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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

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.
ContributorsLinneen, Nick (Author) / Lin, Jerry (Thesis advisor) / Pfeffer, Robert (Thesis advisor) / Lind, Mary (Committee member) / Rege, Kaushal (Committee member) / Nielsen, David (Committee member) / Anderson, James (Committee member) / Arizona State University (Publisher)
Created2014
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Description
Currently, approximately 40% of the world’s electricity is generated from coal and coal power plants are one of the major sources of greenhouse gases accounting for a third of all CO2 emissions. The Integrated Gasification Combined Cycle (IGCC) has been shown to provide an increase in plant efficiency compared

Currently, approximately 40% of the world’s electricity is generated from coal and coal power plants are one of the major sources of greenhouse gases accounting for a third of all CO2 emissions. The Integrated Gasification Combined Cycle (IGCC) has been shown to provide an increase in plant efficiency compared to traditional coal-based power generation processes resulting in a reduction of greenhouse gas emissions. The goal of this project was to analyze the performance of a new SNDC ceramic-carbonate dual-phase membrane for CO2 separation. The chemical formula for the SNDC-carbonate membrane was Sm0.075Nd0.075Ce0.85O1.925. This project also focused on the use of this membrane for pre-combustion CO2 capture coupled with a water gas shift (WGS) reaction for a 1000 MW power plant. The addition of this membrane to the traditional IGCC process provides a purer H2 stream for combustion in the gas turbine and results in lower operating costs and increased efficiencies for the plant. At 900 °C the CO2 flux and permeance of the SNDC-carbonate membrane were 0.65 mL/cm2•min and 1.0×10-7 mol/m2•s•Pa, respectively. Detailed in this report are the following: background regarding CO2 separation membranes and IGCC power plants, SNDC tubular membrane preparation and characterization, IGCC with membrane reactor plant design, process heat and mass balance, and plant cost estimations.
ContributorsDunteman, Nicholas Powell (Author) / Lin, Jerry (Thesis director) / Dong, Xueliang (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor) / School of Sustainability (Contributor)
Created2014-05
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Description
Amine-modified solid sorbents and membrane separation are promising technologies for separation and capture of carbon dioxide (CO2) from combustion flue gas. Amine absorption processes are mature, but still have room for improvement. This work focused on the synthesis of amine-modified aerogels and metal-organic framework-5 (MOF-5) membranes for CO2 separation. A

Amine-modified solid sorbents and membrane separation are promising technologies for separation and capture of carbon dioxide (CO2) from combustion flue gas. Amine absorption processes are mature, but still have room for improvement. This work focused on the synthesis of amine-modified aerogels and metal-organic framework-5 (MOF-5) membranes for CO2 separation. A series of solid sorbents were synthesized by functionalizing amines on the surface of silica aerogels. This was done by three coating methods: physical adsorption, magnetically assisted impact coating (MAIC) and atomic layer deposition (ALD). CO2 adsorption capacity of the sorbents was measured at room temperature in a Cahn microbalance. The sorbents synthesized by physical adsorption show the largest CO2 adsorption capacity (1.43-1.63 mmol CO2/g). An additional sorbent synthesized by ALD on hydrophilic aerogels at atmospheric pressures shows an adsorption capacity of 1.23 mmol CO2/g. Studies on one amine-modified sorbent show that the powder is of agglomerate bubbling fluidization (ABF) type. The powder is difficult to fluidize and has limited bed expansion. The ultimate goal is to configure the amine-modified sorbents in a micro-jet assisted gas fluidized bed to conduct adsorption studies. MOF-5 membranes were synthesized on α-alumina supports by two methods: in situ synthesis and secondary growth synthesis. Characterization by scanning electron microscope (SEM) imaging and X-ray diffraction (XRD) show that the membranes prepared by both methods have a thickness of 14-16 μm, and a MOF-5 crystal size of 15-25 μm with no apparent orientation. Single gas permeation results indicate that the gas transport through both membranes is determined by a combination of Knudsen diffusion and viscous flow. The contribution of viscous flow indicates that the membranes have defects.
ContributorsRosa, Teresa M (Author) / Lin, Jerry (Thesis advisor) / Pfeffer, Robert (Thesis advisor) / Dai, Lenore (Committee member) / Nielsen, David (Committee member) / Arizona State University (Publisher)
Created2010
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Description

