Browsing by Author "Narku-Tetteh, Jessica"
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Item Open Access Achieving net-zero CO2 emissions from indirect co-combustion of biomass and natural gas with carbon capture using a novel amine blend(Faculty of Graduate Studies and Research, University of Regina, 2022-09) Avor, Esther Praise; Idem, Raphael; Jia, Na; Supap, Teeradet; Narku-Tetteh, Jessica; Torabi, FarshidDue to the aggravating effect of climate change as a result of unprecedented levels of greenhouse gases, particularly CO2, in the atmosphere, the need to minimize CO2 emissions into the atmosphere has become very crucial. The energy sector remains the largest source of CO2 emissions, therefore, a technology which allows for achieving netzero CO2 emissions in this sector is imperative. This research work evaluated the possibility of achieving net-zero emissions (on the minimum) through the application of co-combustion of natural gas and biomass for electricity generation. Based on the study, it is was identified that indirect co-combustion of natural gas with biomass (in the form of producer gas) with carbon capture technology is the way to go towards achieving net-zero CO2 emissions. To effectively describe the process as being a net-zero CO2 emissions approach, Life Cycle Assessment data was applied to the various processes involved in the indirect co-combustion of biomass and natural gas coupled with carbon capture technology. In the first phase of this work, 5M MEA, which is the benchmark solvent for CO2 capture was used as the worst-case scenario to determine the ratio of producer gas-to natural gas (on energy basis) sufficient for achieving net-zero CO2 emissions. Using the SaskPower forecasted electricity generation capacity for 2025/2026 as a case study and applying LCA data to 5M MEA as the solvent for CO2 capture, it was determined that on energy basis, 14.5% of producer gas (balance natural gas) is sufficient for achieving netzero CO2 emissions while satisfying the set electricity generation target. The next phase of the work was to develop an amine blend with an improved CO2 removal efficiency compared to the bench-scale 5M MEA. Four different blends were screened to assess their respective performance against 5M MEA. These included 2:2 AMP: 1-(2HE) PRLD, 2:2 AMP: DEA-1,2-PD, 3:1 1-(2HE) PRLD: AMP and 3:1 1-(2HE) PRLD: DEA-1,2-PD bi-blends. Among these solvents, 2:2 AMP: 1-(2HE) PRLD was the optimum solvent as it demonstrated a high CO2 absorption-desorption parameter compared to the other blends. The absorption parameter for 2:2 AMP:1-(2HE) PRLD was 4.5% higher than that for 5M MEA and the desorption parameter 1,667% higher than 5M MEA. In the last phase, the increased CO2 removal efficiency of the solvent was applied to LCA data to determine the ratio of electricity generation from natural gas and producer gas towards achieving net-zero CO2 emissions when the optimum solvent developed is used in place of 5M MEA. It was determined that at a desorption temperature of 110℃, nearly all the CO2 in the rich amine for the optimum was removed. The CO2 removal efficiency of this solvent is about 31% higher than that for 5M MEA, implying this solvent allows for the removal of higher amount of CO2 in the flue gas stream. From the life cycle massessment, using 2:2 AMP: 1-(2HE) PRLD as the absorbent for CO2 capture in place of 5M MEA, it was determined that the producer gas requirements on energy basis, for cocombusting indirectly with natural gas towards achieving net-zero CO2 emissions is just about 8%. The findings from this work demonstrates that co-combusting biomass with natural gas (which is a lesser emitter of CO2 compared to other fossil fuels) allows for satisfying the energy demands while achieving net-zero CO2 emissions when CO2 capture is applied. The major limitation that has faced the application of bioenergy with carbon capture technology has been concerns over its competition with farmlands for food production. The results obtained from this work has showed that lower amount of biomass would be needed for energy generation via co-combustion with natural gas towards achieve net-zero emissions when a solvent with an improved CO2 removal ability is used as the absorbent in the CO2 capture process.Item Open Access Amine and Catalyst Stability Studies in the Catalyst-Aided CO2 Capture Process(Faculty of Graduate Studies and Research, University of Regina, 2021-08) Amoako, Benjamin; Idem, Raphael; Supap, Teeradet; Narku-Tetteh, Jessica; Tontiwachwuthikul, Paitoon; Torabi, FarshidThe