In Situ Infrared Study of Electrocatalytic CO2 Reduction and Other Interfacial Processes in Ionic Liquid-water Mixtures PDF Download
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Author: Marco Papasizza
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Category :
Languages : en
Pages :
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Author: Marco Papasizza
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Languages : en
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Author: Jie Yu
Publisher:
ISBN:
Category : Carbon dioxide mitigation
Languages : en
Pages : 213
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CO2 capture and sequestration from coal-fired power plant flue gas is an attractive technique to control CO2 emissions. Polyamine-based sorbent is considered as a promising sorbent for CO2 capture due to its low equipment corrosion and regeneration energy penalty. One critical aspect of development of polyamine-based CO2 capture process is to understand the nature of the adsorbed species with amine and their evolution in adsorption / desorption process. Fourier transform infrared (FTIR) spectroscopy is a powerful and versatile tool that can provide the insights from molecular level to address these scientific issues. This dissertation is focusing on using in-situ FTIR spectroscopy to discuss several important topics in CO2 capture and utilization processes, including (i) the structure and binding energy of adsorbed CO2/H2O on solid amine sorbent, (ii) the role of H2O in CO2 adsorption/desorption on liquid amine films, (iii) mechanism of water-enhancement on CO2 capture by amine, and (iv) photoelectrocatalytic reduction of CO2 on polyamine/TiO2 thin film.H2O vapor in flue gas has dramatic effects on polyamine-based sorbent. H2O could affect CO2 capture capacity, regeneration energy, and degradation kinetics of the sorbents. This in situ IR study investigated these various effects on polyamine-based sorbents. The results revealed that CO2 adsorbed on primary amine as ammonium carbamate while H2O adsorbed on secondary amine and promoted the formation of carbamic acid. Adsorbed H2O increases the binding strength of CO2 with amine and protects sorbent from SO2 poisoning. The results of this study clarify the role of H2O in polyamine-based sorbent for CO2 capture and provide a molecular basis for the design and operation of polyamine-based CO2 capture processes. The use of FTIR spectroscopy in the investigation of role of water on CO2 capture by amine has enabled us to verify the reaction processes. The results unraveled that adsorption of CO2 on the 20 μm tetraethylenepentamine (TEPA) film at 50 °C followed a zwitterion-intermediate pathway: zwitterion ¿ ammonium carbamate. H2O in the mixed TEPA/H2O (5:1) film decreased the rate of CO2 adsorption, but increased the amine efficiency. The presence of H2O promotes the formation of carbamic acid and produces a broad IR band centered at 2535 cm-1, which can be assigned to (O-H) of hydronium carbamate, -NCOO-···H-OH2+. The broadness of this 2535 cm-1 band ranging from 2100 cm-1 to 2800 cm-1 persists at 120 °C. These broad components of the band can be ascribed to ¿(N-H) in hydrogen-bonded ammonium carbamate, a R-NH3+/R1R2-NH2+···-NCOO- moiety. The binding strength of adsorbed species on the TEPA film increases in the order: adsorbed H2O
Author: Brian A. Rosen
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Languages : en
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Artificial photosynthesis, where one uses electricity from solar, or wind, to convert water and carbon dioxide into a hydrocarbon fuel could provide a viable route to renewable fuels but so far the results have been stymied because of the lack of a CO2 conversion catalyst that operates at low overpotentials. In this study we report a catalyst system that shows CO2 conversion at low overpotentials. The system uses two different catalysts to achieve the conversion. First an ionic liquid or ionic salt is used to catalyze the formation of a (CO2)0̐Ư intermediate. Then a transition metal is used to catalyze the conversion of the (CO2)0̐Ư intermediate into useful products. CO formation is first observed at -250mV with respect to a standard hydrogen electrode compared to 800mV in the absence of the ionic liquid. Thus, CO2 conversion to CO can occur without the large energy loss associated with a high overpotential raising the possibility of practical artificial photosynthesis. The reduction of CO2 in 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM BF4) was studied in an H-type electrochemical cell, an in-situ SFG/SERS cell, and a continuous flow CO2 electrolysis cell. Results from these experiments suggest that the EMIM BF4 is able to catalyze the reaction in such a way that opens the door for the practical low potential and temperature conversion of CO2.
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Category :
Languages : en
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Author: Frank Marken
Publisher: Royal Society of Chemistry
ISBN: 1788014529
Category : Science
Languages : en
Pages : 282
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One of the crucial challenges in the energy sector is the efficient capture and utilisation of CO2 generated from fossil fuels. Carbon capture and storage technologies can provide viable alternatives for energy intensive processes, although implementation of large-scale demonstrators remains challenging. Therefore, innovative technologies are needed that are capable of processing CO2 emission from a wide range of sources, ideally without additional fossil energy demand (e.g. solar driven or overcoming the limits of photosynthesis). This book covers the most recent developments in the field of electrochemical reduction of CO2, from first-principle mechanistic studies to technological perspectives. An introduction to basic concepts in electrochemistry and electrocatalysis is included to provide a background for newcomers to this field. This book provides a comprehensive overview for researchers and industrial chemists working in environmental science, electrochemistry and chemical engineering.
