Environmental Engineering
http://hdl.handle.net/10576/3191
2024-03-27T00:46:17ZCATALYST SYNTHESIS AND ACTIVITY EVALUATION FOR CO2 CONVERSION USING REVERSE WATER GAS SHIFT REACTION
http://hdl.handle.net/10576/48549
CATALYST SYNTHESIS AND ACTIVITY EVALUATION FOR CO2 CONVERSION USING REVERSE WATER GAS SHIFT REACTION
EBRAHIMI, PARISA
Forward and reverse water-gas shift (WGS/RWGS) reactions play a significant role in the production of hydrogen and the reduction of carbon dioxide, respectively. The efficiency of these reactions can be further enhanced by the use of a suitable catalyst. The use of transition metals is an effective alternative to noble metals, since they possess excellent catalytic properties for many of the reforming reactions, especially when incorporated into appropriate supports. Considering the vital role of catalysts in the transformation of hydrocarbon-based energy sources, the majority of research attention has been devoted to the development of catalysts that are highly active, selective, stable, economically feasible, and readily accessible.
The primary objective of this research is to study appropriate transition metal-based catalysts, such as Cu and Ni, supported on reducible supports, such as CeO2, for their performance in converting CO2 into CO. To determine the most suitable conditions for synthesizing Cu/CeO2 catalysts through solution combustion synthesis (SCS), two synthesis parameters, e.g., the ratio of fuel to oxidizer (φ) and the metal loading, were adjusted to obtain the highest combustion temperature and gaseous products during the synthesis of catalysts. Bimetallic catalysts were also evaluated for their effect on activity, selectivity, and reducibility on La2O3-supported catalysts in order to determine if there is any synergistic effect caused by the presence of two metals together, e.g., Cu and Ni, on the catalytic performance in RWGS reaction compared to using Cu or Ni alone as active metals supported on La2O3. To evaluate how a suitable additive may eliminate or reduce carbon deposition and boost hydrogen production in the WGS reaction, ammonia, hydrazine, and urea were used in the feed and the distribution of products in the WGS reaction was estimated via thermodynamic calculations. This study also aimed to evaluate the effect of oxygen content and particle size on catalyst performance by manipulating the calcination temperature and metal loading, respectively, prior to the CO2 conversion experiments. Therefore, the active metal composition and calcination temperatures were adjusted to form different crystal structures to investigate metal-support interaction, surface defects, and oxygen vacancies in Cu/ZrO2 catalysts. The activation energies were estimated, and reaction kinetics models were studied in order to understand the governing mechanism of Cu/ZrO2 in RWGS.
Overall, under the same experimental conditions, CeO2 as support showed better catalytic activity than La2O3, with 70% compared to 57% activity at 600 oC. However, the addition of Cu to La2O3-supported Ni catalysts improves CO selectivity and activity through the formation of stable alloys and improves the performance in the RWGS reaction by adjusting the reducibility of the active metals. Besides, the calcination temperature and amount of copper present in Cu/ZrO2 catalysts have a significant effect on the CO2 conversion performance of Cu/ZrO2, with the highest conversion of 37% observed at 600 °C for the catalyst with 2wt.% copper and calcined at 800 °C; however, increasing the metal loading to 5 wt.% and calcination temperature to 1000 oC resulted in losing the catalytic activity. Other supports, such as cobalt oxide, may also be investigated in the future since it has some characteristics that make it effective for WGS reaction and is expected to perform well in RWGS reaction as well.
2023-06-01T00:00:00ZCo2 Removal Using Imidazolium-Based Ionic Liquid -Aspen Plus Modelling Study
http://hdl.handle.net/10576/48145
Co2 Removal Using Imidazolium-Based Ionic Liquid -Aspen Plus Modelling Study
Qureshi, Tooba Ishtiaq
Novel technologies that decrease the level of CO2 in our atmosphere are crucial for minimizing the potential risks associated with climate change, and immediate advancements are needed for such technologies to operate at global level. Ionic liquids are getting prominence as environmentally sustainable solvents, especially as alternatives to traditional media in chemical processes for CO2 capture. This innovative approach of capturing CO2 is extremely effective and affordable. Ionic Liquids (IL) are genuinely customizable solvents since it is possible to adjust the chemical structure of IL to vary nearly all of its physical and chemical characteristics. Despite the fact that ionic liquids have yet to be used on a wide scale and that the industry is still trailing behind mid-term expectations, their advantages suggest that they might one day become a commercial success.
