填充床反应器中酶法合成生物蜡酯

研究了填充床式反应器酶法合成生物蜡酯的生产工艺。以大豆油、十六醇为原料,在石油醚体系中,使用实验室自制的固定化Candida sp.99-125为催化剂。对操作参数,如填充高度、进料速度、固定化酶用量、底物摩尔比进行了研究。结果表明,固定化酶质量为47 g,填充高度40 cm（内径3.5 cm）,油醇摩尔比1∶2.4,以4 mL/min速度进料保留时间4 h,产率可达83%。固定化酶在使用16批时,产率仍保持在70%以上。同时,对于填充床的填充方式作了初步探索。     

Kilogram-scale ester synthesis of acyl donor and use in lipase-catalyzed interesterifications

Scaling up of Lipozyme-catalyzed ester synthesis with >99% conversion and a reflux trap to remove product water from the reaction mixture is reported. Ethyl stearate was synthesized in 2000-g batch reactions from technical stearic acid. The ethyl stearate was purified to 97% by crystallization and interesterified with sunflower seed oil by means of a lipase catalyst to investigate reaction parameters of temperature, substrate ratio, enzyme content and catalyst water activity. The endpoint of the reaction was defined as the incorporation of stearate into sunflower seed oil corresponding to the amount of stearate necessary to be incorporated into palm oil mid-fraction to produce a cocoa butter substitute. No tristearate was formed at the reaction endpoint in any of the reactions conducted. Reaction times decreased and levels of free fatty acids and diglycerides increased with increasing temperature and with increasing ratio of acyl donor to triglyceride. Increasing the enzyme content of the reaction mixture reduced reaction times but caused higher levels of free fatty acids and diglycerides. In reactions catalyzed by Lipozyme of defined water activity, the shortest reaction times were obtained at intermediate water activity, while free fatty acid and diglyceride levels increased with water activity. When the interesterification reaction was carried out in refluxing pentane with the condensed solvent dried by passage through a reflux trap, the free fatty acid and diglyceride levels were reduced to 6 and 3.3%, respectively.     

Enzymatic alcoholysis of triolein to produce wax ester

An alcoholysis reaction between triolein and oleyl alcohol catalyzed by Lipozyme and Novozyme was carried out to produce oleyl oleate, a wax ester. The effects of various reaction parameters such as time, reaction temperature, amount of enzyme, molar ratio of substrates (oleyl alcohol/triolein), various organic solvents used and the initial water activity, a_w of the reaction system were studied. The best conditions tested to produce wax ester were respectively, incubation time, 5 h; temperature, 50 °C for Lipozyme and 60 °C for Novozyme; weight of enzyme, 0.30 g and molar ratio of oleyl alcohol to triolein, 6:1. The use of organic solvents greatly influenced the activity of lipase. Generally, the activity of lipase was high in nonpolar solvents with log P values greater than 2.50. Heptane and hexane were the best solvents tested. The enzymatic synthesis of oleyl oleate was best carried out at a_w 0.32. Analysis of the yield of the products of the reaction at optimized reaction condition using Lipozyme showed that 75.66% oleyl oleate was produced. © 2001 Society of Chemical Industry     

Continuous ethanol production from carob pod extract by immobilized Saccharomyces cerevisiae in a packed-bed reactor

The continuous production of ethanol from carob pod extract by immobilized Saccharomyces cerevisiae in a packed-bed reactor has been investigated. At a substrate concentration of 150 g dm^?3, maximum ethanol productivity of 16 g dm^?3 h^?1 was obtained at D = 0·4 h^?1 with 62·3% of theoretical yield and 83·6% sugars′ utilization. At a dilution rate of 0·1 h^?1, optimal ethanol productivity was achieved in the pH range 3·5–5·5, temperature range 30–35·C and initial sugar concentration of 200 g dm^?3. Maximum ethanol productivity of 24·5 g dm^?3 h^?1 was obtained at D = 0·5 h^?1 with 58·8% of theoretical yield and 85% sugars′ utilization when non-sterilized carob pod extract containing 200 g dm^?3 total sugars was used as feed material. The bioreactor system was operated at a constant dilution rate of 0·5 h^?1 for 30 days without loss of the original immobilized yeast activity. In this case, the average ethanol productivity, ethanol yield (% of theoretical) and sugars′ utilization were 25 g dm^?3 h^?1, 58·8% and 85·5%, respectively.     

