Microchemical Engineering: Components,Plant Concepts,User Acceptance – Part II

Over the last five years, many activities have focused on the unexploited field of carrying out reactions on small scales. Due to the rapid development of new components, this paper deals with recent developments only in a compressed form. An important point is the analysis of possible plant concepts for microreactors and whether these are a sensible option. Due to the enormous difference in size between the microchannels and the fluid periphery of possible components this is not just a technical question. It touches on the microtechnology concept as a whole. The direction in which the field should be developed and which measures can be taken to influence its development are questions that are addressed here with respect to the big industrial interest in microreactors.     

Microchemical Engineering: Components,Plant Concepts,User Acceptance – Part III

Over the last five years, many activities have focused on the unexploited field of carrying out reactions on small scales. Due to the rapid development of new components, this paper deals with recent developments only in a compressed form. An important point is the analysis of possible plant concepts for microreactors and whether these are a sensible option. Due to the enormous difference in size between the microchannels and the fluid periphery of possible components this is not just a technical question. It touches on the microtechnology concept as a whole. The direction in which the field should be developed and which measures can be taken to influence its development are questions that are addressed here with respect to the big industrial interest in microreactors.     

Mikroverfahrenstechnik: Komponenten – Anlagenkonzeption – Anwenderakzeptanz – Teil 2

Microtechnology: Components – Plant Concepts – User Acceptance Many activities over the last five or so years have focussed on the thus far underdeveloped field of carrying out reactions on small scales. Due to the rapid development of new components, this paper touches on recent developments only in a compressed form. An important point is the analysis of possible plant concepts for microreactors and whether these are a sensible option. Due to the enormous size difference between the microchannels and the fluid periphery of possible components this is not just a technical question, it touches on the microtechnology concept as a whole. The direction in which the field should be developed and which measures can be taken to influence its development, are questions that are addressed here with respect to the big industrial interest in microreactors.     

Mikroverfahrenstechnik: Komponenten – Anlagenkonzeption – Anwenderakzeptanz – Teil 3

Microtechnology: Components – Plant Concepts – User Acceptance Many activities over the last five or so years have focussed on the thus far underdeveloped field of carrying out reactions on small scales. Due to the rapid development of new components, this paper touches on recent developments only in a compressed form. An important point is the analysis of possible plant concepts for microreactors and whether these are a sensible option. Due to the enormous size difference between the microchannels and the fluid periphery of possible components this is not just a technical question, it touches on the microtechnology concept as a whole. The direction in which the field should be developed and which measures can be taken to influence its development, are questions that are addressed here with respect to the big industrial interest in microreactors.     

微反应器在聚合反应中的应用

微反应器因其良好的混合和传热性能近年来开始应用到聚合反应中,并表现出巨大潜力。本文对微反应器在自由基聚合、离子聚合和逐步聚合中的应用进行了系统综述。相比于传统的釜式反应器,微反应器可以更好地调节聚合产物分子量和分子量分布、控制共聚组成和分子结构。在强放热聚合反应中,利用微反应器可以获得窄分子量分布的聚合产物;在扩散控制的聚合反应中,利用微反应器可以大大缩短反应所需时间。微反应器在聚合反应领域中的拓展依赖于对反应机理和微反应器特点的深入理解,相关的基础研究将成为这一领域发展的关键。     

Giant vesicles as microreactors for enzymatic mRNA synthesis

Giant vesicles have attracted much attention as possible microreactors for the conduction of enzymatic reactions in an artificial, cell-sized compartment. In this context, we demonstrated in the first part of the present work that giant vesicles formed from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine in an alternating electric field can be made more permeable to Ca(2+) ions or nucleotide triphosphates by addition of ethanol. This methodology is then applied in a second step whereby these giant vesicles are used as microreactors in which mRNA synthesis can occur. The macromolecules (the DNA template and the enzyme T7 RNA polymerase) are microinjected into a selected giant vesicle, while the substrate molecules (nucleotide triphosphates) are added from the external medium. The fact that mRNA synthesis can be detected is a further step towards our aim: the design of a microreactor that can be seen as a model for a protocell.     

