Volker Hessel

Bio: Volker Hessel is an academic researcher from University of Adelaide. The author has contributed to research in topics: Microreactor & Catalysis. The author has an hindex of 68, co-authored 572 publications receiving 21707 citations. Previous affiliations of Volker Hessel include Mainz Institute of Microtechnology & Fraunhofer Society.

Chemistry in microstructured reactors.

Abstract: The application of microstructured reactors in the chemical process industry has gained significant importance in recent years. Companies that offer not only microstructured reactors, but also entire chemical process plants and services relating to them, are already in existence. In addition, many institutes and universities are active within this field, and process-engineering-oriented reviews and a specialized book are available. Microstructured systems can be applied with particular success in the investigation of highly exothermic and fast reactions. Often the presence of temperature-induced side reactions can be significantly reduced through isothermal operations. Although microstructured reaction techniques have been shown to optimize many synthetic procedures, they have not yet received the attention they deserve in organic chemistry. For this reason, this Review aims to address this by providing an overview of the chemistry in microstructured reactors, grouped into liquid-phase, gas-phase, and gas-liquid reactions.

Applications of Continuous-Flow Photochemistry in Organic Synthesis, Material Science, and Water Treatment

Abstract: Continuous-flow photochemistry in microreactors receives a lot of attention from researchers in academia and industry as this technology provides reduced reaction times, higher selectivities, straightforward scalability, and the possibility to safely use hazardous intermediates and gaseous reactants. In this review, an up-to-date overview is given of photochemical transformations in continuous-flow reactors, including applications in organic synthesis, material science, and water treatment. In addition, the advantages of continuous-flow photochemistry are pointed out and a thorough comparison with batch processing is presented.

