Study of Thermal Degradation for Solid Amines During CO2 Capture Cycling and Mechanism of Porous Polymer Formation PDF Download

Author: Abtin Vafadari
Publisher:
ISBN:
Category : Adsorption
Languages : en
Pages : 149

View

Book Description
Global warming has become one of the major concerns of the industrial world. Among the pollutants, CO2 has the highest impact on the climate change. Many techniques have been proposed to capture carbon dioxide from exhaust gas of the plants and factories. Temperature swing adsorption (TSA) is the most promising technique for CO2 capture due to low capital cost, heat of regeneration, toxicity and corrosive properties. Amine based sorbents can be applied for low temperature carbon dioxide separation from plant exhaust gases. Gas stream after passing through a packed adsorption bed will go to other separation units depending on requirements of the plant or it will be released into atmosphere. After the adsorption bed reaches into saturation point, control system will bypass that process unit and redirect the gas stream to another packed bed with fresh sorbents while the saturated bed is heating for regeneration. Thermal cycling in presence of exhaust gases can cause thermal and oxidative degradation of the sorbents over a long time frame. Also the high temperature of heating during the regeneration can cause some of the species to evaporate. For our in-house built sorbent, Tetraethylenepentamine (TEPA) is the amine source and EPON 826 is used to initiate the long chain polymers for holding the amine groups on the surface of the sorbents and inhibit them from evaporation. After exposure to a certain number of thermal cycles which causes sorbent degradation, they must be replaced with fresh sorbents but unit overhauls are costly and plant owners prefer to avoid that. There are two suggestions for reduction of overhaul costs due to sorbent deformation: One suggestion is to regenerate the sorbents in their original location by washing them with a cheap solution to improve the performance of the sorbents and the other was, to optimize the sorbents so they can resist to more number of thermal cycles. In this study, the amine degradation due to thermal cycling was studied and it was proved that irreversible reactions between CO2 and amine groups or chemisorbed species are the reasons for degradation of sorbents. The other issue in CO2 adsorption by amine based sorbents is the evaporation of amines which can cause environmental issues. By making a porous polymer to replace solid sorbents evaporation of amines to atmosphere can be avoided. After concentration optimization and rapid heating the liquid phase polymers, porous polymer with high porosity was achieved. Although this polymer had a good number of macro pores but it did not have enough capture capacity, further investigation is required to address this issue.

Author: Bohak Yoon
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

View

Book Description
Chemical absorption with aqueous amine-based solvents has been the most promising incumbent technology for post-combustion CO2 capture from flue gas. However, its extensive operation is severely limited by the large cost attributed to the enormous energy requirement for solvent regeneration and degradation issues leading to makeup of amine solvent loss. First-principles atomistic modeling can provide key insights into elucidating chemical phenomena pertinent to degradation behavior in CO2-loaded aqueous amine solution, which is often extremely challenging to be experimentally characterized. In this dissertation, our first-principles works on illuminating the molecular mechanisms governing solvent degradation of aqueous amine during CO2 capture are presented. Using density functional theory based ab initio molecular dynamics with enhanced sampling techniques, we identify elementary reactions governing CO2 capture and degradation. Molecular mechanisms of thermal and oxidative degradation of aqueous amine solvents are discussed in perspective of both thermodynamics and kinetics. We systematically investigate on the factors prevailing key reaction rates, such as amine functional groups, the steric hindrances, classes of amines (primary and secondary), concentration of amines, solvation nature, and temperature conditions. These factors may largely affect relative strengths of both inter- and intramolecular hydrogen bond interactions in CO2-loaded aqueous amine solution. Our theoretical studies further illustrate the importance of an atomistic-level description of solvation structure and dynamics that may primarily govern CO2 reaction with aqueous amine solvents and associated degradation mechanisms. This dissertation highlights the key role of first-principles computational modelling in accurately describing mechanistic understandings on CO2 capture by aqueous amine solvents and associated degradation processes. The enhanced atomisticlevel descriptions will provide more complete explanations for experimental characterizations and valuable suggestions on how to optimize existing solvents and design more cost-efficient solvents for carbon capture processes

Author: Sonil Nanda
Publisher: Elsevier
ISBN: 0323900720
Category : Technology & Engineering
Languages : en
Pages : 338

View

Book Description
Carbon Dioxide Capture and Conversion: Advanced Materials and Process provides information about the fundamental principles and recent development of various methods and processes for CO2 mitigation and transformation. Beginning with a brief overview of recent advancements in CO2 capture and valorization technologies, the book elaborates on CO2 capture and conversion by covering nanoporous materials, biomaterials, innovative solvents, advanced membrane technology, nanocatalyst synthesis and design, cutting-edge characterization techniques as well as reaction mechanisms and kinetics. In addition to techno-economic evaluation and life-cycle assessment for CO2 capture and conversion processes, future perspectives, opportunities and current challenges regarding these processes in terms of their industrial applications, are systematically discussed. Carbon Dioxide Capture and Conversion: Advanced Materials and Process is, therefore, an essential resource for academic researchers, postgraduates, scientists, and engineers seeking fundamental knowledge and practical applications for use in their research and development, studies and industrial operations. - Includes recent developments in nanomaterials and advanced processes implemented for CO2 capture and conversion - Contains state-of-the-art CO2 capture and conversion technology written by leading experts - Offers advanced techniques of nanomaterials synthesis, characterization, evaluation, and industrial implementation in a wide range of CO2 capture and conversion processes

