反应与催化精馏耦合提纯乳酸新工艺的研究

The purification of lactic acid based on the esterification of raw lactic acid from fermentation broth and then the catalytic distillation hydrolysis of methyl lactate simultaneously to achieve pure lactic acid is reported. The esterification kinetics of lactic acid with methanol catalyzed by strong-acid cation-exchange resins (Amberlyst-15,D001, D002, NKC, 002) was studied under the condition that simulates the real catalytic environment. Experimental results were correlated by a Langmuir-Hinselwood model and the nonideality of the solution was taken into account by using activities calculated by the universal quasichemical functional group activity coefficient (UNIFAC) method.A good agreement between the model and the experimental data was achieved. Continuous purification experiments were conducted to find the optimum column configuration and operation condition for the system. The effects of various parameters, e.g. the length of different section of the column, feed rate and ratio of reactants, packing material and catalyst type, were studied. This novel system shows good separation results in lab scale, and is potential for industrial application.     

反应精馏合成乙酸丁酯的实验和模拟(英文)

In this paper, a reactive distillation (RD) column was applied for synthesis n-butyl acetate from n-butanol and acetic acid. The Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic model and an equilibrium stage model for separation were employed to study the RD process. The results obtained from the equilibrium stage model agreed well with the experiments. The effects of operating variables on the n-butanol conversion and n-butyl acetate purity were further investigated. The optimal column configuration for the production of n-butyl acetate was designed with 5 rectifying stages, 8 reaction stages and 13 stripping stages by the simulation study. According to the simulation results, n-butanol conversion and n-butyl acetate purity all reached greater than 96%.     

Experimental and simulation of the reactive dividing wall column based on ethyl acetate synthesis

Reactive dividing wall column(RDWC) is a highly integrated unit which combines reaction distillation(RD) with dividing wall column separation technology into one shell, and it realized the chemical reaction and the separation of multiple product fractions simultaneously. In this paper, the reaction of esterification with acetic acid and ethanol to produce ethyl acetate was used as the research system, experiments and simulations of the RDWC were carried out. This system in the traditional process mostly used the homogeneous catalyst(e.g. sulfuric acid). However, in view of the corrosion of the equipment caused by the acidity of the catalyst, we used the heterogeneous catalysts – iron exchange resins – Amberlyst15 and proposed a novel catalyst loading method. Firstly,the reliability of the model of the simulation was verified by the experimental study on the change of liquid split ratio and reflux ratio. After that, the four-column model was established in Aspen Plus to analyze the effects of the amount of azeotropic agent, reflux ratio and acetic acid concentration. Finally, for a fair comparison, the economic analysis was conducted between traditional RD column and RDWC. The results showed that RDWC can save34.7% of total operating costs and 18.5% of TAC.     

六碳糖和五碳糖同步糖化与共发酵的数学模型

Reliable production of biofuels and specifically bioethanol has attracted a significant amount of re-search recently.Within this context,this study deals with dynamic simulation of bioethanol production processes and in particular aims at developing a mathematical model for describing simultaneous saccharification and co-fermentation (SSCF) of C6 and C5 sugars.The model is constructed by combining existing mathematical mod-els for enzymatic hydrolysis and co-fermentation.An inhibition of ethanol on cellulose conversion is introduced in order to increase the reliability.The mathematical model for the SSCF is verified by comparing the model predic-tions with experimental data obtained from the ethanol production based on kraft paper mill sludge.When fitting the model to the data,only the yield coefficients for glucose and xylose metabolism were fine-tuned,which were found to be 0.43 g·g-1 (ethanol/glucose) and 0.35 g·g-1 (ethanol/xylose) respectively.These promising validation results encourage further model application to evaluate different process configurations for lignocellulosic bioetha-nol technology.     

