用于生物柴油制备的KF/Al2O3固体碱催化剂的研究

采用浸渍法制备了KF/Al₂O₃固体碱催化剂，并将其应用于大豆油与甲醇酯交换制备生物柴油的反应。通过酯交换反应的转化率对催化剂制备工艺进行了优化，得出最佳制备条件：KF理论负载质量分数为Al₂O₃的45%，浸渍时间6 h，焙烧温度500 ℃，优化条件下制备的催化剂在大豆油与甲醇物质的量比为12∶1、催化剂用量为油质量的2%、反应时间3 h和反应温度(60～65) ℃条件下,酯交换转化率可达97.15%。     

KNaHC4H4O6·4H2O/Al2O3固体碱催化制备生物柴油

采用酒石酸钾钠（KNaHC₄H₄O6·4H₂O）和Al₂O₃制备了负载型KNaHC₄H₄O₆·4H₂O/Al₂O₃固体碱催化剂,将其应用于菜籽油和甲醇的酯交换反应制备生物柴油,并以生物柴油的转化率作为评价其催化活性的指标。分别考察了催化剂制备条件和酯交换反应条件对催化剂活性的影响。结果表明,在催化剂用量为菜籽油质量的3.5％、醇油物质的量比为9∶1、反应温度65 ℃和反应时间3 h时,转酯化反应的转化率达96.3%。     

H2对CO气相催化偶联制草酸二乙酯反应的失活机理

重点研究了氢气（H₂）对一氧化碳（CO）催化偶联反应制草酸二乙酯的影响,分别考察了不同H₂浓度、不同温度和不同空时条件下加入H₂对CO偶联反应的影响,结果发现H₂的加入使反应过程中CO转化率、草酸二乙酯选择性和空时收率明显下降,且在实验条件范围内,通入H₂浓度越高、反应温度越高,催化剂活性下降越快.研究得出,H₂气氛下CO偶联反应失活动力学方程为：-da/dt=k_dc^0.65_H2.进一步分析失活动力学方程可知,加氢反应过程中,H₂和CO吸附在同一个活性中心上,H₂在活性中心上的吸附抑制了CO在催化剂上的吸附,从而使得CO催化偶联反应生成草酸二乙酯的速率下降,导致加氢后CO转化率、草酸二乙酯选择性和空时收率降低.     

SO42-/ZrO2催化膜的制备及其酯化性能研究

制备了负载SO24-/ZrO2固体酸陶瓷膜,并对其用于油酸和甲醇酯化反应进行研究。通过测定不同反应温度、不同催化膜负载率和不同甲醇/油酸物质的量的比条件下油酸的转化率,线性回归得到了酯化反应动力学参数。研究结果表明,酯化反应为拟均相二级反应。在最佳反应条件下,反应活化能由49.1 kJ/mol降至34.6 kJ/mol,油酸酯化率达到95.84%。     

Preparation of SO24-/ZrO2 catalytic membrane and its catalytic activity for esterification

制备了负载SO24 -/ZrO2固体酸陶瓷膜,并对其用于油酸和甲醇酯化反应进行研究.通过测定不同反应温度、不同催化膜负载率和不同甲醇/油酸物质的量的比条件下油酸的转化率,线性回归得到了酯化反应动力学参数.研究结果表明,酯化反应为拟均相二级反应.在最佳反应条件下,反应活化能由49.1 kJ/mol降至34.6 kJ/mol,油酸酯化率达到95.84％.     

非均相固体碱催化剂（CaO体系）用于生物柴油的制备

为解决生物柴油酯交换过程中的产物与催化剂分离问题，制备了负载型固体碱催化剂（CaO/SiO₂、CaO/Al₂O₃和CaO/MgO体系），考察该系列催化剂在生物柴油制备中的不同反应特点，对制备的催化剂进行XRD表征，研究了反应条件对反应的影响。结果表明,CaO可以很好地分散在催化剂载体上，该体系催化剂是制备生物柴油的良好非均相催化剂。催化剂的最佳制备条件为：焙烧温度700 ℃，催化剂质量分数为原料油的1%，m（醇）∶m（油）＝18∶1，反应温度60～65 ℃，反应时间10 h。     

