The Experts below are selected from a list of 23403 Experts worldwide ranked by ideXlab platform
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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Integrated Microreactors for Reaction Automation: New Approaches to Reaction Development
Annual Review of Analytical Chemistry, 2010Co-Authors: Jonathan P. Mcmullen, Klavs F. JensenAbstract:Applications of microsystems (Microreactors) in continuous-flow chemistry have expanded rapidly over the past two decades, with numerous reports of higher conversions and yields compared to conventional batch benchtop equipment. Synthesis applications are enhanced by chemical information gained from integrating microreactor components with sensors, actuators, and automated fluid handling. Moreover, miniaturized systems allow experiments on well-defined samples at conditions not easily accessed by conventional means, such as reactions at high pressure and temperatures. The wealth of synthesis information that could potentially be acquired through use of Microreactors integrated with physical sensors and analytical chemistry techniques for online reaction monitoring has not yet been well explored. The increased efficiency resulting from use of continuous-flow microreactor platforms to automate reaction screening and optimization encourages a shift from current batchwise chemical reaction development to this new approach. We review advances in this new area and provide application examples of online monitoring and automation.
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Palladium Membrane Microreactors
Microreaction Technology: Industrial Prospects, 2000Co-Authors: Aleksander J. Franz, Klavs F. Jensen, Martin A. SchmidtAbstract:Novel palladium membrane Microreactors have been designed and microfabricated. Selective hydrogen flux has been demonstrated through the palladium membrane in the microreactor. The membrane Microreactors can be used for a variety of hydrogenation and dehydrogenation reactions, as well as in hydrogen purification applications. The microfabrication process allows for integration of heaters and temperature sensors into the device. The e-beam deposited thin Pd film achieves excellent hydrogen selectivity at high permeation rates. The membrane has good mechanical strength and has been shown to withstand pressure gradients of over 5 atm. A model hydrogenation reaction has been demonstrated in the palladium membrane reactor. Microfabricated palladium membrane reactors enable new applications because of their small size, fast thermal response times, and high efficiency.
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...
Piotr Garstecki - One of the best experts on this subject based on the ideXlab platform.
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Teflon Microreactors for organic syntheses
Sensors and Actuators B: Chemical, 2018Co-Authors: Tomasz Szymborski, Paweł Jankowski, Piotr GarsteckiAbstract:Conducting organic syntheses in Microreactors provides for better selectivity and yield via increased control of reaction conditions. Execution of organic syntheses in microfluidic systems sets stringent requirements on the fluidic systems – a factor that elevates the complexity and cost of fabrication. Here we report design, fabrication and tests of whole-Teflon (polytetrafluoroethylene – PTFE) microreactor that is easy to fabricate and to assemble and that offers the possibility to open it for cleaning and for subsequent reuse. We propose a ‘click’ system for tight bonding of two plates of inexpensive, commercial grade PFTE. The method relies solely on mechanical properties of the material and does not use any solvent or thermal treatment that could impact the surface properties of the microchannels. ‘Click’ system serves also the function of registering the two parts of the reactor with respect to each other. This assures tight positional tolerance after each subsequent re-assembly of the two parts of the microreactor. The Microreactors are hermetic and can be used for a wide range of organic syntheses without a Schlenk line or a fume hood. We provide a proof-of-concept verification of the use of the microreactor in several organic and metalo-organic syntheses. The reactor can readily be used in chemical laboratories interested in executing the organic and metalo-organic syntheses in the micro-scale format.