Microreactors: New Technology for Modern Chemistry

Abstract: 1 State of the Art of Microreaction Technology 1.1 Definition 1.1.1 Microsystems Termed Microreactor 1.1.2 Structural Hierarchy of Microreactors 1.1.3 Functional Classification of Microreactors 1.1.4 Dividing Line Between Analysis and Reaction Systems 1.2 Fundamental Advantages of Microreactors 1.2.1 Fundamental Advantages of Miniaturized Analysis Systems 1.2.2 Fundamental Advantages of Nano-Scale Reactors 1.2.3 Advantages of Microreactors Due to Decrease of Physical Size 1.2.4 Advantages of Microreactors Due to Increase of Number of Units 1.3 Potential Benefits of Microreactors Regarding Applications 1.4 References 2 Modern Microfabrication Techniques for Microreactors 2.1 Microfabrication Techniques Suitable for Microreactor Realization 2.2 Evaluation of Suitability of a Technique 2.3 Anisotropic Wet Etching of Silicon 2.4 Dry Etching of Silicon 2.5 LIGA Process 2.6 Injection Molding 2.7 Wet Chemical Etching of Glass 2.8 Advanced Mechanical Techniques 2.8.1 Surface Cutting with Diamond Tools 2.8.2 Milling, Turning and Drilling 2.8.3 Punching 2.8.4 Embossing 2.9 Isotropic Wet Chemical Etching of Metal Foils 2.10 Electro Discharge Machining (EDM) of Conductive Materials 2.10.1 Wire-Cut Erosion and Die Sinking 2.10.2 -EDM Drilling 2.11 Laser Micromachining 2.12 Interconnection Techniques 2.12.1 Microlamination of Thin Metal Sheets 2.13 Functional Coatings 2.13.1 Functional Coatings for Corrosion Prevention 2.13.2 Functional Coatings for Fouling Prevention 2.14 References 3 Micromixers 3.1 Mixing Principles and Classes of Macroscopic Mixing Equipment 3.2 Mixing Principles and Classes of Miniaturized Mixers 3.3 Potential of Miniaturized Mixers 3.4 Contacting of Two Substreams, e.g. in a Mixing Tee Configuration 3.4.1 Mixing Tee-Type Configuration 3.4.2 Double Mixing Tee-Type Configuration 3.5 Collision of High-Energy Substreams for Spraying/Atomizing 3.5.1 Collision of Three Substreams in a Microjet Reactor 3.6 Injection of Many Small Substreams of One Component into a Main Stream of Another Component 3.6.1 Injection of Multiple Microjets 3.7 Manifold Splitting and Recombination of a Stream Consisting of Two Fluid Lamellae of Both Components 3.7.1 Multiple Flow Splitting and Recombination Combined with Channel Reshaping 3.7.2 Multiple Flow Splitting and Recombination Using Fork-Like Elements 3.7.3 Multiple Flow Splitting and Recombination Using a Separation Plate 3.7.4 Multiple Flow Splitting and Recombination Using a Ramp-Like Channel Architecture 3.8 Injection of Many Substreams of Both Components 3.8.1 Multilamination of Fluid Layers in an Interdigital Channel Configuration 3.8.2 Vertical Multilamination of Fluid Layers Using a V-type Nozzle Array 3.8.3 Multilamination Using a Stack of Platelets with Microchannels 3.8.4 Multilamination Using a Stack of Platelets with Star-Shaped Openings 3.9 Decrease of Diffusion Path Perpendicular to the Flow Direction by Increase of Flow Velocity 3.9.1 Decrease of Layer Thickness by Hydrodynamic Focusing 3.10 Externally Forced Mass Transport, e.g. by Stirring. Ultrasonic Wave, Electrical and Thermal Energy 3.10.1 Dynamic Micromixer Using Magnetic Beads 3.11 References 4 Micro Heat Exchangers 4.1 Micro Heat Exchangers with Wide and Flat Channels 4.1.1 Cross-Flow Heat Exchange in Stacked Plate Devices 4.1.2 Cross-Flow Heat Exchange Based on Cross-Mixing 4.1.3 Counter-Flow Heat Exchange in Stacked Plate Devices 4.1.4 Electrically Heated Stacked Plate Devices 4.2 Micro Heat Exchangers with Narrow and Deep Channels 4.2.1 Heat Exchanger with One-Sided Structured Channels 4.2.2 Heat Exchanger with Double-Sided Structured Channels 4.3 Micro Heat Exchangers with Breakthrough Channels 4.4 Axial Heat Conduction 4.4.1 Numerical Calculations of the Influence of Material on Heat Transfer Efficiency 4.4.2 The Use of Thermal Blocking Structures 4.5 Permanent Generation of Entrance Flow by Fins 4.6 Generation of a Periodic Flow Profile by Sine-Wave Microchannels 4.7 Microtechnology-Based Chemical Heat Pumps 4.8 Performance Characterization of Micro Heat Exchangers 4.8.1 Temperature Profiles of Micro Heat Exchangers Yielded by Thermograms of Infrared Cameras 4.9 References 5 Microseparation Systems and Specific Analytical Modules for Microreactors 5.1 Microextractors 5.1.1 Partially Overlapping Channels 5.1.2 Wedge-Shaped Flow Contactor 5.1.3 Contactor Microchannels Separated by a Micromachined Membrane 5.1.4 Contactor Microchannels Separated by Sieve-Like Walls 5.1.5 Micromixer - Settler Systems 5.2 Microfilters 5.2.1 Isoporous-Sieve Microfilters 5.2.2 Cross-Flow Microfilters 5.3 Gas Purification Microsystems 5.4 Gas Separation Microdevices 5.5 Specific Analytical Modules for Microreactors 5.5.1 Analytical Modules for In-Line IR Spectroscopy 5.5.2 Analytical Module for Fast Gas Chromatography 5.6 References 6 Microsystems for Liquid Phase Reactions 6.1 Types of Liquid Phase Microreactors 6.2 Liquid/Liquid Synthesis of a Vitamin Precursor in a Combined Mixer and Heat Exchanger Device 6.3 Acrylate Polymerization in Micromixers 6.4 Ketone Reduction Using a Grignard Reagent in Micromixers 6.5 Laboratory-Scale Organic Chemistry in Micromixer/Tube Reactors 6.6 Dushman Reaction Using Hydrodynamic Focusing Micromixers and High-Aspect Ratio Heat Exchangers 6.7 Synthesis of Microcrystallites in a Microtechnology-Based Continuous Segmented-Flow Tubular Reactor 6.8 Electrochemical Microreactors 6.8.1 Synthesis of 4-Methoxybenzaldehyde in a Plate-to-Plate Electrode Configuration 6.8.2 Scouting Potentiodynamic Operation of Closed Microcells 6.9 References 7 Microsystems for Gas Phase Reactions 7.1 Catalyst Supply for Microreactors 7.2 Types of Gas Phase Microreactors 7.3 Microchannel Catalyst Structures 7.3.1 Flow Distribution in Microchannel Catalyst Reactors 7.3.2 Partial Oxidation of Propene to Acrolein 7.3.3 Selective Partial Hydrogenation of a Cyclic Triene 7.3.4 H 2 /O 2 Reaction 7.3.5 Selective Partial Hydrogenation of Benzene 7.3.6 Selective Oxidation of 1-Butene to Maleic Anhydride 7.3.7 Selective Oxidation of Ethylene to Ethylene Oxide 7.3.8 Reactions Utilizing Periodic Operation 7.4 Microsystems with Integrated Catalyst Structures and Heat Exchanger 7.4.1 Oxidative Dehydrogenation of Alcohols 7.4.2 Synthesis of Methyl Isocyanate and Various Other Hazardous Gases 7.4.3 H 2 /O 2 Reaction in the Explosion Regime 7.5 Microsystems with Integrated Catalyst Structures and Mixer 7.5.1 Synthesis of Ethylene Oxide 7.6 Microsystems with Integrated Catalyst Structures. Heat Exchanger and Sensors 7.6.1 Oxidation of Ammonia 7.6.2 H 2 /O 2 Reaction 7.7 Microsystems with Integrated Mixer, Heat Exchanger, Catalyst Structures and Sensors 7.7.1 HCN Synthesis via the Andrussov Process 7.8 References 8 Gas/Liquid Microreactors 8.1 Gas/Liquid Contacting Principles and Classes of Miniaturized Contacting Equipment 8.2 Contacting of Two Gas and Liquid Substreams in a Mixing Tee Configuration 8.2.1 Injection of One Gas and Liquid Substream 8.2.2 Injection of Many Gas and Liquid Substreams into One Common Channel 8.2.3 Injection of Many Gas and Liquid Substreams into One Packed Channel 8.2.4 Injection of Many Gas Substreams into One Liquid Channel with Catalytic Walls 8.2.5 Injection of Many Gas and Liquid Substreams into Multiple Channels 8.3 Generation of Thin Films in a Falling Film Microreactor 8.4 References 9 Microsystems for Energy Generation 9.1 Microdevices for Vaporization of Liquid Fuels 9.2 Microdevices for Conversion of Gaseous Fuels to Syngas by Means of Partial Oxidations 9.2.1 Hydrogen Generation by Partial Oxidations 9.2.2 Partial Oxidation of Methane in a Stacked Stainless Steel Sheet System 9.2.3 Partial Oxidation of Methane in a Microchannel Reactor 9.3 Microdevices for Conversion of Gaseous Fuels to Syngas by Means of Steam Reforming 9.3.1 Steam Reforming of Methanol in Microstructured Platelets 9.4 References 10 Microsystems for Catalyst and Material Screening 10.1 Parallel Screening of Heterogeneous Catalysts in a Microchannel Reactor 10.2 Parallel Screening of Heterogeneous Catalysts in Conventional Mini-Scale Reactors 10.3 References 11 Methodology for Distributed Production 11.1 The Miniplant Concept 11.1.1 Miniplant Concept for HCN Manufacture 11.1.2 The Disposable Batch Miniplant 11.2 Paradigm Change in Large-Scale Reactor Design Towards Operability and Environmental Aspects Using Miniplants 11.3 References Index

