猪板油直接萃取制备生物柴油的研究

研究了猪油原位萃取-酶法转化制生物柴油。考察了溶剂用量、萃取时间、萃取温度等对油脂得率的影响,探讨了以Novozyme 435酶为催化剂直接转化猪油生物柴油。结果表明,萃取猪油的较优参数为:乙酸甲酯为萃取剂,乙酸甲酯用量(mL)与猪板油质量(g)比为8∶1,萃取时间3 h,萃取温度50℃;以Novozyme 435脂肪酶转化猪油制备生物柴油,得率为95.12%,当Novozyme 435酶和Lipozyme TLIM酶混合比为1∶1时,生物柴油转化率最高,达97.12%。     

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.     

Biodiesel from fried vegetable oils via transesterification by heterogeneous catalysis

Three solid catalysts have been tested in the transesterification of fried oils: CaO, SrO, K₃PO₄. For CaO and SrO the different efficiency, between their use as powder or granules, has been examined. Another investigated aspect has been the catalytic activity at different catalyst loadings and recycles. At the end granules have been employed in a catalytic bed reactor, comparing results with batch systems. Results have shown that using catalyst as granule does not affect the yields after 3 h of reaction. The use of the catalytic bed reactor has given the possibility to perform the transesterification maintaining the catalyst separated from the reactants, without loss of efficiency; in fact the comparison between trials in batch reactor and in catalytic bed system has not shown differences in yields. After 3 h of reaction, at 65 °C, 5 wt% of catalyst, we have had the following FAME yields: 92% for CaO, 86% for SrO, 78% for K₃PO₄. The transesterification reaction has shown a sensitive influence respect to K₃PO₄ granules amount used; in fact the yield has reached the 85% using 10 wt% of catalyst. The reutilization of the catalyst, without regeneration, has shown a loss of efficiency of about 10-20% in decreasing yield.     

Biodiesel fuel from Jatropha oil via non-catalytic supercritical methanol transesterification

Transesterification of Jatropha oil using supercritical methanol and in absence of a catalyst has been studied under different conditions of temperature (from 512 to 613 K), pressure (from 5.7 to 8.6 MPa) and molar ratio of alcohol to oil (from 10 to 43 mol alcohol per mol oil). The reaction products were analyzed for their content of residual triglycerides, glycerol, monoglycerides, diglycerides, esters and free acids by high performance liquid chromatography (HPLC), thin layer chromatography (TLC) and titration against KOH.The results have revealed that 100% yield of esters can be obtained using super critical methanol within four min only, at a temperature of 593 K and under a pressure of 8.4 MPa pressure. The molar ratio of methanol to oil was 43:1.     

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.     

Biodiesel production through transesterification over natural calciums

Transesterification of palm kernel oil (PKO) with methanol over various natural calciums, including limestone calcite, cuttlebone, dolomite, hydroxyapatite, and dicalcium phosphate, has been investigated at 60 °C and 1 atm. The study showed that dolomite, mainly consisting of CaCO₃ and MgCO₃, is the most active catalyst. The calcination temperature largely affected the physicochemical properties, as evidenced by N₂ adsorption-desorption measurement, TGA, SEM and XRD, and the transesterification performance of the resultant catalysts. It was found that the calcination of dolomite at 800 °C resulted in a highly active mixed oxide. CaO was suggested to be the catalytically active site responsible for the methyl ester formation. Under the suitable reaction conditions, the amount of dolomite calcined at 800 °C = 6 wt.% based on the weight of oil, the methanol/oil molar ratio = 30, and the reaction time = 3 h, the methyl ester content of 98.0% can be achieved. The calcined dolomite can be reused many times. The analyses of some important fuel properties indicated that the biodiesel produced had the properties that meet the standard of biodiesel and diesel fuel issued by the Department of Energy Business, Ministry of Energy, Thailand.     

Biodiesel synthesis from waste vegetable oil via transesterification reaction in supercritical methanol

Response surface methodology (RSM) was applied to analyze the effect of four independent variables (molar ratio of methanol to oil, reaction temperature, pressure and time) on the yield of the biodiesel production via supercritical methanol (SCM) method. Waste vegetable oil (WVO) was used as raw material and transesterification reaction was performed in a supercritical batch reactor. The central composite rotatable design was used to maximize the yield of the biodiesel. The optimal values of variables were determined by RSM to be 33.8:1 (methanol/oil molar ratio) 271.1 °C, 23.1 MPa and 20.4 min reaction time for the maximum predicted yield of 95.27% (g/g). Moreover, an irreversible first order kinetic model was successfully correlated to the experimental transesterification data with 3.37 (s⁻¹) and 31.71 (kJ/mol) as the frequency factor and activation energy of the process.     

