Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 314-328). Available also in a digital version from Dissertation Abstracts.

Thesis (M.S.)--Virginia Polytechnic Institute, 1951. / Vita. Includes bibliographical references (leaves 105-112). Also available via the Internet.

Thesis (Ph. D.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xvi, 214 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 199-208).

Thesis (M.S.)--West Virginia University, 1998. / Title from document title page. Document formatted into pages; contains xi, 84 p. : ill. Includes abstract. Includes bibliographical references (p. 64-67).

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Biodiesel is one of the most widely used biofuels in the world, due in part to its simplicity of production, compatibility with existing engines, and reduction of green house gas emissions. However, technical difficulties with biodiesel include: (1) the need of highly refined oil for ASTM compliance, (2) incompatibility with the petroleum-diesel pipeline distribution system, and (3) a relatively small inventory of expensive feedstocks. Issues (1) and (2) could be overcome by the production of biofuels using chemical processes associated with petroleum refining. Catalytic lipid cracking could result in green diesel, a fuel chemically similar to conventional diesel but derived from a clean renewable feedstock. The impact of phosphorus poisoning on catalytic cracking of lipids has been studied in this work using both homogeneous and heterogeneous catalysts. Catalytic cracking of model lipids was shown to occur in a homogeneous liquid phase with triflic acid, a superacid 100 times more acidic than sulfuric acid. Products obtained from the reaction were heavily oxygenated and generally unsuitable for fuel use, suggesting the need for heterogeneous catalytic cracking. Reaction kinetics show a high linear dependence on Brönsted system acidity, with an overall reaction order of 3. The affect of phosphorus on heterogeneous acid cracking was then studied. Since lipid feedstocks contain small amounts of phospholipids knowledge of the interactions between phospholipids and zeolites is crucial to a system-wide understanding of the lipid cracking process. Phosphorus-containing compounds were used to poison ZSM-5 (a solid zeolite catalyst) in order to simulate the cracking of phospholipids. Model compounds were then cracked over the poisoned zeolite, with differences in product distribution and kinetics based on phosphorus loading recorded. It was shown that phosphorous has a dramatic effect on both conversion and product distribution of cracking reactions. It is believed that phosphorous binds irreversibly to heterogeneous active sites, causing the majority of deactivation. To address the issue of limited feedstock availability, research was also undertaken to find new lipids sources for biofuel use. It was determined that lipids extracted from microorganisms grown in a municipal wastewater treatment system could be suitable. However, any phosphorous must be removed before catalytic cracking of the extracted lipids.

Since careful consideration must be given to the catalyst used in catalytic cracking operation in the petroleum industry to assure economic operation, laboratory catalyst activity test units have been developed. These units approximate the conditions in large scale commercial cracking units. It was the purpose of this investigation to determine the amount of cracking that was obtained from catalytic effects in cracking a standard light East Texas gas oil over a Houdry pellet catalyst when compared to the cracking over silica at temperatures from 500 to 1200 °F in a catalyst activity test unit. A catalyst activity test unit was used to determine the percentage conversion of the feed oil to lower molecular weight hydro-carbons using a Houdry pellet catalyst in one series of tests and silica, which is regarded to be noncatalytic, in another series. Fifteen determinations were made at various temperatures from 580 to 1190 °F and a space velocity of 1.0 volume of feed per volume of catalyst per hour. Ten determinations were made at a space velocity of 2.0 volumes of feed per volume of catalyst per hour at temperatures from 595 to 1160 °F. Data were collected on the quantity of liquid and gaseous products produced, as well as the operating conditions employed. After each cracking determination, the packing was regenerated by heating in the presence of air to burn off any carbonaceous deposits. At a space velocity of 1.0. and various temperatures ranging from 580 to 1190 °F the use of Houdry pellet catalyst produced more cracking than silica at like temperatures. The use of the catalyst effectively reduced the temperatures of the cracking reactions approximately 300 °F at a space velocity of 1.0. The effect of the catalyst was lessened by the effect of temperature at approximately 1200 °F and a space velocity of 1.0. When cracking over silica changing the space velocity from 1.0 to 2.0 raised the temperature required 50 °F for a given amount of cracking. / Master of Science