Author: Omkar Ashok Namjoshi
Publisher:
ISBN:
Category :
Languages : en
Pages : 548

View

Book Description
The thermal degradation of piperazine (PZ)-promoted tertiary amine solvents for CO2-capture has been investigated and quantified in this study, which takes place in the high temperature (>100 °C) section of the capture plant. PZ-promoted tertiary amine solvents possess comparable energy performance to concentrated PZ, considered a benchmark solvent for CO2 capture from flue gas without its solid solubility limits that hinder operational performance. PZ-promoted aliphatic tertiary amine solvents with at least one methyl group, such as methyldiethanolamine (MDEA), were found to be the least stable solvents and can be regenerated in the desorber between 120 and 130 °C. PZ-promoted tertiary amine solvents with no methyl groups, such as ethyldiethanolamine (EDEA), were found to have an intermediate stability and can be regenerated in the desorber between 130 and 140 °C. PZ-promoted tertiary morpholines, such as hydroxyethylmorpholine (HEM), were found to be stable above 150 °C. Tertiary amines with at least one hydroxyethyl or hydroxyisopropyl functional group form intermediate byproducts that can accelerate the degradation rate of the promoter by a factor from 1.5 to 2.3. Tertiary amines with 3-carbon and 5-carbon functional groups, such as dimethylaminopropanol or dimethylaminoethoxyethanol, form stable intermediate byproducts that do not readily react with the promoter. A degradation model for PZ-promoted MDEA that can be used for process design calculations using acidified solvent degradation to model the initial degradation rate over a range of CO2 loading and initial amine concentration was developed. Thermal degradation was modeled using second-order kinetics as a function of free amine and protonated amine. The degradation kinetics, along with the observed degradation products, suggest that the dominant pathway is by free PZ attack on a methyl substituent group of protonated MDEA to form diethanolamine (DEA) and 1-methylpiperazine (1-MPZ). The model predicts total amine loss from experimental CO2 degradation rate measurements within 20%. The modeling work was extended to other PZ-promoted tertiary amine solvents with bulkier substituent groups. PZ attack on ethyl or hydroxyethyl groups was 17% and 4% as fast, respectively, as attack on methyl groups.

Author: Lin Pan
Publisher:
ISBN:
Category : Aromatic amines
Languages : en
Pages : 104

View

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: Dzifa Nugloze
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

View

Book Description
The effects of climate change have attracted concern globally which has led to an increase in research focused on diverse plans and technologies for mitigation. The use of solid catalyst in an amine based post-combustion CO2 capture (PCCC) has become a very attractive option as developments are actively ongoing to address some of the challenges that the conventional capture system faces. This research work evaluated the role that a new super acid, proprietary desorber catalyst (PDC) catalyst has on the amine degradation rate using a formulated optimum 4M DMAE/AMP equimolar blend in a full cycle bench scale CO2 capture pilot plant system. Three solvent blends, 4M DMAE/AMP, 2M PEI/AMP (0.3/1.7) and 2M PEI/HMDA (0.3/1.7) were screened in a preliminary study and compared with 4M BEA/AMP. 4M DMAE/AMP emerged as the optimum solvent amongst all the three formulated ones with high points of improvement in the desorption performance parameters. DMAE/AMP is a good replacement for BEA/AMP as it addresses the problem of potential nitrosamine and nitramine formation. Two basic catalysts, proprietary absorber catalyst (PAC), and activated carbon spheres (ACS) and one acid catalyst, PDC were also synthesized, characterized, screened, and compared with the existing basic catalyst, KMgO/CNT's and acid catalyst, Ce(SO4)2/ZrO2 respectively to evaluate their performances and how suitable they are for use in the PCC process compared to the existing ones. The introduction of ACS in the absorption system increased the rate at which the amine solvent absorbed CO2 by approximately 33 %. In the case of PAC, an absorption rate enhancement of approximately 29 % was obtained. PDC enhanced the CO2 desorption rate by approximately 25 % higher than the non-catalytic desorption using 4M DMAE/AMP. Degradation studies were finally conducted to examine the role that the solid acid catalyst, PDC plays in the stability of the selected amine blend system in a bench-scale pilot plant set-up. PDC inhibited the oxidative degradation rate of both DMAE and AMP by 25 % and 59 % respectively. This means 2M of DMAE would be depleted in 62 days in the presence of PDC compared to 46 days without PDC in an oxidative environment. Similarly, it would take 139 days for 2M of AMP to be depleted compared to 57 days without the presence of PDC. This translates into huge savings in operational cost if PDC is used as a catalyst to both enhance the desorption and limit degradation. The findings of this work would open up new discussions on how solid basic or acid catalysts can be beneficial in addressing one of the major drawbacks to the PCC technology, i.e. degradation.

