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Author: Jie Yu
Publisher:
ISBN:
Category : Carbon dioxide mitigation
Languages : en
Pages : 213
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Book Description
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: Jie Yu
Publisher:
ISBN:
Category : Carbon dioxide mitigation
Languages : en
Pages : 213
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Book Description
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: Long Zhang
Publisher:
ISBN:
Category : Carbon sequestration
Languages : en
Pages : 198
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Book Description
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: Frank Marken
Publisher: Royal Society of Chemistry
ISBN: 1788014529
Category : Science
Languages : en
Pages : 282
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Book Description
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: Rajesh A. Khatri
Publisher:
ISBN:
Category :
Languages : en
Pages : 382
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Book Description
Author: Marco Papasizza
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Duane D. Miller
Publisher:
ISBN:
Category : Carbon dioxide
Languages : en
Pages : 438
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Book Description
"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: So-ngan Pun
Publisher:
ISBN:
Category : Carbon dioxide
Languages : en
Pages : 362
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Author: Robert W. Stevens
Publisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages : 292
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Author: Charles Bradford Arends
Publisher:
ISBN:
Category : Carbon dioxide
Languages : en
Pages : 154
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Book Description
Author: Dan Huang (Chemical engineer)
Publisher:
ISBN:
Category : Catalysis
Languages : en
Pages : 71
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Book Description
TiO2 is modified to Fe-doped TiO2 and ALD Fe-doped TiO2 to test two hypotheses: i) Fe-doped TiO2 can enhance photocatalytic activity under visible light due to the adsorption of visible light and ii) external layer of TiO2 on Fe-doped TiO2 can enhance photocatalytic activity of catalyst by providing more active sites. Photocatalytic activity of catalysts was characterized by the rate of ethanol photooxidation. The results showed that Fe-doped TiO2 and ALD Fe-doped TiO2 have adsorption on visible light range, but do not have visible light photoactivity. This could be explained by that Fe-doped TiO2 and ALD Fe-doped TiO2 do not have enough rutile crystal structure. In addition, external layer on ALD Fe-doped TiO2 does not enhance photocatalytic activity. It can be explained by remaining organic compound on the surface of ALD Fe-doped TiO2 block some active sites. Sol-gel TiO2 and anatase are used to test two hypotheses: i) morphology of catalyst has effect on bacteria degradation and ii) water can facilitate the bacteria degradation on sol-gel TiO2. The results showed bacteria degradation on sol-gel TiO2 is faster than that on anatase, which validated the first hypothesis. It can be explained by that sol-gel TiO2 (rhombus-shaped TiO2 with small particle size) has more effective contact surface with bacteria than anatase (sphere-shaped TiO2 with big particle size). In addition, the presence of water can increase the degradation rate of bacteria, which validated the second hypothesis. Holes produced from UV illumination can react with H2O to produce •OH, and more •OH can facilitate the degradation of bacteria. In-situ diffuse reflectance infrared fourier transform (DRIFT) infrared spectroscopy is the main characterization method in this study to monitor the photooxidation of ethanol and degradation of bacteria. Peak height change was used as quantitative indicator of photooxidation and degradation.
