Microflow chemistry and its electrification for sustainable chemical manufacturing

Sustainability is vital in solving global societal problems. Still, it requires a holistic view by considering renewable energy and carbon sources, recycling waste streams, environmentally friendly resource extraction and handling, and green manufacturing. Flow chemistry at the microscale can enable continuous sustainable manufacturing by opening up new operating windows, precise residence time control, enhanced mixing and transport, improved yield and productivity, and inherent safety. Furthermore, integrating microfluidic systems with alternative energy sources, such as microwaves and plasmas, offers tremendous promise for electrifying and intensifying modular and distributed chemical processing. This review provides an overview of microflow chemistry, electrification, their integration toward sustainable manufacturing, and their application to biomass upgrade (a select number of other processes are also touched upon). Finally, we identify critical areas for future research, such as matching technology to the scale of the application, techno-economic analysis, and life cycle assessment.

Continuous Synthesis of Nanocrystals via Flow Chemistry Technology

Modern nanotechnologies bring humanity to a new age, and advanced methods for preparing functional nanocrystals are cornerstones. A considerable variety of nanomaterials has been created over the past decades, but few were prepared on the macro scale, even fewer making it to the stage of industrial production. The gap between academic research and engineering production is expected to be filled by flow chemistry technology, which relies on microreactors. Microreaction devices and technologies for synthesizing different kinds of nanocrystals are discussed from an engineering point of view. The advantages of microreactors, the important features of flow chemistry systems, and methods to apply them in the syntheses of salt, oxide, metal, alloy, and quantum dot nanomaterials are summarized. To further exhibit the scaling-up of nanocrystal synthesis, recent reports on using microreactors with gram per hour and larger production rates are highlighted. Finally, an industrial example for preparing 10 tons of CaCO₃ nanoparticles per day is introduced, which shows the great potential for flow chemistry processes to transfer lab research to industry.

Homogeneous synthesis of hydroxylamine hydrochloride via acid-catalyzed hydrolysis of nitromethane

A continuous homogeneous synthesis of NH₂OH·HCl was achieved and well described with a segmented semi-empirical kinetics model.

Continuous flow synthesis of ordered porous materials: from zeolites to metal–organic frameworks and mesoporous silica

Herein we review the concepts, challenges and recent developments on the continuous flow synthesis of ordered porous materials.

Application of Microfluidics in Process Intensification

Is it possible to miniaturize a chemical plant? Some strategies, such as the process intensification, sustain that the advancements in equipment and production techniques could substantially decrease the equipment size/production capacity ratio, energy consumption and waste generation, resulting in more economic and sustainable operations and consequently reducing the chemical plant size. However, large reductions of equipment volume represent a major challenge for the conventional technologies. In this context, Microfluidics represents a promising technology in the field of system miniaturization. Accordingly, the present research evaluated the concept of process intensification and its relationship with Microfluidics. Initially, the definition and the classification of process intensification were described, following by the explanation of the Microfluidics, highlighting scale-up strategies and examples using miniaturized systems. Afterward, a methodology for miniaturized devices development for process intensification using numerical simulations was shown. Finally, the conclusions are exposed.

Continuous flow chemistry: where are we now? Recent applications, challenges and limitations

A general outlook of the changing face of chemical synthesis is provided in this article through recent applications of continuous flow processing in both industry and academia. The benefits, major challenges and limitations associated with the use of this mode of processing are also given due attention as an attempt to put into perspective the current position of continuous flow processing, either as an alternative or potential combinatory technology for batch processing.

Design and Scaling Up of Microchemical Systems: A Review

The past two decades have witnessed a rapid development of microreactors. A substantial number of reactions have been tested in microchemical systems, revealing the advantages of controlled residence time, enhanced transport efficiency, high product yield, and inherent safety. This review defines the microchemical system and describes its components and applications as well as the basic structures of micromixers. We focus on mixing, flow dynamics, and mass and heat transfer in microreactors along with three strategies for scaling up microreactors: parallel numbering-up, consecutive numbering-up, and scale-out. We also propose a possible methodology to design microchemical systems. Finally, we provide a summary and future prospects.

Liquid–liquid microflow reaction engineering

Engineering characteristics of liquid–liquid microflow and its advantages in chemical reactions.

A convenient numbering-up strategy for the scale-up of gas–liquid photoredox catalysis in flow

An operationally simple numbering-up strategy for the scale-up of gas–liquid photocatalytic reactions was developed, which provides an excellent flow distribution (SD_w < 10%).