Biodiesel production using tetramethyl- and benzyltrimethyl ammonium hydroxides as strong base catalysts

In recent years, the acceptance of fatty acid methyl esters (biodiesel) as an alternative fuel has rapidly grown in EU. The most common method for biodiesel production is based on triglyceride transesterification to methyl esters with dissolved sodium hydroxide in methanol as catalyst. In this study, cottonseed oil and used frying oil were subjected to the transesterification reaction with tetramethyl ammonium hydroxide and benzyltrimethyl ammonium hydroxide as strong base catalysts. This work investigates the optimum conditions for biodiesel production using amine-based liquid catalysts. Biodiesel ester content was strongly related with the type of feedstock and the reaction variables, such as those of the catalyst concentration, methanol to oil molar ratio, and reaction time. The overall results suggested that the transesterification of cottonseed oil achieved high conversion rates with both catalysts, while the use of waste oil resulted in lower yields of methyl esters due to the possible formation of amides.     

Synthesis of economically viable biodiesel from waste frying oils (WFO)

In present communication, waste frying oil (WFO) has been used as a feedstock for biodiesel synthesis. WFO, procured from a local Indian restaurant possessed an acid value of 0.84 mg KOH/g, which is low enough for single step transesterification reaction. Biodiesel (fatty acid methyl esters) was washed after transesterification reaction and the yield got lowered substantially (from 96% to 86.36%) after water washing owing to loss of esters. 30:100 vol% (methanol to oil), 0.6 wt% NaOCH₃, 60°C temperature and 600 rpm agitation in 1 h reaction time was found to be optimum for transesterification reaction. ¹H NMR spectrum showed a high conversion (95.19%) of fatty acids in WFO to biodiesel in 2 h reaction time. Almost complete conversion (99.68%) was attained in 2 h reaction time. © 2011 Canadian Society for Chemical Engineering     

Metakaolinite as a catalyst for biodiesel production from waste cooking oil

The use of metakaolinite as a catalyst in the transesterification reaction of waste cooking oil with methanol to obtain fatty acid methyl esters (biodiesel) was studied. Kaolinite was thermally activated by dehydroxylation to obtain the metakaolinite phase. Metakaolinite samples were characterized using X-ray diffraction, N₂ adsorption-desorption, simultaneous thermo-gravimetric analyse/differential scanning calorimetry (TGA/DSC) experiments on the thermal decomposition of kaolinite and Fourier-transform infrared spectrometer (FTIR) analysis. Parameters related to the transesterification reaction, including temperature, time, the amount of catalyst and the molar ratio of waste cooking oil to methanol, were also investigated. The transesterification reaction produced biodiesel in a maximum yield of 95% under the following conditions: metakaolinite, 5 wt-% (relative to oil); molar ratio of oil to methanol, 1∶23; reaction temperature, 160°C; reaction time, 4 h. After eight consecutive reaction cycles, the metakaolinite can be recovered and reused after being washed and dried. The biodiesel thus obtained exhibited a viscosity of 5.4?mm²?s^–1 and a density of 900.1 kg?m^–3. The results showed that metakaolinite is a prominent, inexpensive, reusable and thermally stable catalyst for the transesterification of waste cooking oil.     

Optimization of transesterification for methyl ester production from chicken fat

In this study, low cost feedstock chicken fat was used to produce methyl ester. After reducing the free fatty acid level of the chicken fat less than 1%, the transesterification reaction was completed with alkaline catalyst. Potassium hydroxide, sodium hydroxide, potassium methoxide and sodium methoxide were used as catalyst and methanol was used as alcohol for transesterification reactions. The effects of catalyst type, reaction temperature and reaction time on the fuel properties of methyl esters were investigated. The produced chicken fat methyl esters were characterized by determining their viscosity, density, pour point, flash point, acid value, methanol content, heat of combustion value, total-free glycerin, mono-di-tri glycerides, copper strip corrosion and ester yield values. The measured fuel properties of the chicken fat methyl ester met EN 14214 and ASTM D6751 biodiesel specifications when using potassium hydroxide and sodium hydroxide catalysts with high ester yield.     

