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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: 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: 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: 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: Lin Pan
Publisher:
ISBN:
Category : Aromatic amines
Languages : en
Pages : 104
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Book Description
The emissions of CO2 act as a major source for global climate change in today's society and it mainly comes from coal-fired power plants. There are several techniques for CO2 capture such as liquid amine process, membrane separation, chemical looping and solid sorbent process. In my study, the solid amine sorbents are used for CO2 capture due to it can reduce the regeneration energy, avoid the corrosion of equipment and increase the CO2 adsorption and desorption rate compared with liquid amine process. The porous polyvinyl alcohol (PVA) support was synthesized by using glutaraldehyde (GA) as a cross-linking agent and phase inversed in acetone. Polyethyleneimine (PEI) and tetraethylenepentamine (TEPA) were impregnated on PVA support respectively for CO2 adsorption. The performance of sorbents were tested by CO2 capture capacity through weight change method and the nature of CO2 adsorption on sorbents with different amine content (N %) were characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), as well as the formation and desorption of CO2 adsorbed species from fresh and degraded sorbents. Besides, the effect of antioxidant in inhibiting the degradation was also studied.
Author: Jak Tanthana
Publisher:
ISBN:
Category : Adsorption
Languages : en
Pages : 2005
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Book Description
The rapid increase in atmospheric CO2 has become a major environmental concern in recent years. Coal-fired power plants, releasing flue gas containing CO2, account for approximately 30% of total CO2 emissions worldwide. Solid amine sorbents such as amine immobilized on silica (SiO2) has gained significant consideration for capturing CO2 from flue gas due to its lower operation cost and equipment corrosion compared to existing liquid amine process. The -NH2 functional group of these solid amine sorbents binds CO2 through acid-base interactions, allowing CO2 to adsorb and desorb at temperatures in the range of the flue gas operating conditions. Studies have shown that the solid amine sorbents can initially adsorb CO2 at the economical level compared to that of liquid amine processes. The CO2 capture capacity of solid amine sorbents reduce over the period of time due to the thermal instability and contaminant poisoning of the amine. Our current development focuses on improving the sorbent stability and mechanistic study of the interactions between the amine, CO2, and contaminants present in the flue gas. This dissertation presents a study of the use of polyethylene glycol (PEG) to enhance the stability of amine-immobilized silica. Long term stability of tetraethylenepentamine-immobilized on silica (TEPA/SiO2) and PEG-enhanced TEPA/SiO2 (PEG/TEPA/SiO2) were evaluated by performing multiple cycles of CO2 capture on the sorbents under the constant monitoring of in situ infrared and mass spectrometers. PEG/TEPA/SiO2 shows slower degradation than TEPA/SiO2. The IR absorbance spectra reveal that the accumulation of the strongly adsorbed CO2 species as bicarbonates and carboxylates is the cause of sorbent degradation. The IR absorbance spectra further suggested that the presence of PEG decreased the formation of these strongly adsorbed CO2, reducing the degradation of the sorbent. The interactions between the -NH2 groups, CO2, and other electron acceptor species present in the flue gas govern the CO2 capture capacity and long term stability of the sorbent. The flue gas from coal-fired power plants contains 40-250 ppm of SO2 and 5-7 vol% of H2O. Although the presence of these species in the flue gas is expected to influence the performance of the sorbent, the extent of the interaction between the amine groups and these species has not been studied. CO2 capture under the presence of 250 ppm in the CO2 adsorption stream was performed on TPSENa sorbent (29 wt% TEPA, 18 wt% PEG, 49 wt% SiO2, 3.8 wt% EPON, and 0.2 wt% Na2CO3). The initial CO2 capture capacity of TPSENa was 1.195 mmol-CO2/g-sorb. which decreased to 0.532 mmol-CO2/g-sorb. after 24 cycles of CO2 capture under presence of 250 ppm SO2. The CO2 capture capacity of TPSENa showed a slight reduction from 0.869 to 0.764 mmol-CO2/g-sorb. under the absence of SO2. The IR absorbance spectra indicate that formation of both strongly-adsorbed CO2 species and SO2-adsorbed species accelerated the degradation of the sorbent in the presence of SO2. The development of high stability solid amine sorbent requires an in-depth understanding of the interaction between CO2 and the amine groups. The mechanism of CO2 adsorption on amine groups follows acid-base type interaction where the CO2 acts as the acidic species and amine groups are the basic site. The products of the reaction between CO2 and the amine are ammonium ion (NH3+), carbamate, and bicarbonates. The evidence of the formation of carbamate and bicarbonates are commonly available in literatures while that of the ammonium ion is scarce. The in situ injection of HCl on TEPA/SiO2 was performed under constant infrared spectroscopic monitoring to elucidate the acid-base reaction. The IR spectra of TEPA/SiO2 after HCl injection shows similar absorption features to those of TEPA/SiO2 during CO2 adsorption, evidences for the formation of NH3+. IR spectra also suggests that HCl is likely to react with primary amine (-NH2) of TEPA and then further reacts with secondary amine (-NH), resulting in the decrease in the available amine sites for CO2 adsorption. The in situ injection of H2O on TEPA/SiO2 caused the removal of TEPA from SiO2. The results of this study have provided the several key information of which should prove to be helpful in the development of highly stable solid amine sorbent. The study of PEG-enhanced TEPA/SiO2 has shown that the stability can be improved by addition of chemical stabilizers which slows down the formation of the carboxylate species. The SO2 poisoning of the sorbent is caused by (i) accelerating the formation of strongly adsorbed CO2 species and (ii) depositing of SO2-adsorbed species on the amine sites. The further studies should focus on development of the sorbent with high resistance to HCl and SO2. Additional of aromatic amine to the alkyl amine on silica support may reduce the HCl and SO2 poisoning as the aromatic amine has a strong reactivity toward the acidic gaseous species. The addition of these compounds requires optimization to ensure that the sorbent resistance to SO2 while stability and capture capacity are not significantly affected.
