High-efficiency and safe synthesis of tonalid via two Friedel-Crafts reactions in continuous-flow microreactors

Tonalid,an important fragrance ingredient with widespread applicatio n,was synthesized via two FriedelCrafts reactions,which were catalyzed by AlCl_(3).The traditional tonalid production was conducted in batch stirring tank reactors,suffering from low production capacity and the safety hazard of temperature runaway.To solve these problems,the continuous-flow technologies were developed for the highefficiency and intrinsically safe synthesis of tonalid in microreactors.Catalyst AlCl_(3)was neatly homogenized in proper solvents by forming complex with reactant,which was a necessary step for the continuous synthesis in microreactors.Several reaction conditions,including reactant molar ratio,catalyst concentration,temperature,and microchannel hydrodynamic diameter,were investigated for the two Friedel-Crafts reactions in micro reactors.At optimized conditions,the yields of the two Friedel-Crafts reactions were 44.15%and 97.55%,respectively.In comparison with the batch reactors,the reaction times of these two reactions could both be reduced by nearly two thirds in microreactors at the similar yield.

Continuous synthesis of N,N-dicyanoethylaniline in microreactors:Reaction kinetics and process intensification

Cyanoethylation of phenylamine is one of the important steps for the production of dicyanoethyl-based disperse dyes.However,the exothermic nature of this reaction and the inherent instability of intermittent dynamic operation pose challenges in achieving both high safety and reaction efficiency.In this study,a continuous cyanoethylation of phenylamine for synthesizing N,N-dicyanoethylaniline in a microreactor system has been developed.By optimizing the reaction conditions,the reaction time was significantly reduced from over 2 h in batch operation to approximately 14 min in the microreactor,while high conversion and selectivity were maintained.Based on the reaction network constructed,the reaction kinetics was established,and the kinetic parameters were then determined.These findings provide valuable insights into a controllable cyanoethylation reaction,which would be helpful for the design of efficient processes and optimization of reactors.

Enhancement of liquid-liquid micromixing performance in curved capillary microreactor by generation of Dean vortices

Micromixing efficiency is an important parameter for evaluating the multiphase mass transfer performance and reaction efficiency of microreactors.In this work,the novel curved capillary reactor with different shapes was designed to generate Dean flow,which was used to enhance the liquid-liquid micromixing performance.The Villermaux-Dushman probe reaction was employed to characterize the micromixing performance in different curved capillary microreactors.The effects of experiment parameters such as liquid flow rate,inner diameter,tube length,and curve diameter on micromixing performance were systematically investigated.Under the optimal conditions,the minimum value of the segmentation factor XS was 0.008.It was worth noting that at the low Reynolds number(Re<30),the change of curved shape on the capillary microreactor can significantly improve the micromixing performance with XS reduced by 37.5%.Further,the correlations of segment index XS with dimensionless factor such as Reynolds number or Dean number were developed,which can be used to predict the liquid-liquid micromixing performance in capillary microreactors.

Assessing mixing uniformity in microreactors via in-line spectroscopy

Mixing behavior is critical for enhancing the selectivity of fast chemical reactions in microreactors.A high Reynolds number(Re)improves the mixing rate and selectivity of the reactions,but some exceptions of increasing side product yield with the higher Re have been reported.This study investigated the mixing uniformity in microreactors with in-line UV-vis spectroscopy to clarify the relationship between reaction selectivity and chaotic mixing with the higher Re.A colorization experiment of thymolphthalein in an acidic solution was conducted with an excess acid amount to the base to indicate a non-uniformly mixed region.Non-uniformity significantly increased with Re.At the same time,the degree of mixing,which was measured by a usual decolorization experiment,showed that the mixing rate increased with Re.The in-line analysis of the Villermaux-Dushman reaction during the mixing clarified that side product yield significantly increased with Re at around 300 and then decreased at around 1100.These results suggest the compensation effect between the mixing uniformity and mixing rate on the selectivity of the mixing-sensitive reactions.Faster mixing,characterized by a larger Re,can disturb mixing uniformity and,in some cases,decrease reaction selectivity.

An efficient microreactor with continuous serially connected micromixers for the synthesis of superparamagnetic magnetite nanoparticles

A new microreactor with continuous serially connected micromixers(CSCM)was tailored for the coprecipitation process to synthesize Fe_(3)O_(4) nanoparticles.Numerical simulation reveals that the two types of CSCM microchannels(V-typed and U-typed)proposed in this work exhibited markedly better mixing performances than the Zigzag and capillary microchannels due to the promotion of Dean vortices.Complete mixing was achieved in the V-typed microchannel in 2.7 s at an inlet Reynolds number of 27.Fe_(3)O_(4) nanoparticles synthesized in a planar glass microreactor with the V-typed microchannel,possessing an average size of 9.3 nm and exhibiting superparamagnetism,had obviously better dispersity and uniformity and higher crystallinity than those obtained in the capillary microreactor.The new CSCM microreactor developed in this work can act as a potent device to intensify the synthesis of similar inorganic nanoparticles via multistep chemical precipitation processes.