application of sol id base and sol id acid catalysts to improve CO2 capture has been one of the most notable technological advancements in amine-based post -combust ion capture. Despite the inherent benefits of the catalysts, the amine solvent is st i l l prone to degradation, which is a major operational problem associated with the capture process. The nature of solvent degradation in catalyst -aided CO2 capture has not been reported before, and thus, the effect of catalyst on solvent or vice versa is unknown. This work evaluates the effect of catalyst on solvent degradation and vice versa using BEA-AMP bi -blend solvent and recent absorber and desorber catalysts , which have produced remarkable CO2 capture performance. The absorber and desorber catalysts are CNTs/K-MgO and Ce(SO4 )2 /ZrO2 , respectively. A preliminary stability study was conducted under typical absorption conditions in a semi -batch mode. The results revealed that CNTs/K-MgO increases solvent degradation. Degradation was direct ly proportional to temperature in the region of 313-333K. It was also found that the catalyst reduces the activat ion energy of degradation by 11%. In addition, NH3 emissions from the degradation cell s increased wi th temperature . However, emissions were lower with the addition of catalyst due to the presence of colloidal silica used in binding the catalyst . The absorber catalyst was further investigated using normal conditions of the absorber during capture . The results showed 41 and 30% increments in degradation rates of BEA and AMP, respectively, with the catalyst . The effect of Ce(SO4 )2 /ZrO2 on the solvent was investigated in a bench-scale CO2 capture plant . The catalyst increased degradation by 23% for BEA and 20% for AMP. The effect of catalytic degradation on performance was evaluated by comparing the CO2 cyclic capacities of the catalytic and non-catalytic runs on the f irst and last days of the experiment . The results showed that the cyclic capacity of the catalytic run was 25% higher than the non-catalytic run on the last day, which is 18% lower than that obtained on the first day. Again, the decline in cyclic capacity of the catalytic system was faster by 10% due to the additional effect of catalyst on speeding amine degradation. The Ce(SO4 )2 /ZrO2 -aided degraded solvent was further tested with CNTs/K-MgO in the semi -batch mode. Further degradation was observed, showing that the combined ef fect of both catalysts would be higher in a typical capture plant . The fresh and spent catalysts from the test runs were characterized and compared to assess the stability of the catalysts. From the results, there were changes to the physical and chemical properties of the catalysts, which are known to be essential for CO2 capture. Increased degradation translates to a higher solvent replacement cost . Therefore, the findings of this work would represent the first step in developing better catalysts that would have a significantly reduced effect on the stability of the solvent to lower the cost of capture.Item Open Access Beyond Net-Zero Carbon Emissions in Industrial Process through Catalyst-Aided Amine Solvents for the Indirect Co-Combustion of Natural Gas and Biomass(2024-11-06) Nii-Adjei Adjetey, Samuel; Appiah, Foster; Natewong, Paweesuda; Narku-Tetteh, Jessica; Supap, Teeradet; Idem, RaphaelThis poster demonstrate research efforts undertaken to explore innovative approaches to achieving net-zero carbon emissions in industrial processes by integrating catalyst-enhanced amine solvents for the indirect co-combustion of natural gas and biomass. The research focuses on the development and optimization of heterogeneous solid-base catalysts to enhance CO₂ absorption rates, improve solvent loading, and increase overall process efficiency. Various catalysts, including PEI-modified catalysts, K/MgO, K/MgO-CaO, and activated carbon blends, were synthesized and evaluated. Results indicated significant improvements in CO₂ capture rates, with the K/MgO-CaO catalyst demonstrating notable chemical, thermal, and mechanical stability. Furthermore, a life cycle assessment (LCA) based on the ReCiPe methodology highlighted the environmental benefits of this novel catalyst-solvent system compared to conventional MEA-based carbon capture and the novel solvent AMP:PRLD. This work presents a promising pathway for power and energy sectors to enhance sustainability, reduce emissions, and move beyond net-zero targets.Item Open Access Development of Criteria for Selection of Components for Formulation of Amine