CO2 and SO2 Capture by Aromatic and Aliphatic Amine Sorbents PDF Download
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Author: Ernesto Silva Mojica
Publisher:
ISBN:
Category : Aliphatic compounds
Languages : en
Pages : 107
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Book Description
The emissions of CO2 to the atmosphere have rapidly increased in the last decades due to the industrialization and the increasing energy demand. Due to the potential effect that CO2 has as global warmer, industrialized and emerging countries are putting efforts on developing technologies to reduce emissions. Coal fired power plants produce 55% of U.S. electricity and more than 33% of global CO2 emissions, representing the largest stationary source of CO2. As a co-product of the combustion process of sulfur-containing coal, SO2 is produced and represents between 0.2 and 0.3 v% of the power plant flue gas composition. SO2 is a serious pollutant, precursor of the acid rain and particulate materials. The release of SO2 to the atmosphere can cause respiratory diseases and destruction of eco-systems. Some existing CO2 capture technologies are inefficient to be applied in power plants due to the large flow rates and high concentration of CO2 in the flue gas. Other technologies such as the liquid amine process are not economically viable because the energy requirements for operation and regeneration are excessive. In addition those processes cause rapid corrosion to the equipment. The adsorption on solid sorbents is potentially the most suitable process for the treatment of flue gas from power plants. The development of solid sorbents by functionalization of solid supports with amine functional groups has been recently studied. The goals during the sorbent development are (i) a high CO2 selectivity and adsorption capacity, (ii) the long term stability and cycle life, (iii) resistivity toward thermal and oxidative degradation, (iv) resistance to SO2 and (iv) low cost. In this thesis, the resistance of aliphatic amine and aromatic anime sorbents towards SO2 was studied by in-situ infrared spectroscopy (IR) and mass spectrometry (MS). An operational condition to improve the CO2 adsorption capacity of an amine sorbent was also studied by introducing H2O in the flue gas. The hypothesis included the use of an aromatic amine to prepare a low basicity sorbent for SO2 capture and to reduce the SO2 poisoning on a CO2 capture sorbent. In addition, it is thought that the presence of H2O in the flue gas improves the adsorption capacity of an amine sorbent due to the formation of different adsorbed species. The IR and MS results showed that the aromatic amine sorbent has a weak adsorption capacity of CO2 and SO2, leading to CO2 capture processes at low temperature. SO2 strongly adsorbs on the aliphatic amine sorbent, causing accumulation of sulfate and sulfite species and reducing the availability of amine sites for CO2 adsorption. The performance of CO2 capture in simulated practical conditions showed the improvement in capture capacity of a sorbent by more than 60% when the flue gas is saturated with H2O.
Author: Ernesto Silva Mojica
Publisher:
ISBN:
Category : Aliphatic compounds
Languages : en
Pages : 107
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Book Description
The emissions of CO2 to the atmosphere have rapidly increased in the last decades due to the industrialization and the increasing energy demand. Due to the potential effect that CO2 has as global warmer, industrialized and emerging countries are putting efforts on developing technologies to reduce emissions. Coal fired power plants produce 55% of U.S. electricity and more than 33% of global CO2 emissions, representing the largest stationary source of CO2. As a co-product of the combustion process of sulfur-containing coal, SO2 is produced and represents between 0.2 and 0.3 v% of the power plant flue gas composition. SO2 is a serious pollutant, precursor of the acid rain and particulate materials. The release of SO2 to the atmosphere can cause respiratory diseases and destruction of eco-systems. Some existing CO2 capture technologies are inefficient to be applied in power plants due to the large flow rates and high concentration of CO2 in the flue gas. Other technologies such as the liquid amine process are not economically viable because the energy requirements for operation and regeneration are excessive. In addition those processes cause rapid corrosion to the equipment. The adsorption on solid sorbents is potentially the most suitable process for the treatment of flue gas from power plants. The development of solid sorbents by functionalization of solid supports with amine functional groups has been recently studied. The goals during the sorbent development are (i) a high CO2 selectivity and adsorption capacity, (ii) the long term stability and cycle life, (iii) resistivity toward thermal and oxidative degradation, (iv) resistance to SO2 and (iv) low cost. In this thesis, the resistance of aliphatic amine and aromatic anime sorbents towards SO2 was studied by in-situ infrared spectroscopy (IR) and mass spectrometry (MS). An operational condition to improve the CO2 adsorption capacity of an amine sorbent was also studied by introducing H2O in the flue gas. The hypothesis included the use of an aromatic amine to prepare a low basicity sorbent for SO2 capture and to reduce the SO2 poisoning on a CO2 capture sorbent. In addition, it is thought that the presence of H2O in the flue gas improves the adsorption capacity of an amine sorbent due to the formation of different adsorbed species. The IR and MS results showed that the aromatic amine sorbent has a weak adsorption capacity of CO2 and SO2, leading to CO2 capture processes at low temperature. SO2 strongly adsorbs on the aliphatic amine sorbent, causing accumulation of sulfate and sulfite species and reducing the availability of amine sites for CO2 adsorption. The performance of CO2 capture in simulated practical conditions showed the improvement in capture capacity of a sorbent by more than 60% when the flue gas is saturated with H2O.
