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Volker Hessel - One of the best experts on this subject based on the ideXlab platform.
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membrane Microreactors gas liquid reactions made easy
Chemsuschem, 2013Co-Authors: Timothy Noël, Volker HesselAbstract:Getting phases together: Membrane Microreactors provide new opportunities for gas-liquid reactions. The advantages of this Microreactor concept are a large interfacial area, a greater flexibility with regard to flow rates, and the opportunity to immobilize a catalyst on the membrane.
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micro process engineering a comprehensive handbook
2009Co-Authors: Volker Hessel, J Jaap C Schouten, A Renken, Junichi YoshidaAbstract:VOLUME I: Fundamentals, Operations and Catalysts FLUID DYNAMICS IN MICROCHANNELS Multiphase Flow Microfluidic Networks Boiling and Two-Phase Flow in Microchannels Microscale Flow Visualization Modeling of Microfluidic Devices MIXING IN MICROSYSTEMS Characterization of Mixing and Segregation in Homogeneous Flow Systems Passive and Active Micromixers Mixing and Contacting of Heterogeneous Systems HEAT/MASS TRANSFER Heat Transfer in Homogeneous Systems Transport Phenomena in Microscale Reacting Flows Fluid-Fluid and Fluid-Solid Mass Transfer MICROSTRUCTURED DEVICES FOR PURIFICATION AND SEPARATION PROCESSES Extraction Capillary Electrochromatography MICROSTRUCTURED REACTORS Homogeneous Reactions Heterogeneous Multiphase Reactions Photoreactors Microstructured Reactors for Electrochemical Synthesis VOLUME II: Devices, Reactions and Applications Microreactor DESIGN, FABRICATION AND ASSEMBLY Silicon and Glass Microreactors Metallic, Steel, Ceramic and Plastic Microreactors BULK AND FINE CHEMISTRY Liquid- and Liquid-Liquid-Phase Reactions - Aliphatic Substitution Reactions Liquid- and Liquid-Liquid-Phase Reactions - Aromatic Substitution Reactions Liquid- and Liquid-Liquid-Phase Reactions - Addition and Elimination Liquid- and Liquid-Liquid-Phase Reactions - Coupling Reactions Liquid- and Liquid-Liquid-Phase Reactions - Oxidations and Reduction Gas-Liquid-Phase Reactions: Substitution Gas-Liquid-Phase Reactions: Addition Gas-Liquid-Phase Reactions: Reduction Gas-Liquid-Phase Reactions: Miscellaneous Reactions POLYMERIZATION Free Radical Polymerization Living Radical Polymerization Cationic Polymerization Polycondensation FUNCTIONAL MATERIALS Organic Particles and Pigments Inorganic Particles Polymer Particles Microencapsulates, Proteins and Lipids/Vesicles Oil-in-Water and Water-in-Oil Emulsions Double, Triple and Complex Multilayered Emulsions Microreactor Applications in the Consumer Goods Industry FUEL PROCESSING Application and Operation of Microreactors for Fuel Conversion Steam Reforming Partial Oxidation CO Clean-Up: Water Gas Shift and Methanation Reactions CO Clean-Up: Preferential Oxidation VOLUME III: System, Process and Plant Engineering Microreactor SYSTEMS DESIGN AND SCALE-UP Structured Multi-Scale Process Systems Design and Engineering - The Role of Microreactor Technology in Chemical Process Design Reaction and Process System Analysis, Miniaturization and Intensification Strategies Principles and Guidelines for Selection of Microstructured Devices for Mixing and Reaction Catalyst Development, Screening and Optimization SENSING, ANALYSIS, AND CONTROL Microtechnology and Process Analytics Optical In-Line Spectroscopy in Microchemical Processes On-Line Monitoring of Reaction Kinetics in Microreactors Using Mass Spectrometry and Micro-NMR Spectroscopy Automation and Control of Microprocess Systems Microreactor PLANTS: CASE STUDIES Industrial Microreactor Process Development up to Production Microreactor Plant for the Large-Scale Production of a Fine Chemical Intermediate: A Technical Case Study Development and Scale-Up of a Microreactor Pilot Plant Using the Concept of Numbering-Up Microstructures as a Tool for Production in the Tons per Hour Scale ECONOMICS AND ECO-EFFICIENCY ANALYSES The Economic Potential of Microreaction Technology Life Cycle Assessment of Microreaction Technology Versus Batch Technology - A Case Study Exergy Analysis of a Micro Fuel Processing System for Hydrogen ald Electricity Production - A Case Study
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direct fluorination of toluene using elemental fluorine in gas liquid Microreactors