Blends Based on Structure and Activity Relationships of Amines, and Validation of Formulated Blends in a Bench Scale CO2 Capture Pilot Plant(Faculty of Graduate Studies and Research, University of Regina, 2017-09) Narku-Tetteh, Jessica; Idem, Raphael; Ibrahim, Hussameldin; Supap, Terradet; deMontigny, David; Zeng, FanhuaDue to modernisation and industrialisation, an increase in the global energy demand is inevitable. Nuclear, fossil fuels, renewables, hydro and biomass are the major sources of energy. However, considering the current energy framework, fossil fuels appear to be the most reliable and stable energy source. As a result, emphasis on the reduction of emissions of carbon dioxide (CO2, a major type of greenhouse gas (GHG)) is very crucial because almost all fossil fuel activities lead to generation of this environmentally harmful GHG. Scientists have shown that the average global temperature has increased by up to about 1 degree over the last century. Thus, if this issue is left unabated, it will have long lasting consequences both on human lives and the environment. Extreme weather conditions, heat waves, sea level rise, wild fires, health problems are glaring repercussions of global warming and climate change. Various strategies such as use of alternative energy, energy conservation or fossil fuel-energy coupled with carbon capture and sequestration (CCS) are all attempts to mitigate this problem. However, CCS stands out to be the anchor technique due to its compatibility with existing energy infrastructure in conjunction with the reliability of fossil fuel-based energy itself. Post combustion capture which uses a regenerable liquid sorbent, appears to be the predominant technology used and has proven to be successful in most industrial applications. However, this technology is still far from being perfect. My thesis research addresses the imperfections and challenges identified with this technique from the context of sorbent formulation. Optimum sorbent performance cannot be achieved with one single amine sorbent. It is therefore essential to develop new amine sorbent systems by blending and combining their individual strengths to achieve an optimum performance sorbent. Most approaches used to solve this problem use indirect means whereas we need the type of studies that will directly link the chemical structure of the amine sorbent to its performance since this will provide the key in unlocking the rationale in selecting the blend components. For this reason, my research objective focuses on coming up with a rational way to use a fundamental chemical structure – activity relationship study to develop and formulate an optimum sorbent blend. This novel blend is validated in a bench scale pilot plant to ensure that the developed criterion leads to a blend that is practical and implementable. The effects of the chemical structure, namely, side chain structure and number of hydroxyl groups in primary, secondary and tertiary amines as well as the alkanol chain length in primary alkanolamines and the alkyl chain length in secondary and tertiary alkanolamines on amin activities such as CO2 absorption and desorption kinetics, equilibrium loading, heat duty, cyclic capacity, heat of absorption and pKa were studied and used to develop rational criteria for selecting components to formulate an optimum amine blend. Based on the criteria, amines that had a combination of high CO2 absorption parameter and high CO2 desorption parameter were selected. Their mixing ratios and concentrations were varied to obtain the best overall performance. The optimum blend was then validated in a bench scale pilot plant and compared with the benchmark 7M MEA-MDEA solvent blend. The role of a solid acid catalyst in aiding CO2 desorption and further enhancing the performance of the developed novel blend was tested and, again, compared to the benchmark 7M MEA-MDEA blend. The results of this study showed that, in comparison with their straight-chain analogues, steric hindrance present in branched-chain alkanolamines resulted in much faster desorption rate, higher equilibrium CO2 loading and cyclic capacity, much lower heat duty for solvent regeneration, but just a slight decrease in CO2 absorption rate. The effect of chain length studies also showed that, longer alkanol chain lengths of primary alkanolamines and longer alkyl chain lengths of secondary and tertiary alkanolamines led to higher equilibrium CO2 loading and pKa. However, the influence of mass transfer limitations on these positive effects resulted in a maximum