树脂D001负载磷钨酸催化合成肉桂酸酯

以肉桂酸和正丁醇反应为例,采用强酸性阳离子树脂D001负载磷钨酸为催化剂,合成了肉桂酸酯。考察了醇酸摩尔比、反应时间和反应温度、催化剂用量和催化剂的重复使用性对反应酯化率的影响。结果表明,在反应温度100℃、反应时间3 h、酸醇摩尔比1∶3、催化剂质量占肉桂酸总质量15%的较优条件下,酯化率达92.4%。催化剂不经处理重复使用4次,酯化率都在83%以上。依据该较佳的工艺条件,进一步催化合成其他肉桂酸酯,酯化率均超过85%,表明树脂D001负载磷钨酸催化效果良好。     

微波辐射下阳离子交换树脂催化合成对硝基苯甲酸乙酯

以对硝基苯甲酸和乙醇为原料,H-732强酸性阳离子交换树脂为催化剂,在微波辐射条件下合成对硝基苯甲酸乙酯,探讨了微波功率、醇酸摩尔比、催化剂用量、反应时间对产品产率的影响。结果表明,H-732强酸性阳离子交换树脂在微波辐射条件下对酯化反应有良好的催化能力;醇酸摩尔比为3∶1,催化剂用量为对硝基苯甲酸质量的20%,反应时间15 min,微波功率为250 W时,对硝基苯甲酸乙酯的产率最高为87.45%,催化剂可以重复使用,再生后催化性能保持良好。     

活性炭负载磷钨酸催化合成乳酸正戊酯

以磷钨酸/活性涂为催化剂,催化酯化合成乳酸正戊酯。通过正交设计法考察了催化剂用量、醇酸摩尔比、反应时间及带水剂用量等因素对反应的影响。结果表明:在催化剂用量1.8 g、醇酸摩尔比1.5、反应时间2 h和带水剂环己烷5 mL的条件下,乳酸正戊酯的酯化率大于96.2%,并且催化剂可多次使用,活性没有明显下降。     

一水合硫酸氢钠催化合成硬脂酸己酯的研究

用一水合硫酸氢钠催化硬脂酸与正己醇的酯化反应合成了硬脂酸己酯。考察了催化剂用量、醇酸摩尔比、反应时间对酯化反应的影响。在典型反应条件下(正己醇与硬脂酸摩尔比=1．5：1，0．6g催化剂/0．2mol硬酯酸，反应时间2．5h)，转化率为99.64％，酯化率为99．55％，产品收率为99．66％。     

己二酸二正辛酯的催化合成及反应动力学

以己二酸和正辛醇为原料,环境友好型磷钨杂多酸为催化剂,甲苯为带水剂,合成了己二酸二正辛酯。由均匀设计法设计实验,考察了醇酸摩尔比,催化剂用量,带水剂用量和反应时间对酯化率的影响,经单因素实验优化得到的最佳工艺条件为:醇酸摩尔比2.8:1,催化剂用量为酸质量的1.2,带水剂用量为酸质量的75,反应时间3h,酯化率达99.23。同时建立了该酯化合成的表观动力学模型,得到的反应速率方程为:r=-dcA/dt=2.657×1010e-94998/RTcAcBmol/(L.min)。     

硝酸改性蒙脱土催化制备十六酸十六醇酯

用硝酸改性蒙脱土(MMT)制备酸性催化剂H-MMT,并以此为催化剂催化十六酸和十六醇酯化,制备十六酸十六醇酯。通过XRD、N2吸附-脱附、UV和FTIR等方法对催化剂进行表征。并考察反应时间、催化剂加入量、醇酸摩尔比、反应温度和催化剂重复利用次数对酯化率的影响。研究结果表明,反应时间3.5 h,催化剂加入量为十六酸质量的5%,醇酸摩尔比为1.3∶1,在180℃下反应酯化率能达到95%以上,催化剂重复使用4次,酯化率仍可达到88%左右。     

己二酸二甲酯绿色合成新工艺研究

以NKC-9干氢型阳离子交换树脂为催化剂、己二酸和甲醇为原料采用催化酯化—吸附脱水联合工艺合成了己二酸二甲酯。实验考察了醇酸物质的量比、催化剂用量和反应时间对酯化反应的影响,得到了较佳工艺条件:醇酸物质的量比为2.6∶1,催化剂用量为22g/moL,反应时间为6h,酯化率可达到99.18%。在该工艺条件下,催化剂重复使用6次,酯化率仍可达到98.32%。     

