酶促反应结晶研究进展

在“双碳”背景下,绿色可持续的酶促反应正受到工业界的广泛关注,但在实际应用中仍面临着诸多挑战,如反应平衡的限制、不稳定产物的分解、酶的产物抑制等。结晶作为一种高效成熟的分离技术,可通过移除液相产物的方式有效解决上述问题。同时,结晶也是晶体产品的“生成”过程,其与酶促反应耦合可一步实现晶体产品的高效、绿色、可控制备。综述了近年来酶促反应结晶的研究进展,介绍了原位产物结晶（ISPC）技术的发展历程,并讨论了结晶与酶促反应耦合时的相互影响关系;从结晶方式和过程控制角度阐述了酶促反应结晶的实现形式和连续化过程;最后,对酶促反应结晶这一耦合过程的发展和应用进行了总结和展望。     

分散染料自动连续化生产新工艺

分散染料传统生产工艺具有工作强度大、生产效率和生产质量低下等问题,需要工厂创新生产工艺。本文将偶氮类分散染料为例,分析分散染料的自动连续化生产新工艺,工厂可以通过重氮化反应及偶合反应生产环节的自动连续化,实现分散染料生产的自动连续化。和传统生产工艺相比,自动连续化生产新工艺的生产效率和生产质量有所提升,排放的染料废水能够循环利用,真正实现了绿色清洁生产,值得推广应用。     

乙烯齐聚的连续化反应研究

在四元催化体系间歇釜式反应的基础上 ,本文对乙烯齐聚的连续化反应进行了系统研究 ,设计并安装了一套连续化反应装置 ,包括预反应器、反应器和闪蒸后处理装置。在连续化反应装置上 ,分别考察了催化剂进料速度、反应压力和催化剂浓度对乙烯齐聚连续化反应的影响 ,同时获得了连续化反应的最佳反应条件。经过研究发现 ,该四元催化体系的间歇釜式反应的最佳反应条件 ,也同时是连续化反应的最佳反应条件 ,齐聚反应的催化活性、C=4 -10 的选择性、1-C=4 -10 的线性选择性及产物分布等基本相同。实验证明 ,该连续化反应工艺流程可行 ,可作为未来工业化的模型装置。     

乙烯齐聚的连续化反应研究

在四元催化体系间歇釜式反应的基础上,本文对乙烯齐聚的连续化反应进行了系统研究,设计并安装了一套连续化反应装置,包括预反应器,反应器和闪蒸后处理装置。在连续化反应装置上,分别考察了催化剂进料速度,反应压力和催化剂浓度对然齐聚连续化反应的影响,同时获得了连续化反应的最佳反应条件。经过研究发现,该四元催化剂体系的间歇釜式反应的最佳反应条件,也同时是连续化反应的最佳反应条件,齐聚反应的催化活性,Ｃ的选择性     

萘啶酸的合成与表征

以2-氨基-6-甲基吡啶、原甲酸三乙酯和乙酰乙酸乙酯为原料,通过缩合反应、热成环反应、乙基化反应和氧化反应,制备得到萘啶酸,并对其进行了红外和核磁表征.对其进行了工艺改进,实现乙基化反应和氧化反应连续操作,提高总收率.     

橡胶双转子连续混炼机母炼全过程各阶段的实验研究

本研究针对块状橡胶串联式连续混炼装备和方法,采用了自主研发的块状橡胶串联式连续混炼实验平台,主要针对双转子连续混炼机母炼过程,通过设计连续母炼全过程各阶段对比实验,得到未添加硫化体系的各阶段连续母炼胶。通过Payne效应、硅烷化反应指数、门尼黏度来判断胶料的质量水平,实验结果表明:胶料在依次通过连续混炼机各混炼模块后,各组样品的Payne效应依次呈现下降趋势,实现填料的良好分散;各组样品硅烷化反应程度整体呈现上升趋势,说明橡胶连续母炼系统能够实现白炭黑的硅烷化反应。胶料进入双转子连续混炼机后门尼黏度也在持续下降,最终门尼黏度维持在55左右,适宜后续的加工。     

淤浆床炔化法催化合成1，4—丁炔二醇连续化的热模研究

为了采用内过滤器实现炔化反应的连续化，在完善冷模研究后，首先对多种过滤介质在热模条件下进行筛选，以获得一种符合炔化反应工艺要求，并且过滤性能稳定持久的过滤介质。实验证明采用管式内过滤器可以解决在反应工艺条件下淤交床连续化的气液固分离问题。通过对比淤浆反应器在连续及间歇操作下的反应工艺及反应速率的一致性，从而建立了反应动力学模型，为进一步开发放大提供依据。     

反胶团酶反应过程开发研究进展

反胶团酶反应具有水相与有机相酶反应的共同优点 ,因而受到人们的重视。制约其实际应用的重要原因在于如何解决酶的重复利用问题。最初人们采用水溶液萃取法回收酶 ,但由于条件苛刻 ,酶活回收率较低。相变法利用温度的改变使体系分相以实现酶的回收 ,操作简便 ,但仍有较大的酶活损失。连续流两相离心反应器可以实现反胶团酶反应的连续操作且酶的损失很小 ,但该反应器传质速率较低因而转化率不高。膜反应器是反胶团酶反应中研究最多也最有应用前途的一种反应器形式。文中介绍了反胶团酶反应中酶重复利用的方法 ,对其过程开发的最新进展进行了综述。     