纳米钙基CO2吸附剂反应吸附与分解动力学

采用TGA测定纳米钙基CO₂吸附剂在500～650℃温度范围内,CO₂分压0.015～0.025 MPa氮气气氛中的吸附反应动力学。针对纳米钙基CO₂吸附剂吸附CO₂反应特征,提出以两倍最大吸附速率对应的时间点前后分别为快速反应段与慢速反应段。分别采用Boltzmann方程与Avrami-Erofeev方程拟合快速反应段与慢速反应段吸附反应动力学方程,得到纳米钙基CO₂吸附剂在快速反应段与慢速反应段的活化能分别为27.52、70.25 kJ·mol^-1。吸附率拟合与实验值平均相对误差分别为10.29％、4. 17%。研究测试了纳米钙基CO₂吸附剂在650～800℃温度范围内,N₂,0.02、0.04 MPa CO₂分压氮气气氛中的分解反应动力学。忽略反应过程中传热、传质影响,采用收缩核模型,分别求得吸附剂在N₂,0.02、0.04 MPa CO₂分压氮气气氛中的活化能为141.9、34.7、113.2 kJ·mol^-1。碳酸钙分解率与实验值比较平均相对误差分别小于5.66% 、7.82%、5.01%。     

纳米钙基CO2吸附剂反应吸附与分解动力学

采用TGA测定纳米钙基CO₂吸附剂在500～650℃温度范围内,CO₂分压0.015～0.025 MPa氮气气氛中的吸附反应动力学。针对纳米钙基CO₂吸附剂吸附CO₂反应特征,提出以两倍最大吸附速率对应的时间点前后分别为快速反应段与慢速反应段。分别采用Boltzmann方程与Avrami-Erofeev方程拟合快速反应段与慢速反应段吸附反应动力学方程,得到纳米钙基CO₂吸附剂在快速反应段与慢速反应段的活化能分别为27.52、70.25 kJ·mol^-1。吸附率拟合与实验值平均相对误差分别为10.29％、4. 17%。研究测试了纳米钙基CO₂吸附剂在650～800℃温度范围内,N₂,0.02、0.04 MPa CO₂分压氮气气氛中的分解反应动力学。忽略反应过程中传热、传质影响,采用收缩核模型,分别求得吸附剂在N₂,0.02、0.04 MPa CO₂分压氮气气氛中的活化能为141.9、34.7、113.2 kJ·mol^-1。碳酸钙分解率与实验值比较平均相对误差分别小于5.66% 、7.82%、5.01%。     

KNO3/HMS催化酯交换法合成碳酸二月桂酯

研究了KNO₃/HMS对碳酸二甲酯（DMC）与月桂醇酯交换反应制备碳酸二月桂酯（DDC）的催化性能。用XRD、FTIR对KNO₃/HMS催化剂进行了表征,采用Hammett指示剂-苯甲酸法测定了催化剂碱强度和碱量分布的情况,并考察了KNO₃负载量、焙烧温度以及反应条件对KNO₃/HMS催化剂性能的影响。研究表明,KNO₃负载后载体HMS仍保持良好的孔结构,KNO₃的最佳负载量为13%（质量分数）,催化剂的总碱量也在此时达到最高,最佳焙烧温度为600℃;在反应物DMC/月桂醇摩尔比为1∶4、DMC的滴加温度为140℃、反应时间为5 h、催化剂用量为反应物总质量的1%条件下,催化剂的效果最佳,DDC的收率和选择性分别为81.9%和99.5%。     

杂多酸催化合成乳酸丁酯的动力学研究

在343.15 K~379.15 K内,对负载型硅钨杂多酸催化乳酸与丁醇酯化合成乳酸丁酯反应的动力学进行了研究,测定了搅拌转速、反应温度、催化剂用量、醇酸摩尔比等条件对酯化反应速率的影响。结果表明,杂多酸催化合成乳酸丁酯的酯化反应为二级可逆反应。采用拟均相模型,对实验所得数据进行线性回归处理,得到了实验条件范围内该酯化反应的动力学方程及各动力学参数。     

Fe2(SO4)3/C催化餐饮废油脂中游离脂肪酸酯化反应的动力学

The esterification of free fatty acids(FFA) in waste cooking oil with methanol in the presence of Fe₂(SO₄)₃/C(ferric sulfate/active carbon) catalyst was studied.The effects of different temperature,methanol/FFA mole ratio and amount of catalyst on the conversion of FFA were investigated.The results demonstrated that under optimal esterification conditions the final acid value of the resultant system can be reduced to ～1(mg KOH)·g^-1,which met fully the requirements in post-treatment for efficient separation of glycerin and biodiesel.The kinetics of the esterification were also investigated under different temperatures.The results indicated that the rate-control step could be attributed to the surface reaction and the esterification processes can be well-depicted by the as-calculated kinetic formula in the range of the experimental conditions.     