硝酸改性蒙脱土催化制备十六酸十六醇酯

用硝酸改性蒙脱土(MMT)制备酸性催化剂H-MMT,并以此为催化剂催化十六酸和十六醇酯化,制备十六酸十六醇酯。通过XRD、N2吸附-脱附、UV和FTIR等方法对催化剂进行表征。并考察反应时间、催化剂加入量、醇酸摩尔比、反应温度和催化剂重复利用次数对酯化率的影响。研究结果表明,反应时间3.5 h,催化剂加入量为十六酸质量的5%,醇酸摩尔比为1.3∶1,在180℃下反应酯化率能达到95%以上,催化剂重复使用4次,酯化率仍可达到88%左右。     

硅藻土负载对甲苯磺酸催化合成乙酸正丁酯

以对甲苯磺酸为活性组分,硅藻土为载体,通过浸渍法制备出硅藻土负载对甲苯磺酸催化剂(p-CH_3C_6H_4SO_3H/硅藻土),对催化剂进行FT-IR、XRD、EDS、SEM表征。以p-CH_3C_6H_4SO_3H/硅藻土为催化剂,催化乙酸与正丁醇液相合成乙酸正丁酯。采用正交试验考察催化剂用量、醇酸摩尔比、反应温度及反应时间对酯化率的影响。结果表明:硅藻土负载对甲苯磺酸可作为催化合成乙酸正丁酯的有效催化剂。在优化反应条件下,即对甲苯磺酸负载量为20%(占硅藻土的质量比),催化剂用量占反应物质量分数2.1%,醇酸摩尔比为2.5∶1,反应温度为120℃,反应时间2.5 h,酯化率可达97.2%。催化剂重复利用5次,酯化率仍保持为84.5%。与传统浓硫酸催化酯化工艺相比,此工艺具有操作简单、绿色环保、重复使用性能好等优点,具有良好的工业开发价值。     

强酸性树脂催化制备柠檬酸三丁酯

以强酸性树脂为催化剂合成柠檬酸三丁酯。主要考察了催化剂用量、酸醇摩尔比、反应时间及催化剂重复使用对酯化反应的影响。结果表明酯化反应的最佳条件为:醇酸摩尔比为5.5∶1,催化剂用量为柠檬酸质量的11%,反应温度为130℃,反应时间为小时4 h,此条件下酯转化率达到91%以上。并且经过简单处理后可以重复使用。     

Base/acid-catalyzed FAEE production from hydroxylated vegetable oils

In this study was developed a new methodology to produce fatty acid ethyl esters from castor oil. The base-catalyzed transesterification step was followed by on pot addition of sulfuric acid. That addition implicated the successful separation of FAEEs/glycerin phases due to soap breaking. The study was carried out through an experimental design where the variables studied in the first step were the molar ratio alcohol:oil and the catalyst amount in the transesterification process. As expected, the on pot addition of concentrated sulfuric acid yields FFAs that increase the acid value in the FAEEs phase. A second step esterification of these free fatty acids from FAEE raw mixture was investigated. The esterification of FFA was carried out in 60:1 and 80:1 M ratios (alcohol:free fatty acids) and concentrated sulfuric acid 5% and 10% w/w (based on free fatty acids). Consequently, these two steps yielded more fatty ethyl esters and assure that the following important requirements in the FAEEs production process from castor oil are satisfied: complete reaction, best separation of FAEEs/glycerin phases, removal of catalyst, limpid glycerin, and absence of free fatty acids.     

Heterogeneous esterification of oil with high amount of free fatty acids

Frying oils have become the newest raw material for the transesterification reaction for the production of biodiesel. However, these compounds usually come with a certain amount of free fatty acids. These impurities can be transformed into esters and the production of biodiesel could be increased.The use of basic resins to perform the esterification reaction into biodiesel is studied in this work. The effect of the most relevant variables of the process such as reaction temperature, molar ratio between alcohol and oil, amount of catalyst and amount of free fatty acids fed with the oil have been analyzed. For this purpose, an ideal frying oil using oleic acid and soybean oil was made. The alcohol used was ethanol.The esterification of free fatty acid using this heterogeneous catalyst appears as a great alternative to purify frying oil; in this case, the final conversion achieved was around 80%.     

