无电荷超滤膜酶膜反应器中的辅酶截留

构建了无电荷超滤膜酶膜反应器,考察了影响辅酶截留率的多种因素.实验结果表明,连续超滤膜反应器中加入聚乙烯亚胺(PEI,50 kDa),NAD 能够有效地被超滤膜截留.在Tris-HCl缓冲液中,PEI/NAD 摩尔比为5:1时,达到较高的辅酶截留率(R=0.823).溶液离子强度的增加减少辅酶的截留率,但可增加超滤膜超滤流速.在含盐溶液中,添加0.5%或1.O%的牛血清白蛋白可增加NAD 截留率.本装置对NADH的截留率高于NAD 的截留率,因此PEI适用于辅酶再生体系.同时还考察了1,3-丙二醇酶催化体系中PEI对甘油脱氢酶和1,3-丙二醇氧化还原酶酶活力的影响.     

手性化合物酶法制备中辅酶再生体系的构建与应用进展

辅酶的再生与反复利用对氧化还原型生物催化剂在手性化合物中的生产具有重要作用。辅酶的酶催化法再生具有高效、专一的特点,根据其催化环境可分为单细胞内辅酶再生体系、双细胞耦合体系及胞外酶耦合体系。本文详细阐述了酶法再生中各种辅酶再生体系的构建方法,特别指出了辅酶再生体系使用中可能遇到的问题并给出了解决方法,如利用离子液体解决有机底物低水溶性的问题,利用共价固定方法解决小分子辅酶的留存问题,无细胞抽提液中内源性辅酶再生酶的利用等。除此之外,对每种辅酶再生方法与体系在工业催化中应用的优势与局限性作了评述,特别关注了辅酶再生体系反复多批次利用的问题。     

伴有辅酶再生的多酶反应技术进展

伴有辅酶再生的多酶反应技术是酶工程领域的重要课题。本文就辅酶再生及伴有辅酶再生的多酶反应器技术最新进展进行评述。     

酶膜反应器及其工业应用研究

综述了在工业上具有重要应用的生物催化反应设备-酶膜反应器的概念及其发展、分类和操作特性。特别介绍了两种典型的酶膜反应器——搅拌式酶膜反应器与活塞流式酶膜反应器的结构设计和在工业应用中的生产工艺流程,有重点地介绍了酶膜反应器在工业生产中的几种应用研究,指出酶膜反应器是工业生产的新型反应器,并对酶膜反应器的发展方向阐述了相关建议。     

酶膜反应器在生化领域的应用及其电场强化的研究

概述了酶膜反应器的理论研究和应用现状 ,比较酶膜反应器与传统反应器的特点和优势。重点介绍了酶膜反应在生化领域的应用情况及其效能 ,指出了酶膜反应器在应用中所面临的制约因素。同时 ,对电场强化酶膜反应器的机理及其研究及应用情况进行了叙述 ,并讨论了提高酶膜反应器效能的途径。     

反冲式膜生物反应器生产L—天冬氨酸

设计了用于游离细胞生物转化的反冲式膜反应器，反应器内增加搅拌装置以减轻细胞对膜的堵塞。实验体系采用含天冬氨酸酶的大肠杆菌细胞转化反丁烯二酸为Ｌ－天冬氨酸。研究了膜孔径大小和细胞浓度对反应器的影响。并与利用固定细胞的填充床反应器进行了比较     

酶膜反应器的应用研究

介绍了酶膜反应器的基本概念,主要就酶膜反应器目前存在的突出问题和相应的解决方法进行了讨论,并对酶膜反应器的前景进行了展望。     

辅酶自循环的氧化还原级联体系在生物催化过程中的应用：机遇与挑战

氧化还原酶是生物催化过程中应用最为广泛的一类酶，其可以在温和条件下高选择性进行催化，在化工、医药、农业等领域发挥着重要作用。大部分氧化还原酶催化的反应需要烟酰胺辅因子参与。烟酰胺辅因子价格昂贵，大量外源添加会加重成本，无法满足工业生产的要求，因此开发高效经济的辅因子再生策略对氧化还原酶的工业应用具有重要意义。在常用的辅因子再生方法中，酶法因其高效绿色的特点得到了广泛的应用。其中，辅酶自循环的氧化还原级联体系是一种特殊的酶法再生烟酰胺辅因子策略，它能结合多酶级联催化，在不添加任何共底物的情况下，完成烟酰胺辅因子内部的自给自足循环再生。相比其他酶法再生策略，其具有副产物少、原子经济性高等突出优势。本文按照酶促反应进行的顺序将辅酶自循环的氧化还原级联体系分为四大类进行讨论，并以醇/醛脱氢酶为基础，综述了该体系应用于生物催化过程的机遇与挑战，为进一步开发更高效的辅酶自循环的氧化还原级联体系提供思路。     

