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Author: Mathew Isenberg
Publisher:
ISBN:
Category : Amines
Languages : en
Pages : 109
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Book Description
Over the past 50 years the use of fossil fuels has lead to a 22% increase in the CO2 concentration levels in the atmosphere. It has also been recognized that the energy producing sector, coal-fired power plants in particular, contribute approximately 33% of the total global emissions. It is of immediate concern that a technology be developed that can be retrofit to the power plants in order to capture CO2 from the flue gas, eliminating a significant source of CO2 emissions. Current commercialized technologies such as liquid amine scrubbing using monoethanolamine (MEA) and chilled ammonia capturing processes have demonstrated successful capture of CO2 gas but involve using highly toxic and corrosive compounds with high heats of regeneration. Development of a solid immobilized amine sorbent that exhibits high CO2 capture and cyclical stability may prove to be a more sensible solution due to its low heat of regeneration, toxicity, and corrosive properties. In this study, fumed silica was chosen as the solid support because of its high commercial availability and high surface area. In this thesis, silica based sorbents were developed through impregnation of tetraethylenepentamine (TEPA) at various weight percent ratios and further modified with the addition of polyethylene glycol (PEG) to aid in dispersing TEPA and cyclical stability of the sorbent. Although the development of sorbents using the same compounds have been reported on in literature, there has been no work done using infrared (IR) characterization to determine the way the compounds interact with each other and with the surface. This thesis has been constructed in order to develop an understanding of these surface interactions and use it to fabricate the best possible sorbent. The IR results concluded that the co-impregnation of PEG and TEPA with corresponding TEPA/PEG/SiO2 weight ratios of 24/36/40 yielded the highest CO2 capture capacity (2.53 mmolCO2/gramSorbent) and best cyclical stability (3% degradation). A gram scale process was also developed for the adsorption and regeneration of CO2 gas from a feed stream of 15% CO2. The process was designed mirroring industrial conditions and resulted in good initial CO2 regeneration concentrations.
Author: Mathew Isenberg
Publisher:
ISBN:
Category : Amines
Languages : en
Pages : 109
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Book Description
Over the past 50 years the use of fossil fuels has lead to a 22% increase in the CO2 concentration levels in the atmosphere. It has also been recognized that the energy producing sector, coal-fired power plants in particular, contribute approximately 33% of the total global emissions. It is of immediate concern that a technology be developed that can be retrofit to the power plants in order to capture CO2 from the flue gas, eliminating a significant source of CO2 emissions. Current commercialized technologies such as liquid amine scrubbing using monoethanolamine (MEA) and chilled ammonia capturing processes have demonstrated successful capture of CO2 gas but involve using highly toxic and corrosive compounds with high heats of regeneration. Development of a solid immobilized amine sorbent that exhibits high CO2 capture and cyclical stability may prove to be a more sensible solution due to its low heat of regeneration, toxicity, and corrosive properties. In this study, fumed silica was chosen as the solid support because of its high commercial availability and high surface area. In this thesis, silica based sorbents were developed through impregnation of tetraethylenepentamine (TEPA) at various weight percent ratios and further modified with the addition of polyethylene glycol (PEG) to aid in dispersing TEPA and cyclical stability of the sorbent. Although the development of sorbents using the same compounds have been reported on in literature, there has been no work done using infrared (IR) characterization to determine the way the compounds interact with each other and with the surface. This thesis has been constructed in order to develop an understanding of these surface interactions and use it to fabricate the best possible sorbent. The IR results concluded that the co-impregnation of PEG and TEPA with corresponding TEPA/PEG/SiO2 weight ratios of 24/36/40 yielded the highest CO2 capture capacity (2.53 mmolCO2/gramSorbent) and best cyclical stability (3% degradation). A gram scale process was also developed for the adsorption and regeneration of CO2 gas from a feed stream of 15% CO2. The process was designed mirroring industrial conditions and resulted in good initial CO2 regeneration concentrations.
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.
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Category :
Languages : en
Pages :
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The solid amine sorbent for CO2 capture process has advantages of simplicity and low operating cost compared to the MEA (monoethanolamine) process. Solid amine sorbents reported so far suffered from either low CO2 capture capacity or low stability in the flue gas environment. This project is aimed at developing a SO2-resistant solid amine sorbent for capturing CO2 from coal-fired power plants with SCR/FGD which emits SO2 ranging from 15 to 30 ppm and NO ranging from 5 to 10 ppm. The amine sorbent we developed in a previous project degraded rapidly with 65% decrease in the initial capture capacity in presence of 1% SO2. This amine sorbent was further modified by coating with polyethyleneglycol (PEG) to increase the SO2-resistance. Polyethylene glycol (PEG) was found to decrease the SO2-amine interaction, resulting in the decrease in the maximum SO desorption temperature (Tmax) of amine sorbent. The PEG-coated amine sorbent exhibited higher stability with only 40% decrease in the initial capture capacity compared to un-coated amine sorbents. The cost of the solid amine sorbent developed in this project is estimated to be less than $7.00/lb; the sorbent exhibited CO2 capture capacity more than 2.3 mmol/g. The results of this study provided the scientific basis for further development of SO2-resistant sorbents.
