有机溶剂体系固定化脂肪酶催化合成生物柴油

探讨了有机溶剂体系固定化Candida antarctica脂肪酶催化大豆色拉油合成生物柴油的过程。将固定化Candida antarctica脂肪酶置于有机溶剂体系中催化合成生物柴油的效果较好。研究发现,在40℃下反应10 h,固定化Candida antarctica脂肪酶以石油醚作为有机溶剂转化率最高,当总醇油物质的量比为3∶1,固定化酶占5%(相对于油质量),加入5%质量分数的水时固定化酶反应活性最高,酯化率可以达到88.4%。固定化酶重复使用10次仍具有较高活性。     

固定化酶催化高酸废油脂合成生物柴油的研究

探讨了固定化C.antarctica脂肪酶催化高酸废油脂与甲醇合成生物柴油.通过脂肪酶酯交换工艺路线进行催化合成生物柴油的研究,系统研究了甲醇的加入方式、反应体系中的水、游离脂肪酸对反应的影响.结果表明,一次性加入等摩尔当量的甲醇,对脂肪酶的活性具有一定的抑制作用,两次等当量加入甲醇,最终酯化率可达90.6%;当反应体系中的水含量低于0.1%时,水对酶反应速率和甲酯产量影响甚小,而水含量高于0.1%时,酶反应速率和甲酯产率随着水含量的增加而降低;游离脂肪酸对反应的影响较小,固定化c.antarctica脂肪酶的催化稳定性和使用寿命至少达100 d.     

固定化洋葱假胞菌G63脂肪酶转酯化大豆油合成生物柴油

对固定化洋葱假胞菌G63脂肪酶催化大豆油和甲醇合成生物柴油的工艺进行了研究。通过甲基三甲氧基硅和四甲氧基硅缩水和水解反应形成的硅胶包埋固定化洋葱假胞菌G63脂肪酶。研究了酶用量、醇油摩尔比、反应温度、含水量对合成生物柴油的影响。优化的转酯化反应条件为：醇油摩尔比4：1,含水量5％,固定化脂肪酶15％,反应温度50℃,48h后转化率可以达到96．4％。固定化脂肪酶经多次使用后活力未见明显下降。     

乙酸甲酯体系酶法崔化煎炸废油制备生物柴油

煎炸废油经过脱胶、脱酸、脱色处理后,以其为原料和乙酸甲酯在固定化脂肪酶的催化下反应制备生物柴油。考察反应条件对酯交换反应的影响,得到的最佳条件为：煎炸废油2．0g、固定化脂肪酶Novozym435的用量为油重的9％、有机溶剂叔丁醇2．0mL、乙酸甲酯与煎炸废油摩尔比9：1、有机碱三羟甲基氨基甲烷的用量为油重的15％、反应时间12h、反应温度60℃、摇床转速为150r／min。在此条件下生物柴油的得率为80．73％。     

固定化荧光假单胞菌脂肪酶用于催化低酸值餐饮废油的酯交换反应

动植物油脂的酯交换反应是制备脂肪酸烷基酯的一个重要反应。其中,脂肪酸甲酯、乙酯为普通石化柴油的优质替代燃料。脂肪酶易于固定在海于连续生产生物柴油,试验研究了一株商业荧光假单胞菌(P.fluorescens ATCC 13525)固定化脂肪酶催化低酸值餐饮废油和甲醇合成生物柴油的最优工艺条件。通过对反应温度、pH值、醇油物质的量比、酶的用量,反应时间等重要参数的研究,得到最优工艺条件:当反应温度为40℃,pH 7.0,醇油物质的量比4∶1,酶用量为3.0 g,反应时间48 h,反应体系含水量为8%时,生物柴油的得率最高。所制备的产品经分析测试,完全可以替代普通石化柴油,而且对现有内燃机无需做任何改动。     