用棉籽油制备生物柴油

采用棉籽油为原料连续化生产生物柴油,研究了工艺及设备的设计。由棉籽油与甲醇在催化剂NaOH存在下由酯交换反应制得生物柴油。在优化条件下反应50 min,转化率达到99%。生产的生物柴油,各项指标与天然柴油相似。其各项燃烧指标优于或与普通柴油相仿,满足欧洲Ⅱ排放标准。     

Biodiesel from activated sludge through in situ transesterification

BACKGROUND: The microbial biomass present in activated sludge contains lipidic compounds that can be used as biodiesel feedstock. In this study, the production of biodiesel from activated sludge from Tuscaloosa, AL was optimized based on the yield of fatty acid methyl esters (FAMEs). In situ transesterification was used with sulfuric acid as catalyst. A general factorial design of 4 × 6 × 5 for temperature, methanol to sludge ratio and catalyst concentration, respectively, was considered for optimization. RESULTS: Biodiesel yield can be adequately described by the quadratic response surface model with R² of 0.843 and statistically insignificant lack of fit (p = 0.152). Numerical optimization showed that an optimum biodiesel yield of 4.88% can be obtained at 55 °C, 25 methanol to sludge ratio and 4% volume sulfuric acid. The optimum experimental biodiesel yield was indeed obtained at that condition but with a value of 4.79 ± 0.02%. The highest error was 2.30% which indicates good agreement between the model and the experimental data. CONCLUSIONS: Acid‐catalyzed polymerization of unsaturated fatty acids or their esters at temperature above 60 °C significantly decreased biodiesel yield. The fatty acid profile of the biodiesel produced indicates that activated sludge may be used as biodiesel feedstock. Copyright © 2009 Society of Chemical Industry     

杂化膜催化酯化与固体碱酯交换集成工艺制备生物柴油

以废鸡油为原料,建立杂化膜催化酯化-固体碱催化酯交换集成工艺制备生物柴油。考察醇油质量比、反应温度等对酯化反应的影响。采用气相色谱分析产物中脂肪酸组成;核磁共振氢谱计算鸡油中甘油三酯酯交换反应的转化率。结果表明,最佳工艺条件为:反应温度338 K,甲醇与废鸡油质量比为3∶1,鸡油酯化反应转化率为93.5%。气相色谱显示,废鸡油原料中含有的五种脂肪酸都转化成为脂肪酸甲酯,鸡油酯交换反应转化率为98.1%。制备出的生物柴油样品酸值、密度、运动黏度、闪点和硫含量多项指标均满足我国GBT 20828—2015、美国ASTM 6751—06e1和欧洲EN 14214生物柴油标准。     

Biodiesel production by the transesterification of cottonseed oil by solid acid catalysts

Methyl esters (biodiesel) were produced by the transesterification of cottonseed oil with methanol in the presence of solid acids as heterogeneous catalysts. The solid acids were prepared by mounting H₂SO₄ on TiO₂ · nH₂O and Zr(OH)₄, respectively, followed by calcining at 823K. TiO₂-SO₄ ²⁻ and ZrO₂-SO₄ ²⁻ showed high activity for the transesterification. The yield of methyl esters was over 90% under the conditions of 230°C, methanol/oil mole ratio of 12:1, reaction time 8 h and catalyst amount (catalyst/oil) of 2% (w). The solid acid catalysts showed more better adaptability than solid base catalysts when the oil has high acidity. IR spectral analysis of absorbed pyridine on the samples showed that there were Lewis and Br?nsted acid sites on the catalysts. Translated from The Chinese Journal of Process Engineering, 2006, 6(4): 571–575 [译自: 过程工程学报]     

杂化膜催化酯化与固体碱酯交换集成工艺制备生物柴油

以废鸡油为原料,建立杂化膜催化酯化-固体碱催化酯交换集成工艺制备生物柴油。考察醇油质量比、反应温度等对酯化反应的影响。采用气相色谱分析产物中脂肪酸组成;核磁共振氢谱计算鸡油中甘油三酯酯交换反应的转化率。结果表明,最佳工艺条件为:反应温度338 K,甲醇与废鸡油质量比为3∶1,鸡油酯化反应转化率为93.5%。气相色谱显示,废鸡油原料中含有的五种脂肪酸都转化成为脂肪酸甲酯,鸡油酯交换反应转化率为98.1%。制备出的生物柴油样品酸值、密度、运动黏度、闪点和硫含量多项指标均满足我国GBT 20828—2015、美国ASTM 6751—06e1和欧洲EN 14214生物柴油标准。     