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: Uma Tumuluri
Publisher:
ISBN:
Category : Adsorption
Languages : en
Pages : 170
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Book Description
CO2 capture using amine sorbents is a promising technology for CO2 capture from point sources because of its low energy requirement, low equipment corrosion. Thermal swing adsorption (TSA) using amine sorbents, which operates with CO2 adsorption at 40-55°C and desorption at 100-120°C, could be a cost-effective process for removal of CO2 from coal-fired power plants becasue of the availability of steam for sorbent regeneration. In situ FTIR spectroscopy was used to study the interaction of CO2 with amine sorbents. Adsorbed CO2 on amine sorbents exists in the form of carbamate-ammonium ion pairs, carbamate-ammonium zwitterions and carbamic acid. Carbamate and carbamic acid on sorbents with low amine density desorbed at a faster rate than those on sorbents with high amine density after switching the flow from CO2 to Ar at 55°C. Evaluation of the desorption temperature profiles showed that the temperature required to achieve maximum desorption of CO2 (Tmax. des) increases with the amine density. Flue gas emitted from coal fired power plants after selective catalytic reduction and flue gas desulfurization units contains approximately 3-4% O2, 12-15% CO2, 5-10% H2O, 50-200 ppm SO2, 100-400 ppm NOx. The long term stability of the amine sorbents in flue gas conditions is one of the key operational aspects that the determine the economic viability of the CO2 capture using amine sorbents. The performance of the amine sorbents in the simulated flue gas conditions was evaluated using in situ FTIR spectroscopy. FTIR results revealed that sulfates/sulfites that are formed in presence of SO2 and SO2/H2O bind strongly with amine sites. Evaluation of the break through curves revealed that the competitive adsorption of SO2 and CO2 on the amine sites occurs at low CO2 concentration. The adsorption of CO2 dominates the SO2 at high CO2 concentration. In situ FTIR SO2 capture studies on amine sorbents revealed that SO2 adsorbs in form of ammonium ions and sulfates on the amine sorbents. Analysis of the IR spectra of the adsorbed SO2 revealed that the sorbents containing primary and secondary amine adsorb SO2 irreversibly and tertiary amine sorbents adsorbed SO2 reversibly. The results of these fundamental studies help in designing a suitable sorbent for CO2 capture process, which has high CO2 capture capacity and high SO2 tolerance.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
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.
Author: Sihan Wang
Publisher:
ISBN:
Category : Carbon sequestration
Languages : en
Pages :
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Book Description
Over loading of CO2 emission has been a severe environment problem and the fact of greenhouse issue has become a huge impact to our daily life. The largest and inevitable emission of CO2 gas is the coal-fired power plant, and the most commonly used CO2 capture sorbent is liquid amine. However, there are lots of inconvenience of using liquid amine including equipment corrosion, high regeneration energy and slow diffusion of the CO2 gas, which would cost the capture procedure a huge amount of expense. Nevertheless, the solid sorbent is in face of the issue that the capture capacities and SO2 resistance is really low. So in this research, the modified amine-functionalized solid sorbents for CO2 adsorption and SO2 resistance have been created. The problem of lower CO2 capture capacity was modified by double impregnation, and the issue of lower heat transfer rate was improved by adding heat transfer agent during pelletization. The characterization of the sorbent and pellets capture behavior was done by CO2 capture weight method and in-situ DRIFT spectra, and the SO2 resistance behavior has also been discussed with EDS mapping and quantification.