Conversion of waste cooking oil to biodiesel using ferric sulfate and supercritical methanol processes

In this comparative study, conversion of waste cooking oil to methyl esters was carried out using the ferric sulfate and the supercritical methanol processes. A two-step transesterification process was used to remove the high free fatty acid contents in the waste cooking oil (WCO). This process resulted in a feedstock to biodiesel conversion yield of about 85-96% using a ferric sulfate catalyst. In the supercritical methanol transesterification method, the yield of biodiesel was about 50-65% in only 15 min of reaction time. The test results revealed that supercritical process method is probably a promising alternative method to the traditional two-step transesterification process using a ferric sulfate catalyst for waste cooking oil conversion. The important variables affecting the methyl ester yield during the transesterification reaction are the molar ratio of alcohol to oil, the catalyst amount and the reaction temperature. The analysis of oil properties, fuel properties and process parameter optimization for the waste cooking oil conversion are also presented.     

亚临界甲醇中麻疯树油制备生物柴油的研究

对麻疯树油在催化剂对甲苯磺酸作用下与亚临界甲醇反应制备脂肪酸甲酯(生物柴油)进行了研究。结果表明在反应温度170℃、醇油摩尔比40:1、催化剂用量占油重的0.75%和反应时间30 m in的条件下,反应产物中脂肪酸甲酯含量可达93%以上。制备的生物柴油,各项指标与柴油相似。主要性能指标,符合ASTMPS121-99(USA)和0#矿物柴油标准。     

Development of solid base catalyst X/Y/MgO/-AlO for optimization of preparation of biodiesel from L.seed oil

The preparation and regeneration conditions of the identified catalyst X/Y/MgO/?-Al₂O₃ with high catalytic activity were studied and optimized. The biodiesel was prepared by transesterification of Jatropha curcas seed oil produced in Guizhou with methanol at its reflux temoerature in the presence of X/Y/MgO/?-Al₂O_{3 .} The pilot plant tests were carried out in a 100 L reaction vessel. Both average yield and fatty acid methyl esters (FAME) content reached more than 96.50% under the optimum reaction conditions of the pilot plant tests designed with an oil/methanol molar ratio of 1 : 10, catalyst concentration of 1.00%, and reaction time of 3 h at reflux temperature. In addition, analysis shows that the quality of biodiesel meets the standard EN 14214.     

Transesterification of karanja (Pongamia pinnata) oil by solid basic catalysts

The transesterification of karanja oil with methanol was carried out using solid basic catalysts. Alkali metal‐impregnated calcium oxide catalysts, due to their strong basicity, catalyze the transesterification of triacylglycerols. The alkali metal (Li, Na, K)‐doped calcium oxide catalysts were prepared and used for the transesterification of karanja oil containing 0.48–5.75% of free fatty acids (FFA). The reaction conditions, such as catalyst concentration, reaction temperature and molar ratio of methanol/oil, were optimized with the solid basic Li/CaO catalyst. This catalyst, at a concentration of 2 wt‐%, resulted in 94.9 wt‐% of methyl esters in 8 h at a reaction temperature of 65 °C and a 12 : 1 molar ratio of methanol to oil, during methanolysis of karanja oil having 1.45% FFA. The yield of methyl esters decreased from 94.9 to 90.3 wt‐% when the FFA content of karanja oil was increased from 0.48 to 5.75%. The performance of this catalyst was not significantly affected in the presence of a high FFA content up to 5.75%. The catalytic activities of Na/CaO and K/CaO were also studied at the optimized reaction conditions. In these two cases, the reaction initially proceeds slowly, however, leading to similar yields as in the case of Li/CaO after 8 h of reaction time. The purified karanja methyl esters have an acid value of 0.36 mg KOH/g and an ester content of 98.6 wt‐%, which satisfy the American as well as the European specifications for biodiesel in terms of acid value and ester content.     

Transesterification of rapeseed oil in subcritical methanol conditions

In this study, transesterification of rapeseed oil using subcritical methanol conditions was studied. 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, the catalyst type and content, reaction temperature and pressure, the presence of hexane as co-solvent, the methanol oil molar ratio and the methanol hexane 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, saponification value, iodine value, acidity index and water content, according to ISO norms. High methyl ester yield and fast reaction rate could be obtained even if the reaction pressure was relatively low, which is quite favorable to the production of biodiesel in industry.     