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Category :
Languages : en
Pages :
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Book Description
Through a U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) funded cooperative agreement DE-NT0005649, ADA Environmental Solutions (ADA) has begun evaluating the use of solid sorbents for CO2 capture. The project objective was to address the viability and accelerate development of a solid-based CO2 capture technology. To meet this objective, initial evaluations of sorbents and the process/equipment were completed. First the sorbents were evaluated using a temperature swing adsorption process at the laboratory scale in a fixed-bed apparatus. A slipstream reactor designed to treat flue gas produced by coal-fired generation of nominally 1 kWe was designed and constructed, which was used to evaluate the most promising materials on a more meaningful scale using actual flue gas. In a concurrent effort, commercial-scale processes and equipment options were also evaluated for their applicability to sorbent-based CO2 capture. A cost analysis was completed that can be used to direct future technology development efforts. ADA completed an extensive sorbent screening program funded primarily through this project, DOE NETL cooperative agreement DE-NT0005649, with support from the Electric Power Research Institute (EPRI) and other industry participants. Laboratory screening tests were completed on simulated and actual flue gas using simulated flue gas and an automated fixed bed system. The following types and quantities of sorbents were evaluated: 87 supported amines; 31 carbon based materials; 6 zeolites; 7 supported carbonates (evaluated under separate funding); and 10 hydrotalcites. Sorbent evaluations were conducted to characterize materials and down-select promising candidates for further testing at the slipstream scale. More than half of the materials evaluated during this program were supported amines. Based on the laboratory screening four supported amine sorbents were selected for evaluation at the 1 kW scale at two different field sites. ADA designed and fabricated a slipstream pilot to allow an evaluation of the kinetic behavior of sorbents and provide some flexibility for the physical characteristics of the materials. The design incorporated a transport reactor for the adsorber (co-current reactor) and a fluidized-bed in the regenerator. This combination achieved the sorbent characterization goals and provided an opportunity to evaluate whether the potential cost savings associated with a relatively simple process design could overcome the sacrifices inherent in a co-current separation process. The system was installed at two field sites during the project, Luminant's Martin Lake Steam Electric Station and Xcel Energy's Sherburne County Generating Station (Sherco). Although the system could not maintain continuous 90% CO2 removal with the sorbents evaluated under this program, it was useful to compare the CO2 removal properties of several different sorbents on actual flue gas. One of the supported amine materials, sorbent R, was evaluated at both Martin Lake and Sherco. The 1 kWe pilot was operated in continuous mode as well as batch mode. In continuous mode, the sorbent performance could not overcome the limitations of the cocurrent adsorbent design. In batch mode, sorbent R was able to remove up to 90% CO2 for several cycles. Approximately 50% of the total removal occurred in the first three feet of the adsorption reactor, which was a transport reactor. During continuous testing at Sherco, CO2 removal decreased to approximately 20% at steady state. The lack of continuous removal was due primarily to the combination of a co-current adsorption system with a fluidized bed for regeneration, a combination which did not provide an adequate driving force to maintain an acceptable working CO2 capacity. In addition, because sorbent R consisted of a polymeric amine coated on a silica substrate, it was believed that the 50% amine loaded resulted in mass diffusion limitations related to the CO2 uptake rate. Three additional supported amine materials, sorbents AX, F, and BN, were selected for evaluation using the 1 kW pilot at Sherco. Sorbent AX was operated in batch mode and performed similarly to sorbent R (i.e. could achieve up to 90% removal when given adequate regeneration time). Sorbent BN was not expected to be subject to the same mass diffusion limitations as experienced with sorbent R. When sorbent BN was used in continuous mode the steady state CO2 removal was approximately double that of sorbent R, which highlighted the importance of sorbents without kinetic limitations.