Purification of docosahexaenoic acid from tuna oil by a two-step enzymatic method: Hydrolysis and selective esterification

Purification of docosahexaenoic acid (DHA) was attempted by a two-step enzymatic method that consisted of hydrolysis of tuna oil and selective esterification of the resulting free fatty acids (FFA). When more than 60% of tuna oil was hydrolyzed with Pseudomonas sp. lipase (Lipase-AK), the DHA content in the FFA fraction coincided with its content in the original tuna oil. This lipase showed stronger activity on the DHA ester than on the eicosapentaenoic acid ester and was suitable for preparation of FFA rich in DHA. When a mixture of 2.5 g tuna oil, 2.5 g water, and 500 units (U) of Lipase-AK per 1 g of the reaction mixture was stirred at 40°C for 48 h, 83% of DHA in tuna oil was recovered in the FFA fraction at 79% hydrolysis. These fatty acids were named tuna-FFA-Ps. Selective esterification was then conducted at 30°C for 20 h by stirring a mixture of 4.0 g of tuna-FFA-Ps/lauryl alcohol (1:2, mol/mol), 1.0 g water, and 1,000 U of Rhizopus delemar lipase. As a result, the DHA content in the unesterified FFA fraction could be raised from 24 to 72 wt% in an 83% yield. To elevate the DHA content further, the FFA were extracted from the reaction mixture with n-hexane and esterified again under the same conditions. The DHA content was raised to 91 wt% in 88% yield by the repeated esterification. Because selective esterification of fatty acids with lauryl alcohol proceeded most efficiently in a mixture that contained 20% water, simultaneous reactions during the esterification were analyzed qualitatively. The fatty acid lauryl esters (L-FA) generated by the esterification were not hydrolyzed. In addition, L-FA were acidolyzed with linoleic acid, but not with DHA. These results suggest that lauryl DHA was generated only by esterification.     

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.     

Esterification of Free Fatty Acids in <Emphasis Type="Italic">Zanthoxylum bungeanum</Emphasis> Seed Oil for Biodiesel Production by Stannic Chloride

In this study, SnCl₄ was chosen as a solid catalyst for esterification of free fatty acids (FFA) in Zanthoxylum bungeanum seed oil (ZSO). A central composite rotatable design was used to investigate the effect of the methanol-to-oil molar ratio, catalyst amount and reaction time on the SnCl₄-catalyzed esterification of FFA. The methanol-to-oil molar ratio and reaction time clearly affected the conversion efficiency of FFA in the test ranges. Response surface methodology was used to optimize the conditions for SnCl₄-catalyzed esterification. A quadratic polynomial equation was obtained for conversion efficiency of FFA by multiple regression analysis and verification experiments confirmed the validity of the predicted model. Under the optimum conditions, the conversion efficiency of FFA in vegetable oil reached above 96 %. This study demonstrates the effectiveness of SnCl₄ as an acid catalyst for the reduction of high FFA content in vegetable oils to a low level by one-step esterification.     

Purification of docosahexaenoic acid by selective esterification of fatty acids from tuna oil with Rhizopus delemar lipase

To purify docosahexaenoic acid (DHA), we attempted the selective esterification of fatty acids originating from tuna oil with lipases. Tuna oil was hydrolyzed in NaOH-ethanol solution, and the resulting fatty acid mixture [DHA, 23.2%; named tuna-free fatty acid (FFA)] was used as a starting material. Rhizopus delemar which acted lightly on DHA, was a suitable catalyst for the selective esterification of tuna-FFA, and lauryl alcohol was the best substrate. The reaction proceeded most effectively when a mixture of 2.4 g lauryl alcohol/tuna-FFA (2:1, mol/mol), 0.6 g water, and 600 U Rhizopus lipase was incubated at 30°C for 20 h with stirring at 500 rpm. Under these conditions 72% of tuna-FFA was esterified, and 84% of DHA was recovered in the unesterified fatty acid fraction. The DHA content in the fatty acid fraction rose from 23 to 73% with this reaction. To further elevate the DHA content, the unesterified fatty acids were extracted, and then esterified again under the same conditions. By this repeated esterification, DHA was purified to 89% with a recovery of 71% of its initial content.     

Kinetic studies on the esterification of free fatty acids in jatropha oil

Kinetic studies have been carried out on the esterification of free fatty acids (FFAs) in jatropha oil with methanol in the presence of sulphuric acid catalyst at 5 and 10 wt% concentrations relative to free fatty acids (0.4–0.8 wt% relative to oil) and methanol–FFA mole ratios ranging from 20:1 to 80:1. It has been found that a 60:1 methanol–FFA mole ratio and 5 wt% catalyst at 60°C and 500 rpm or above provided a final acid value lower than 1 mg KOH/g oil within 60 min. A kinetic model has been proposed with second‐order kinetics for both the forward and backward reactions. The effect of temperature on the reaction rate constants and equilibrium constant has been determined using Arrhenius and von't Hoff equations, respectively. The heat of reaction was found to be ?11.102 kJ/mol.     

