Browsing by Subject "hydrocarbons"

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    Volatility Characterization Of Particle Emissions From Premixed Low Temperature Compression Ignition Combustion
    (2016-07) Lucachick, Glenn
    This thesis constitutes an extensive volatility characterization of particles from engines operating in two low temperature combustion (LTC) modes, partially premixed compression ignition (PPCI), and reactivity controlled compression ignition (RCCI). Low temperature combustion is of research interest because it offers the potential to reduce soot and oxides of nitrogen (NOx) while capitalizing on the inherently high efficiency of compression ignition engines. While particle emissions from conventional diesel combustion (CDC) have been extensively studied and characterized, particle emissions from LTC modes have been shown to be distinctly different, and demand investigation. These particles have been shown to be primarily organic material with small amounts of solid soot and ash, in contrast to particles from CDC that are primarily soot with small amounts of adsorbed organic material. In this work, advanced aerosol experimental techniques have been applied to characterize the volatility of these particles. The results have shown that their composition results in formation that is especially sensitive to dilution conditions. The experimental data have been used to develop aerosol simulations that identify formation mechanisms responsible for the unique volatility characteristics of LTC particle emissions. Particle volatility characteristics shown in the experiments suggest that heavy unburned oil and fuel alkanes contribute greatly to particle growth, forming the bulk of total particle volume. Further, elevated levels of lower molecular weight, low volatility organic compounds resulting from LTC may contribute to the inception of particles due to homogeneous nucleation; however, the results show that despite ultra-low fuel sulfur concentrations, heterogeneous nucleation of particles by sulfuric acid and water is most likely contributor to nucleation mode particle formation for LTC modes.
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    Zeolite MFI Membranes Towards Industrial Applications
    (2020-11) Duan, Xuekui
    Zeolite membranes have been the interest of research for decades due to their potentials in various separation applications including gas separation, water purification, pervaporation, etc. Among the zeolite materials studied, MFI zeolite (Silicalite-1 and ZSM-5) is one of the major subjects of research, mainly because of its suitability for the separation of hydrocarbons, such as n-butane from iso-butane and para-xylene from its isomers. Besides, all-silica Silicalite-1 and high-silica ZSM-5 have been explored for organic/water pervaporation as well by utilizing their high hydrophobicity. Despite years of research efforts on these applications, the industrialization of MFI membranes has not been achieved. One reason is that the cost associated with the fabrication of these membranes is too high to be commercially attractive. The high-cost, specially engineered silica membrane supports account for a major share of the total cost. Alternative supports such as polymeric supports and low-cost and commercially available alumina supports are possible substitutes to explore. Another problem is the lack of demonstration of high membrane separation performance at industrially relevant conditions (high temperature and high pressure). It is thus the goal of this thesis to address these problems and make progress towards the commercialization of MFI membranes. First, the recent advances of MFI zeolite membranes were reviewed. Then, the fabrication of high-performance MFI membranes using aqueous dispersions of open-pore, two-dimensional MFI zeolite nanosheets on low-cost polymeric substrates was demonstrated. Next, progress towards making MFI membranes on alumina supports has been made. Despite these efforts to use other supports, we failed to make high-performance membranes as comparable to the silica-supported ones. Besides these efforts, ultra-thin MFI membranes fabricated using dc-5 nanosheets as seeds were showed to have high xylene isomer separation performance at industrial conditions and high performance for H2/hydrocarbons separation and ammonia/H2/N2 separation. These works demonstrated the potential of high-performance MFI membranes for energy-efficient separation processes in industrial conditions.