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。     

疏水改性氧化钙催化制备生物柴油的研究

以溴化苄作为改性剂,采用化学键合方法对市售氧化钙进行表面改性,考察改性氧化钙固体碱催化菜籽油-甲醇酯交换反应制备生物柴油的性能,并在此基础上对该催化体系的耐水性进行考察。通过对反应体系中醇/油摩尔比、催化剂用量和反应时间进行优化,最终得出在醇/油摩尔比为15∶1,催化剂用量为5%以及表面改性剂溴化苄用量为0.2%时,表面改性氧化钙上生物柴油产率在反应3h即可达到99.8%,而未改性氧化钙为催化剂时在相同反应条件下生物柴油产率仅为35.3%。     

Production of mixed methyl/ethyl esters from waste fish oil through transesterification with mixed methanol/ethanol system

Biodiesel (mixed fatty acid methyl/ethyl esters) was prepared from waste fish oil through base-catalyzed transesterification with mixed methanol/ethanol system. Effect of methanol/ethanol (% v/v), type and concentration of the catalyst, mixed alcohols to oil molar ratio, the reaction temperature, and the reaction time on the biodiesel yield was optimized. Maximum biodiesel yield (97.30?wt%) was produced by implementing 1:1 methanol/ethanol (v/v), 1.0?wt% KOH, 6:1 mixed alcohols to oil molar ratio, 40°C reaction temperature, and 30?min of reaction time. Conversion of the waste fish oil to mixed methyl/ethyl esters was confirmed by ¹H NMR spectroscopy. Fuel properties of the resulting biodiesel in addition to its blends with petrodiesel were in good agreement with specifications of ASTM D6751 and ASTM D7467, respectively. Therefore, it was concluded that using mixed alcohol system for biodiesel production could reduce the production cost through reducing conditions required for maximum conversion.     

Synthesis of biodiesel from soybean oil and methanol catalyzed by zeolite beta modified with La

La/zeolite beta was prepared by an ion exchange method and used to synthesize the biodiesel (fatty acid methyl esters, FAME). The La(NO₃)₃ was applied as the ion exchange precursor to incorporate La ion into zeolite beta. The composition of the zeolite beta before and after ion exchange was analyzed by the SEM microphotographs and EDS spectrograms, the Brønsted and Lewis acid sites were investigated by FTIR imaging. The transesterification was carried out in a batch reactor and the composition of the FAME product was determined by a potassium hydroxide saponification method. The syntheses conditions with respect to catalytic activities have been optimized individually. Results of the experiment showed that La/zeolite beta shows higher conversion and stability than zeolite beta for the production of biodiesel, which may be correlated to the higher quantity of external Brønsted acid sites available for the reactants. The product consists of a mixture of monoalkyl esters primarily, and when the methanol/ soybean oil molar ratio was 14.5, reaction temperature at 333 K, reaction time 4 h and catalyst/soybean oil mass ratio of 0.011, the conversion of triglyceride 48.9 wt% was obtained from this optimal reaction condition.     

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.     

Biodiesel production using supercritical methanol/carbon dioxide mixtures in a continuous reactor

Fatty acid methyl esters (biodiesel) were produced by the transesterification of triglycerides with compressed methanol (critical point at 240 °C and 81 bar) in the presence of solid acids as heterogeneous catalyst (SAC-13). Addition of a co-solvent, supercritical carbon dioxide (critical point at 31 °C and 73 bar), increased the rate of the supercritical alcohols transesterification, making it possible to obtain high biodiesel yields at mild temperature conditions. Experiments were carried out in a fixed bed reactor, and reactions were studied at 150-205 °C, mass flow rate 6-24 ml/min at a pressure of 250 bar. The molar ratio of methanol to oil, and catalyst amount were kept constant (9 g). The reaction temperature and space time were investigated to determine the best way for producing biodiesel. The results obtained show that the observed reaction rate is 20 time faster than conventional biodiesel production processes. The temperature of 200 °C with a reaction time of 2 min were found to be optimal for the maximum (88%) conversion to methyl ester and the free glycerol content was found below the specification limits.     