代谢工程在发酵甘油产1,3-丙二醇中的应用进展

文章在介绍1,3-丙二醇代谢途径和关键酶的基础上,综述了代谢工程在发酵甘油产1,3-丙二醇中的应用进展,主要包括在原始生产菌中过表达关键酶、阻断副产物的代谢途径以及构建辅酶再生系统,并展望了1,3-丙二醇发酵生产的前景。     

酶膜生物反应器应用及展望

酶膜生物反应器是一种新型的、有发展前途的生物反应器，它在进行生物催化的同时，也在进行产物的分离、浓缩及催化剂的回收。介绍了酶膜反应器的概念、研究近况、特有的优点及问题。对酶膜反应器的不同分类方式及应用研究进行了综述，并加以展望。     

Comparison of different catalysts in the membrane-supported dehydrogenation of propane

Dehydrogenation of propane is studied in a high temperature packed bed catalytic membrane reactor with a hydrogen-selective silica membrane. The silica membrane is prepared by a two-step sol–gel process. The removal of hydrogen in the membrane reactor results in higher propane conversion and higher propene yields in comparison to an equivalent fixed-bed reactor. Unfortunately, as a result of the H₂ removal coking is favoured in the membrane reactor. Therefore, the higher propene yields are found only for the first 100–120 min time on stream. However, the lower selectivity of the membrane reactor due to coking is compensated to some extend by a reduced hydrogenolysis. Two commercial dehydrogenation catalysts of different activity were tested in the membrane reactor: Cr₂O₃/Al₂O₃ and Pt–Sn/Al₂O₃. The two catalysts show a different activity, coking, and regeneration behaviour in the membrane-supported propane dehydrogenation.     

浸没式膜生物反应器膜污染研究现状

简要分析了浸没式膜生物反应器(SMBR)中膜污染的机理.在文献和现场考察的基础上,对膜材料、混合液特性、操作参数与条件、膜的清洗与再生等几个主要方面的研究现状进行了分析和综述,指出目前研究的不足在于缺乏反应器结构优化及反应器内流场优化方面的研究.     

Fluidized bed magnetic ion exchange (MIEX®) as pre-treatment process for a submerged membrane reactor in wastewater treatment and reuse

Magnetic ion exchange (MIEX®) resin can effectively remove significant amounts of organic matter from biologically treated sewage effluent. The MIEX® process has mainly been used as a batch process, which requires a large area for accommodating both contact tank and settling tank in the treatment process. In this study, a fluidized bed MIEX® reactor (a semi-continuous process) was used as a pre-treatment for a submerged membrane. When used as a pre-treatment for a submerged membrane, the fluidized bed MIEX® contactor could remove a significant amount of organic matter in the wastewater (80% removal). This pre-treatment helped to reduce membrane fouling and keep transmembrane pressure low during the membrane operation of 8 h (less than 19 kPa). The regeneration of MIEX® resin (number of regeneration, regeneration time, etc.) did not have any adverse effect on the organic removal by MIEX®.     

丁烷氧化制顺酐循环流化床反应系统的温度匹配(I)反应系统模型

以VPO催化剂上正丁烷选择氧化制顺酐为例 ,对以变价金属复合氧化物为催化剂、按照氧化 -还原机理进行的一大类烃类选择氧化反应催化循环的温度匹配问题进行了初步模拟 .结果表明 ,使烃类选择氧化 (催化剂被还原 )和催化剂氧化再生分开进行 ,特别是根据催化剂氧化再生动力学的要求 ,适当调节再生过程的温度 ,既能明显改善反应系统的性能 ,又可以大幅度降低催化剂固体颗粒的循环量 ,取得节能降耗的效果 .本文介绍模型的建立和求解方法     

Dynamics of penicillin G hydrolysis in an electro‐membrane reactor

Analysis of penicillin G hydrolysis in a membrane reactor with membrane‐entrapped penicillin G acylase is performed using a mathematical model of the reactor system. An electric field imposed to the reactor is considered to enhance transport rates of reaction components and reaction rate. Diffusion, electrophoretic migration and electro‐osmotic flux across the membrane are considered. The analysis focuses on possible effects of the principal operational parameters (electric field intensity, inlet substrate concentration, membrane thickness) on reactor performance. Multiplicities of steady states are frequently encountered. The membrane reactor performance can be easily targeted towards the required reaction regime by applying a constant or periodically varying electric field to the system. The periodic alternation of the polarity of the electric field substantially increases the effectiveness factor of penicillin hydrolysis compared with the steady state operation. Proper adjustments of electric field intensity may also compensate for the decay in enzyme activity. © 2001 Society of Chemical Industry     

