共查询到20条相似文献,搜索用时 15 毫秒
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采用TiCl4和La(NO3)3·6H2O共沉淀法制备固体超强酸SO4^2-/TiO2-La2O3催化剂。制备条件为nTi/nLa比为8:1,-15℃陈化24h,120℃干燥12h,浸渍液硫酸浓度为0.5mol·L^-1,浸渍4h,120℃干燥1h,400℃焙烧4h的催化剂对乳酸与乙醇的酯化反应有较高的活性。将此催化剂用于乳酸和乙醇合成乳酸乙酯的酯化反应,考察了催化剂用量、乙醇和乳酸的物质的量的比、反应时间、带水剂环己烷的用量对酯化反应的影响。实验结果表明,醇酸物质的量的为2.0:1,催化剂用量为所用乳酸质量的1.4%,环己烷为乙醇体积的78%,反应时间4h条件下酯化产率达82%。催化剂易回收,使用寿命长的优点。 相似文献
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将固体酸SO42-/ZrO2-Fe2O3用于催化L-乳酸和2-异亚丙基氨基氧基乙醇的酯化反应.确定了最佳反应条件:带水剂为甲苯,醇酸摩尔比为3.5:1,催化剂用量为L-乳酸质量的6%,反应时间为8 h,在此条件下酯化率可达62.5%. 相似文献
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固体超强酸负载镧催化合成乳酸乙酯 总被引:1,自引:0,他引:1
以乳酸和乙醇为原料,在SO42-/La2O3-TiO2的催化下,以氧化钙为脱水剂,采用索氏提取器进行回流脱水合成乳酸乙酯。对影响乳酸乙酯酯化率的诸因素进行了考察。结果表明,加入脱水剂和带水剂可以显著提高乳酸乙酯的产率。适宜反应条件为:SO42-/La2O3-TiO2中La3+浓度为0.07 mol/L,陈化14 h,在450℃下焙烧3 h;醇∶酸(摩尔比)=2∶1,催化剂用量为乳酸质量的2.0%,带水剂苯25 mL/0.1 mol乳酸,反应3 h时,酯化率达84.2%。且该催化剂有良好的重复和再生性。 相似文献
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In this study, the feasibility of recovery of lactic acid by batch reactive distillation using cation exchange resin as a
catalyst was investigated. For the recovery of lactic acid, two reactions, esterification and hydrolysis, are involved and
hence, an apparatus with two distillation columns was developed and operated in a batch mode to ensure enough residence time
in the reboiler and column. The effects of operation variables such as catalyst loading, reactant mole ratio, feed concentration,
type of alcohols and partial condenser temperature on the yield were studied. In this study, the reaction products of the
esterification (methyl lactate and water) were distilled to the hydrolysis part to be recovered into pure lactic acid. The
yield of lactic acid increased as catalyst loading in the esterification part increased and reactant mole ratio and feed lactic
acid concentration decreased. Methanol as a reactant gave higher yield than any other alcohols. The yield of recovered lactic
acid was as high as 90%. The yield of lactic acid was closely related to the boiling temperature of the reaction mixture in
the esterification part 相似文献
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Satoshi Hasegawa Masanori Azuma Koji Takahashi 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(11):1503-1510
BACKGROUND: Lipase‐catalyzed esterification of lactic acid with ethanol was investigated; however, some difficulties exist with such a system. Because of its high polarity, lactic acid is immiscible with non‐polar organic solvents, which have generally been used for non‐aqueous enzyme reactions. In addition, the strong acidity of lactic acid causes acid inactivation of enzymes and acid‐catalyzed, non‐enzymatic esterification. RESULT: In the present study, particular polar organic solvents, such as 1,4‐dioxane, were found to suppress the enzyme inactivation and non‐enzymatic esterification caused by the acidity. The magnitude of this effect varied with solvents and strongly correlated with the Kamlet‐Taft parameter β, which indicates the basicity of the solvents in non‐aqueous systems. An immobilized lipase from Candida antarctica was found to be the most active and stable enzyme for the reaction. Based on the findings, lipase‐catalyzed esterification of lactic acid (1.0 mol L?1) could be continued for up to 4 weeks without any loss of enzyme activity. CONCLUSION: In addition to miscibility with lactic acid, the effect of these polar solvents, which is to suppress the acidity of lactic acid and is presumably due to the basicity, appears to play a very important role in the efficient enzymatic reaction of lactic acid. Copyright © 2008 Society of Chemical Industry 相似文献
