As the world energy demand increases and the utilization of non-traditional fossil fuels becomes more attractive, natural gas, from shale gas and in gaseous and liquefied forms, becomes one of the most promising alternative fuels nowadays. The natural gas offers lower fuel production and transportation costs, a lower carbon content, a higher combustion efficiency and a greater applicability to most of existing power plants and combustion engines. Challenges exist, especially in improving its ignition characteristics and to further reduce its greenhouse gas and particulate matter emissions. To overcome these restraints, hydrogen addition, catalyst modification and fuel lean combustion have been investigated recently. In this thesis, the ignition and emission properties of methane and its mixtures with hydrogen additive are first studied in the mini-channel reactor. Numerical investigations have been performed using the CHEMKIN PRO software for pure methane and the mixtures of methane and hydrogen in non-catalytic and catalytic combustion. These effects of the hydrogen fractions, Pt-catalyst, wall temperature and inlet conditions on the ignition delay and NO formation are investigated. Available gas phase kinetics and heterogeneous surface reaction mechanisms in the literature are implemented and analyzed. As the second part of this thesis, natural gas combustion on a counter-flow burner is investigated experimentally and numerically, with a focus on NO formation. The NO profiles, measured by the FT-IR spectroscopy, are compared with model results from CHEMIKIN and with the GRI-Mech 3.0 mechanism. The formation mechanism of NO and effects of the different fuel/oxidizer ratios on the NO formation are investigated.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--Worcester Polytechnic Institute. / Keywords: deactivation; hysteresis; kinetics; structure sensitivity; methane oxidation on palladium. Includes bibliographical references (p. 150-158).

Thesis (Ph. D.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains xii, 162 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 139-150).

The increase in environmental levels of platinum can in part be attributed to the introduction of motor vehicle catalytic converters. Quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) has been evaluated as a analytical tool for the determination of platinum in environmental samples, such as vegetation, roadside dust, soil and sediment. Instrumental parameters were studied and a forward power of 1.4 kW and nebuliser flow rate of 0.95 1 min-1 were shown to give the optimum signal response for the 195Pt+ isotope. A detection limit of 0.12 ng ml-1 was achieved. Iridium was shown to be the most suitable choice for use as an internal standard with the 191Ir+ isotope being monitored. Various digestion methods were studied with aqua regia / hydrofluoric acid open vessel digestion being found to give good recovery for 2 certified reference materials, NIST 2556 (Used Autocatalyst, Pellets) and 2557 Used Autocatalyst, Monolith) with concentrations of 681 (38) mug g-1 and 1085 (32) mug g-1 respectively [certified values 697.4 (2.3) mug g-1 and 1131 (11) mug g-1]. Attention has been given to the problem of spectroscopic interference on 195Pt+ from hafnium oxide. Various correction methods were evaluated with a modification proposed to a previous method of mathematical correction being found to provide the best correction for the 179Hf16O+. An 'in-house' reference sample was prepared from a used catalytic converter and its platinum content of 3563 (176) ng g-1 established through inter-laboratory and inter-method procedures. Common rye grass (Lolium perenne) was shown to uptake platinum from both solid and liquid platinum-containing matrices. The methods developed were applied to a study of roadside dust samples taken from a busy section of the London M25 orbital motorway. The measured platinum levels of up to 194 ng g-1 agree with published literature from other European countries and represent a useful contribution to the knowledge concerning roadside platinum in the UK.

