catalyst characterization. The catalyst was characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Fourier-transform infrared spectroscopy. The transesterification of palm oil and methanol results showed that p-toluenesulfonic acid/MCM-41/ceramic membrane had the highest catalytic activity with immersing p-toluenesulfonic acid solution concentration of 0.15 mol/L. Different operation parameters of the transesterification of palm oil with methanol, such as catalyst amount, catalytic mass ratio, reaction time, reaction temperature and methanol/palm oil molar ratio were investigated. Under the optimum conditions of 4 % of fresh catalyst (catalytic mass ratio is 4.37 %), 80 min of reaction time, reaction temperature of 120 °C and methanol to palm oil molar ratio of 12:1, a relatively high fatty acid methyl ester yield of 95.6 % was obtained.     

邻苯二甲酸酐一缩二乙二醇酯的合成

讨论了邻苯二甲酸酐一缩二乙二醇酯的合成工艺,分别以硫酸和对甲基苯磺酸为催化剂合成邻苯二甲酸酐一缩二乙二醇酯。结果表明,对甲基苯磺酸作催化剂的选择性较好,合成邻苯二甲酸酐一缩二乙二醇酯的最佳反应条件为:以对甲基苯磺酸为催化剂,其加入量为一缩二乙二醇质量的1%,反应温度185 ℃,邻苯二甲酸酐和一缩二乙二醇物质的量比为1∶2,反应时间10 h,产品纯度大于98.0%。