Author: Rajesh A. Khatri
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Author: Barbara H. Stuart
Publisher: John Wiley & Sons
ISBN: 0470011130
Category : Science
Languages : en
Pages : 242
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Book Description
Provides an introduction to those needing to use infrared spectroscopy for the first time, explaining the fundamental aspects of this technique, how to obtain a spectrum and how to analyse infrared data covering a wide range of applications. Includes instrumental and sampling techniques Covers biological and industrial applications Includes suitable questions and problems in each chapter to assist in the analysis and interpretation of representative infrared spectra Part of the ANTS (Analytical Techniques in the Sciences) Series.
Author: Laura Marcela Reyes
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
The conversion of CO2 into fuels or chemical feedstocks is valuable for not only mitigating the rising atmospheric concentration of CO2, but also for utilizing CO2 as a globally available, abundant, and renewable resource. Indium oxide defected with oxygen vacancies and hydroxides, In2O3-x(OH)y, is a catalyst material that facilitates the light-assisted, gas-phase heterogeneous reduction of CO2 via the reverse water gas shift (RWGS) reaction, CO2 + H2 -> CO + H2O. The extent of defects in In2O3-x(OH)y correlates strongly with the rate of CO2 conversion as well as the CO2 adsorption capacity. Prior to this work, the specific interactions between the RWGS reactants, CO2 and H2, and the In2O3-x(OH)y surface were largely unknown. The work herein explores the In2O3-x(OH)y surface chemistry through carefully designed in situ thermogravimetric analysis and infrared spectroscopy techniques to identify and investigate surface-adsorbed CO2 and H2 species. CO2 adsorbs as a complex mixture of carbonates, bicarbonates, carboxylates, and linear CO2 species, which adsorb at readily available and specific surface sites, forming a partial monolayer with varying adsorption strengths. H2 easily reduces the In2O3-x(OH)y surface, resulting in a broad and intense infrared absorbance peak due to the delocalization of conduction band electrons, the intensity of which decreases with an increase in defects, agreeing with our understanding that defects promote charge trapping at the surface to be used in chemical reactions. The coadsorption of CO2 and H2 results in a strongly adsorbed formate species, providing indirect evidence for H2 heterolytic dissociation, in addition to possibly identifying formate as an intermediate for the RWGS reaction or a bystander that instead leads to methanol synthesis. Through detailed CO2 and H2 adsorption studies, this thesis has provided us with valuable insight into the In2O3-x(OH)y surface and its complex chemistry â a critical contribution to the development of a viable CO2 utilization technology.
Author: Steven L Suib
Publisher: Newnes
ISBN: 0444538836
Category : Technology & Engineering
Languages : en
Pages : 659
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Book Description
New and Future Developments in Catalysis is a package of books that compile the latest ideas concerning alternate and renewable energy sources and the role that catalysis plays in converting new renewable feedstock into biofuels and biochemicals. Both homogeneous and heterogeneous catalysts and catalytic processes will be discussed in a unified and comprehensive approach. There will be extensive cross-referencing within all volumes.This volume presents a complete picture of all carbon dioxide (CO2) sources, outlines the environmental concerns regarding CO2, and critically reviews all current CO2 activation processes. Furthermore, the volume discusses all future developments and gives a critical economic analysis of the various processes. - Offers in-depth coverage of all catalytic topics of current interest and outlines future challenges and research areas - A clear and visual description of all parameters and conditions, enabling the reader to draw conclusions for a particular case - Outlines the catalytic processes applicable to energy generation and design of green processes
Author: Annemie Bogaerts
Publisher: MDPI
ISBN: 3038977500
Category : Technology & Engineering
Languages : en
Pages : 248
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Book Description
Plasma catalysis is gaining increasing interest for various gas conversion applications, such as CO2 conversion into value-added chemicals and fuels, N2 fixation for the synthesis of NH3 or NOx, methane conversion into higher hydrocarbons or oxygenates. It is also widely used for air pollution control (e.g., VOC remediation). Plasma catalysis allows thermodynamically difficult reactions to proceed at ambient pressure and temperature, due to activation of the gas molecules by energetic electrons created in the plasma. However, plasma is very reactive but not selective, and thus a catalyst is needed to improve the selectivity. In spite of the growing interest in plasma catalysis, the underlying mechanisms of the (possible) synergy between plasma and catalyst are not yet fully understood. Indeed, plasma catalysis is quite complicated, as the plasma will affect the catalyst and vice versa. Moreover, due to the reactive plasma environment, the most suitable catalysts will probably be different from thermal catalysts. More research is needed to better understand the plasma–catalyst interactions, in order to further improve the applications.