Synthesis of biodiesel from soybean oil and methanol catalyzed by zeolite beta modified with La3+

La/zeolite beta was prepared by an ion exchange method and used to synthesize the biodiesel (fatty acid methyl esters, FAME). The La(NO₃)₃ was applied as the ion exchange precursor to incorporate La ion into zeolite beta. The composition of the zeolite beta before and after ion exchange was analyzed by the SEM microphotographs and EDS spectrograms, the Brønsted and Lewis acid sites were investigated by FTIR imaging. The transesterification was carried out in a batch reactor and the composition of the FAME product was determined by a potassium hydroxide saponification method. The syntheses conditions with respect to catalytic activities have been optimized individually. Results of the experiment showed that La/zeolite beta shows higher conversion and stability than zeolite beta for the production of biodiesel, which may be correlated to the higher quantity of external Brønsted acid sites available for the reactants. The product consists of a mixture of monoalkyl esters primarily, and when the methanol/ soybean oil molar ratio was 14.5, reaction temperature at 333 K, reaction time 4 h and catalyst/soybean oil mass ratio of 0.011, the conversion of triglyceride 48.9 wt% was obtained from this optimal reaction condition.     

Biodiesel production from highly unsaturated feedstock via simultaneous transesterification and partial hydrogenation in supercritical methanol

In this study, a supercritical one-pot process combining transesterification and partial hydrogenation was proposed to test its technical feasibility. Simultaneous transesterification of soybean oil and partial hydrogenation of polyunsaturated compounds over Cu catalyst in supercritical methanol was performed at 320 °C and 20 MPa. Hydrogenation proceeded simultaneously during the transesterification of soybean oil in supercritical methanol, and hydrogenation occurred during the reaction despite the absence of hydrogen gas. The polyunsaturated methyl esters obtained in the biodiesel were mainly converted to monounsaturated methyl esters by partial hydrogenation. Key properties of the partially hydrogenated methyl esters were improved and complied with standard specifications for biodiesel.     

Production of biodiesel through optimized alkaline-catalyzed transesterification of rapeseed oil

Present work reports an optimized protocol for the production of biodiesel through alkaline-catalyzed transesterification of rapeseed oil. The reaction variables used were methanol/oil molar ratio (3:1-21:1), catalyst concentration (0.25-1.50%), temperature (35-65 °C), mixing intensity (180-600 rpm) and catalyst type. The evaluation of the transesterification process was followed by gas chromatographic analysis of the rapeseed oil fatty acid methyl esters (biodiesel) at different reaction times. The biodiesel with best yield and quality was produced at methanol/oil molar ratio, 6:1; potassium hydroxide catalyst concentration, 1.0%; mixing intensity, 600 rpm and reaction temperature 65 °C. The yield of the biodiesel produced under optimal condition was 95-96%. It was noted that greater or lower the concentration of KOH or methanol than the optimal values, the reaction either did not fully occur or lead to soap formation.The quality of the biodiesel produced was evaluated by the determinations of important properties such as density, specific gravity, kinematic viscosity, higher heating value, acid value, flash point, pour point, cloud point, combustion point, cold filter plugging point, cetane index, ash content, sulphur content, water content, copper strip corrosion value, distillation temperature and fatty acid composition. The produced biodiesel was found to exhibit fuel properties within the limits prescribed by the latest American Standards for Testing Material (ASTM) and European EN standards.     

以单体酸为原料制备生物柴油

研究了以单体酸为原料制备生物柴油的方法,反应以对甲苯磺酸为催化剂,单体酸与甲醇进行酯化反应获得脂肪酸甲酯。分别考察了酯化反应条件如甲醇与脂肪酸的摩尔比、反应时间、催化剂浓度以及反应温度对酯化率的影响。通过正交实验得到最佳酯化反应参数：醇酸摩尔比3∶1,反应时间3 h,对甲苯磺酸用量6%,反应温度60 ℃,该条件下单体酸酯化率达98.25%。实验制得的单体酸甲酯生物柴油的主要性能指标符合ASTM质量标准,并与0^#柴油性质接近。     

Effect of Different Cosolvents on Transesterification of Waste Cooking Oil in a Microreactor

Biodiesel was prepared from waste cooking oil combined with methanol. The process was performed via transesterification in a microreactor using kettle limescale as a heterogeneous catalyst and various cosolvents under different conditions. n‐Hexane and tetrahydrofuran were selected as cosolvents to investigate fatty acid methyl esters (FAMEs). To optimize the reaction conditions, the main parameters affecting FAME% including reaction temperature, catalyst concentration, oil‐to‐methanol volumetric ratio, and cosolvent‐to‐methanol volumetric ratio were studied via response surface methodology. Under optimal reaction conditions and in the presence of the cosolvents n‐hexane and tetrahydrofuran, high FAME purities were achieved. Considering the experimental results, the limescale catalyst is a unique material, and the cosolvent method can reduce significantly the reaction time and biodiesel production cost.