Modification of selected indian vegetable fats into cocoa butter substitutes by lipase-catalyzed ester interchange

A few solid and semi-solid fats of tree origin in India, namely sal (Shorea robusta), kokum(Garcinia indica), mahua (Madhuca latifolia), dhupa (Vateria indica) and mango (Mangifera indica), were chosen for modification into cocoa butter substitutes by lipase-catalyzed ester interchange with methyl palmitate and/or stearate. Hexane solutions of mixtures of fat and methyl ester(s) in various molar proportions were passed through a column of Lipozyme™, a lipase fromMucor miehei immobilized on a macroparticulate ion-exchange resin. The interesterified fats were purified by extraction with 95% ethanol followed by silica column chromatography. Interesterified dhupa, kokum and sal fats compared well with cocoa butter in the total fatty acid composition and the 2-position of triacylglycerols, as well as glyceride composition. In particular, interesterified kokum fat resembled cocoa butter well in solid fat content and peak melting temperature as determined by differential scanning calorimetry. IICT Communication No. 2743.     

Continuous alcohol production from whey permeate using immobilised cell reactor systems

The present paper reports the performance of a bioreactor packed with alginate-entrapped Kluyveromyces marxianus NCYC179 for continuous fermentation of whey permeate to ethanol. A maximum ethanol productivity as 28.21 gl^?1 h^?1 was attained at D=0.42h^?1 and 75% lactose consumption (substrate feed rate in the inflowing medium was 200 g lactose I^?1). However, the higher dilution rates (0.6-1.Oh^?1) resulted in poor productivities and higher substrate washout in the effluent samples. The maximum specific ethanol production (qpi) and maximum specific lactose uptake (qsi) of the immobilised Kluyveromyces marxianus NCYC179 was found to be 3.88g ethanol/g immobilised cell/hx10^?2 and 8.75g lactose consumed/g immobilised cell/hx10^?2 respectively. A bead size of 2.5 mm in diameter and activation period of 24h of alginate beads in lactose solution (10%) prior to their packing in column reactor were found to support the efficient working of the bioreactor. The immobilised cell bioreactor system was operated continuously at a constant dilution rate of 0.15h^?1 and 10% lactose for 562 h without any significant change in the efficiency (varied from 84 to 88% of theoretical) and viability of the entrapped yeast cells (dropped from 84 to 81%).     

Continuous production of acyl <Emphasis Type="SmallCaps">l</Emphasis>-ascorbates using a packed-bed reactor with immobilized lipase

Saturated acyl (6-O-caproyl, lauroyl, and myristoyl) and unsaturated acyl (6-O-oleoyl, linoleoyl, and arachidonoyl) l-ascorbates were continuously synthesized at 50°C using a system where a column packed with ascorbic acid powder and a packed-bed reactor with an immobilized lipase from Candida antarctica were connected in series. A productivity of 1.6–1.9 kg/L reactor·d was achieved for at least 11 d. The surface tension of the caproyl or lauroyl l-ascorbate in aqueous solution was measured at various temperatures and pH to estimate the critical micelle concentration (CMC) of the acyl l-ascorbate. The CMC values were independent of temperature but dependent on the pH. The value of the caproyl ascorbate increased with an increase in pH.     

Continuous enzymatic synthesis of Z-kyotorphin amide in an enzyme-immobilized fixed-bed reactor

α-Chymotrypsin immobilized on natural and inexpensive supports such as diatomaceous earth was used as catalyst for Z-Tyr-Arg-NH₂ (Z-kyotorphin amide) synthesis. In order to obtain the optimal reaction conditions, a 2² factorial experimental design was used. The factors considered were cosolvent (dimethylformamide) concentration and temperature; optimal product yield was achieved at 40% (v/v) dimethylformamide and 25°C. A sequential kinetic model was considered which generally gave good agreement between experimental and theoretical data for continuous synthesis of Z-kyotorphin amide in a packed-bed immobilized reactor system. The activation energy for the synthesis was determined to be 48.0 ± 2.3 kJ mol^?1.     