Preparation of coemissive luminescent nanoparticles in continuous-flow microreactors for efficient light-harvesting systems

To address the energy challenges,scientists have designed various artificial light-harvesting systems inspired by photosynthesis.Notably,for light-harvesting systems,an energytransfer efficiency close to 100%with an antenna effect greater than 10 is generally considered a good application criterion.[1]Today,building an efficient light-harvesting system at a low cost is still demanding.

Kinetics measurement of ethylene-carbonate synthesis via a fast transesterification by microreactors

High-purity ethylene carbonate(EC)is widely used as battery electrolyte,polycarbonate monomer,organic intermediate,and so on.An economical and sustainable route to synthesize high-purity ethylene carbonate(EC)via the transesterification of dimethyl carbonate(DMC)with ethylene glycol(EG)is provided in this work.However,this reaction is so fast that the reaction kinetics,which is essential for the industrial design,is hard to get by the traditional measuring method.In this work,an easy-to-assemble microreactor was used to precisely determine the reaction kinetics for the fast transesterification of DMC with EG using sodium methoxide as catalyst.The effects of flow rate,microreactor diameter,catalyst concentration,reaction temperature,and reactant molar ratio were investigated.An activity-based pseudohomogeneous kinetic model,which considered the non-ideal properties of reaction system,was established to describe the transesterification of DMC with EG.Detailed kinetics data were collected in the first 5 min.Using these data,the parameters of the kinetic model were correlated with the maximum average error of 11.19%.Using this kinetic model,the kinetic data at different catalyst concentrations and reactant molar ratios were predicted with the maximum average error of 13.68%,suggesting its satisfactory prediction performance.

Study of Macro-Mixing in a Microreactor

The transfer rate between fluids in a microreactor is directly influenced by the mixing within the reactor, which subsequently impacts the reaction rate. This paper investigates the flow behavior and macro-mixing performance in a microreactor. First, the flow performance of the Ehrfeld Miprowa microreactor is studied. Cold experiments are conducted to examine fundamental flow laws and verify the accuracy of the chosen computational fluid dynamics simulation model.Subsequently, macro-mixing performance in the microreactor, both with and without internal components, is investigated through both experiment and simulation. A bromocresol violet–NaOH–H2SO4 system is utilized in the macro-mixing experiments, which explore the effects of flow rate and internal components on macro-mixing. The Navier–Stokes equation is adopted as the computational model for macro-mixing simulations, which also consider the mass transfer and diffusion of tracer. The simulation results are in good agreement with the experimental results. Both experimental and simulation results demonstrate that the presence of internal components in the microreactor enhance its macro-mixing performance.

基于温度原位监测的微反应器在HNS微流道制备过程中的应用

针对含能材料微流道制备过程中缺乏温度原位监测手段的问题,提出一种集成薄膜温度传感器的微反应器系统;微反应器由包含薄膜温度传感器的玻璃基片与包含微流道的硅基片键合组成;微流道的上游、中游、下游分别放置了3个温度传感器,以实现微反应过程中高空间分辨率的温度测量;基于该微反应器,搭建了六硝基茋(HNS)连续化微流道制备系统,实时监测了HNS微纳米化及球形化过程中的温度变化。结果表明,微反应器具有精度高、耐腐蚀、可观测的优点;HNS微纳米化是一个放热反应,流体最大温升为6.4℃,由于HNS的逐渐析出,流体中的固体含量增大,流速变慢,流体温度的分布发生变化;在HNS球形化过程中,两相流体的混合是一个放热过程,流体最大温升为2.3℃;微流道中游处的温度明显高于上游与下游,说明当液滴流动至中游时,HNS微球已经制备完成。