Esterification with ethanol to produce biodiesel from high acidity raw materials: Kinetic studies and analysis of secondary reactions

In this work, the esterification reaction of free fatty acids (FFA) in sunflower oil, coconut oil and concentrated FFA, with ethanol, methanol and ethanol 96%, using homogeneous acid catalysts to produce biodiesel is studied. Kinetic parameters are estimated with a simplified model, and then used to predict the reaction behavior. Reactions other than the reversible esterification are considered to explain the behavior that this system displays. Such reactions are the triglycerides conversion by acid catalyzed transesterification and hydrolysis. In addition, we include kinetic studies of the reaction that occur between the sulphuric acid and methanol (or ethanol), forming mono and dialkylsulphates. This reaction produces water and consumes methanol (or ethanol), and consequently has a direct impact in the esterification reaction rate and equilibrium conversion. The concentration of sulphuric acid decreases to less than 50% of the initial value due to the reaction with the alcohol. A minimum in the acidity due to the free fatty acids as a function of time was clearly observed during the reaction, which has not been reported earlier. This behavior is related to the consecutive reactions that take place during the esterification of FFA in the presence of triglycerides. The phase separation due to the presence of water, which is generated during the reaction, is also studied.     

Biodiesel Production Over Arenesulfonic Acid-Modified Mesostructured Catalysts: Optimization of Reaction Parameters Using Response Surface Methodology

The catalytic activity of different heterogeneous sulfonic acid-modified catalysts has been assayed in the simultaneous esterification of FFA and transesterification of triglycerides of crude palm oil (FFA content of 5.6 wt%) with methanol, demonstrating the applicability of this kind of acid solids to the one-step production of biodiesel from FFA-containing vegetable oils. The yield towards fatty acid methyl esters (FAMEs) obtained over these acid materials is enhanced when increasing the acid strength of the catalytic site. Likewise, the use of mesostructured supports has been shown as a factor improving the catalytic performance as compared with macroporous sulfonic acid-based resins, likely due to an enhancement of the mass transfer rates of large molecules, such as triglycerides, within the catalyst structure. Thus, the combination of the open mesoporous structure of a SBA-15 silica support with relatively strong arenesulfonic acid sites leads to a material able to yield high conversion of triglycerides and free fatty acids. Furthermore, a study on the transesterification reaction of crude palm oil with methanol through a surface response analysis has provided as optimal conditions the following: temperature 160 °C, catalyst loading 5.1 wt% referred to the amount of palm oil, and methanol to oil molar ratio 30. Under these conditions, almost 90% of the starting oil is converted to FAME after reacting for just 2 h of reaction. Likewise, surface response analysis has evidenced a strong interaction between temperature and methanol to oil ratio.     

Large-scale purification of γ-linolenic acid by selective esterification using Rhizopus delemar lipase

γ-Linolenic acid (GLA) is a physiologically valuable fatty acid, and is desired as a medicine, but a useful method available for industrial purification has not been established. Thus, large-scale purification was attempted by a combination of enzymatic reactions and distillation. An oil containing 45% GLA (GLA45 oil) produced by selective hydrolysis of borage oil was used as a starting material. GLA45 oil was hydrolyzed at 35°C in a mixture containing 33% water and 250 U/g-reaction mixture of Pseudomonas sp. lipase; 91.5% hydrolysis was attained after 24 h. Film distillation of the dehydrated reaction mixture separated free fatty acids (FFA; acid value 199) with a recovery of 94.5%. The FFA were selectively esterified at 30°C for 16 h with two molar equivalents of lauryl alcohol and 50 U/g of Rhizopus delemar lipase in a mixture containing 20% water. The esterification extent was 52%, and the GLA content in the FFA fraction was raised to 89.5%. FFA and lauryl esters were not separated by film distillation, but the FFA-rich fraction contaminated with 18% lauryl esters was recovered by simple distillation. To further increase the GLA content, the FFA-rich fraction was selectively esterified again under similar conditions. As a result, the GLA content in the FFA fraction was raised to 97.3% at 15.2% esterification. After simple distillation of the reaction mixture, lauryl esters contaminating the FFA-rich fraction were completely eliminated by urea adduct fractionation. When 10 kg of GLA45 oil was used as a starting material, 2.07 kg of FFA with 98.6% GLA was obtained with a recovery of 49.4% of the initial content.