This study reviews catalytic ozonation AOPs and traditional ozone-based AOPs to compare their efficiency for degradation of ozone-recalcitrant compounds. With the world’s population increasing and water becoming a scarce resource, it is important to improve current water recycling methods. Recycling water will play a large role in accommodating the increasing demand, but it will also be necessary to be improve the level of treatment in order to account for emerging contaminants (ECs) such as pharmaceuticals and personal care products. Advanced oxidation processes (AOPs) have been developed to degrade ECs that are not effectively removed by conventional wastewater treatment. The goal of implementing AOPs is to promote the formation of hydroxyl radicals (•OH), which are stronger oxidants than ozone, to degrade recalcitrant compounds. Current AOPs under investigation include ozonation of metal and carbon-based catalysts, known as catalytic ozonation. Traditional ozone-based AOPs currently in use include UV combined with ozone (UV/O3) and hydrogen peroxide combined with ozone (H2O2/O3). Seventeen studies were reviewed to analyze the effectiveness of multiple carbon- and metal oxide-catalytic ozonation AOPs, compared to traditional AOPs. These studies varied in reactor type, water source, pH, catalyst pretreatment, inclusion of competitor species, and flow regime. The variety of testing conditions made comparison difficult, so all studies were compared based on contaminant removal efficiency and degradation rate, as well as general EC degradation and removal of TOC. The addition of metal oxides during ozonation consistently increased rate of removal and in some cases, even doubled the reaction rate. Catalytic ozonation consistently decreased total organic carbon (TOC) levels amongst multiple studies, even in the presence of competitor species. Future work should study the formation and subsequent breakdown of reaction intermediates, role of competitor species, and impact of sorption to the ozonation catalyst.

The RNA World hypothesis describes a period of time during the origins of life in which RNA molecules performed all catalysis and were the only form of information storage. A great deal of evidence has been obtained in support of this hypothesis, however a few key demonstrations are lacking. The first demonstration is of a molecule capable of self-replication that could have plausibly arisen from the prebiotic soup. Previously in the Lehman Laboratory, a 198-nucleotide RNA was discovered that could be fragmented into as many as four pieces ranging from 39 - 63 nucleotides in length. When these pieces were incubated together in a test tube, they re-formed the necessary covalent bonds to regenerate the full-length 198-nucleotide RNA. Furthermore, the full-length RNAs were catalytically active and made copies of themselves from the remaining pieces in solution, providing a model system of self-replication. I was able to remove >10% of the total length of the RNA, which substantially reduced the catalytic activity of the full-length molecule. I discovered several mutations that restored catalytic activity by improved folding and increased catalytic rates using in vitro selection. A subset of these mutations was found to aid in the assembly of the shortened full-length RNA from smaller fragments than were possible in the original system, enhancing the prebiotic relevance of this system. A second demonstration to bolster the RNA World hypothesis would be showing that RNA is capable of harvesting energy from its environment by performing oxidation and reduction reactions. Again using in vitro selection, I have completed five rounds of selection geared towards identifying a ribozyme that reduces benzoic acid to benzaldehyde using Zn2+ and NADH. Results to date suggest the selection is working and it should be continued for another five to ten generations. Finally, I have discovered an RNA sequence that forms knots during transcription, a phenomenon heretofore undocumented in RNA. This new topology has implications for RNA stability by rendering RNA more resistant to hydrolysis, and could impact catalysis through formation of more complex, knotted active sites. Taken together, these findings have improved our understanding of RNA folding and catalysis, and the plausibility of the RNA World.

No description available.

<p> An experimental investigation of polymerisation of several monomers in wood was performed using free radical initiators such as benzoyl peroxide and 2-azo-bis-isobutyronitrile. The most promising comonomer system appeared to be styrene and acrylonitrile. As a result of copolymerisation of styrene and acrylonitrile in the cell cavities of wood, many improvements in physical properties of wood resulted. The improvement in physical properties of wood containing thermo-catalytically copolymerised styrene and acrylonitrile was found to be better than those of radiation initiated graft copolymerised wood. Thermo-catalytically produced wood polymer combinations showed as much improvement in physical properties as shown by those produced by radiation initiation without the use of swelling agents.</p> / Thesis / Master of Science (MSc)

Recently there has been increasing interest in using glycerol as a substrate on steam reforming due to the increase of biodiesel production. With the increase of biodiesel production a glut of glycerol has resulted and this would be a more suitable substrate for value added production of hydrogen from reforming. Reforming biorenewable viscous fluids such as glycerol is difficult due to mass transfer limitations associated with vaporizing glycerol to gas phase before steam reforming. This study was to evaluate the feasibility of reforming electrically atomized liquid phase glycerol by means of a technique called electro-spray. It was hypothesized that reforming electrically charged glycerol nanodroplets on an oppositely charged conductive catalyst will increase the reforming performance as opposed to a neutral catalyst-substrate system. Hydrogen yield, selectivity was increased by 20%, 25% respectively when nanodroplets introduced. Exerting an electrical charge to the substrate-catalytic system significantly enhanced the reforming performance irrespective of the physical phase.