Doctor of Philosophy, University of Akron, 2009, Chemical Engineering

The increase in CO2 emissions over past decades are the result of a growing dependence on fossil fuels. Examination of CO2 emission sources revealed that more than 33% of global CO2 emissions result from coal-fired power plants, which represent the largest stationary source of CO2. Two proposed approaches for reduction of CO2 emissions: (i) a short term (i.e. 7-10 years) capture of CO2 from coal-fired power plants and (ii) a long term (i.e. 10-15 years) approach is the replacement of coal-fired power plants by coal-based fuel cells. These approaches purify CO2 for sequestration. Carbon capture from existing power plants could be accomplished by passing the flue gas through a sorbent. The sorbent captures the CO2 from the flue gas then regenerated producing purified CO2. Direct coal fuel cells directly convert coal to electricity through the electrochemical oxidation of carbon. The mixing of air and coal does not occur in the fuel cell, leading to highly concentrated CO2 effluent for sequestration. CO2 capture was investigated by transient flow, bed temperature measurement, and temperature programmed CO2 desorption coupled with IR effluent measurement of seventeen sorbents, which had SiO2, carbon, or beta zeolite as a support. The heat released during the exothermic adsorption of CO2 onto amine resulted in a bed temperature rise. The heat generated could be dissipated with a smaller particle size and greater thermal conductivity. The heat released was used to verify the capture capacity using a thermal camera and high throughput adsorber that screened thirteen sorbents simultaneously. The carbon initially investigated produced an ammonia odor and had a low capture capacity. The ammonia odor was the result of acid-base interaction between the support and amine groups. The use of a neutral carbon increased the capture capacity to 2.8 mmol CO2/g-sorbent. Beta zeolite, which captures 1.8 mmol CO2/g-sorbent, was found to contain acid sites that lowered the capture capaci (open full item for complete abstract)

Committee: Steven S.C. Chuang PhD (Advisor) Subjects: Chemical Engineering; Energy; Environmental Engineering

Doctor of Philosophy, The Ohio State University, 2012, Chemistry

Separation efficiency is inversely proportional to the diameter of the particles of the stationary phase. Accordingly, a major aim of current separations research is focused on the reduction of both the diameter and particle-to-particle size variation of sorbent materials utilized as stationary phases. Herein, novel methods for the fabrication and application of various nanoscale stationary phases are described. Electrospinning is a simple and cost-effective method of generating nanofibers; here both polymeric and carbon electrospun nanofibers are applied as sorbent materials. Carbon nanofibers are of particular interest; graphite and glassy carbon are widely utilized in separation science due to their chemical and mechanical stability and unique selectivity. Electrospun carbon nanofibers have proven to be ideal for use as an extractive phase for solid phase microextraction (SPME) and have been successfully coupled to both gas and liquid chromatography. The high surface area nanofibrous mat provides extraction efficiencies for both polar and nonpolar compounds that range from 2-8 times greater than those attainable using currently available commercial SPME fibers. The electrospun nanofibrous SPME phases proved to be very stable when immersed in a range of solvents, demonstrating increased stability relative to conventional liquid SPME coatings. The chemical and mechanical stability of the electrospun carbon nanofiber SPME phases expands the range of compounds that are applicable to SPME while extending the lifetime of the SPME fibers. Molecularly imprinted (MI) electrospun polymeric and carbon nanofibers were also generated using the template molecule dibutyl butyl phosphonate (DBBP), a surrogate for chemical warfare agents. Nicotine was also used as a template molecule. The MI-nanofibers imprinted with DBBP were applied as an adsorbent for SPME. The MI-SPME fibers preferentially adsorbed the DBBP template molecule relative to the non-imprinted SPME fibers, demo (open full item for complete abstract)

Committee: Susan Olesik PhD (Advisor); Claudia Turro PhD (Committee Member); Anne Co PhD (Committee Member); Hua Wang PhD (Committee Member) Subjects: Analytical Chemistry; Chemistry; Nanotechnology; Polymers

Master of Science, University of Akron, 2011, Chemical Engineering

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 hy (open full item for complete abstract)

Committee: Steven S.C. Chuang Dr. (Advisor); George Chase Dr. (Committee Member); Bi-min Zhang Newby Dr. (Committee Member) Subjects: Chemical Engineering; Climate Change; Energy; Engineering; Environmental Engineering; Technology

Doctor of Philosophy, University of Akron, 2011, Chemical Engineering

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 (open full item for complete abstract)

Committee: Steven Chuang Dr. (Advisor); George Chase Dr. (Committee Member); Edward Evans Dr. (Committee Member); Stephen Cheng Dr. (Committee Member); Christopher Miller Dr. (Committee Member) Subjects: Chemical Engineering