固定化脂肪酶转酯化菜籽油合成生物柴油

采用无溶剂体系,对固定化洋葱假胞菌脂肪酶催化转酯化菜籽油和甲醇合成生物柴油的工艺进行了考察。优化的转酯化反应条件为：醇油比4：1,含水量4％,固定化脂肪酶10％,反应温度50℃．12h后转化率达到了93．6％。固定化脂肪酶具有良好的操作稳定性,经多次使用后活力未见显著的下降。     

Penicillium expansum TS414脂肪酶催化合成生物柴油的研究

为了促进酶法生产生物柴油工艺在工业上的应用,对固定化Penicillium expansum TS414脂肪酶进行了相关研究。结果表明,固定化Penicillium expansum TS414脂肪酶具有最佳的酯交换性能。在固定化酶量为20％、乙醇,大豆油摩尔比为3：1、水分含量为4％的酯交换条件下,反应8h,反应转化率可达92．6％。此外,固定化酶具有良好的操作稳定性一使用8批次后,酶活仅损失17．3％。P．expansum TS414固定化脂肪酶的酯交换性能较好、价格较为低廉,可成为合成生物柴油的良好催化剂。     

Penicillium expansum TS 414脂肪酶催化合成生物柴油研究

为促进酶法生产生物柴油工艺在工业上应用,对固定化Penicillium expansum TS 414脂肪酶进行相关研究。结果表明,固定化Penicillium expansum TS 414脂肪酶具有最佳酯交换性能,在固定化酶量为20%,乙醇/大豆油摩尔比为3:1,水分含量为4%酯交换条件下,反应8h,反应转化率可达92.6%;此外,固定化酶具有良好操作稳定性,使用8批次后,酶活仅损失17.3%。P.expansum TS414固定化脂肪酶酯交换性能较好、价格较为低廉,可成为合成生物柴油良好催化剂。     

固定化酶催化酯化反应合成生物柴油的研究

采用固定化脂肪酶Novozym435催化油酸与甲醇进行甲酯化反应合成生物柴油。通过考察固定化酶的催化反应进程,确定脂肪酶催化酯化反应的基本规律,并通过研究酶的用量、反应时间、催化介质有机溶剂、底物甲醇的抑制、水分的抑制和两种底物酸／醇摩尔比等因素对酯化过程的影响,得到酯化工艺的最佳条件是：在石油醚体系中,4％wt固定化脂酶,温度为40℃,油酸与甲醇摩尔比为1：1．5,甲醇分3次流加,反应时间为24h,酯化率可以达到95％。催化剂循环使用5次,仍具有90％的转化率。酯化后产物经气质联用仪分析．脂肪酸甲酯的纯度可达到96％。     

新型两步法餐饮废油制备生物柴油

采用两步法催化高酸值餐饮废油（Waste Cooking Oil,WCO）制备生物柴油;第一步先用单质碘（I2）催化废油中游离脂肪酸和甲醇酯化生成脂肪酸甲酯（生物柴油）,第二步再用KOH催化废油中的甘油三酯和甲醇进行酯交换。结果表明,I2对酯化反应具有很强的催化活性,而且可以回收利用。通过正交试验得到最佳酯化反应参数：12用量1．3％（w／w,WCO）,反应温度80℃,醇油质量比1．75：1,反应时间3h,在该反应条件下酸值由120．86（KOH）／（mg／g）降为1．89（KOH）／（mg／g）;酯交换条件为：KOH用量1％,反应温度85℃,反应时间0．5h,醇油质量比0.3：1,经过两步催化,生物柴油的总得率为95．1％。     

Pretreatment of immobilized Candida antarctica lipase for biodiesel fuel production from plant oil

The effects of the pretreatment of immobilized Candida antarctica lipase enzyme (Novozym 435) on methanolysis for biodiesel fuel production were investigated. Methanolysis progressed much faster when Novozym 435 was preincubated in methyl oleate for 0.5 h and subsequently in soybean oil for 12 h. The initial reaction rate of methanolysis catalyzed by both the non-treated and preincubated enzyme decreased significantly with increasing water content. The initial reaction rate increased with increasing methanol content, showed a maximum, and thereafter decreased when the methanol content was increased further. The variation of the initial reaction rate with the methanol content was therefore analyzed using a Michaelis-Menten-type equation with substrate inhibition. Based on this equation, a procedure for the stepwise addition of methanol to the reaction mixture so as to maintain the desired methanol content was determined. When preincubated Novozym 435 was used, the ME content reached over 97% within 3.5 h by stepwise addition of 0.33 molar equivalent of methanol at 0.25-0.4 h intervals.     