乌索酸的生产工艺

Production of ursolic acid, the anti-hepatitis effective composition from natural plant, Sambucus chinensis Lindl. was carried out and the scale-up preparation technology was studied. Extraction of the herb Sambucus chinensis Lindl. was extracted in reflux with 7 volume times of refluxing ethanol at 80℃ for 1 h for two times. The extract was purified with a seh-made specific impurity remover ＂YCXY-1＂ to yield ursolic acid of high purity. A new ＂Extraction/Gelation＂ technology for the production of ursolic acid was developed. The specific impurity remover ＂YCXY-1＂ showed high effectiveness in purification. The purity of the mass-produced ursolie acid was up to 99.8%. The chemical structure of the product was confirmed by the physicochemical constants and spectroscopic identification. The production of high-purity ursolic acid was optimized with natural plant as raw material and with only ethanol as extracting solvent. The difficulties such as isolation and impurity removal were addressed effectively. The novel technology is reasonable, convenient, practical, low-cost, high-yield, suitable for mass production.     

微通道反应器内异辛醇混硝化过程行为

In this paper, the nitration characteristic of alcohols with mixed acid for the synthesis of energetic materials in a stainless steel microreactor was investigated experimentally. The nitration of iso-octanol with HNO3-H2SO4 mixed acid was chosen as a typical model reaction which involved fast and strong exothermic liquid-liquid heterogeneous reaction process. The influences of mixed acid composition, flow rate, organic/aqueous flow ratio and reaction temperature have been investigated. The results indicated that the reaction could be conducted safely and stably in the microreactor at 25-40°C, which are enhanced compared to 15°C or below for safe operating conditions in the conventional reactors. Moreover, the 98.2% conversion of iso-octanol could be obtained and no by-products were detected in all cases.     

甲苯液相催化氧化过程模拟与优化

Liquid-phase oxidation of toluene with air has become the main technology for producing benzoic acid in a reactor at present. Based on the kinetic model of the toluene oxidation process obtained from laboratory and mass balance of key component, a novel model is established to simulate the industrial toluene oxidation process, in which the effects of benzaldehyde and benzyl alcohol are considered and the kinetic parameters are revised by industrial data. The simulation results show that the error of benzoic acid yield is within 3.5%. Based on the simulation model, to maximize the benzoic acid yield, an optimization model is proposed to optimize the operating parameters, including toluene feed-in mass flux and temperature. The optimization result indicates that on the allowable operating conditions the maximum benzoic acid yield obtained with the reaction temperature at 167.2 C an the mass flux at 104.1 t·h^- 1 is greater than the current one, which can be used to guide industrial reactor s operation.     

SIMULTANEOUS ION-EXCHANGE AND ADSORPTION OF LACTIC ACID ON D354 RESIN

From a number of ion-exchange resins and adsorbents,a macro-pore weak-base type anionion-exchange resin,D354,was selected for the separation of lactic acid.Experimental data showedthat simultaneous ion-exchange and physical adsorption existed in the lactic acid-D354 system.Amathematical model was suggested to simulate the experimental data.Also,the effects of inorganicsalts on the ion-exchange.equilibrium were studied.The difference in ion-exchange equilibrium be-tween DL-and L-lactic acid was observed.     

小麦秸秆制备乙酰丙酸的动力学研究

Levulinic acid is considered as a promising green platform chemical derived from biomass. The kinetics of levulinic acid accumulation in the hydrolysis process of wheat straw was investigated in the study. Using dilute sulfuric acid as a catalyst, the ki-netic experiments were performed in a temperature range of 190-230C and an acid concentration range of 1%-5% (by mass). A simple model of first-order series reactions was developed, which provided a satisfactory interpretation of the experimental results. The kinetics of main intermediates including sugar and 5-hydroxymethylfurfural (5-HMF) were also established. The kinetic pa-rameters provided useful information for understanding the hydrolysis process.     