Author: Bryce Dutcher
Publisher:
ISBN: 9781339054704
Category : Amines
Languages : en
Pages : 171
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Book Description
Strong evidence exists suggesting that anthropogenic emissions of CO2 have been contributing to global climate change. Because of this, it becomes imperative to mitigate anthropogenic CO2. Unfortunately, the best available current technology for CO2 capture, amine scrubbing, is a costly operation due to the energy required for regeneration of the amine. Solid Na2CO3 is considered a potential alternative to amine scrubbing due to its low heat of reaction, but it is not commercially viable due to its low reaction rates for both CO2 sorption and desorption. In order to increase the reaction rate, this project studied nanoporous FeOOH and TiO(OH)2 as supporting materials for Na2CO3. Because regeneration of the sorbent is the most energy-intensive step when using Na2CO3 for CO2 sorption, this project focused on the decomposition of NaHCO3, which is equivalent to CO2 desorption. FeOOH and TiO(OH)2 are shown to be thermally stable with and without the presence of NaHCO3 at temperatures necessary for sorption and regeneration, up to about 200°C. More significantly, it is observed that these supports not only increase the surface area of NaHCO3, but they also have a catalytic effect on the decomposition of NaHCO3. For example, the rate constant for the decomposition of NaHCO3 at 120 °C is increased from 0.02 min-1 without a support to 0.46 min-1 with 50 wt.% FeOOH and 0.39 min-1 with 50 wt.% TiO(OH)2. The activation energy is reduced from 80 kJ/mol without a support to 44 kJ/mol with 50 wt.% FeOOH and to 35 kJ/mol with 50 wt.% TiO(OH)2. This increase in reaction rate could translate into a substantial decrease in the cost of using Na2CO3 for CO2 capture. Amine-functionalized sorbents, like solid Na2CO3, have potentially lower energy requirements than aqueous amines due to the absence of bulk water, and they retain many of the advantages of aqueous amines such as high reaction rates and high CO2 capacity. Here, the structure and stability of a recently developed amine functionalized silica sorbent is investigated.
Author: Nick Linneen
Publisher:
ISBN:
Category : Adsorption
Languages : en
Pages : 150
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Book Description
Post-combustion carbon capture is a viable option for reducing CO2 greenhouse gas emissions, and one potentially promising technology for this route is adsorption using chemically and physically based sorbents. A number of exceptional CO2 sorbents materials have been prepared including metal organic frameworks, zeolites, and carbon based materials. One particular group of capable materials are amine based solid sorbents that has shown to possess high adsorption capacities and favorable adsorption kinetics. A key variable in the synthesis of an amine based sorbent is the support which acts as the platform for the amine modification. Aerogels, due to their high porosities and surface areas, appear to be a promising support for an amine modified CO2 sorbent. Therefore, in order to develop a commercially viable CO2 sorbent, particulate aerogels manufactured by Cabot Corporation through an economical and proprietary ambient drying process were modified with amines using a variety of functionalization methods. Two methods of physical impregnation of the amino polymer TEPA were performed in order to observe the performance as well as understand the effects of how the TEPA distribution is affected by the method of introduction. Both samples showed excellent adsorption capacities but poor cyclic stability for lack of any covalent attachment. Furthermore the method of TEPA impregnation seems to be independent on how the polymer will be distributed in the pore space of aerogel. The last two methods utilized involved covalently attaching amino silanes to the surface silanols of the aerogel. One method was performed in the liquid phase under anhydrous and hydrous conditions. The materials developed through the hydrous method have much greater adsorption capacities relative to the anhydrous sample as a result of the greater amine content present in the hydrous sample. Water is another source of silylation where additional silanes can attach and polymerize. These samples also possessed stable cyclic stability after 100 adsorption/regeneration cycles. The other method of grafting was performed in the gas phase through ALD. These samples possessed exceptionally high amine efficiencies and levels of N content without damaging the microstructure of the aerogel in contrast to the liquid phase grafted sorbents.