Journal of Fluorine Chemistry, 2000Co-Authors: K Jahnisch, Volker Hessel, Manfred Prof Dr Baerns, W Ehrfeld, V Haverkamp, Holger Lowe, Ch Wille, A E GuberAbstract:Abstract Direct fluorination of toluene, pure or dissolved in either acetonitrile or methanol, using elemental fluorine was investigated in gas/liquid Microreactors, namely a falling film Microreactor and a micro bubble column. The experiments included measurements at high substrate concentrations and at high fluorine contents diluted in a nitrogen carrier gas, e.g. up to 50 vol.% fluorine. Results obtained were compared to the performance of a laboratory bubble column which served as a technological benchmark. Due to the formation of liquid layers of only a few tens of micrometers thickness, the Microreactors provide very large interfacial areas, e.g. up to 40,000 m 2 /m 3 . These values exceed by far those of the laboratory bubble column as well as all other devices applied in practice. The potential for enhancing mass and heat transfer was verified by several experiments resulting in an increase in conversion and selectivity for the Microreactors compared to the laboratory benchmark. For the falling film Microreactor, yields of up to 28% of monofluorinated ortho and para products for a degree of toluene conversion of 76% were obtained. These values are of the same order as described for the industrially applied Schiemann process. Space-time yields of the Microreactors, when referred to the reaction channel volume, were orders of magnitude higher than those of the laboratory bubble column. Taking into account the construction material needed, the corresponding figures of merit, for an idealized geometry as well as the existing total reactor geometry, still indicate technological and economic benefits. A variation of operating conditions for the direct fluorination revealed that conversion can be increased in the Microreactors by using higher fluorine-to-toluene ratios and reaction temperatures. The choice of solvent is also essential, with acetonitrile yielding much better results than methanol.
Klavs F. Jensen - One of the best experts on this subject based on the ideXlab platform.
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a teflon Microreactor with integrated piezoelectric actuator to handle solid forming reactions
Lab on a Chip, 2011Co-Authors: Simon Kuhn, Lei Gu, Patrick L Heider, Timothy Noël, Klavs F. JensenAbstract:We present a general inexpensive method for realizing a Teflon stack Microreactor with an integrated piezoelectric actuator for conducting chemical synthesis with solid products. The Microreactors are demonstrated with palladium-catalyzed C–N cross-coupling reactions, which are prone to clogging microchannels by forming insoluble salts as by-products. Investigations of the ultrasonic waveform applied by the piezoelectric actuator reveal an optimal value of 50 kHz at a load power of 30 W. Operating the system at these conditions, the newly developed Teflon Microreactor handles the insoluble solids formed and no clogging is observed. The investigated reactions reach full conversion in very short reaction times and high isolated yields are obtained (>95% yield).
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teflon coated silicon Microreactors impact on segmented liquid liquid multiphase flows
Langmuir, 2011Co-Authors: Simon Kuhn, Ryan L Hartman, Mahmooda Sultana, Kevin D Nagy, Samuel Marre, Klavs F. JensenAbstract:We describe fluoropolymer modification of silicon Microreactors for control of wetting properties in chemical synthesis applications and characterize the impact of the coating on liquid−liquid multiphase flows of solvents and water. Annular flow of nitrogen gas and a Teflon AF (DuPont) dispersion enable controlled evaporation of fluoropolymer solvent, which in turn brings about three-dimensional polymer deposition on microchannel walls. Consequently, the wetting behavior is switched from hydrophilic to hydrophobic. Analysis of Microreactors reveals that the polymer layer thickness increases down the length of the reactor from ∼1 to ∼13 μm with an average thickness of ∼7 μm. Similarly, we show that Microreactor surfaces can be modified with poly(tetrafluoroethylene) (PTFE). These PTFE-coated Microreactors are further characterized by measuring residence time distributions in segmented liquid−liquid multiphase flows, which display reduced axial dispersion for the coated Microreactors. Applying particle imag...