trend for initial rate of CO2 absorption for secondary and tertiary alkanolamines. On the other hand, the increase in the chain lengths also caused the generation of larger amounts of bicarbonate ions which resulted in higher CO2 desorption rates and cyclic capacity, but lower heat duty. However, the longer chain alkanolamines also had high viscosities which adversely modified their performance by also introducing mass transfer limitations. The developed criteria, in terms of absorption parameter and desorption parameter, resulted in formulating an excellent bi-solvent aqueous amine blend (comprising 2M BEA + 2M AMP), which had an outstanding desorption characteristics/heat duty as well as very good absorption characteristics. In addition, this work developed a new non-trial-and-error procedure to determine the heat of CO2 absorption based on Gibbs-Helmholtz equation. Also, the pilot plant studies showed that the novel blend, 4M BEA-AMP blend showed outstanding performance in absorber efficiency, heat duty and cyclic capacity over the 7M MEA-MDEA blend, implying that it is a good potential solvent for post combustion CO2 capture thereby validating the developed selection criteria that yielded the 2M BEA + 2M AMP blend. The addition of catalyst in the process led to tremendous improvements in all the performance indicators of the two solvent blend systems.Item Open Access Oxidative Degradation of Diethanolamine Solvent Induced By Nitrogen Dioxide and Dissolved Materials in Post-Combustion Capture of CO2 From Industrial Exhaust Gas Streams(Faculty of Graduate Studies and Research, University of Regina, 2021-09) Pradoo, Patit; Idem, Raphael; deMontigny, David; Ibrahim, Hussameldin; Supap, Teeradet; Narku-Tetteh, Jessica; Zeng, FanhuaSolvent degradation is a serious and well-known operational problem in the postcombustion CO2 capture process using amine-based solvents. It is caused by undesired side reactions between the amine and flue gas impurities such as oxygen, nitrogen oxides (NOx), sulfur oxides (SOx), and fly ash particulate, resulting in a significant decrease in performance and efficiency as well as an increase in operational costs for solvent management. In addition, there are human and environmental concerns regarding the emergence of carcinogenic compounds, N-nitrosamines, which are contributed by the reaction between secondary amines and NOx in the flue gas. Moreover, heavy metalcontaining compounds from fly ash, equipment leaching, and metal-based corrosion inhibitor, once dissolved into the solution, can play a catalytic role by accelerating the degradation reactions. This study aimed to understand the role of degradation-inducing components, namely oxygen, nitrogen dioxide, and dissolved transition metals on the degradation of a secondary amine solvent, diethanolamine (DEA), by measuring the degradation rate of DEA, formation rate of products (i.e. formate and monoethanolamine), and emission rate of ammonia. The degradation experiments were performed at 80 ℃ at atmospheric pressure for 14 days by continuously passing synthetic flue gas through 5 M diethanolamine solution (⍺ = 0.2 mol/mol) associated with dissolved metal. Iron (II), iron (III), and copper (II) at concentrations 0, 1, and 100 μM were studied. The synthetic flue gas contained 6% O2 with 0 – 50 ppm NO2. Degradation products in the liquid phase were identified by GC-MS and CE-DAD. The off-gas was analyzed for ammonia production. Degradation products identified in this study include MEA, MDEA, bicine, ammonia, formate, acetate, glycolate, oxalate, HEOD, BHEP, and N,N-Bis(2- hydroxyethyl)formamide. Formation pathways for all the products are proposed. In terms of the catalytic effect, the ranking was as follows: 1 μM iron (III) > 1 μM iron (II). Copper (II) did not exhibit a catalytic effect towards DEA degradation or ammonia emission. Dissolved metal at concentration of 100 μM, however, considerably reduced the degradation rate of DEA as well as the formation rate of products. This suggests saltingout effect, in which the high concentration of metal salt can lower the solubility of oxygen, resulting in less degradation. NO2 was found to increase the degradation rate of DEA as well as the emission rate of ammonia. The presence of dissolved iron also promoted the DEA degradation rate under the influence of NO2. The synergistic effect of NO2 and dissolved iron caused DEA to degrade more substantially. Therefore, in the real-world operation where NO2 and dissolved iron are encountered, secondary amines like DEA should be avoided.