INTERNAL THERMOSYPHON REBOILER

A very serious problem of instability that arises in the vertical thermosyphon reboilers can be solved by a newly developed equipment called internal thermosyphon reboiler. Experiments were carried out in both quartz tube and copper tube with the same geometrical dimensions. The former allowed better visual observation and the latter gave more quantitative informations. Water, sulfuric acid, triethanol-amine, heavy oil, ethanol-water, methanol-ethanol, ethanol-propanol and some other mixtures were used as working media. Particles of polypropene with density very close to water were used as the tracer in water system for investigating the flow characteristics. Rate of circulation, flow patterns, rate of heat transfer and fouling in this equipment were studied. A flow model and a design method were proposed. The results calculated could predict the characteristics of two-phase flow and heat transfer inside this boiling equipment.     

Purification of lactic acid from fermentation broth by spherical anion exchange polymer

Lactic acid, as a versatile chemical, was purified from fermentation broth by solid phase extraction with a spherical porous poly(4‐vinylpyridine). Adsorption isotherm of lactic acid on poly(4‐vinylpyridine) was first investigated with model solutions. The factors which affect the performance of separation and purification were then investigated. The obtained results indicate that the sorbent had a high adsorption capability of lactic acid, of which the maximum adsorbed lactic acid was 180.0 mg g⁻¹. Under the optimal condition the lactic acid was purified from fermentation broth by solid phase extraction with the purity of 88% and recovery yield of 95%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

发酵液中乳酸的分离提取研究进展

乳酸是合成聚乳酸的原料,生物法制备乳酸是目前工业上生产乳酸的主要方法。但乳酸发酵液成分复杂,后续的分离提纯过程成了制约乳酸生产的技术瓶颈和难点,也决定着乳酸的品质与收率。本文对乳酸发酵液的主要的分离提取工艺进行了介绍,包括结晶分离技术、酯化水解法、萃取法、分子蒸馏法、膜分离法、吸附法及与发酵耦合的原位分离技术。并提出单一的分离技术很难有效提取乳酸,需将多种技术集成、改良提纯工艺路线。其中,将各种新型高效的集成技术与发酵过程的有机结合,实现连续或半连续的发酵过程,可提高乳酸产率和产品质量,有望形成高效率、高品质、低污染、低能耗、可工业化的乳酸提纯工艺路线。     

Lactic Acid Extraction and Enzymatic Esterification for the Ethyl Lactate Production from Rice

Polylactic acid has received much attention because of its biodegradable characteristics. However, to produce the polylactic acid, enormous energy is required at the current purification processes developed up to now. In this work, in order to reduce energy consumption, we proposed a novel purification method which combines lactic acid extraction and enzyme esterification instead of the dehydration and the chemical esterification which are conventionally used. As a result, the new purification method is found to be excellent as the solvents used in this work. It revealed that some solvents (diethyl ether, tert-butyl methyl ether, and methy isobuthyl ketone) have excellent abilities for both lactic acid extraction and enzymatic esterification.     

RD生物吸附氧化法处理尼龙66化工废水

本文主要介绍了RD生物吸附氧化法应用于尼龙66化工废水处理。试验结果证明，该法应用于神马尼龙化工公司项目扩建后的污水处理系统的改造，经济技术效果良好，为以后在实际生产中的应用提供了理论依据。     

丙交酯连续化生产流程设计研究

丙交酯是两步法合成高分子量聚乳酸的中间原料,为了实现聚乳酸大型工业化生产的目标,先就两步法聚乳酸中间试验的流程和设备进行研究和设计。文章以乳酸催化反应合成丙交酯过程为研究对象,根据乳酸合成丙交酯的过程中各个步骤的反应条件及其生成物的特性,结合连续化生产流程的一般规律,通过物性计算和流程优化,设计了由乳酸合成丙交酯的连续化工艺流程。在此设计基础上,建成了100 t/a规模的中间试验装置。通过中间试验装置的试验运行,证明了文中设计工艺流程的可行性,并具有进一步放大生产的可能性。     