Author: Lin Zhang (auteur d'une thèse en Chimie physique et chimie analytique).)
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Category :
Languages : en
Pages : 0
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This thesis studies photoelectrochemical CO2 reduction reaction (PEC CO2RR) on p-type semiconductor CuCo2O4 addressing the cocatalytic role of imidazolium based RTILs by scanning photoelectrochemical microscopy (SPECM). CuCo2O4 was studied in different solvent supporting electrolyte systems including: aqueous solution (0.1 M KHCO3 and 0.1 M Na2SO4), binary mixture solution (25 vol.% [C2mim][BF4]/H2O and 25 vol.% [C4mim][BF4]/H2O) and pure RTILs ([C2mim][BF4], [C4mim][BF4]) to explore by SPECM the role of RTILs in CuCo2O4 semiconductor PEC performance. Significantly enhanced photoreduction current under both UV-vis and visible light illumination is reported in 25 vol.% [C2mim][BF4]/H2O solution. Only CO generated from PEC CO2RR was detected using an in-situ detection method based on a home-made dual tip optical fiber-ultramicroelectrode (OF-UME) and from bulk electrolysis under illumination. The formation of CO at potentials more positive than the thermodynamic value clearly points out that direct CO2 reduction on the electrode surface is not the mechanism. A possible reaction scheme for the PEC CO2RR mediated by [C2mim]+ is proposed. Thus, our results have demonstrated for the first time the cocatalytic role of [C2mim]+ for the PEC CO2RR. In addition, electrochemical CO2RR has also been studied on various synthesized transition metal-nitrogen-carbon catalysts (M-N-Cs) by rotating disk electrode. 25%Fe25%Co-N-C exhibited the best performance among the studied M-N-Cs in this thesis. The presence of Co sites in that catalyst provided synergic effect for the generation of distributed Fe-rich microcubes, which act as active sites in electrochemical CO2RR.
Author: Duane D. Miller
Publisher:
ISBN:
Category : Carbon dioxide
Languages : en
Pages : 438
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"Coal fired power plants release large quantities of CO2 and trace amounts of SO2 into the atmosphere, affecting global warming and worldwide climate change. CO2 is a concern as a greenhouse gas in relation to global temperature raise. SO2 is a concern in environmental protection as a precursor for acid rain. The impact of CO2, SO2, and H2S on the environment demonstrate the removal process is a subject of study of great importance. Removal of these gases has been focused on the development of amine based sorbents for sequestration by the adsorption and desorption process. Fourier Transform Infrared spectroscopy (FTIR) is a powerful tool for investigating the adsorption/desorption process and structure of adsorbing molecules. The application of FTIR, coupled with ab initio quantum chemistry, can provide a direct means for understanding the interactions that occur during chemisorption. The removal of CO2 and H2S by an amine based sorbent has been studied. The hypothesis for this study is to investigate the use of polyethylene glycol (PEG) to promote tetraethylenepentamine (TEPA) CO2 and H2S removal capacity. It is thought that the use of PEG may improve the catalytic adsorption capacity through hydrogen bonding. This study used in situ FTIR and ab initio quantum chemistry to investigate the adsorption and desorption processes during CO2 and H2S capture at the molecular level. The FTIR results determine that PEG interacts with the primary amine functional groups of TEPA dispersing the adsorption sites leading to improved adsorption capacity for CO2 and H2S. Ab initio quantum chemistry determined that PEG lowers the binding energy of CO2 and H2S leading to a lower desorption temperature. Removal of the nauseous gas SO2 by an amine based sorbent is studied. The hypothesis investigated the use of 1,3-phenylenediamine low basic property for creating a reusual solid amine based sorbent for SO2 removal. It is thought that the low basic property of the aromatic amine will allow the effective SO2 adsorption and desorption at low temperature. This study used in situ FTIR spectroscopy to investigate the adsorption and desorption processes during SO2 capture. The result of this study determined that 1,3-phenylenediamine basic property allowed SO2 adsorption and desorption at 373 K, however, sorbent deactivation occurs. The in situ UV-Visible spectroscopic technique provided insight that deactivation is the result of agglomeration of 1,3-phenylenediamine. Addition of PEG prevent the agglomeration and improved the adsorption capacity of 1,2-phenylenediamine through hydrogen bonding with the primary amine functional group. Amine based sorbents have proven as an effective and economic process for the removal of CO2 and the hazardous gases H2S and SO2. Advancing knowledge in the area of amine based sorbents will improve our ability for hazardous waste management. Hazardous waste management may also be achieved by the oxidation and reduction (redox) of toxic materials. TiO2 based catalysts have the ability to oxidize a number of hazardous materials to nontoxic products where TiO2 has become the benchmark semiconductor in photo-detoxification of contaminated water. This work also investigates the photocatalytic dehydrogenation process over TiO2 based catalysts. The hypothesis investigated the relationship of the photogenerated electrons and adsorbed species during the photocatalytic dehydrogenation of 2-propanol. It is thought that the interaction of the photogenerated electrons and adsorb species may be elucidated from the reaction mechanism during the photocatalytic dehydrogenation of 2-propanol. 2-propanol is used as a model compound because it provides a simple and standard way to measure the photocatalytic activity during the gas/liquid phase reactions. This study suggest that in the presence of adsorbed H2O, the dehydrogenation process proceeded by a hydroxyl radical species while in the absence of adsorbed H2O the active species is an adsorbed ion. Au/TiO2 unique ability to generate adsorbed oxygen ions resulted in higher catalytic activity in the absence of adsorbed H2O under UV-irradiation. The reaction pathway for the photocatalytic dehydrogenation of 2-propanol is strongly dependent on the coverage of surface H2O."--Abstract.
