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 …

I and i

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

The Design and Analysis of Experiments

CO2 conversion covers a wide range of possible application areas from fuels to bulk and commodity chemicals and even to specialty products with biological activity such as pharmaceuticals. In the present review, we discuss selected examples in these areas in a combined analysis of the state-of-the-art of synthetic methodologies and processes with their life cycle assessment. Thereby, we attempted to assess the potential to reduce the environmental footprint in these application fields relative to the current petrochemical value chain. This analysis and discussion differs significantly from a viewpoint on CO2 utilization as a measure for global CO2 mitigation. Whereas the latter focuses on reducing the end-of-pipe problem “CO2 emissions” from todays’ industries, the approach taken here tries to identify opportunities by exploiting a novel feedstock that avoids the utilization of fossil resource in transition toward more sustainable future production. Thus, the motivation to develop CO2-based chemistry does...

Sustainable Conversion of Carbon Dioxide: An Integrated Review of Catalysis and Life Cycle Assessment

Despite being first demonstrated over 160 years ago, and offering significant environmental benefits and high electrical efficiency, it is only in the last two decades that fuel cells have offered a realistic prospect of being commercially viable. The solid oxide fuel cell (SOFC) offers great promise and is presently the subject of intense research activity. Unlike other fuel cells the SOFC is a solid-state device which operates at elevated temperatures. This review discusses the particular issues facing the development of a high temperature solid-state fuel cell and the inorganic materials currently used and under investigation for such cells, together with the problems associated with operating SOFCs on practical hydrocarbon fuels.

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Solid oxide fuel cells

A study is conducted to demonstrate catalytic dehydrogenation of light alkanes on metals and metal oxides. The study provides a complete overview of the materials used to catalyze this reaction, as dehydrogenation for the production of light olefins has become extremely relevant. Relevant factors, such as the specific nature of the active sites, as well as the effect of support, promoters, and reaction feed on catalyst performance and lifetime, are discussed for each catalytic Material. The study compares different catalysts in terms of the reaction mechanism and deactivation pathways and catalytic performance. The duration of the dehydrogenation step depends on the heat content of the catalyst bed, which decreases rapidly due to the endothermic nature of the reaction. Part of the heat required for the reaction is introduced to the reactors by preheating the reaction feed, additional heat being provided by adjacent reactors that are regenerating the coked catalysts.

Catalytic dehydrogenation of light alkanes on metals and metal oxides.

Development and Performance of Iron Based Oxygen Carriers for Chemical Looping

The current production of hydrogen, predominantly through steam methane reforming, causes up to 3% of global CO2 emissions. Since hydrogen is expected to play an increasingly important role as clean energy vector of the future, a carbon-efficient two step chemical looping process is developed to address the limitations of current H2 production technology. This process operates between 923 and 998 K and involves oxides of iron, nickel, and calcium as solid intermediates. In the first step, an H2-rich stream is produced by co-feeding steam and methane to these materials in a fixed bed, while in the second step, a CO-rich stream is produced by regenerating the materials with an air-like mixture. Proof-of-concept experiments achieved an H2 concentration of more than 65 mol% and a CO2 conversion of more than 80%. Cyclic tests indicate that carbon deposition is mitigated and the molar ratio of H2 to CO produced is approximately 2. Experimental results prove that the process concept allows circumventing the thermodynamic equilibrium constraints on conventional methane reforming for syngas production. 

Intensifying blue hydrogen production by in situ CO2 utilisation

The kinetics of redox reactions of iron oxide in oxygen carrier 50Fe(2)O(3)/MgAl2O4 are examined using different time-resolved techniques. Reduction kinetics are studied by H-2 temperature-programmed reduction (H-2-TPR) monitored by time-resolved in situ XRD. In contrast to conventional TPR, in situ XRD distinguishes the three-stage reduction of Fe2O3 -> Fe3O4 -> FeO -> Fe. It also shows that the oxidation of Fe -> Fe3O4 by CO2 has no intermediate crystalline phases, explaining why its kinetics can easily be investigated by conventional CO2 temperature-programmed oxidation (CO2-TPO). A shrinking core model which takes into account solid state diffusion allows describing the experimental data.

Kinetics of Multi‐Step Redox Processes by Time‐Resolved In Situ X‐ray Diffraction

Chemical looping can be considered a technology platform, which refers to one common basic concept that can be used for various applications. Compared with a traditional catalytic process, the chemical looping concept allows fuels’ conversion and products’ separation without extra processes. In addition, the chemical looping technology has another major advantage: combinability, which enables the integration of different reactions into one process, leading to intensification. This review collects various important state-of-the-art examples, such as integration of chemical looping and catalytic processes. Hereby, we demonstrate that chemical looping can in principle be implemented for any catalytic reaction or at least assist in existing processes, provided that the targeted functional group is transferrable by means of suitable carriers.

https://biblio.ugent.be/publication/8697368/file/8697371.pdf

Vladimir Galvita

Papers

Development and Performance of Iron Based Oxygen Carriers for Chemical Looping

Intensifying blue hydrogen production by in situ CO2 utilisation

Kinetics of Multi‐Step Redox Processes by Time‐Resolved In Situ X‐ray Diffraction

Intensification of Chemical Looping Processes by Catalyst Assistance and Combination

Behaviour of Platinum-Tin during CO2-assisted propane dehydrogenation: Insights from quick X-ray absorption spectroscopy