Biodiesel production from waste tallow

In the present investigation an attempt has been made to use waste tallow as low cost sustainable potential feed stock for biodiesel production. Effect of various process parameters such as amount of catalyst, temperature and time on biodiesel production was investigated. The optimal conditions for processing 5 g of tallow were: temperature, 50 and 60 °C; oil/methanol molar ratio 1:30 and 1:30, amount of H₂SO_4, 1.25 and 2.5 g for chicken and mutton tallow, respectively. Under optimal conditions, chicken and mutton fat methyl esters formation of 99.01 ± 0.71% and 93.21 ± 5.07%, was obtained after 24 h in the presence of acid. The evaluation of transesterification process was followed by gas chromatographic analysis of tallow fatty acid esters. A total of 98.29% and 97.25% fatty acids were identified in chicken and mutton fats, respectively. Both fats were found highly suitable to produce biodiesel with recommended fuel properties.     

Biodiesel production from waste cooking oil via alkali catalyst and its engine test

Waste cooking oils (WCO), which contain large amounts of free fatty acids produced in restaurants, are collected by the environmental protection agency in the main cities of China and should be disposed in a suitable way. Biodiesel production from WCO was studied in this paper through experimental investigation of reaction conditions such as methanol/oil molar ratio, alkaline catalyst amount, reaction time and reaction temperature which are deemed to have main impact on reaction conversion efficiency. Experiments have been performed to determine the optimum conditions for this transesterification process by orthogonal analysis of parameters in a four-factor and three-level test. The optimum experimental conditions, which were obtained from the orthogonal test, were methanol/oil molar ratio 9:1, with 1.0 wt.% sodium hydroxide, temperature of 50 °C and 90 min. Verified experiments showed methanol/oil molar ratio 6:1 was more suitable in the process, and under that condition WCO conversion efficiency led to 89.8% and the physical and chemical properties of biodiesel sample satisfied the requirement of relevant international standards. After the analysis main characteristics of biodiese sample, the impact of biodiesel/diesel blend fuels on an YC6M220G turbo-charge diesel engine exhaust emissions was evaluated compared with 0# diesel. The testing results show without any modification to diesel engine, under all conditions dynamical performance kept normal, and the B20, B50 blend fuels (include 20%, 50% crude biodiesel respectively) led to unsatisfactory emissions whilst the B′20 blend fuel (include 20% refined biodiesel) reduced significantly particles, HC and CO etc. emissions. For example CO, HC and particles were reduced by 18.6%, 26.7% and 20.58%, respectively.     

Biodiesel from an alkaline transesterification reaction of soybean oil using ultrasonic mixing

The feasibility of using ultrasonic mixing to obtain biodiesel from soybean oil was established. The alkaline transesterification reaction was studied at three levels of temperature and four alcohol-to-oil ratios. Excellent yields were obtained for all conditions. For example, at 40°C with ultrasonic agitation and a molar ratio of 6∶1 methanol/oil, the conversion to FAME was greater than 99.4% after about 15 min. For a 6∶1 methanol/oil ratio and a 25 to 60°C temperature range, a pseudo second-order kinetic model was confirmed for the hydrolysis of DG and TG. Reaction rate constants were three to five times higher than those reported in the literature for, mechanical agitation. We suspect that the observed mass transfer and kinetic rate enhancements were due to the increase in interfacial area and activity of the microscopic and macroscopic bubbles formed when ultrasonic waves of 20 kHz were applied to a two-phase reaction system.     

Hydrogen production via chemical looping dry reforming of methane: Process modeling and systems analysis

The present study presents and analyses a family of “chemical looping dry reforming” (CLDR) processes that produce inherently separated syngas (H₂ and CO) streams via a combination of methane cracking in a “cracker reactor” and the Boudouard reaction (i.e., conversion of the formed carbon with CO₂ to CO) in a “CO₂ reactor,” and then further maximize the H₂ yield via conversion of the produced CO via water-gas-shift. Remaining CO₂ emissions are minimized via CO₂ capture and sequestration. Four different configurations are evaluated which differ in how the heat required for the highly endothermic dry reforming reaction is supplied: (i) combustion of additional CH₄ feed (CLDR-CH₄); (ii) combustion of some of the CO produced in the CO₂ reactor (CLDR-CO); and combustion of some of the carbon produced in the cracker reactor with (iii) pure oxygen (CLDR-C-oxy); or (iv) with air (CLDR-C-air). Process models are developed to comparatively analyze the mass and energy balances of these configurations, and benchmark them against H₂-production via conventional dry reforming and steam reforming of methane. Our results show that CLDR-C-oxy is the most promising H₂-production pathway among the chemical looping and conventional technologies both in terms of chemical energy efficiency and in terms CO₂ emissions. Thus, the unique flexibility offered by the production of inherently separated syngas streams in CLDR enables overcoming the disadvantage of the strongly endothermic dry reforming reaction by combusting carbon internally in the reactor and thus achieving highly effective heat integration. Overall, the results support the technical viability and demonstrate the promise for strong process intensification of CLDR compared to conventional dry reforming and even steam reforming, the most widely used H₂-production pathway to-date.     