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micromachined reactors for catalytic partial oxidation reactions
Aiche Journal, 1997Co-Authors: R Srinivasan, M.p. Harold, M.a. Schmidt, I-ming Hsing, Samara L Firebaugh, Klavs F. Jensen, Peter E Berger, Jan J Lerou, Janice RyleyAbstract:Silicon-based microfabrication of a novel chemical reactor (Microreactor) having submillimeter flow channels with integrated heaters, and flow and temperature sensors is described. The potential application of this reactor to partial-oxidation reactions is explored by using Pt-catalyzed NH 3 oxidation as a model reaction. Investigation of reactor behavior as a function of operating conditions shows that conversion and selectivity behavior of conventional laboratory reactors can be reproduced and demonstrates the feasibility of conducting chemical reactions in microfabricated systems. Ignition-extinction behavior is explored, along with high-temperature Microreactor materials degradation. Potential applications and scale-up of Microreactors are also discussed.
Alexander T Nijhuis - One of the best experts on this subject based on the ideXlab platform.
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Microreactors with integrated uv vis spectroscopic detection for online process analysis under segmented flow
Lab on a Chip, 2013Co-Authors: Jun Yue, J Jaap C Schouten, Floris H Falke, Alexander T NijhuisAbstract:Combining reaction and detection in multiphase microfluidic flow is becoming increasingly important for accelerating process development in Microreactors. We report the coupling of UV/Vis spectroscopy with Microreactors for online process analysis under segmented flow conditions. Two integration schemes are presented: one uses a cross-type flow-through cell subsequent to a capillary Microreactor for detection in the transmission mode; the other uses embedded waveguides on a microfluidic chip for detection in the evanescent wave field. Model experiments reveal the capabilities of the integrated systems in real-time concentration measurements and segmented flow characterization. The application of such integration for process analysis during gold nanoparticle synthesis is demonstrated, showing its great potential in process monitoring in Microreactors operated under segmented flow.
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integration of Microreactors with spectroscopic detection for online reaction monitoring and catalyst characterization
Industrial & Engineering Chemistry Research, 2012Co-Authors: Jun Yue, J Jaap C Schouten, Alexander T NijhuisAbstract:Microreactor technology has gained significant popularity in the chemical and process industry in the past decade. The development of Microreactors either as innovative production units for chemical synthesis or as promising laboratory tools for reaction and kinetic studies relies highly on the capability of performing online analyses, which opens great opportunities for the integration of spectroscopic detection techniques. This paper gives an overview of the state-of-the-art in the combination of Microreactors with spectroscopic analyses for online reaction monitoring and catalyst characterization. In this upcoming field, many studies have been carried out combining fluorescence, ultraviolet–visible, infrared, Raman, X-ray, and nuclear magnetic resonance spectroscopy. Current research progress is reviewed, with emphasis on the existing integration schemes and selected application examples that demonstrate the potential of online spectroscopic detection for rapid Microreactor process analysis and optimiz...
Dongye Wang - One of the best experts on this subject based on the ideXlab platform.
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High surface area optofluidic Microreactor for redox mediated photocatalytic water splitting
International Journal of Hydrogen Energy, 2014Co-Authors: Lin Li, Guanyi Wang, Qiang Liao, Rong Chen, Dongye WangAbstract:Abstract Photocatalytic water splitting is a promising approach for hydrogen generation, but the low efficiency of current photoreactors limits its widespread exploitation and commercialization. Recent developments in optofluidic Microreactors open a window for advancing photocatalytic water splitting technology. Nevertheless, existing optofluidic Microreactors with the planar design show the low active surface area and rate of mass transport, thereby restricting the hydrogen production performance. In this work, we proposed an optofluidic Microreactor with staggered micro-pillars in the reaction micro-chamber. Such design not only enlarges the surface area to load catalyst but also induces perturbation to the liquid flow and shortens the transport length, which increases the active surface area and enhances the mass transfer and eventually boosts the hydrogen production rate. To evaluate the performance of this new optofluidic Microreactor, a redox mediated water splitting reaction was implemented. Results showed that the developed Microreactor with micro-pillar structure exhibited a higher reaction rate. As compared to the conventional planar optofluidic Microreactor, the maximal increment of the reaction rate could reach 56%.