陶瓷基微反应器制备的研究进展

微反应器中亚毫米级的流体通道具有高效的传质传热效应,使其能够强化反应过程。随着微细加工技术的发展,制备出了耐高温耐腐蚀的陶瓷基微反应器,适用于更严苛的反应条件,然而陶瓷基微反应器的制备存在微结构成型工艺复杂、密封难度较大等问题。本文主要介绍不同陶瓷材料微反应器的制备工艺,重点论述陶瓷基微反应器制备过程中常规微加工技术的优化和新型微加工技术的引入,对比这些技术对微结构成型的改善效果。列举常用的陶瓷微通道密封连接方法,概述其特点和适用范围。并提出在陶瓷基微反应器制备的后续研究过程中,应注重陶瓷基微反应器制备的成功率和新技术的开发,完善陶瓷基微反应器的性能,将陶瓷基微反应器引入到更广泛的应用体系中。     

微反应器内的有机合成前沿进展

微反应器一般是指特征尺寸为微米至百微米级的微型反应器,是微化工系统的核心设备之一。与传统的釜式反应器相比,微反应器在危险或易燃易爆产品的合成过程及快反应过程中体现出独特优势。凭借其优异的传热传质性能,微反应器技术使这些危险化工过程变得更精准、更高效、更安全,具有重要的工业应用价值,也是化工领域的重点发展方向之一。本文主要介绍了近年来微反应器技术在医药、农药、染颜料合成等精细化工领域的进展,重点综述了在霍夫曼重排、环加成、重氮化和偶合、烷基化、氮氧化等典型“强放热快反应”有机合成方向的研究进展,并展望了其发展前景。     

微反应器内的有机合成前沿进展

微反应器一般是指特征尺寸为微米至百微米级的微型反应器,是微化工系统的核心设备之一。与传统的釜式反应器相比,微反应器在危险或易燃易爆产品的合成过程及快反应过程中体现出独特优势。凭借其优异的传热传质性能,微反应器技术使这些危险化工过程变得更精准、更高效、更安全,具有重要的工业应用价值,也是化工领域的重点发展方向之一。本文主要介绍了近年来微反应器技术在医药、农药、染颜料合成等精细化工领域的进展,重点综述了在霍夫曼重排、环加成、重氮化和偶合、烷基化、氮氧化等典型“强放热快反应”有机合成方向的研究进展,并展望了其发展前景。     

微反应器研究与应用新进展

近5年许多研究和开发活动集中于进行小尺度反应这一未开发领域。着重分析了基于微反应器的生产装置设想的可行性以及它是否是一个理智的选择。侧重介绍了微反应器在热交换、光化学反应和电化学反应、气相/液相反应以及不同种类气相反应等方面的应用实例。指出应采取冷静乐观的态度对待微反应器和微化学工程,它不仅需要现代的加工方法,还特别需要大量的适用知识。     

连续微反应加氢技术在有机合成中的研究进展

加氢反应是有机合成中很常见的一种反应类型,采用常规的间歇加氢釜具有反应效率低、操作烦琐和安全性差等问题。而连续加氢微反应器进行非均相催化加氢反应能提供更高的传质性能,催化剂的回收利用与产物的纯化也更为方便,能极大地提高生产效率,减少贵金属催化剂的损失。因为这些优点,连续微反应加氢技术得到了越来越多的关注。本文阐述了连续微反应加氢技术中常用的微反应器与固体金属催化剂类型,以及不同官能团非均相高效催化加氢的研究进展,在此基础,对该技术在精细化工领域的应用进行了展望。连续微反应加氢技术使得加氢过程可以在更安全、更高效、更环保的条件下完成,具有很高的工业应用价值,是未来化学化工领域重点发展的方向之一。     

微反应器内聚合物合成研究进展

微反应器作为化学工程学科的前沿和热点方向,逐渐成为聚合物合成的新装备、新工艺与新产品开发的重要平台,得到学术界和产业界的广泛关注。微反应器可实现可控的多相微尺度流动,能够强化聚合反应中的混合、传质和传热过程,严格控制反应时间,实现反应单元的模块化组合。与传统搅拌反应器相比,这些特点使得微反应器在控制聚合物分子量分布,简化反应环境,提高反应选择性,调节聚合物分子结构和宏观形貌等方面展现出了一定优势。本文全面综述了聚合物合成微反应器理论和技术的研究进展,并在新过程和新产品开发、反应动力学测量、微尺度基础研究和反应器放大等方面进行了展望。     

Single-phase fluid flow distribution and heat transfer in microstructured reactors

Single-phase microreactors and micro-heat-exchangers have been widely used in industrial and scientific applications over the last decade. In several cases, operation of microreactors has shown that their expected efficiency cannot be reached either due to non-uniform distribution of reactants between different channels or due to flow maldistribution between individual microreactors working in parallel. The latter problem can result in substantial temperature deviations between different microreactors resulting in thermal runaway which could arise from an exothermic reaction. Thus advances in the understanding of heat transfer and fluid flow distribution continue to be crucial in achieving improved performance, efficiency and safety in microstructured reactors used for different applications. This paper presents a review of the experimental and numerical results on fluid flow distribution, heat transfer and combination thereof, available in the open literature. Heat transfer in microchannels can be suitably described by standard theory and correlations, but scaling effects (entrance effects, conjugate heat transfer, viscous heating, and temperature-dependent properties) have often to be accounted for in microsystems. Experiments with single channels are in good agreement with predictions from the published correlations. The accuracy of multichannel experiments is lower due to flow maldistribution. Special attention is devoted to theoretical and experimental studies on the effect of a flow maldistribution on the thermal and conversion response of catalytic microreactors. The review concludes with a set of design recommendations aimed at improving the reactor performance.     