This simulation study investigates the potential of using an ionic liquid as a solvent for carbon sequestration to reduce CO2 emissions and purify industrial waste streams. Specifically, the absorbent EMIMNTF2 (1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide) is studied for its ability to capture CO2 and high energy savings. The study uses the ASPEN PLUS V11 software with the COSMOSAC property model to examine the impact of changing waste stream compositions on process performance, optimize the flow rate of the ionic liquid, and assess the effects of temperature, and vapor/liquid flow ratios on absorber stages. The study also performs an economic analysis and heat integration to demonstrate the efficacy and suitability of the Aspen Plus model in simulating IL absorption with a high percentage of CO2 capture.
Results show that [EMIM][NTF2] can remove up to 99.4% of CO2 from waste industrial effluents using three distinct compositions. Additionally, a flow rate of 20,000 kg/h for the ionic liquid is optimized for the highest purity values of CO2 and CH4, and the total annualized cost for the process is 2.1 million dollars with operating expenses of 1.8 million dollars for a 20-year of plant life with a plant capacity of 4000 kg/h (0.035 Mt/year).
This study proposes a conceptual framework for developing novel ionic liquids for CO2 capture and demonstrates that sustainable [EMIM][Tf2N]-based absorption technique for CO2 capture has the potential to be an industrial technology.
2023-06-01T00:00:00ZThe Application of Nanoparticles Made from Aluminium Foil Waste in Remediating Boron from Desalinated Water
http://hdl.handle.net/10576/48140
The Application of Nanoparticles Made from Aluminium Foil Waste in Remediating Boron from Desalinated Water
Malik, Aakasha
Desalination is a method used to eradicate several salts and minerals so that their concentrations can fall in the acceptable range. Boron is a widely known drinking water contaminant and is broadly dispersed in the ecosystem, from biological or anthropogenic sources, which is why it is significant to remove before reusing the water, as it can have adverse effects on plants and animals. Due to the challenges involved in the removal of boron by desalination, there has been an integration of technologies to increase the removal rate. In this study, boron removal using Aluminium oxide nanoparticles synthesized from Aluminium foil waste was investigated, which is considered an environmentally friendly, cost-effective method, to reduce boron concentrations in desalinated water. Furthermore, the removal was examined at different pH values, initial boron concentration, temperature, and contact time for optimum values. The effect of pH on adsorption showed that the highest adsorption occurred at a higher pH of 10 and temperature variations showed no effect on the adsorption of the nanoparticles. The results were further analysed and compared using Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich adsorption isotherms and kinetic studies. The adsorption isotherms were best fitted to the Langmuir model, the maximum adsorption capacity was 344.8 mg/g at room temperature, while the adsorption kinetics were adequately explained by the pseudo-second order kinetic equation with correlation coefficient (R2 : 0.99).
2023-06-01T00:00:00ZKinetics of CO2 Reaction with Amino-Butanol and Piperazine Using Stopped-Flow Apparatus
http://hdl.handle.net/10576/48134
Kinetics of CO2 Reaction with Amino-Butanol and Piperazine Using Stopped-Flow Apparatus
Fezouni, Fatima Younis
This research project focuses on the kinetics of CO2 reaction with Amino-butanol (AB) and Piperazine (PZ) for carbon capture. The study examines the CO2 reaction rate of different concentrations of the AB-PZ solution (0.2, 0.4, and 0.6 mol/L) at different temperatures. The results reveal that increasing the concentration of the AB-PZ solution enhances the CO2 reaction rate at higher temperatures, and the 0.6 mol/L solution showed the highest efficiency compared to the lower concentration solutions. At 323 K, the CO2 reaction rate of the 0.6 mol/L solution was significantly higher than the efficiency of the 0.2 and 0.4 mol/L solutions. The temperature also has a significant effect on the CO2 reaction rate, with higher temperatures resulting in higher reaction rates.
Moreover, the study suggests that AB-PZ solution could be an effective solution for carbon capture and further optimization of solvent concentration and temperature could lead to even higher reaction rates. The results show that increasing the concentration of Amino Butanol and Piperazine in the CO2 capture solution leads to an increase in the reaction rate constant and CO2 capture capacity. The highest CO2 capture values were observed for the 0.6 mol/L AB-PZ concentration, indicating its potential as a CO2 capture solvent.
In conclusion, this study demonstrates the potential of AB-PZ solution as an effective carbon capture solvent. The results provide insights into the factors that affect CO2 reaction rates and CO2 capture capacity, and suggest that optimization of solvent concentration and temperature could lead to even higher efficiency.
2023-06-01T00:00:00Z