固定化青霉素酰化酶生产6-APA的流程设计

针对本组研制的一种新型固定化青霉素酰化酶,以动力学方程为基础,分别进行了批式反应和连续反应的计算．对于批式反应,计算了不同浓度底物的水解过程和各种抑制因子对反应过程的影响;对于连续反应,计算了不同级数下的需酶量、转化率和成本消耗。结果表明,三、四级连续反应是可行的,有工业应用的前景。     

酶解-膜分离耦合技术制备米糠蛋白活性多肽的研究

为了探索米糠蛋白活性多肽的最佳酶法制备方法,进行了三种酶解-膜分离耦合反应模式制备活性多肽的研究.结果表明,间歇反应条件下蛋白转化率为47.50%,生产效率为1.98g肽/AU酶,均为传统方法的1.27倍;连续补水反应模式蛋白转化率最高,即68.54%,分别是传统方法的1.84倍、间歇反应模式的1.47倍、连续补料反应模式的1.19倍;连续补料反应模式的蛋白转化率为57.61%,是传统制取方法的1.54倍,其生产效率最高,即11.46g肽/AU酶,分别是传统方法的7.37倍、间歇反应模式的5.79倍、连续补水反应模式的2.81倍.上述结果显示,三种酶膜耦合反应模式都能强化反应过程、提高蛋白转化效率和生产效率.就来源广泛的米糠蛋白而言,连续补料酶膜耦合反应模式是一种比较好的多肽制备方法,蛋白转化率和酶利用率均显著提高.     

膜反应器中辅酶再生体系的构建与研究进展

在膜反应器中基于膜介质支持构建辅酶再生的酶催化体系并实现酶促反应的连续进行是辅酶依赖型生物酶工业化应用的一个有效技术手段。本文总结了辅酶再生的意义与辅酶再生体系在膜反应器中的构建情况,并提出了在这过程中所需注意的问题及解决思路。     

Enzymatic production of fructooligosaccharides from inexpensive and abundant substrates using a membrane reactor system

The concept of zero waste in the sugar industry has encouraged the development of technologies that promote utilization of by-products, including the enzymatic conversion of waste feed stocks into nutraceutical products. Here we investigated a membrane reactor for the production of fructooligosaccharides (FOS) with immobilized enzyme (Pectinex Ultra SP-L) system using pretreated molasses as substrate with cleaning efficiency and less fouling as performance tools. The resulting spectra showed a high FOS yield of 63% with 89% conversion from available sucrose. So, the enzymatic membrane reactor system with innovative continuous separation of enzyme was proved to fit for the production of FOS.     

A fundamental analysis of continuous flow bioreactor models and membrane reactor models to process industrial wastewaters

We analyse the steady-state treatment of industrial wastewaters in a continuous flow bioreactor and in an idealised continuous flow membrane reactor. The reaction is assumed to be governed by Contois growth kinetics, which is often used to model the growth of biomass in wastewaters containing biodegradable organic materials. We show that a flow reactor with idealised recycle has the same performance as an idealised membrane reactor and that the performance of a non-idealised membrane reactor is identical to an appropriately defined continuous flow bioreactor with non-idealised recycle. The performance of all three reactor types can therefore be obtained by analysing a flow reactor with recycle. The steady-states of the model are found and their stability determined as a function of the residence time. The performance of the reactor at large residence times is obtained. In the limit as the residence time becomes very large, all three reactor configurations have identical performances. Thus the main advantage of using a membrane reactor, or a flow reactor with recycle, for the treatment of industrial wastewaters and slurries is to improve the performance at low residence times.     

酶解反应与膜分离耦合连续制备酪蛋白磷酸肽

采用酶解反应与膜分离耦合新工艺连续水解全酪蛋白制备酪蛋白磷酸肽(CPPs)。考察了超滤膜对胰蛋白酶及底物溶液的截留效果;研究了初始底物质量浓度、初始酶质量浓度、反应体积、膜渗透通量等参数对反应器性能和反应转化率的影响规律;利用高效凝胶排阻色谱系统(HPSEC)对酶解产物进行检测分析;建立了酶膜反应器连续水解动力学模型,并对间歇与连续酶解过程进行比较分析,证明反应-分离耦合技术可使酶解效率及蛋白酶利用率大幅提高,并使产物得到调控与富集,为CPPs的酶法制备提供了一种更为有效的方法。     

Theoretical analysis of inhibition effect on steady states of enzymatic membrane reactor with substrate and product retention for reaction producing weak acid