Steam reforming is the most economical and widely-used route for the conversion of light hydrocarbon (such as natural gas) to various valued-added products. This process is commonly carried out over a low-cost alumina-supported nickel catalyst, which often suffers from carbon deposition resulting in loss of active sites, flow and thermal maldistribution, as well as excessive pressure drop. A bimetallic catalyst with improved anti-coking properties was formulated by incorporating the nickel-based system (15% loading) with cobalt metal (5% loading). Two-level factorial design was employed to investigate the effect of major preparation variables, namely impregnation pH value (2-8), calcination temperature (873-973 K), heating rate (5-20 K min-1) and time (1-5 h). The catalysts prepared were subjected to various characterisation techniques to determine key physicochemical properties (i.e. BET area, H2-chemisorption and NH3- TPD acidity). X-ray diffraction revealed that NiO, Co3O4, NiCo2O4 and a proportion of Ni(Co)Al2O4 aluminates were transformed during H2-reduction to active Co and Ni crystallites. TEM images showed an egg yolk profile in the low-pH catalyst suggesting that main deposition site was located in the particle centre, while metal deposition occurred primarily around the particle exterior for the high-pH catalyst. Temperature programmed experiments were carried out to examine the extent of conversion, type of surface species and solid-state kinetics (using the Avrami-Erofeev model) involved during various stages in catalyst life-cycle (calcination, reduction, oxidation and regeneration). Steam reforming analysis suggested that enhanced catalyst activity may be due to synergism in the Co-Ni catalyst. Specifically, the low-pH catalyst exhibited better resistance towards carbon-induced deactivation than the high-pH formulation. The study also provided the first attempt to develop a quantitative relation between catalyst preparation conditions and its performance (activity, product selectivity and deactivation) for steam reforming reaction. Deactivation and reforming kinetic coefficients were simultaneously evaluated from propane reforming conversion-time data under steam-to-carbon ratios of 0.8-1.6 and reaction temperatures between 773-873 K. The time-dependent optimum operational policy derived based on these rate parameters gave better conversion stability despite the heavy carbon deposit. Thermal runs further showed that the catalysts regenerated via two-stage reductive-oxidative coke burn-off exhibited superior surface properties compared to those rejuvenated by a single-step oxidation.

Steam reforming is the most economical and widely-used route for the conversion of light hydrocarbon (such as natural gas) to various valued-added products. This process is commonly carried out over a low-cost alumina-supported nickel catalyst, which often suffers from carbon deposition resulting in loss of active sites, flow and thermal maldistribution, as well as excessive pressure drop. A bimetallic catalyst with improved anti-coking properties was formulated by incorporating the nickel-based system (15% loading) with cobalt metal (5% loading). Two-level factorial design was employed to investigate the effect of major preparation variables, namely impregnation pH value (2-8), calcination temperature (873-973 K), heating rate (5-20 K min-1) and time (1-5 h). The catalysts prepared were subjected to various characterisation techniques to determine key physicochemical properties (i.e. BET area, H2-chemisorption and NH3- TPD acidity). X-ray diffraction revealed that NiO, Co3O4, NiCo2O4 and a proportion of Ni(Co)Al2O4 aluminates were transformed during H2-reduction to active Co and Ni crystallites. TEM images showed an egg yolk profile in the low-pH catalyst suggesting that main deposition site was located in the particle centre, while metal deposition occurred primarily around the particle exterior for the high-pH catalyst. Temperature programmed experiments were carried out to examine the extent of conversion, type of surface species and solid-state kinetics (using the Avrami-Erofeev model) involved during various stages in catalyst life-cycle (calcination, reduction, oxidation and regeneration). Steam reforming analysis suggested that enhanced catalyst activity may be due to synergism in the Co-Ni catalyst. Specifically, the low-pH catalyst exhibited better resistance towards carbon-induced deactivation than the high-pH formulation. The study also provided the first attempt to develop a quantitative relation between catalyst preparation conditions and its performance (activity, product selectivity and deactivation) for steam reforming reaction. Deactivation and reforming kinetic coefficients were simultaneously evaluated from propane reforming conversion-time data under steam-to-carbon ratios of 0.8-1.6 and reaction temperatures between 773-873 K. The time-dependent optimum operational policy derived based on these rate parameters gave better conversion stability despite the heavy carbon deposit. Thermal runs further showed that the catalysts regenerated via two-stage reductive-oxidative coke burn-off exhibited superior surface properties compared to those rejuvenated by a single-step oxidation.