Catalytic properties of a lipase from Photobacterium lipolyticum for biodiesel production containing a high methanol concentration

Biodiesel, an alternative fuel, is generated via the transesterification reaction of vegetable oil or animal oil with alcohol. Currently, many reports have noted that microbial lipases might be utilized for the production of biodiesel. Among them, immobilized Candida antarctica lipase B (Novozym435) is frequently utilized for its biocatalytic efficiency and availability. However, as the enzyme is unstable in a medium containing high concentrations of methanol, a multi-stepwise methanol supply is required for the efficient production of biodiesel. Photobacterium lipolyticum lipase (M37) was determined to be quite stable in a medium containing a high concentration of methanol. The enzyme activity was maintained for longer than 48 h without any loss at a methanol concentration of 10%. In an effort to evaluate enzyme performance in the production of biodiesel, we have compared M37 lipase and Novozym435 in the biodiesel production reaction using fresh or waste oil and methanol. In the 3-stepwise methanol feeding method generally conducted for Novozym435 in biodiesel production, the M37 lipase showed a similar or superior conversion yield to Novozym435. However, the M37 lipase evidenced significantly higher conversion yields in the 2 and 1 step methanol feeding reactions. Particularly in the 1 step process using 10% of methanol where almost no conversion was detected by Novozym435, the biodiesel yield achieved with M37 lipase reached a level of up to 70% of the possible maximum yield. Consequently, this methanol-tolerant lipase, M37, has been shown to be a suitable enzyme for use in the biodiesel production process.     

固定化Enterobacter agglomerans脂肪酶生产菜籽油生物柴油的研究

用硅藻土对实验室筛选得到的成团肠杆菌脂肪酶干燥酶粉进行固定化,固定化酶在有机溶剂体系下催化生产生物柴油。在最佳反应条件,即菜籽油15.47 mL,固定化脂肪酶用量1 000 U,甲醇为酰基受体(7.15 mL,3次等量加入),5 mL正己烷,振荡速度180 r/min,35℃反应48 h时,转化率达91.03%。实验结果表明,油酸含量高有利于生产生物柴油,而芥酸有不利影响。固定化酶稳定性好,重复使用8次,转化率仍大于50%,同时还具有一定的适应性,可催化大豆油和葵花籽油生产生物柴油。研究表明,固定化酶可用于催化生产生物柴油,并有效降低酶催化法的生产成本。     

固定化脂肪酶催化酯交换合成生物柴油研究

以苯乙烯为单体,二乙烯苯为交联剂,过氧化苯甲酞为引发剂,明胶为分散剂,采用悬浮聚合法制备St-DVB-CBA三元共聚高分子微球,将其作为固定化脂肪酶载体,通过共价结合法进行脂肪酶固定化,探讨固定化脂肪酶催化大豆油酯交换反应活性。实验结果表明:固定化脂肪酶在醇油摩尔比为3∶1,分三次加入;固定化酶加入量15wt.%(油重);反应时间24 h;反应温度40℃;正己烷加入量15wt.%(油重);水分含量4wt.%(油重);转化率最高,可达90.08%;固定化脂肪酶重复使用时显示出较好稳定性和催化活性。     