Lactic acid: recent advances in products,processes and technologies — a review

Lactic acid, the most widely occurring hydroxycarboxylic acid, is an enigmatic chemical. It was discovered a long time ago and its use in food preservation and processing and as a specialty chemical has grown over the years with current production of about 120 000 t yr^?1. Its potential as a major chemical feedstock, derived from renewable carbohydrates by sustainable technologies, to make plastics, fibers, solvents and oxygenated chemicals, had also been recognized. Recently, new technologies have emerged that can overcome major barriers in separations and purification and processing. Advances in electrodialysis (ED) and bipolar membranes and one particular process configuration termed the ‘double ED’ process, a specific combination of desalting ED followed by ‘water‐splitting’ ED with bipolar membranes, has given very promising results, showing a strong potential for an efficient and economic process for recovery and purification of lactic acid without generating a salt waste. For the production of polymers, several advances in catalysts and process improvements have occurred in the technology to produce dilactide and its polymerization to produce plastics and fibers by Natureworks LLC, which is the leader in lactic polymer technology and markets. Other advances in esterification technology with pervaporation and development of biosolvent blends also have a high potential for ‘green’ solvents in many applications. Recently, a considerable amount of pioneering effort in technology, product development and commercialization has been expended by several companies. To overcome the barriers to replace long‐established petroleum‐derived products, further real support from consumer, regulatory and government organizations is also needed. Copyright © 2006 Society of Chemical Industry     

Optimizing the Alcohol Precipitation of Danshen by Response Surface Methodology

Alcohol precipitation (AP) is a common method to achieve separation and purification in the process of food and herbal preparations. The response surface methodology (RSM) was applied to study and optimize the AP of Danshen, regarding the recovery of danshensu (RD) and the removal of saccharides (RS). A fractional factorial design was initially performed and solid content, ethanol consumption, acid consumption, and temperature showed significant influence on RD and RS. A Box-Behnken design with 28 experimental runs was then applied and two polynomial equations were established, based on which the effects of significant factors and their interactions were discussed. The optimum operating conditions were solid content at 66.0%, ethanol consumption at 4.3 mL/g, acid consumption at 0 g/g, and temperature at 10.7°C. The average experimental RD and RS under the optimum conditions were obtained to be 66.25 ± 1.01% and 61.64 ± 1.84%, respectively, which agreed well with the predicted values (68.85% for RD and 61.92% for RS).     

不同聚乳酸切片的流变性能比较及其对熔融纺丝性能的影响研究

利用毛细管流变仪对四种不同聚乳酸切片的流变行为进行了对比分析,并探讨了流变性能差异对熔融纺丝性能的影响。结果表明:四种聚乳酸熔体均呈现剪切变稀现象,具有非牛顿流体的流动特征;随着温度升高,聚乳酸熔体的非牛顿指数n增大;四种聚乳酸熔体的粘流活化能E_η较小,粘度随温度的变化小,有利于纺丝成型;四种聚乳酸熔体的结构粘度指数△η介于0.8~1.4,可纺性和稳定性较好。     

Lactic acid recovery from fermentation broth using one‐stage electrodialysis

One‐stage electrodialysis (ED) for lactic acid recovery with two‐ and three‐compartment water‐splitting ED (WSED) was investigated using various ion‐exchange membranes in order to overcome the inefficiency of two‐stage ED, which consists of desalting ED for recovery and partial purification and subsequent WSED for acidification. The two‐compartment WSED had a low current efficiency and high energy consumption in spite of a simple stack configuration. A three‐compartment WSED successfully converted sodium lactate in the fermentation broth into lactic acid and sodium hydroxide with average yields of 96% and 93%, respectively. In relation to lactic acid purification, of the membranes tested in this study, the highest glucose rejection, 98.3%, was achieved using a PC 100D membrane. The CMS membrane rejected magnesium and calcium at levels as high as 81.7% and 78.5%, respectively. We concluded that the three‐compartment WSED with properly chosen membranes, enabled lactic acid to be recovered directly from the fermentation broth. © 2001 Society of Chemical Industry