Esterification of free fatty acids in waste cooking oils (WCO): Role of ion-exchange resins

Although WCO plays a crucial role for the economical production of biodiesel, free fatty acid (FFA) level in the nature of WCO cause saponification problems during transesterification. Acidic ion-exchange resins can be used to decrease WCO free fatty acid level. In this study, activities of resins (Amberlyst-15 (A-15), Amberlyst-35 (A-35), Amberlyst-16 (A-16) and Dowex HCR-W2) in direct FFA esterification were examined in the temperature range of 50–60 °C and the effect of catalyst amount (1–2 wt%) on FFA conversion was also analyzed. FFA conversion increased with increasing reaction temperature and catalyst amount. Order of catalytic activities was found as A-15 > A-35 > A-16 > Dowex HCR-W2. This was related to the size of average pore diameters and magnitude of BET surface area.     

Solid superacid catalyzed glycerol esterification of free fatty acids in waste cooking oil for biodiesel production

The free fatty acids (FFAs) of waste cooking oil (WCO) are readily esterified with crude glycerol in the presence of the solid superacid SO/ZrO₂–Al₂O₃. This reaction lowers the acidity of WCO before biodiesel production. The solid superacid SO/ZrO₂–Al₂O₃ catalyzes both FFA esterification and TAG glycerolysis during the reaction. The conversion of FFA in the WCO with an acid value of 88.4 ± 0.5 mg KOH/g to acylglycerols was 98.4% under optimal conditions (mole ratio of glycerol to FFA = 1.4:1; reaction time = 4 h; reaction temperature = 200°C; catalyst loading = 0.3 wt%) obtained through an orthogonal experiment. The final FAME product with a FAME content of 96.9 ± 0.3 wt% yield was 94.8 wt%, after transesterification of the esterified WCO with methanol, catalyzed by potassium hydroxide. The FAME composition of the products produced by transesterification were identified and quantified by GC–MS. The results suggest that this new glycerol esterification process, using a solid superacid catalyst, affords a promising method to convert oils with high FFA levels, like WCO, to biodiesel. The process has the inherent advantage of easy separation steps for removing excess alcohol and significant savings in energy, when compared to acid catalyzed reactions with methanol to lower acidity. Practical applications : In this work, WCO with a high acid value was esterified with crude glycerol catalyzed by solid super acid, whose formula was expressed as SO/ZrO₂–Al₂O₃. There are distinct advantages to this new esterification process, which include easy separation of the excess crude glycerol by sedimentation or centrifugation, the use of the low cost reactant crude glycerol direct from the byproducts of transesterification, the potential to achieve a very low content of FFAs by post‐refining to improve the yield of the final product, and time and energy saving are found as compared to the traditional methanol esterification process. This new technology provides a promising alternative method for processing feedstocks of high acid value, such as WCO, for the production of biodiesel.     

Two step biodiesel production from Calophyllum inophyllum oil: Studies on thermodynamic and kinetic modelling of modified β‐zeolite catalysed pre‐treatment

Biodiesel is one of the alternative fuels that can help in reducing oil dependence. β‐Zeolite was modified with phosphoric acid and the modified β‐zeolite was used as catalyst for the esterification of free fatty acids (FFA) present in pinnai oil and its effect on esterification reaction was studied. Influence of catalyst amount, methanol to oil ratio and temperature on specific reaction rate was modelled using Langmuir–Hinshelwood (LH) kinetics, pseudo first order kinetics and Arrhenius equation, respectively. The kinetic constant values obtained in LH kinetics show that the adsorption capacity of FFA on catalyst surface was approximately 23 times higher than that of methanol. From pseudo first order kinetic modelling it is found that methanol to oil molar ratio of 9 gives the optimum k value. Thermodynamic studies were also performed to prove the endothermic nature of Pβ catalysed esterification reaction. © 2011 Canadian Society for Chemical Engineering     

棕榈油酯交换制备生物柴油的反应动力学

在甲醇与棕榈油的摩尔比为6∶1和催化剂KOH用量为棕榈油质量1.0%的条件下,研究不同温度下棕榈油制备生物柴油的酯交换反应动力学,采用Origin软件拟合曲线方程,建立棕榈油酯交换反应的宏观动力学模型。研究结果表明:棕榈油制备生物柴油的酯交换反应遵循1.40级动力学方程,反应速率随温度的升高而加快,二者符合Arrhenius方程,该反应的活化能为27.23 kJ/mol,频率因子为1.4×103。文中研究建立的反应动力学模型将对扩大试验研究提供理论依据和基础数据支持。     