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: Hailiang Jin
Publisher:
ISBN:
Category : Carbon dioxide
Languages : en
Pages : 116
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Book Description
The impurities in flue gas from coal fire power plant such as SO2, could poison CO2 sorbent due to its strong acidity. To reinforce the stability of sorbent in presence of SO2, polymeric SO2-resistant coating was developed and characterized by in-situ FTIR spectroscopy. This coating was prepared by crosslinking poly(ethylenemine) with an epoxy and applied to CQA-12, a solid amine sorbent. The effect of the epoxy composition on the stability and adsorption / desorption kinetics of the coated sorbent was investigated by FTIR and mass spectrometry. The results revealed that this polymeric coating enhanced the resistance to SO2 poisoning, thus the multi-cyclic stability of the sorbent in presence of SO2, by converting the amine sites to secondary and tertiary amine. Though it reduced the initial CO2 capture capacity due to blocked amine sites. Increased amount of epoxy was found to strengthen the SO2 resistance. The FTIR spectra denoted that the introduction of epoxy increased the ratio of weakly adsorbed CO2 to strongly adsorbed CO2, i.e., reduced the binding strength of amine/CO2.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Post combustion CO2 capture is most commonly carried out using an amine solution that results in a high parasitic energy cost in the stripper unit due to the need to heat the water which comprises a majority of the amine solution. It is also well known that amine solvents suffer from stability issues due to amine leaching and poisoning by flue gas impurities. Solid sorbents provide an alternative to solvent systems that would potentially reduce the energy penalty of carbon capture. However, the cost of using a particular sorbent is greatly affected by the usable lifetime of the sorbent. This work investigated the stability of a primary amine-functionalized ion exchange resin in the presence of O2 and SO2, both of which are constituents of flue gas that have been shown to cause degradation of various amines in solvent processes. The CO2 capture capacity was measured over multiple capture cycles under continuous exposure to two simulated flue gas streams, one containing 12 vol% CO2, 4% O2, 84% N2, and the other containing 12.5 vol% CO2, 4% O2, 431 ppm SO2, balance N2 using a custom-built packed bed reactor. The resin maintained its CO2 capture capacity of 1.31 mol/kg over 17 capture cycles in the presence of O2 without SO2. However, the CO2 capture capacity of the resin decreased rapidly under exposure to SO2 by an amount of 1.3 mol/kg over 9 capture cycles. Elemental analysis revealed the resin adsorbed 1.0 mol/kg of SO2. Thermal regeneration was determined to not be possible. The poisoned resin was, however, partially regenerated with exposure to 1.5M NaOH for 3 days resulting in a 43% removal of sulfur, determined through elemental analysis, and a 35% recovery of CO2 capture capacity. Evidence was also found for amine loss upon prolonged (7 days) continuous exposure to high temperatures (120 C) in air. It is concluded that desulfurization of the flue gas stream prior to CO2 capture will greatly improve the economic viability of using this solid sorbent in a post-combustion CO2 capture process.
Author: W. Richard Alesi Jr.
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Author: Jennifer Wilcox
Publisher: Springer Science & Business Media
ISBN: 1461422140
Category : Science
Languages : en
Pages : 337
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Book Description
This book approaches the energy science sub-field carbon capture with an interdisciplinary discussion based upon fundamental chemical concepts ranging from thermodynamics, combustion, kinetics, mass transfer, material properties, and the relationship between the chemistry and process of carbon capture technologies. Energy science itself is a broad field that spans many disciplines -- policy, mathematics, physical chemistry, chemical engineering, geology, materials science and mineralogy -- and the author has selected the material, as well as end-of-chapter problems and policy discussions, that provide the necessary tools to interested students.