Scouring-ball effect of microsized silica particles on operation stability of the membrane reactor for acetone ammoximation over TS-1

A ceramic membrane reactor system was developed for the continuous ammoximation of acetone to acetone oxime over titanium silicalites-1 (TS-1) catalysts. The effects of catalyst concentration and microsized silica particles on the performances of the membrane reactor system were examined in detail. For the membrane reactor system the optimal catalyst concentration is 17.0 g L^?1, obviously higher than the one obtained from the previous experiments in a batch glass reactor, because the strong adhesion of TS-1 catalyst particles on the surface of the pipeline, the tank and the membrane leads to the decrease of effective catalyst concentration. Adding the microsized silica particles can effectively inhibit the decrease of TS-1 catalysts concentration in reaction slurry and improve the operation stability of the membrane reactor system significantly, benefiting from the scouring effect and the attachment of TS-1 particles on the surfaces of larger silica particles. According to the estimation of hydrodynamic forces acting on particles, microsized silica particles are hard to deposit on the contact surfaces at the studied conditions and therefore a longer stable operation of the membrane reactor system has been achieved.     

Regeneration of phenol‐saturated activated carbon in an electrochemical reactor

The regeneration of phenol‐saturated activated carbon in an electrochemical reactor was investigated in order to develop a novel regeneration method of activated carbon. The regeneration of spent activated carbon saturated with phenol was conducted in a stirred electrochemical reactor under different operating conditions. The influences of operating parameters, such as regeneration current intensity and time, on regeneration efficiency were systematically investigated. The regeneration efficiency can reach over 80% under continuous stirring in the reactor, and it only decreases by less than 5% after four regeneration cycles. Electrochemical regeneration in the stirred electrochemical reactor is shown to be an effective method for the regeneration of phenol‐saturated activated carbon with a much higher regeneration efficiency compared with a process using NaOH solution. © 2002 Society of Chemical Industry     

STRUCTURE OPTIMIZATION OF A CIRCULATING MOVING BED REACTOR

A stress distribution model for a liquid-solid circulating moving bed reactor that consists of a bottom reaction chamber, a top regeneration chamber, a coupling standpipe, a particle transportation system, and a bottom standpipe is established based on the equations of continuity and momentum balance. Simulations show that the stress concentration regions are at the bottom of the regeneration chamber and the coupling standpipe. To reduce the maximal stress and increase the operation flexibility in a reactor for the 2000-ton-per-year production of linear alkylbenzene, the regeneration chamber should have a low height-to-radius ratio (about 9), a suitable half-conical angle between 28° and 35°, and standpipe radius of about 0.05 m.     

Study on the stress distribution and modeling of the stand pipe in a circulating moving bed

The liquid-solid circulating moving bed reactor is a novel one, which consists of two reaction chambers and a particle transport system. Particles move down to the lower reaction chamber from the upper reaction chamber through a coupling standpipe and to the particle transport system through a bottom standpipe, and are then conveyed into the upper reaction chamber through a riser. A stress distribution model based on the equations of continuity and momentum balance in the reactor is established and used for simulations which shows that the stress concentration regions are at the coupling standpipe and the bottom of the regeneration chamber. To reduce the largest stress in the stress concentration regions and to minimize catalyst consumption, the regeneration chamber should be designed to give a low ratio of height to diameter. Zoning diagrams of the flow patterns in the bottom standpipe are proposed and the flow patterns can be readily deduced from the pressure gradient.     

STRUCTURE OPTIMIZATION OF A CIRCULATING MOVING BED REACTOR

A stress distribution model for a liquid-solid circulating moving bed reactor that consists of a bottom reaction chamber, a top regeneration chamber, a coupling standpipe, a particle transportation system, and a bottom standpipe is established based on the equations of continuity and momentum balance. Simulations show that the stress concentration regions are at the bottom of the regeneration chamber and the coupling standpipe. To reduce the maximal stress and increase the operation flexibility in a reactor for the 2000-ton-per-year production of linear alkylbenzene, the regeneration chamber should have a low height-to-radius ratio (about 9), a suitable half-conical angle between 28° and 35°, and standpipe radius of about 0.05 m.