Stepwise ethanolysis of tuna oil using immobilized Candida antarctica lipase

Ethanolysis of fish oil under mild conditions has been strongly desired for preparing the starting materials for the purification of ethyl docosahexaenoate. Thus, we attempted ethanolysis of tuna oil using immobilized Candida antarctica lipase. The immobilized lipase was inactivated in the presence of 2 3 molar equivalent of ethanol against the total fatty acids in tuna oil. To avoid such inactivation, the first step of ethanolysis was conducted at 40 degrees C in a mixture of tuna oil and 1 3 molar equivalent of ethanol using 4% immobilized lipase. After a 10-h reaction, ethanol was consumed and 33% of tuna oil was converted to its corresponding ethyl esters (E-FAs). The reactant is named Gly/E-FA33. The lipase was not inactivated in the presence of 2 3 molar equivalent of ethanol against the total fatty acids in Gly/E-FA33. These findings and the consideration of several factors affecting ethanolysis of tuna oil led to the development of the two- and three-step ethanolyses. The two-step reaction was performed as follows: the first step was carried out at 40 degrees C for 12 h in a mixture of tuna oil and 1 3 molar equivalent of ethanol with 4% immobilized lipase; the second step was performed for 36 h (total reaction period, 48 h) after adding 2 3 molar equivalent of ethanol. On the other hand, the three-step reaction was conducted as follows: the first step was conducted under the same conditions as those in the two-step ethanolysis; in the second and third steps, 1 3 molar equivalent of ethanol was added after 12 and 24 h, respectively; and in the third step, the mixture was shaken for 24 h (total, 48 h). Both types of ethanolyses achieved the conversion of 95% or more of tuna oil to its corresponding E-FAs. To investigate the lipase stability, the two- and three-step ethanolyses were repeated by transferring the enzyme to a fresh substrate mixture of the first step after finishing one cycle of reaction. The two- and three-step reactions maintained over 95% of the conversion for 70 d and over 100 d, respectively.     

固定化脂酶催化合成生物柴油的研究

探讨了酶法制备生物柴油的过程,通过脂肪酶酯化和醇解两种工艺路线合成生物柴油的试验研究,考察了反应条件如醇油比、催化剂用量、反应温度、反应时间等对酯化率和产品纯度的影响.试验表明,采用分批加入甲醇的酯化工艺,酯化率可以达到95%以上;采用醇解工艺菜籽油酯化率达95%以上,产品经GC分析其纯度可达98%以上,固定化酶的半衰期至少达100 d.     

选择性修饰MCM-41固定化脂肪酶及其催化合成甾醇酯的应用

将南极假丝酵母脂肪酶B（Candida antarctica lipase B,CALB）与三亚油酸甘油三酯进行分子对接,得到CALB的活性中心组成,其氨基酸残基中游离ε-NH2分布在远离活性中心的位置上,—COOH有小部分分布在活性中心。针对CALB活性基团的分布特点将MCM-41修饰成具有醛基的G-MCM-41及具有氨基的NH2-MCM-41。当G-MCM-41与CALB固定时,醛基与ε-NH2结合,酶负载量为87.4 mg/g,活性为1 176 U/g,活性较高,当NH2-MCM-41与CALB固定时,氨基与—COOH结合,酶负载量为89.6 mg/g,活性为672 U/g,活性相对较低,结果证明了CALB分子氨基酸残基分布的结论。以一级大豆油和植物甾醇为底物,固定化脂肪酶催化酯交换反应,经响应面试验优化后酯交换率达到87.4%。     

Regeneration of immobilized Candida antarctica lipase for transesterification

Immobilized lipase from Candida antarctica was employed to convert triglycerides to biodiesel using alcohol. Immobilized lipase is frequently deactivated by lower alcohols with deactivation being caused by the immiscibility between triglycerides and methanol or ethanol. When the lower alcohol is adsorbed to the immobilized enzyme, the entry of triglycerides is blocked, which causes the reaction to stop. An alcohol with three or more carbon atoms, preferably 2-butanol or tert-butanol, can regenerate the deactivated immobilized enzyme. The present work established that the activity of immobilized lipase could be significantly increased when such alcohols were used for an immersion pretreatment of the enzyme. The activity of the commercially available immobilized enzyme, Novozyme 435, increased about tenfold in comparison to the enzyme not subjected to any pretreatment. Following complete deactivation of the enzyme by methanol, washing with 2-butanol and tert-butanol successfully regenerated the enzyme and restored it to about 56% and 75% of its original activity level, respectively.