Over the past 50 years the use of fossil fuels has lead to a 22% increase in the CO2 concentration levels in the atmosphere. It has also been recognized that the energy producing sector, coal-fired power plants in particular, contribute approximately 33% of the total global emissions. It is of immediate concern that a technology be developed that can be retrofit to the power plants in order to capture CO2 from the flue gas, eliminating a significant source of CO2 emissions. Current commercialized technologies such as liquid amine scrubbing using monoethanolamine (MEA) and chilled ammonia capturing processes have demonstrated successful capture of CO2 gas but involve using highly toxic and corrosive compounds with high heats of regeneration. Development of a solid immobilized amine sorbent that exhibits high CO2 capture and cyclical stability may prove to be a more sensible solution due to its low heat of regeneration, toxicity, and corrosive properties. In this study, fumed silica was chosen as the solid support because of its high commercial availability and high surface area.
In this thesis, silica based sorbents were developed through impregnation of tetraethylenepentamine (TEPA) at various weight percent ratios and further modified with the addition of polyethylene glycol (PEG) to aid in dispersing TEPA and cyclical stability of the sorbent. Although the development of sorbents using the same compounds have been reported on in literature, there has been no work done using infrared (IR) characterization to determine the way the compounds interact with each other and with the surface. This thesis has been constructed in order to develop an understanding of these surface interactions and use it to fabricate the best possible sorbent. The IR results concluded that the co-impregnation of PEG and TEPA with corresponding TEPA/PEG/SiO2 weight ratios of 24/36/40 yielded the highest CO2 capture capacity (2.53 mmolCO2/gramSorbent) and best cyclical stability (3% degradation).
A gram scale process was also developed for the adsorption and regeneration of CO2 gas from a feed stream of 15% CO2. The process was designed mirroring industrial conditions and resulted in good initial CO2 regeneration concentrations.