微反应器发展概况

微反应器和微混合器作为实现高效混合的最重要的手段之一被越来越多的科技工作者和商业领域青睐。介绍了微反应器的概念、特点和种类;从其几何特征出发阐述了微反应器内微混合机理。简略介绍了微反应器具有的独特优越性。总结了近年来国内外微反应器的研究发展情况和存在的问题。     

Propane combustion in non-adiabatic microreactors: 2. Flow configuration in posted microreactors

The aim of this paper is to analyze cross-flow operation in a microreactor with posted catalytic inserts for Pt-catalyzed propane combustion under fuel-lean conditions. The insert consists of 150 posts arranged in-line in six rows. The posts are static pillar-like structures in the flow channel, which act as static mixers and provide higher catalytic surface area. Computational Fluid Dynamics (CFD) simulations are used to compare the post microreactors for axial- and cross-flow configurations. In cross-flow case, where the bulk flow is in transverse direction across the six rows of posts, significant flow mal-distribution is observed. Tapering of the inner walls of the microreactor solid structure, at an angle of 5.766°, is proposed for obtaining more uniform flow distribution. For the cross-flow microreactors with tapered inner walls (referred to as “tapered-post”), the flow distribution becomes more uniform as the flow rate is decreased. The axial- and tapered-post microreactors show similar propane conversion for a wide range of operating conditions. Tapered-post microreactors have lower pressure drop and more uniform wall temperatures because the reaction zone is spread over the entire length of the catalytic insert. We also show that tapered-post microreactors have lower heat losses, and therefore are more stable towards device extinction. Consequently, the primary advantages of tapered-post microreactors are better thermal management and ability to operate at more fuel-lean conditions.     

微通道壁面刻蚀孔缺陷对通道内部流场的影响

Microchannel reactors are commonly used in micro-chemical technology. The performance of microreactors is greatly affected by the velocity field in the microchannel. The flow field is disturbed by the cylindrical etch holes caused by air dust on the microchannel surface during its processing procedure. In this approach, a two-dimensional computational fluid dynamics (CFD) model is put forward to study the effect of etch holes on flow field. The influenced area of single or two concave etch holes is studied for the case of laminar flow. The hole diameter, the Reynolds number and the distance between the center of holes are found to have influences on the flow field. Numerical results indicate that the effects of etch hole on the flow field should be evaluated and the way of choosing the economic class of cleanroom for microreactor manufacture is presented.     

Review: Microstructured reactors for distributed and renewable production of fuels and electrical energy

The current paper provides an overview of recent and past research activities in the field of microreactors for energy related topics. The main research efforts in this field are currently focussing on fuel processing as hydrogen source, mostly for distributed consumption through fuel cells. Catalyst development, reactor design and testing for reforming and removal of carbon monoxide through water-gas shift, preferential oxidation, selective methanation and membrane separation are therefore under investigation. An increasing number of integrated complete micro fuel processors has been developed for a large variety of fuels, assisted by static and dynamic simulation of these systems. The synthesis of liquid fuels is another emerging topic, namely Fischer-Tropsch synthesis, methanol and dimethylether production from synthesis gas and biodiesel production.     

β-甲基萘醌合成的催化研究进展

β-甲基萘醌(2-甲基-1,4-萘醌)在医学方面应用广泛,是合成K系维生素的重要中间体,合成这种物质的反应工艺要求较高。本文综述了近年来合成K系维生素中间体β-甲基萘醌(2-甲基-1,4-萘醌)以及相似机理的同环氧化反应所使用的催化剂以及这一类反应在催化领域的研究进展。结合现有问题,提出了适宜的发展方向。     

Chromatography as an inspiration for microreactors

In the shift from batch to continuous operations, microreactors, at least in academic research, have become an important segment. One of the next steps in process intensification is believed to be the reduction of axial dispersion, which will not only yield higher efficiencies but also allow integration of the reactor unit with downstream processing. Chromatographic (micro)devices are very interesting in this context as they successfully combine a narrow residence time distribution with a high separation factor. In the present review the low dispersion in microreactors is discussed, with emphasis on throughput, packing and flow distribution units. Subsequently, the relevance and progress during the last decade of combined reaction and separations in chromatographic and membrane based systems is treated. © 2015 Society of Chemical Industry