In 2019, the World Health Organization stated that climate change and air pollution is the greatest growing threat to humanity. With a world population of close to 8 billion people, the rate of population growth continues to increase nearly 1.05% each year. As the world population grows, carbon dioxide emissions

In 2019, the World Health Organization stated that climate change and air pollution is the greatest growing threat to humanity. With a world population of close to 8 billion people, the rate of population growth continues to increase nearly 1.05% each year. As the world population grows, carbon dioxide emissions and climate change continue to accelerate. By observing increasing concentrations of greenhouse gas emissions in the atmosphere, scientists have correlated that the Earth’s temperature is increasing at an average rate of 0.13 degrees Fahrenheit each decade. In an effort to mitigate and slow climate change engineers across the globe have been eagerly seeking solutions to fight this problem. A new form of carbon dioxide mitigation technology that has begun to gain traction in the last decade is known as direct air capture (DAC). Direct air capture works by removing excess atmospheric carbon dioxide from the air and repurposing it. The major challenge faced with DAC is not capturing the carbon dioxide but finding a useful way to reuse the post-capture carbon dioxide. As part of my undergraduate requirements, I was tasked to address this issue and create my own unique design for a DAC system. The design was to have three major goals: be 100% self-sufficient, have net zero carbon emissions, and successfully repurpose excess carbon dioxide into a sustainable and viable product. Arizona was chosen for the location of the system due to the large availability of sunlight. Additionally, the design was to utilize a protein rich hydrogen oxidizing bacteria (HOB) known as Cupriavidus Necator. By attaching a bioreactor to the DAC system, excess carbon dioxide will be directly converted into a dense protein biomass that will be used as food supplements. In addition, my system was designed to produce 1 ton (roughly 907.185 kg) of protein in a year. Lastly, by utilizing solar energy and an atmospheric water generator, the system will produce its own water and achieve the goal of being 100% self-sufficient.

ContributorsMacIsaac, Ian (Author) / Lin, Jerry (Thesis director) / Ovalle-Encinia, Oscar (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor) / Historical, Philosophical & Religious Studies, Sch (Contributor)
Created2022-05
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Description
This study deals with various flow field designs for anode, cathode, and coolant plates for optimizing the performance of proton exchange membrane fuel cell using H2 and air. In particular, the 3D models with various flow field patterns such as single parallel serpentine (anode), multi parallel (anode), multi-parallel serpentine (cathode),

This study deals with various flow field designs for anode, cathode, and coolant plates for optimizing the performance of proton exchange membrane fuel cell using H2 and air. In particular, the 3D models with various flow field patterns such as single parallel serpentine (anode), multi parallel (anode), multi-parallel serpentine (cathode), multi serpentine (cathode) have been evaluated for enhancing the fuel cell performance at 60 oC, with three different coolant flow designs (mirror serpentine, multi serpentine and parallel serpentine). Both the peak power and limiting current density are considered based on the parameters such as temperature distribution, pressure distribution, reactants/species distribution and the membrane water content on the active area (50 cm2) region. It is interesting to note that the coolant channel also has a significant effect in regulating the fuel cell performance at high current densities, in addition to reactant gas flow channels. The simulated single cell with Nafion (thickness: 18 m) demonstrates a peak power density of 0.97 W.cm-2 with single parallel serpentine (anode), multi parallel serpentine (cathode) and serpentine (coolant) and 0.91 W.cm-2 with multi parallel (anode), multi serpentine (cathode), and parallel serpentine (coolant) flow field designs. The simulated fuel cell performance is also experimentally validated with four cells at 60 oC using H2 fuel and air as the oxidant.
ContributorsAhmed, Rafiq (Author) / Mada Kannan, Arunachala (Thesis advisor) / Torres, Cesar (Committee member) / Lin, Jerry (Committee member) / Arizona State University (Publisher)
Created2023