Author: Wei-Yin Chen
Publisher: Springer
ISBN: 9781441979926
Category : Science
Languages : en
Pages : 2130
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Book Description
There is a mounting consensus that human behavior is changing the global climate and its consequence could be catastrophic. Reducing the 24 billion metric tons of carbon dioxide emissions from stationary and mobile sources is a gigantic task involving both technological challenges and monumental financial and societal costs. The pursuit of sustainable energy resources, environment, and economy has become a complex issue of global scale that affects the daily life of every citizen of the world. The present mitigation activities range from energy conservation, carbon-neutral energy conversions, carbon advanced combustion process that produce no greenhouse gases and that enable carbon capture and sequestion, to other advanced technologies. From its causes and impacts to its solutions, the issues surrounding climate change involve multidisciplinary science and technology. This handbook will provide a single source of this information. The book will be divided into the following sections: Scientific Evidence of Climate Change and Societal Issues, Impacts of Climate Change, Energy Conservation, Alternative Energies, Advanced Combustion, Advanced Technologies, and Education and Outreach.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Through a U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) funded cooperative agreement DE-NT0005649, ADA Environmental Solutions (ADA) has begun evaluating the use of solid sorbents for CO2 capture. The project objective was to address the viability and accelerate development of a solid-based CO2 capture technology. To meet this objective, initial evaluations of sorbents and the process / equipment were completed. First the sorbents were evaluated using a temperature swing adsorption process at the laboratory scale in a fixed-bed apparatus. A slipstream reactor designed to treat flue gas produced by coal-fired generation of nominally 1 kWe was designed and constructed, which was used to evaluate the most promising materials on a more meaningful scale using actual flue gas. In a concurrent effort, commercial-scale processes and equipment options were also evaluated for their applicability to sorbent-based CO2 capture. A cost analysis was completed that can be used to direct future technology development efforts. ADA completed an extensive sorbent screening program funded primarily through this project, DOE NETL cooperative agreement DE-NT0005649, with support from the Electric Power Research Institute (EPRI) and other industry participants. Laboratory screening tests were completed on simulated and actual flue gas using simulated flue gas and an automated fixed bed system. The following types and quantities of sorbents were evaluated: 87 supported amines, 31 carbon based materials, 6 zeolites, 7 supported carbonates (evaluated under separate funding), 10 hydrotalcites. Sorbent evaluations were conducted to characterize materials and down-select promising candidates for further testing at the slipstream scale. More than half of the materials evaluated during this program were supported amines. Based on the laboratory screening four supported amine sorbents were selected for evaluation at the 1 kW scale at two different field sites. ADA designed and fabricated a slipstream pilot to allow an evaluation of the kinetic behavior of sorbents and provide some flexibility for the physical characteristics of the materials. The design incorporated a transport reactor for the adsorber (co-current reactor) and a fluidized-bed in the regenerator. This combination achieved the sorbent characterization goals and provided an opportunity to evaluate whether the potential cost savings associated with a relatively simple process design could overcome the sacrifices inherent in a co-current separation process. The system was installed at two field sites during the project, Luminant's Martin Lake Steam Electric Station and Xcel Energy's Sherburne County Generating Station (Sherco). Although the system could not maintain continuous 90% CO2 removal with the sorbents evaluated under this program, it was useful to compare the CO2 removal properties of several different sorbents on actual flue gas. One of the supported amine materials, sorbent R, was evaluated at both Martin Lake and Sherco. The 1 kWe pilot was operated in continuous mode as well as batch mode. In continuous mode, the sorbent performance could not overcome the limitations of the co-current adsorbent design. In batch mode, sorbent R was able to remove up to 90% CO2 for several cycles. Approximately 50% of the total removal occurred in the first three feet of the adsorption reactor, which was a transport reactor. During continuous testing at Sherco, CO2 removal decreased to approximately 20% at steady state. The lack of continuous removal was due primarily to the combination of a co-current adsorption system with a fluidized bed for regeneration, a combination which did not provide an adequate driving force to maintain an acceptable working CO2 capacity. In addition, because sorbent R consisted of a polymeric amine coated on a silica substrate, it was believed that the 50% amine loaded resulted in mass diffusion limitations related to the CO2 uptake rate. Th ...
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Category :
Languages : en
Pages :
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Book Description
A method is provided for making low-cost CO.sub. 2 sorbents that can be used in large-scale gas-solid processes. The improved method entails treating an amine to increase the number of secondary amine groups and impregnating the amine in a porous solid support. The method increases the CO.sub. 2 capture capacity and decreases the cost of utilizing an amine-enriched solid sorbent in CO.sub. 2 capture systems.
Author: Duong D Do
Publisher: World Scientific
ISBN: 1783262249
Category : Technology & Engineering
Languages : en
Pages : 915
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Book Description
This book covers topics of equilibria and kinetics of adsorption in porous media. Fundamental equilibria and kinetics are dealt with for homogeneous as well as heterogeneous particles. Five chapters of the book deal with equilibria and eight chapters deal with kinetics. Single component as well as multicomponent systems are discussed. In kinetics analysis, we deal with the various mass transport processes and their interactions inside a porous particle. Conventional approaches as well as the new approach using Maxwell-Stefan equations are presented. Various methods to measure diffusivity, such as the Differential Adsorption Bed (DAB), the time lag, the diffusion cell, chromatography, and the batch adsorber methods are also covered by the book. It can be used by lecturers and engineers who wish to carry out research in adsorption. A number of programming codes written in MatLab language are included so that readers can use them directly to better understand the behavior of single and multicomponent adsorption systems.