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Palraj Kasinathan Dong Won Hwang Uhwang Lee Young Kyu Hwang Jong-San Chang 《Chemical engineering science》2011,(20):4549
Fermentation-derived ammonium lactate was converted into ethyl lactate by decomposition in various organic solvents followed by esterification with ethanol over Amberlyst catalyst. The ammonium lactate was decomposed more efficiently in an organic solvent with high boiling point, where the produced lactic acid was stabilized well as a monomer without oligomerization. However, only the nonreactive phosphate-type solvent such as triethyl phosphate and tributyl phosphate showed a notable ethyl lactate yield in the subsequent esterification reaction compared with dimethyl sulfoxide and N-methyl pyrolidine. The lactic acid yield in ammonium lactate decomposition and the subsequent ethyl lactate yield were also highly dependent on solvent ratio to ammonium lactate, temperature and pressure in ammonium lactate decomposition reaction. The amino acid impurity contained in the fermented ammonium lactate as well as the unreacted ammonium lactate reduced the acid strength of Amberlyst-36, which resulted in the final ethyl lactate yield. 相似文献
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固体超强酸SO_4~(2-)/TiO_2催化合成亚油酸乙酯 总被引:4,自引:0,他引:4
用两相滴定沉淀法制备了SO2-4/TiO2固体超强酸催化剂,得到了适合亚油酸酯化的催化剂制备工艺条件:硫酸浸渍浓度0 75mol/L,浸渍时间4h,焙烧温度450℃,焙烧时间4h。首次将该催化剂用于亚油酸的酯化反应催化合成亚油酸乙酯,考察了物料比、反应时间、催化剂用量对亚油酸与乙醇酯化反应的影响规律,最佳反应条件为:n(无水乙醇)/n(亚油酸)=4,w(催化剂)=3%(相对于亚油酸),反应时间8h,亚油酸转化率可达93%。 相似文献
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研究了脱铝超稳Y沸石催化乳酸与正丁醇的酯化反应 ,考察了催化剂硅铝化、催化剂用量、反应物配比和反应时间对酯化反应的影响。结果表明 ,在优惠反应条件下 ,反应在 1h内完成 ,酯收率达 74 %以上 ,催化剂可重复使用。 相似文献
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离子液体催化合成食用香料乳酸乙酯的研究 总被引:1,自引:0,他引:1
以离子液体[HSO3-pmim]HSO4为催化剂,乳酸和乙醇为原料合成乳酸乙酯。通过正交实验考察了影响酯化反应的主要因素,确定最佳合成条件为:[HSO3-pmim]HSO4用量10mL,酸醇摩尔比1.0∶1.5,反应温度110℃,反应时间2.0h,酯化率达96.7%。离子液体易分离回收,可重复使用。 相似文献
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采用间氨基苯甲酸与甲醇(乙醇)直接酯化法合成目标产物,重点研究了催化剂种类、催化剂用量、反应时间等条件对酯化反应的影响。研究表明,本反应的合适催化剂是浓硫酸,在催化剂用量为间氨基苯甲酸用量的1.5倍、反应时间为8 h的条件下,酯化反应收率达到最大值(甲酯化收率97.5%,乙酯化收率98.3%)。气相色谱测定含量在98%以上。 相似文献
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以磷钨酸作催化剂,油酸和无水乙醇为原料制备油酸乙酯。考察了油酸与乙醇物质的量比、催化剂用量、反应时间对酯化率的影响。结果表明:磷钨酸对合成油酸乙酯具有良好的催化活性,合成的优化条件为:酸醇物质的量比为1:6,催化剂用量为0.4g,回流反应2 h,酯化率可达到96.3%。 相似文献
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M.L. Pisarello 《Fuel Processing Technology》2010,91(9):1005-1014
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. 相似文献
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2-氯丙酸乙酯的制备 总被引:1,自引:0,他引:1
以乳酸、乙醇、二氯亚砜为主要原料,经过酯化、氯化反应,合成了2-氯丙酸乙酯。并用^13CNMR谱、气相色谱对其分子结构和纯度进行了鉴定分析。该产物是α取代丙酸系列除草剂的重要中间体。 相似文献