Biodiesel production from vegetable oil using heterogenous acid and alkali catalyst

Zanthoxylum bungeanum seed oil (ZSO) with high free fatty acids (FFA) can be used for biodiesel production by ferric sulfate-catalyzed esterification followed by transesterification using calcium oxide (CaO) as an alkaline catalyst. Acid value of ZSO with high FFA can be reduced to less than 2 mg KOH/g by one-step esterification with methanol-to-FFA molar ratio 40.91:1, ferric sulfate 9.75% (based on the weight of FFA), reaction temperature 95 °C and reaction time 2 h, which satisfies transesterification using an alkaline catalyst. The response surface methodology (RSM) was used to optimize the conditions for ZSO biodiesel production using CaO as a catalyst. A quadratic polynomial equation was obtained for biodiesel conversion by multiple regression analysis and verification experiments confirmed the validity of the predicted model. The optimum combination for transesterification was methanol-to-oil molar ratio 11.69:1, catalyst amount 2.52%, and reaction time 2.45 h. At this optimum condition, the conversion to biodiesel reached above 96%. This study provided a practical method to biodiesel production from raw feedstocks with high FFA with high reaction rate, less corrosion, less toxicity, and less environmental problems.     

Study on the glycerolysis reaction of high free fatty acid oils for use as biodiesel feedstock

Biodiesel is the main alternative to fossil diesel and it may be produced from different feedstocks such as semi-refined vegetable oils, waste frying oils or animal fats. However, these feedstocks usually contain significant amounts of free fatty acids (FFA) that make them inadequate for the direct base catalyzed transesterification reaction (where the FFA content should be lower than 4%). The present work describes a possible method for the pre-treatment of oils with a high content of FFA (20 to 50%) by esterification with glycerol. In order to reduce the FFA content, the reaction between these FFA and an esterification agent is carried out before the transesterification reaction. The reaction kinetics was studied in terms of its main factors such as temperature, % of glycerin excess, % of catalyst used, stirring velocity and type of catalyst used. The results showed that glycerolysis is a promising pre-treatment to acidic oils or fats (> 20%) as they led to the production of an intermediary material with a low content of FFA that can be used directly in the transesterification reaction for the production of biodiesel.     

微量酸催化麻疯树籽油制备生物柴油(英文)

Biodiesel produced from crude Jatropha curcas L.oil with trace sulfuric acid catalyst(0.02%-0.08% oil) was investigated at 135-184 ℃.Both esterification and transesterification can be well carried out simultane-ously.Factors affecting the process were investigated,which included the reaction temperature,reaction time,the molar ratio of alcohol to oil,catalyst amount,water content,free fatty acid(FFA) and fatty acid methyl ester(FAME) content.Under the conditions at 165 ℃,0.06%(by mass) H2SO4 of the oil mass,1.6 MPa and 20:1 methanol/oil ratio,the yield of glycerol reached 84.8% in 2 hours.FFA and FAME showed positive effect on the transesterification in certain extent.The water mass content below 1.0% did not show a noticeable effect on trans-esterification.Reaction kinetics in the range of 155 ℃ to 175 ℃ was also measured.     

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.     

A kinetic study of the esterification of free fatty acids (FFA) in sunflower oil

The kinetics of the esterification of free fatty acids (FFA) in sunflower oil with methanol in the presence of sulphuric acid at concentrations of 5 and 10 wt% relative to free acids as catalyst and methanol/oleic acid mole ratios from 10:1 to 80:1 was studied. The experimental results were found to fit a first-order kinetic law for the forward reaction and a second-order one for the reverse reaction.The influence of temperature on the kinetic constants was determined by fitting the results to the Arrhenius equation. The energy of activation for the forward reaction decreased with increasing catalyst concentration from 50 745 to 44 559 J/mol.Based on the experimental results, a methanol/oleic acid mole ratio of 60:1, a catalyst (sulphuric acid) concentration of 5 wt% and a temperature of 60 °C provided a final acid value for the oil lower than 1 mg KOH/g oil within 120 min. This is a widely endorsed limit for efficient separation of glycerin and biodiesel during production of the latter.