Efficient lipase-catalyzed production of tailor-made emulsifiers using solvent engineering coupled to extractive processing

Within the framework of enzymatic biosurfactant synthesis, the development of reaction processes leading to a selective and efficient production is of crucial interest. In this work, we proposed an enzymatic method for producing 1(3)-monooleoyl-rac-glycerol using a commercial immobilized lipase, the Lipozyme®. To avoid the blockage of the enzyme by the presence of insoluble glycerol, the latter was adsorbed onto dried silica gel. The selective monoester production (83%) was obtained using 2-methyl-2-butanol amended n-hexane (90:10, vol/vol) as reaction medium. The observed decrease in the substrate conversion, in a medium containing 2-methyl-2-butanol, was countered by coupling to the reaction an inline selective recovery method for the produced monoester by adsorption onto a silica gel column located at the outflow of the reaction vessel. This process leads to an efficient monooleoyl glycerol production with a high oleic acid conversion (71%) and to the recovery of a 100% pure monooleoyl glycerol.     

Continuous process for production of hydrogenated nitrile butadiene rubber using a Kenics® KMX static mixer reactor

A continuous process for hydrogenating nitrile butadiene rubber (NBR) was developed and its performance was experimentally investigated. A Kenics® KMX static mixer (SM) is used in the process as a gas–liquid reactor in which gaseous hydrogen reacts with NBR in an organic solution catalyzed by an organometallic complex such as an osmium complex catalyst. The Kenics® KMX SM was designed with 24 mixing elements with 3.81 cm diameter and arranged such that the angle between two neighboring elements is 90°. The internal structure of each element is open blade with the blades being convexly curved. The dimensions of the SM reactor are: 3.81 cm ID 80 S and 123 cm length and was operated cocurrently with vertical upflow. The NBR solutions of different concentrations (0.418 and 0.837 mol/L with respect to [C?C]) were hydrogenated by using different concentrations of the osmium catalyst solution at various residence times. The reactions were conducted at a constant temperature of 138°C and at a constant pressure of 3.5 MPa. From the experimental results, it is observed that a conversion and/or degree of hydrogenation above 95% was achieved in a single pass from the designed continuous process. This is the first continuous process for HNBR production that gives conversions above 95% till date. Optimum catalyst concentration for a given mean residence time to achieve conversions above 95% were obtained. Finally, a mechanistic model for the SM reactor performance with respect to hydrogenation of NBR was proposed and validated with the obtained experimental results. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Pilot batch production of specific-structured lipids by lipase-catalyzed interesterification: Preliminary study on incorporation and acyl migration

Effects of water content, reaction time, and their relationships in the production of two types of specific-structured lipids (sn-MLM- and sn-LML-types: L-long chain fatty acids; M-medium chain fatty acids) by lipase-catalyzed interesterification in a solvent-free system were studied. The biocatalyst used was Lipozyme IM (commercial immobilized lipase). The substrates used for sn-MLM-type were fish oil and capric acid, and medium chain triacylglycerols and sunflower free fatty acids for sn-LML-type. The observed incorporation with the time course agrees well with the Michaelis-Menten equation, while the acyl migration is proportional to time within the range of 20 mol% acyl migration (MLM-type: M _f =0.2225 T, R²=0.98; LML-type: M _f =0.5618 T, R²=0.99). As water content (wt%, on the enzyme basis) increased from 3.0 to 11.6% for MLM-type and from 3.0 to 7.2% for LML-type in the solvent-free systems, the incorporation rates in the first 5 h increased from 3.34 to 10.30%/h, and from 7.29 to 11.12%/h, respectively. However, the acyl migration rates also increased from 0.22 to 1.12%/h and from 0.56 to 1.37%/h, respectively. Different effects in the production of two totally position-opposed lipids can be observed. Presumably these are caused by the different chain length of the fatty acids. The relationships between reaction time and water content are inverse and give a quantitative prediction of incorporation and acyl migration in selected reaction conditions and vice versa. The acyl migration can not be totally avoided in present systems, but can be reduced to a relatively low level. Acyl migration during the downstream processing has also been observed and other factors influencing the acyl migration are briefly discussed.     