Biodiesel production via peanut oil extraction using diesel-based reverse-micellar microemulsions

Vegetable oils have been studied as a feasible substitute for diesel fuel, and short term tests using neat vegetable oils have shown results comparable to those of diesel fuel. However, engine problems arise due to the high oil viscosity after long-term usage. Vegetable oil/diesel blending as biodiesel fuel has been shown to be one technique to reduce vegetable oil viscosity. The goal of this research is to demonstrate the feasibility of producing this biodiesel fuel via vegetable oil extraction using diesel-based reverse-micellar microemulsions as an extraction solvent. In this extraction technique, peanut oil is directly extracted into the oil phase of the microemulsion based on the “likes dissolve likes” principle and the product of the extraction process is peanut oil/diesel blend. The results show that diesel-based reverse micellar extract oil from peanuts more effectively than both diesel and hexane alone under the same extraction condition. An extraction efficiency of 95% was achieved at room temperature and short extraction time of 10 min in just a single extraction step. The extracted peanut oil/diesel blend was tested for peanut oil fraction, viscosity, cloud point and pour point, which all meet the requirements for biodiesel fuel.     

Dioxygen activation at non-heme iron: insights from rapid kinetic studies

One of the common biochemical pathways of binding and activation of dioxygen involves non-heme iron centers. The enzyme cycles usually start with an iron(II) or diiron(II) state and traverse via several intermediates (detected or postulated) such as (di)iron(III)-superoxo, (di)iron(III)-(hydro)peroxo, iron(III)iron(IV)-oxo, and (di)iron(IV)-oxo species, some of which are responsible for substrate oxidation. In this Account, we present results of kinetic and mechanistic studies of dioxygen binding and activation reactions of model inorganic iron compounds. The number of iron centers, their coordination number, and the steric and electronic properties of the ligands were varied in several series of well-characterized complexes that provided reactive manifolds modeling the function of native non-heme iron enzymes. Time-resolved cryogenic stopped-flow spectrophotometry permitted the identification of kinetically competent intermediates in these systems. Inner-sphere mechanisms dominated the chemistry of dioxygen binding, intermediate transformations, and substrate oxidation as most of these processes were controlled by the rates of ligand substitution at the iron centers.     

酯交换法制备碳酸二甲酯过程模拟与系统火用分析

针对酯交换制备过程中甲醇?碳酸二甲酯共沸体系难分离的问题,分别选择变压精馏、碳酸乙烯酯(EC)萃取精馏与乙二醇(EG)萃取精馏3种分离过程进行模拟与能量集成,对比了3种工艺流程的分离能耗,采用有效能(?)分析方法分析了能耗最低的变压分离过程的有效能(?)损失. 结果表明,3种工艺流程的能耗EG萃取精馏>EC萃取精馏>变压精馏,碳酸二甲酯生产过程中内部循环物流能量是输入总能量的1.55倍,变压共沸分离过程的?损失为7.9%。     

Biodiesel production from high FFA rubber seed oil

Currently, most of the biodiesel is produced from the refined/edible type oils using methanol and an alkaline catalyst. However, large amount of non-edible type oils and fats are available. The difficulty with alkaline-esterification of these oils is that they often contain large amounts of free fatty acids (FFA). These free fatty acids quickly react with the alkaline catalyst to produce soaps that inhibit the separation of the ester and glycerin. A two-step transesterification process is developed to convert the high FFA oils to its mono-esters. The first step, acid catalyzed esterification reduces the FFA content of the oil to less than 2%. The second step, alkaline catalyzed transesterification process converts the products of the first step to its mono-esters and glycerol. The major factors affect the conversion efficiency of the process such as molar ratio, amount of catalyst, reaction temperature and reaction duration is analyzed. The two-step esterification procedure converts rubber seed oil to its methyl esters. The viscosity of biodiesel oil is nearer to that of diesel and the calorific value is about 14% less than that of diesel. The important properties of biodiesel such as specific gravity, flash point, cloud point and pour point are found out and compared with that of diesel. This study supports the production of biodiesel from unrefined rubber seed oil as a viable alternative to the diesel fuel.