CTAB/SDBS水基囊泡相磁流体制备及稳定性研究

以阳离子表面活性剂十六烷基三甲基溴化胺(CTAB)和阴离子表面活性剂十二烷基苯磺酸钠(SDBS)为原料复配自发形成囊泡相,并以其为微反应器,Fe^(2+)和Fe^(3+)在囊泡内发生反应,得到平均粒径为20m的Fe_(3)O_(4)纳米晶囊泡分散液作为水基磁流体。采用广角X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电镜(TEM)、扫描电镜(SEM)、磁滞回线(VSM)等对合成的Fe_(3)O_(4)纳米晶以及磁流体进行分析表征。结果表明,以合适的阴阳离子表面活性剂获得的囊泡相为微反应器形成的水基囊泡相磁流体,在室温稳定性优良,静置60h其稳定性系数仍然可达97%。在磁场反复作用后,囊泡相水基磁流体仍具有良好的稳定性,其中的Fe_(3)O_(4)纳米粒子颗粒均匀,具有超顺磁性特征,磁饱和度达到59emu/g。

微反应器内环酯类锂电池添加剂合成研究进展

锂电池电解液添加剂是一类在锂电池中用量不大,但对改善锂电池高低温性能,提高使用寿命和循环次数等方面发挥重要作用的高附加值电子化学品。随着锂电池等下游应用长期向好地发展,添加剂的需求量不断增长,但传统的釜式反应器由于传递性能不佳导致产品质量稳定性较差且污染严重。微反应器在微米尺度对流体有着高效分散和混合的优势,能显著提高生产效率、降低生产成本,在锂电池添加剂合成方面受到越来越广泛的关注。本文结合微反应器优异的传递性能,系统综述了微反应器在环酯类锂离子电池电解液添加剂合成中的应用进展,并对添加剂的微化工合成领域的研究方向进行了展望。

微反应器内FOX-7的连续合成工艺

研究以2-甲基-4,6-嘧啶二酮(MPO)为原料,在微通道反应器中探索了与硝硫混酸的硝化反应规律,并进一步通过水解反应来制备1,1-二氨基-2,2-二硝基乙烯(FOX-7)。研究通过引入惰性溶剂正辛烷,使反应体系呈弹状流,反应发生于分散液滴内部,解决了硝化中间体2-(二硝基亚甲基)-5,5-二硝基嘧啶-4,6-二酮(TNMPO)在微通道反应器中的堵塞难题,实现了过程强化和连续化;并研究了反应温度、停留时间、物料配比、水解条件等因素对产品收率的影响,提出了微反应器与搅拌釜串联的反应工艺。结果表明,在硝酸与MPO摩尔比为4.4,微反应器中停留时间3 min,反应温度30 oC时,串联搅拌釜保温反应30 min后,用冰水水解开环2 h,FOX-7收率可达90.1%,纯度高于99%。

微反应器内甲苯连续二硝化制备二硝基甲苯

为实现二硝基甲苯(DNT)的安全高效生产,采用微反应技术,以甲苯为原料、硝硫混酸为硝化剂,研究了甲苯连续二硝化反应过程基本规律。提高反应温度、增大硝酸与甲苯的摩尔比、降低混酸含水量、减小硝硫摩尔比、集成釜式搅拌操作有利于DNT的生成;降低反应温度、提高混酸含水量和硝硫摩尔比,有利于降低2,4-/2,6-DNT比值。针对80/20DNT产品进行了硝化工艺优化。在反应温度75℃、混酸含水量14%(质量分数)、硝硫摩尔比1/4或1/3、搅拌时间5 min条件下,产物中一硝基甲苯(MNT)含量小于0.2%,2,4-和2,6-DNT含量大于96%,2,4-/2,6-DNT比值小于4.25,其他DNT异构体含量均小于4%,符合行业标准。绝热条件下,室温进料,混酸含水量14%(质量分数),硝硫摩尔比1/4,搅拌时间10min,生产的产品质量符合行业标准。研究结果为甲苯连续二硝化工艺开发及80/20DNT产品的连续制备提供了基础。

套管膜式微反应器内高效安全的气液传质-反应过程研究进展

近年来,套管膜式微反应器由于具有传质距离短、气液接触面积大和高透气性等优点,极大地提高了气液传质和反应速度,被视为加快气液传质和流动反应过程的强大工具。目前,套管膜式微反应器已被应用于建立快速准确的气液体系基本参数流动测量平台、实现高效安全的气液反应过程和强化气体介导的生物酶催化反应过程。详细介绍了套管膜式微反应器的构造、组装和操作方式,重点概述了该反应器在不同气液传质-反应过程中的最新研究进展。最后,结合当前的研究热点,展望了套管膜式微反应器的进一步开发方向和未来潜在的应用领域。