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An FEP Microfluidic Reactor for Photochemical Reactions
MDPI AG, 2018Co-Authors: Tomasz Szymborski, Paweł Jankowski, Dominika Ogończyk, Piotr GarsteckiAbstract:Organic syntheses based on photochemical reactions play an important role in the medical, pharmaceutical, and polymeric chemistry. For years, photochemistry was performed using high-pressure mercury lamps and immersion-wells. However, due to excellent yield, control of temperature, selectivity, low consumption of reagents and safety, the Microreactors made of fluorinated ethylene propylene (FEP) tubings have recently been used more frequently. Fluoropolymers are the material of choice for many types of syntheses due to their chemical compatibility and low surface energy. The use of tubing restricts the freedom in designing 2D and 3D geometries of the sections of the Microreactors, mixing sections, etc., that are easily achievable in the format of a planar chip. A chip microreactor made of FEP is impracticable to develop due to its high chemical inertness and high melting temperature, both of which make it difficult (or impossible) to bond two plates of polymer. Here, we demonstrate a ‘click’ system, where the two plates of FEP are joined together mechanically using a tenon and a mortise. The concept was presented by us previously for a preparation polytetrafluoroethylene (PTFE) microreactor (Szymborski et al. Sensors Actuators, B Chem. 2017, doi:10.1016/j.snb.2017.09.035). Here, we use the same strategy for FEP plates, test the use of the chips in photochemistry and also describe a custom-designed non-transparent polyethylene (PE) mask-holder with a circular opening to guide and focus the ultraviolet (UV) illumination. The solutions that we describe offer tight microreactor chips, preventing any leakage either of the liquid reagents or of UV light outside the reactor. This allows for conducting photochemical synthesis without a fume hood and without special protection against UV radiation
Sen Lin - One of the best experts on this subject based on the ideXlab platform.
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Bioinspired Design of Alcohol Dehydrogenase@nano TiO2 Microreactors for Sustainable Cycling of NAD+/NADH Coenzyme
Nanomaterials, 2018Co-Authors: Sen Lin, Shiyong Sun, Ke Wang, Kexuan Shen, Ren Yuquan, Fan XiaoyuAbstract:The bioinspired design and construction of enzyme@capsule Microreactors with specific cell-like functionality has generated tremendous interest in recent years. Inspired by their fascinating complexity, scientists have endeavored to understand the essential aspects of a natural cell and create biomimicking Microreactors so as to immobilize enzymes within the hierarchical structure of a microcapsule. In this study, simultaneous encapsulation of alcohol dehydrogenase (ADH) was achieved during the preparation of microcapsules by the Pickering emulsion method using amphiphilic modified TiO2 nanoparticles (NPs) as building blocks for assembling the photocatalytic microcapsule membrane. The ADH@TiO2 NP Microreactors exhibited dual catalytic functions, i.e., spatially confined enzymatic catalysis and the membrane-associated photocatalytic oxidation under visible light. The sustainable cycling of nicotinamide adenine dinucleotide (NAD) coenzyme between NADH and NAD+ was realized by enzymatic regeneration of NADH from NAD+ reduction, and was provided in a form that enabled further photocatalytic oxidation to NAD+ under visible light. This bioinspired ADH@TiO2 NP microreactor allowed the linking of a semiconductor mineral-based inorganic photosystem to enzymatic reactions. This is a first step toward the realization of sustainable biological cycling of NAD+/NADH coenzyme in synthetic functional microsystems operating under visible light irradiation.
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bioinspired design of alcohol dehydrogenase nano tio2 Microreactors for sustainable cycling of nad nadh coenzyme
Nanomaterials, 2018Co-Authors: Sen Lin, Shiyong Sun, Ke Wang, Kexuan Shen, Yuquan Ren, Xiaoyu FanAbstract:The bioinspired design and construction of enzyme@capsule Microreactors with specific cell-like functionality has generated tremendous interest in recent years. Inspired by their fascinating complexity, scientists have endeavored to understand the essential aspects of a natural cell and create biomimicking Microreactors so as to immobilize enzymes within the hierarchical structure of a microcapsule. In this study, simultaneous encapsulation of alcohol dehydrogenase (ADH) was achieved during the preparation of microcapsules by the Pickering emulsion method using amphiphilic modified TiO2 nanoparticles (NPs) as building blocks for assembling the photocatalytic microcapsule membrane. The ADH@TiO2 NP Microreactors exhibited dual catalytic functions, i.e., spatially confined enzymatic catalysis and the membrane-associated photocatalytic oxidation under visible light. The sustainable cycling of nicotinamide adenine dinucleotide (NAD) coenzyme between NADH and NAD+ was realized by enzymatic regeneration of NADH from NAD+ reduction, and was provided in a form that enabled further photocatalytic oxidation to NAD+ under visible light. This bioinspired ADH@TiO2 NP microreactor allowed the linking of a semiconductor mineral-based inorganic photosystem to enzymatic reactions. This is a first step toward the realization of sustainable biological cycling of NAD+/NADH coenzyme in synthetic functional microsystems operating under visible light irradiation.
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...