Novel Process Windows for Enabling, Accelerating, and Uplifting Flow Chemistry

Abstract: Novel Process Windows make use of process conditions that are far from conventional practices. This involves the use of high temperatures, high pressures, high concentrations (solvent-free), new chemical transformations, explosive conditions, and process simplification and integration to boost synthetic chemistry on both the laboratory and production scale. Such harsh reaction conditions can be safely reached in microstructured reactors due to their excellent transport intensification properties. This Review discusses the different routes towards Novel Process Windows and provides several examples for each route grouped into different classes of chemical and process-design intensification.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

Organic Photoredox Catalysis

Abstract: In this review, we highlight the use of organic photoredox catalysts in a myriad of synthetic transformations with a range of applications. This overview is arranged by catalyst class where the photophysics and electrochemical characteristics of each is discussed to underscore the differences and advantages to each type of single electron redox agent. We highlight both net reductive and oxidative as well as redox neutral transformations that can be accomplished using purely organic photoredox-active catalysts. An overview of the basic photophysics and electron transfer theory is presented in order to provide a comprehensive guide for employing this class of catalysts in photoredox manifolds.

Kirk-Othmer Encyclopedia of Chemical Technology数据库介绍及实例

Abstract: 介绍了Kirk—Othmer Encyclopedia of Chemical Technology（化工技术百科全书）（第五版）电子图书网络版数据库，并对该数据库使用方法和检索途径作出了说明，且结合实例简单地介绍了该数据库的检索方法。

Formation of dispersions using “flow focusing” in microchannels

Abstract: A flow-focusing geometry is integrated into a microfluidic device and used to study drop formation in liquid–liquid systems. A phase diagram illustrating the drop size as a function of flow rates and flow rate ratios of the two liquids includes one regime where drop size is comparable to orifice width and a second regime where drop size is dictated by the diameter of a thin “focused” thread, so drops much smaller than the orifice are formed. Both monodisperse and polydisperse emulsions can be produced.