Continuous production of biodiesel with supercritical methanol: Optimization of a scale-up plug flow reactor by response surface methodology

A scale-up plug flow reactor was evaluated for the continuous production of biodiesel from refined palm kernel oil (PKO) with supercritical methanol and optimized by response surface methodology. The effects of the operating temperature (270–350 °C), pressure (15.0–20.0 MPa) and methanol:PKO molar ratio (20:1–42:1) were evaluated at a constant residence time of 20 ± 2 min by using a central composite design. Analysis of variance demonstrated that a modified quadratic regression model gave the best coefficient of determination (R² = 0.9615) and adjusted coefficient of determination (Adj. R² = 0.9273). The interaction terms in the regression model illustrated small synergistic effects of both temperature–pressure and temperature–methanol:PKO molar ratio. The optimal conditions were 325 ± 5 °C, 18.0 ± 0.5 MPa and a methanol:PKO molar ratio of 42 ± 2:1, attaining a maximum production rate of 18.0 ± 1.5 g biodiesel/min with a fatty acid methyl ester content of 93.7 ± 2.1%. The product obtained from the optimal conditions had high cetane number, and could be considered as a fuel additive for cetane number enhancement.     

精制松香酯化法的无色松香树脂生产线设计

对精制松香酯化法生产无色松香树脂的生产线进行设计,根据生产工艺,以松脂为原料,经过前处理、水蒸气蒸馏、减压水蒸气蒸馏和减压精馏,生产精制松香,再以精制松香通过酯化生产无色松香树脂,生产线的设计充分考虑松脂、松香、松香树脂等物料特性以及生产规模、设备设施匹配。设计了年产3 000 t无色松香树脂的生产线,通过调试,得率≥93%,生产的产品具有颜色浅、软化点高和耐热性耐候性优良等特点,颜色(哈森色号)≤50,酸值≤30 mg KOH/g,软化点100～105℃,粘度(180℃)≥850 mPa.s,热稳性(180℃,4 h)(哈森色号)≤200。     

酯溶性氯乙烯-醋酸乙烯酯共聚树脂的研发生产

对比进口与国产氯乙烯-醋酸乙烯酯共聚树脂的常规性能和应用性能,查找了国产氯醋树脂质量差距;针对氯乙烯和醋酸乙烯酯悬浮聚合过程提出了优化措施,改善了氯醋树脂的颗粒形态和分子组成的均匀度,进而提升了酯溶性等应用性能.     

Optimization of the reaction conditions in the lipase-catalyzed synthesis of structured triglycerides

Structured triglycerides of the ABA-type, containing one type of fatty acid (A) in the sn-1 and sn-3 positions and a second type of fatty acid (B) in the sn-2 position of the glycerol, were synthesized using lipases. The highest yields and purities were achieved in a two-step process, where a triglyceride of the B-type was subjected to an alcoholysis reaction in an organic solvent catalyzed by sn-1,3-regiospecific lipases yielding the corresponding 2-monoglyceride (2-MG). Using this strategy, e.g., 2-monopalmitin (2-MP) was obtained in up to 88% yield at >95% purity by crystallization. Esterification of 2-MP with oleic acid resulted in the formation of 1,3-oleyl-2-palmitoyl-glycerol in up to 72% yield containing 94% palmitic acid in the sn-2 position. The best lipases were from Rhizomucor miehei, Rhizopus delemar, and Rhizopus javanicus. Water activity, solvent, and carrier for lipase immobilization strongly influenced the yield and purity of the products in both steps. Furthermore, 2-MG from fish oil were produced by alcoholysis in up to 84% yield at >95% purity.     

浮动床离子交换器在生产中的应用

介绍了浮动床离子交换器的原理、结构特点和树脂再生情况。应用于脱盐水生产中效果良好 ,结构合理 ,生产能力大 ,水质优 ,再生剂比耗低 ,废水排放达标     

连续搅拌反应釜热稳定的最大允许温差

对通常用的连续搅拌反应釜热稳定的最大允许温差公式加以修正，重新导出适用于多级反应的公式：ΔΤ＜（１＋ｎＸＡ１－ＸＡ）ＲＴ２Ｅ。     

Intensified production of biodiesel using a spinning disk reactor

This work achieves continuous transesterification of soybean oil and methanol in a spinning disk reactor. The effects of the methanol-to-oil molar ratio, catalyst type, catalyst concentration, reaction temperature, flow rate, and rotational speed were investigated. Optimal yield of 96.9% was obtained with a residence time of 2–3 s at a molar ratio of 6, potassium hydroxide concentration of 1.5 wt%, temperature of 60 °C, flow rate of 773 mL/min, and rotational speed of 2400 rpm. The production rate of 1.86 mol/min was high compared to that of other reactors for continuous transesterification process, indicating that a spinning disk reactor is a promising alternative method for continuous biodiesel production.