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Optofluidic Microreactors with TiO2-Coated Fiberglass
ACS applied materials & interfaces, 2013Co-Authors: Rong Chen, Qiang Liao, Hong Wang, Xun Zhu, Yong-zhong Wang, Dongye WangAbstract:Optofluidic Microreactors are promising prospects for photocatalytic reactions. However, because the flow type in conventional designs is typically laminar, the mass transport mainly relies on diffusion, and thus the rate of mass transport is limited. Accordingly, poor mass transport reduces the photocatalytic reaction rate. To alleviate the limitation of mass transport, in this work, we proposed a novel optofluidic Microreactor with TiO2-coated fiberglasses immersed in the microreaction chamber. Such a design enables enhanced mass transport by shortening the transport length and inducing the perturbation to liquid flow so as to improve the performance. We demonstrated the feasibility of the optofluidic Microreactor with the TiO2-coated fiberglass by the photocatalytic water treatment of methylene blue under UV irradiation. Results showed that the proposed optofluidic Microreactor yielded much higher degradation efficiency than did the conventional optofluidic Microreactor as a result of enhanced mass tra...
Rong Chen - One of the best experts on this subject based on the ideXlab platform.
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Highly-durable optofluidic Microreactor for photocatalytic water splitting
Energy, 2015Co-Authors: Rong Chen, Qiang Liao, Lin Li, Hong Wang, Muxing ZhangAbstract:PDMS (Polydimethylsiloxane) is a typical material used to fabricate optofluidic Microreactors for photocatalytic water splitting application. However, conventional direct catalyst coating methods are unable to load catalysts firmly and uniformly on the PDMS substrate, which results in weak bond between the catalysts and substrate and thus poor durability and performance. To resolve this problem, a new casting-transfer method was proposed for loading catalysts on the PDMS substrate to fabricate the optofluidic Microreactor in this work. By performing the tape testing and long-term testing, it was shown that the optofluidic Microreactor fabricated by the new method exhibited critically high durability as compared to the conventional one. The hydrogen production rate was also higher than the conventionally fabricated Microreactor. In addition, it was found that the optofluidic Microreactor with the micro-grooved structure yielded higher hydrogen production rate than did the conventional planar optofluidic Microreactor as a result of enhanced mass transport and reaction area. This method creates a new avenue to fabricate the PDMS based Microreactors with high durability.
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High surface area optofluidic Microreactor for redox mediated photocatalytic water splitting
International Journal of Hydrogen Energy, 2014Co-Authors: Lin Li, Guanyi Wang, Qiang Liao, Rong Chen, Dongye WangAbstract:Abstract Photocatalytic water splitting is a promising approach for hydrogen generation, but the low efficiency of current photoreactors limits its widespread exploitation and commercialization. Recent developments in optofluidic Microreactors open a window for advancing photocatalytic water splitting technology. Nevertheless, existing optofluidic Microreactors with the planar design show the low active surface area and rate of mass transport, thereby restricting the hydrogen production performance. In this work, we proposed an optofluidic Microreactor with staggered micro-pillars in the reaction micro-chamber. Such design not only enlarges the surface area to load catalyst but also induces perturbation to the liquid flow and shortens the transport length, which increases the active surface area and enhances the mass transfer and eventually boosts the hydrogen production rate. To evaluate the performance of this new optofluidic Microreactor, a redox mediated water splitting reaction was implemented. Results showed that the developed Microreactor with micro-pillar structure exhibited a higher reaction rate. As compared to the conventional planar optofluidic Microreactor, the maximal increment of the reaction rate could reach 56%.
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Optofluidic Microreactors with TiO2-Coated Fiberglass
ACS applied materials & interfaces, 2013Co-Authors: Rong Chen, Qiang Liao, Hong Wang, Xun Zhu, Yong-zhong Wang, Dongye WangAbstract:Optofluidic Microreactors are promising prospects for photocatalytic reactions. However, because the flow type in conventional designs is typically laminar, the mass transport mainly relies on diffusion, and thus the rate of mass transport is limited. Accordingly, poor mass transport reduces the photocatalytic reaction rate. To alleviate the limitation of mass transport, in this work, we proposed a novel optofluidic Microreactor with TiO2-coated fiberglasses immersed in the microreaction chamber. Such a design enables enhanced mass transport by shortening the transport length and inducing the perturbation to liquid flow so as to improve the performance. We demonstrated the feasibility of the optofluidic Microreactor with the TiO2-coated fiberglass by the photocatalytic water treatment of methylene blue under UV irradiation. Results showed that the proposed optofluidic Microreactor yielded much higher degradation efficiency than did the conventional optofluidic Microreactor as a result of enhanced mass tra...