Author: Samuel Leo Madorsky
Publisher:
ISBN:
Category : Polymerization
Languages : en
Pages : 346

View

Book Description

Author: Haley Maren Stowe
Publisher:
ISBN:
Category :
Languages : en
Pages : 356

View

Book Description
Aqueous amine-based chemical scrubbing has been considered the most promising near-term solution for CO2 capture from flue gas, yet the underlying reaction mechanisms are still not fully understood. Moreover, its widespread implementation is hindered by the high cost associated with the parasitic energy consumption during solvent regeneration, along with degradation and corrosion problems. First-principles-based atomistic modeling can play a significant role in elucidating the complex physicochemical phenomena underlying CO2 reaction-diffusion behavior in aqueous amine-based solvent, especially when direct experimental characterization at the atomic level may be difficult. An improved fundamental understanding of these reaction mechanisms and intermolecular interactions can be used to provide explanations for experimental observations and fundamental data, and improve kinetic and thermodynamic models for process optimization. Here, our recent theoretical works on the molecular mechanisms underlying CO2 capture and solvent regeneration in aqueous amines are presented. Through systematic comparative analyses of primary, tertiary, and sterically hindered amines, and diamines, we provide significant insights into how the mechanisms and rates of competing CO2 absorption routes can be influenced by the solvent structure, the relative strengths of intra- and intermolecular hydrogen bond interactions, and steric constraints. We also use a theoretical approach to examine the mechanisms occurring during thermal degradation, as well as the process underlying leaching of metal ions into solution due to corrosion and subsequent oxidative degradation, which remain unclear. These studies further demonstrate the importance of a detailed atomic-level description of the solution structure and dynamics to describe the reactions and in predicting the thermodynamic and kinetic properties in CO2-loaded aqueous amines. Moreover, an accurate description of solvent composition near the gas interface and near the iron surface is critical in predicting the CO2 capture and corrosion processes, respectively. This dissertation highlights the increasingly important role of first-principles-based computer simulations in the detailed mechanistic study of CO2 capture by amine-based solvents, including solvent degradation and corrosion processes. The improved understanding gained from computational studies combined with experiment validations will greatly aid in the design and development of new solvents and inhibitors in efforts to improve the efficiency of commercial-scale applications

Author: Jak Tanthana
Publisher:
ISBN:
Category : Amines
Languages : en
Pages : 168

View

Book Description
The rapid increase in CO2 emission in recent years has become a major concern because of its potential link to global climate change. Among CO2 contributors, coal-fire power plant accounts for more than 30% of total CO2 emission worldwide. Three major approaches for capture of CO2 are proposed: postcombustion, oxyfuel and precombustion. Each has distinct advantages and disadvantages. Postcombustion utilizing amine based absorption process by far is the most fundamentally established and can be retrofitted to existing coal-fire power plants around the globe. Limited by high heat of reaction, the amine absorption process requires a significant amount of energy during solvent regeneration. Large physical facility foot print and corrosive problems are among the important issues which need to be addressed. Utilizing sorbent impregnated with amine specie shows competitive CO2 capture ability and may lead to a more practical solution from its lower operating temperature in the regeneration step, smaller foot print and less corrosion. Many solid sorbent products available commercially can be tailored to meet certain specifications such as controlled pore size distribution, high porosity or govern specific reactions at relatively low cost. Silica fume was chosen in this study due to its high availability, high surface area and flexibility to modify surface properties using various methods of treatments. In this study, silica support sorbent was impregnated with tetraethylenepentamine by various wt% concentrations applying an ex-situ impregnation method. Acid and Base treatment of amine impregnated samples were employed in the study. The sorbents were then characterized as to their performance of CO2 absorption-desorption. The capturing performance and effect from acid/ base were evaluated. Results of this study concluded that ex-situ impregnation can be used to successfully prepared tetraethylenepentamine impregnated SiO2. The sorbents exhibited ability to perform CO2 absorption-desorption exceeding primary target capture performance set by Department of Energy (DoE) under optimized concentration of tetraethylenepentamine. Intensity of IR absorbance may correlate with the concentration of amine functional groups on surface of SiO2. Weakly and strongly bonded CO2 with tetraethylenepentamine were suggested. Hypothesized form of absorbed species of monodentate bicarbonate and bidentate bicarbonate were detected in the study. Acid treatment causes performance degradation which was evident from the degradation of the amine functional groups on the silica surfaces while base treatment did not improve nor degrade the sorbent performance. Hence, CO2 absorption-desorption mechanism is not altered by the base treatment.

Author: Wei-Yin Chen
Publisher: Springer
ISBN: 9781441979926
Category : Science
Languages : en
Pages : 2130

View

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.