Author: Long Zhang
Publisher:
ISBN:
Category : Carbon sequestration
Languages : en
Pages : 198
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Clean energy and environment is a 21st-century contemporary challenge we human being faces. Tremendous effort has been paid to explore and develop technologies to produce green energy, to reduce the emissions of wastes, and to utilize these wastes and renewable sources. Catalysis technologies and CO2 capture and utilization technologies are among the most important stepping stones to achieve the challenging goals to secure the environment for human survival and development. The advancement in these technologies requires a molecular-level or quantum-level fundamental understanding of the processes involved. One critical aspect of importance is the nature of the adsorbed species and their evolution in these green chemical processes. Fourier transform infrared (FTIR) spectroscopy is a powerful and versatile tool that can provide the insights to address these scientific issues. This dissertation, with a focus on the applications of in-situ FTIR spectroscopy, discusses about a few important topics in CO2 capture and other green processes, including (i) the catalytic asymmetric hydrogenation of a-amino ester, a potential chemical building block and starting material for biocompatible polymers, (ii) the oxidative and CO2-induced degradation of supported polyethylenimine (PEI) adsorbents for CO2 capture, (iii) the utilization of CO2 by the catalytic conversion of CO2 to carbonates, a precursor for polycarbonates and polyurethanes, (iv) the catalytic conversion of 2,3-butanediol to 1,3-butadiene, the monomer for synthetic rubbers, and (v) the electron-induced IR absorbance in photocatalytic processes on TiO2. A wide array of FTIR techniques, including diffuse reflectance, attenuated total reflectance, and transmission IR has been applied. The FTIR results revealed the vital hydrogen bonding interactions in the catalytic asymmetric hydrogenation of a-amino ester which led to the prochiral structures. The oxidative degradation and CO2-induced degradation pathways were elucidated with the help of various FTIR studies conducted. The mechanism of the oxidative degradation of amines was proposed for the first time that the solid amines underwent the deactivation to imines and further oxidation to amides. The effects of amine loading, temperature, and water vapor on CO2-induced degradation were clarified. The FTIR spectra evidenced the successful conversion of CO2 to dimethyl carbonate and 2,3-butanediol to 1,3-butadiene, and helped the comprehension of the kinetics and the nature of the dehydrating agent in the reactions. In-situ FTIR was also used to differentiate the contributions from the conduction-band electrons and shallow-trapped electrons to the polaronic light absorbance. A modelling method was developed to analyze the IR spectra. The modelling results revealed the correlation of these differently sourced absorbance and the generation of photocurrent and the charge transportation process in photocatalysis.
Author: Rajesh A. Khatri
Publisher:
ISBN:
Category :
Languages : en
Pages : 382
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Author: Marko M. Melander
Publisher: John Wiley & Sons
ISBN: 1119605636
Category : Science
Languages : en
Pages : 372
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Book Description
Atomic-Scale Modelling of Electrochemical Systems A comprehensive overview of atomistic computational electrochemistry, discussing methods, implementation, and state-of-the-art applications in the field The first book to review state-of-the-art computational and theoretical methods for modelling, understanding, and predicting the properties of electrochemical interfaces. This book presents a detailed description of the current methods, their background, limitations, and use for addressing the electrochemical interface and reactions. It also highlights several applications in electrocatalysis and electrochemistry. Atomic-Scale Modelling of Electrochemical Systems discusses different ways of including the electrode potential in the computational setup and fixed potential calculations within the framework of grand canonical density functional theory. It examines classical and quantum mechanical models for the solid-liquid interface and formation of an electrochemical double-layer using molecular dynamics and/or continuum descriptions. A thermodynamic description of the interface and reactions taking place at the interface as a function of the electrode potential is provided, as are novel ways to describe rates of heterogeneous electron transfer, proton-coupled electron transfer, and other electrocatalytic reactions. The book also covers multiscale modelling, where atomic level information is used for predicting experimental observables to enable direct comparison with experiments, to rationalize experimental results, and to predict the following electrochemical performance. Uniquely explains how to understand, predict, and optimize the properties and reactivity of electrochemical interfaces starting from the atomic scale Uses an engaging “tutorial style” presentation, highlighting a solid physicochemical background, computational implementation, and applications for different methods, including merits and limitations Bridges the gap between experimental electrochemistry and computational atomistic modelling Written by a team of experts within the field of computational electrochemistry and the wider computational condensed matter community, this book serves as an introduction to the subject for readers entering the field of atom-level electrochemical modeling, while also serving as an invaluable reference for advanced practitioners already working in the field.