微反应器在含能材料合成中的应用及展望

目前传统的间歇制备过程由于受制于宏观尺度难以对工艺参数、产物结构及性能实现精准调控,导致产物的均一性差,制备过程存在显著的安全隐患。因此,如何实现含能材料的安全、可控和高效的制备已成为目前研究的热点。微反应器以其微型化、集成化、高度安全性和出色的传质传热效率等诸多优势,高度契合含能材料制备过程的需求。因此,微反应器技术逐渐引起了研究者的广泛关注,在含能材料制备中崭露头角。本文介绍了微反应器在危险化工合成过程及含能材料制备中应用的国内外研究进展,特别关注了其在单质含能材料和复合含能材料制备中的潜在应用,对未来的研究方向进行了展望,强调了未来微反应器技术领域的发展需求包括规模化生产、三废处理及智能化平台建设等。

微反应技术在含能材料连续安全合成中的应用与发展

含能材料广泛应用于兵器工业、航空航天及民用建设等领域。其合成过程复杂、危险性高,传统釜式反应工艺难以满足产品质量和过程安全控制的要求。微反应技术具有热质传递速率高和安全性好等优点,在含能材料领域具有广阔的发展前景。为此,本文从微反应技术基本原理、含能化合物合成、含能颗粒材料制备和超声微反应器四方面展开综述,基于化学工程视角,阐释微化工技术在含能材料领域的应用特点。同时,总结并展望了技术领域的研究难点与未来发展方向,包括反应动力学/热力学、高黏/含固流体混合强化、反应放大与智能系统、三废处理及如何与人工智能等新兴学科结合等问题。

羟乙基乙二胺的连续流制备工艺

以乙二胺和环氧乙烷为原料,在具有特殊微结构的连续流微反应器内发生乙氧基化反应合成羟乙基乙二胺。考察了原料物质的量比、乙二胺含水量、反应温度、停留时间对反应的影响。结果表明,在n(乙二胺)∶n(环氧乙烷)=3∶1、乙二胺含水量为0.96%(质量分数)、反应温度为80℃、停留时间为60 s的最佳工艺条件下,环氧乙烷转化率接近100%,羟乙基乙二胺的选择性为87.4%,二羟乙基乙二胺的选择性为9.2%。间歇釜式反应工艺在相同物料比和反应温度条件下,羟乙基乙二胺的选择性为83.5%,二羟乙基乙二胺的选择性为15.9%。连续流微反应器能有效提高羟乙基乙二胺的选择性,降低副反应的发生,同时大大缩短了反应时间,提高了反应效率。

螺旋微反应器内传热过程模拟仿真与尺度放大

为提升微反应器制备含能材料的热安全性,采用基于有限体积法的计算流体力学模拟仿真方法,对螺旋微反应器内结构参数对流动与传热的影响规律进行了研究。结果表明,在螺旋微通道中,连续流动的流体在离心力的影响下会产生连续的二次流扰动方向变化,有助于增强流体的传热性能。增大螺旋微反应器的曲率、减小无量纲螺距值和增大流体流速,能够有效提升努塞尔数和控制沿程阻力系数。螺旋微反应器的传热性能存在“放大效应”,当螺旋管管道半径放大到2.5 mm以上时,热阻系数增大,传热性能降低。将螺旋管的管道半径控制在2.5 mm,能够在维持较高传热性能的同时,使换热流体通量增大了25倍,且压降降低了98.9%。

连续流微反应器内蒽醌硝化反应规律研究

蒽醌类染料是染料行业用量仅次于偶氮染料的第二大类染料,通过蒽醌硝化反应制备的硝基蒽醌是合成各类蒽醌类染料的重要原料之一。采用热质传递性能优异的微反应器,研究了蒽醌连续硝化反应过程中反应温度、蒽醌体积流量、n(HNO_(3))/n(蒽醌)、蒽醌浓度、停留时间及硫酸质量分数等关键工艺参数对蒽醌硝化反应的影响。结果表明,在蒽醌硝化反应过程中,一硝化和二硝化反应竞争显著;调节过程工艺参数,在促进蒽醌转化率的同时,会显著影响一硝化和二硝化产物的比例。充分利用微反应器的优势精确调控过程参数,是提高单一硝化产物选择性的有效措施。

微型反应器在沉淀硫酸钡生产中的应用

针对传统沉淀硫酸钡生产过程中存在能耗大、反应过程难以控制、硫酸钡产品批次间差异大、杂质多、粒径分布宽等问题,创新采用微型反应器来改进传统芒硝法生产硫酸钡工艺。利用微型反应器具有高效传质与传热的特点,通过精准控制物料配比及反应条件,形成条件可控、高通量的物料微腔并流连续合成硫酸钡的生产技术。微型反应器体系内物料BaS和Na2SO4充分混合且受热均匀,保证了反应过程的一致性,具有产率高、稳定性好、产品一致性及均匀性好、能耗少、反应体积小等优点,能提高合成效率与产量,提升硫酸钡产品品质,实现大规模连续生产。