The aim of this study is to formulate a model of enzymatic membrane reactor (EMR), i.e., a continuous, stirred tank bioreactor with full enzyme recycle, for a reaction producing a weak acid, and to explore the effect of substrate and product inhibition of different mechanisms coupled with transport properties of the membrane on the static behaviour of the system. The inhibition of an enzyme by a substrate leads to the non-monotonicity of reaction rate expression with respect to the substrate concentration. If a product of enzymatic reaction, taking place in the EMR, influences the pH of a reaction mixture this is also the factor causing the non-monotonicity of the substrate and product dependent reaction rate. The character of these dependencies affects substantially the structure of the steady states of the reactor. The bifurcation diagrams, shown in the work, are of different characters depending on the bifurcation parameter. It has been found, that bifurcation diagrams for competitive and uncompetitive inhibition by a substrate differ in the number and position of bifurcation points. Steady states of multiplicity five have been localised in case of uncompetitive inhibition by the substrate at high affinity of the enzyme to this substrate. Retention of reagents, related to transport properties of a membrane, influences significantly the effectiveness of a process. A specially written software in Delphi™ has been used for the calculations.     

A hybrid membrane-emulsion reactor for the enzymatic hydrolysis of lipids

A hybrid reactor, consisting of a stirred vessel, a hydrophilic membrane loop and a hydrophobic membrane loop, is presented for the continuous enzymatic hydrolysis of soybean oil in an emulsion. The permeates of the hydrophilic and the hydrophobic membrane consist of a single water phase and a single lipid phase, respectively. No lipase activity could be detected in the permeates of both membranes, which implies that all enzyme is retained in the system. An important advantage of this system is that it combines the high surface area in an emulsion with the containment of lipase in a membrane reactor. It is further shown that the stability of the system can be improved considerably by the addition of CaCl₂ to the water phase. Under comparable conditions the enzyme stability in the hybrid reactor is lower than the stability in a stirred vessel. The composition of the emulsion appears to influence the flux of the membranes. The flux of the hydrophobic membrane increases with an increasing oil fraction of the emulsion while the flux of the hydrophilic membrane has an optimum for two different oil fractions—0 and 0.55 (v/v).     

Microbial oxidation of naphthalene to cis-1,2-dihydroxy-1,2-dihydronaphthalene in a membrane bioreactor

A microbial dihydroxylation process for the production of cis-1,2-dihydroxy-1,2-dihydronaphthalene from naphthalene is reported. The oxidation reaction was initially studied in a stirred tank reactor using resting cells of a Pseudomonas fluorescens mutant, grown on glucose as carbon source and acetyl salicylate as inducer of the naphthalene dioxygenase enzymatic system. In these conditions the productivity of the system was limited by the efficiency of the oxygenation and by a reversible product inhibition phenomenon. In order to overcome the inhibitory effect of the 1,2-dihydrodiol accumulation, the biotransformations were carried out in a stirred reactor equipped with a membrane ultrafiltration device. In this way, the cells and the insoluble naphthalene were retained and recycled into the vessel, while the soluble diol was continuously removed through the membrane permeate. The diol was recovered by selective adsorption on a column packed with an adsorbent resin, allowing the rapid and direct recycle of the reaction medium back to the enzymatic reactor. This system afforded a final yield three-fold higher than that of the batch process, exhibiting a bioconversion rate of 1·3 g h⁻¹ dm⁻³ for more than 16 h of continuous working.     

乳酸连续化发酵进展

对一些新型的乳酸连续化发酵装置,包括恒浊器、两级恒化器、两级固定床、两级膜细胞循环反应器、三相流化床-电渗析、塑料支持生物膜反应器及相应的发酵条件进行了综述;讨论了连续化发酵的控制(无反馈控制、反馈控制)、数学模型、最优化方法;并分析了不同连续化发酵装置的优缺点及前景.     

Analysis of process integration and intensification of enzymatic cellulose hydrolysis in a membrane bioreactor

Enzymatic cellulose hydrolysis has been studied for many years, generating rich literatures and knowledge in respect to the underlying reaction mechanism, reaction kinetics, and bioreactor systems. This paper attempts to offer some additional information and new understanding of how reaction kinetics and reactor productivity can be improved in a process involving simultaneous reaction and product separation using a purpose‐built membrane reactor with a single combined reaction zone and separation zone. Different operating strategies of batch, fed batch and continuous cellulose hydrolysis were investigated with intermittent or simultaneous removal of products (reducing sugars) to reduce enzyme inhibition and improve reactor productivity. The effect of continuous and selective product removal, reduced enzyme inhibition and higher enzyme concentration in retention were examined for the potential benefit in process integration and intensification in order to lower the high process cost of the enzymatic hydrolysis process, mainly due to slow reaction kinetics and expensive enzymes. A mathematical model was offered to account for the effect of selective product (reducing sugars) separation, permeate flux, reduced cellulase inhibition, dynamic structural change of the solid substrate and possible shear deactivation of the enzyme. Computer analysis was also carried out to analyse the quasi‐steady state of the reaction intermediates in order to gain an insight into the reaction mechanism in simultaneous reaction and separation systems. Some original analysis and simulation of the effect of membrane separation parameters on the overall reactor performance is offered, including the effect of membrane selectivity (rejection coefficient) and flux. Copyright © 2005 Society of Chemical Industry