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Fischer-Tropsch (FT) synthesis is a reaction which entails the conversion of synthesis gas, also known as syngas (a mixture of H2 and CO gases), to liquid hydrocarbon fuels, oxygenated hydrocarbons, chemicals and water. This syngas mixture is obtained from natural gas, coal, petroleum, biomass or even from organic wastes. In this study cobalt catalysts supported on novel carbon spheretitania (CS-TiO2) composite materials were synthesized and tested for their performance in the FT process. Initially carbon spheres (d = 80-120 nm) were prepared in a vertical swirled floating chemical vapour deposition reactor without the use of a catalyst. The rate of production was controlled and the highest production rate of about 195 mg/min was obtained at an acetylene (C2H2) flow rate of 545 mL/min at 1000 °C. The produced carbon spheres (CSs) had a narrow size distribution with a uniform diameter size. Purification and functionalisation of the CSs improved the total surface area, due to the removal of PAHs which blocked the CS pores. The introduction of functional groups to the CSs was achieved and these changed the wetting properties of the CSs. Functionalising the CSs for longer than 17 h in HNO3 destroyed the morphology of the CSs. After successful preparation of functionalised CSs, the interactions between CSs and TiO2 were studied by in the TiO2 composite using two different sol-gel methods, namely the conventional sol-gel and the surfactant wrapping sol-gel method. The surfactant wrapping sol-gel method entailed the modification of the CSs by dispersing them in a surfactant, in this case hexadecyltrimethylammonium bromide or CTAB [(CH3(CH2)15N(CH3)3Br]. This introduced alkyl “tails” which eased the dispersability of the CSs before coating them with Ti[O(CH2)3CH3]4 (a source of TiO2) to produce a homogeneously coated CS-TiO2 composite material (defined as ASW3). It should be mentioned that many, many experiments were performed to develop an efficient and reliable method to make homogeneously coated CS-TiO2 composites since it was found to be very difficult to achieve an interaction between carbonaceous materials and TiO2 especially by sol-gel procedures. The traditional sol-gel method was used to prepare CS-TiO2 composites with different ratios viz. 1CS-1SG, 1CS-2.5SG, 1CS-5SG, 1CS-10SG, 1CS-25SG and 1CS-50SG. These composites showed weak interactions between CSs and TiO2 even at high TiO2 loading ratio. Interestingly the surface area of these composites showed high values of 80 and 85 m2/g for 1CS-5SG and 1CS-10SG, respectively. At lower TiO2 ratios the measured surface area was similar to that of CSs, i.e 10 m2/g for 1CS-1TiO2. At high TiO2 ratios the measured surface area was similar to that of TiO2, i.e 49 m2/g for 1CS-50TiO2. The TEM images of CS-TiO2 (ASW3) composites prepared by surfactant wrapping methods showed a successful TiO2 coating of CSs. The TiO2 grain size was 8.0 nm with both anatase and rutile phases. High surface areas (up to 98 m2/g) of composite materials were achieved by employing this procedure. The high surface areas achieved suggest that the interaction between CSs and TiO2 was homogeneous and the increase was due to the “bridge” formed between CSs and TiO2. A series of cobalt catalysts (10% by weight) supported on these materials was carried out by the deposition precipitation method using Co(NO3)2·6H2O as the metal precursor. After appropriate drying and calcination the catalysts were characterized using traditional characterisation techniques and tested in the FT reaction using a fixed bed reactor. The the 10%Co/CS catalyst produced a CO conversion of 15.2% while the catalyst had a low total BET surface area (6 m2/g) compared to non-carbonaceous catalysts with higher BET surface areas. This observation suggests that the surface area did not necessarily play a role in the CO conversion, but that other properties (reducibility and dispersion) of CSs influenced the catalyst activity. After coating CSs with TiO2 and loading cobalt to produce 10%Co/ASW3 both the BET surface area of the catalyst and the CO conversion increased to 83 m2/g and 20.1%, respectively. CO-TPD of 10%Co/ASW3 showed a large amount of strongly adsorbed CO. This increased CO was due to the interaction between CSs and TiO2 which developed CO adsorptive sites.

Thesis advisor: John Ebel / The New Madrid Seismic Zone (NMSZ) is well known for producing some of the largest intra-cratonic earthquakes within the North American Plate. The common hypothesis for the geological structure within the NMSZ is that stress is released across three major faults: the Cottonwood Grove Fault, the New Madrid North Fault, and the Reelfoot Thrust Fault. Evidence exists that would suggest an alternative model of geologic deformation in the area: that stress is being released across more than these three faults. A geologic and geophysical investigation was done to investigate a hypothetical fault west of Dyersburg, TN to test the alternative multi-fault hypothesis. A seismically created sand blow was logged in close proximity to the fault projection. Weathering of the sand blow indicated that the age of the sand blow came from a seismic event prior to the 1811-1812 earthquakes. There was no evidence to confirm this sand blow was created by a hypothetical fault in close proximity. A seismic exploration of the area was done across four seismic lines, primarily mapping Quaternary-age Mississippi River flood plain deposits. These seismic surveys yielded no evidence to suggest the presence of an additional fault. Across all surveys no evidence was found to conclusively support any existing theory on fault movement in the NMSZ. / Thesis (MS) — Boston College, 2014. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.

Thesis (Chem.E)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographies. / by Kenneth George Hellyar. / Chem.E

Le développement et l'utilisation des procédés industriels à basse température ont été très importants durant ces dernières années. Le développement est surtout dû à l'accroissement de la demande en produits liquides (purs ou mélanges) sur le marché mondial. L'auteur de cette thèse propose une analyse approfondie des trois grandes familles de procédés de liquéfaction du gaz naturel utilisés en Algérie. Il commence par examiner les traitements subis par le gaz naturel avant sa liquéfaction qui consiste à le ramener à une température de -160°C et à une pression légèrement supérieure à la pression atmosphérique. Il analyse ensuite, à l'aide du logiciel ASPEN PLUS, les différentes performances des trois types de cycles et conclut en montrant que le cycle Propane-MCR est thermodynamiquement le plus avantageux.

Le développement et l'utilisation des procédés industriels à basse température ont été très importants durant ces dernières années. Le développement est surtout dû à l'accroissement de la demande en produits liquides (purs ou mélanges) sur le marché mondial. L'auteur de cette thèse propose une analyse approfondie des trois grandes familles de procédés de liquéfaction du gaz naturel utilisés en Algérie. Il commence par examiner les traitements subis par le gaz naturel avant sa liquéfaction qui consiste à le ramener à une température de -160°C et à une pression légèrement supérieure à la pression atmosphérique. Il analyse ensuite, à l'aide du logiciel ASPEN PLUS, les différentes performances des trois types de cycles et conclut en montrant que le cycle Propane-MCR est thermodynamiquement le plus avantageux.

<p>Ethanol production at Lantmännen Agroetanol AB in Norrköping began in December 2000. The objective of this master's thesis is to find and optimize factors affecting the yield of the liquefaction, a part of the upstream process. To measure successfulness of liquefaction it is desired that amount of non-solubilized starch is quantified, and hence a method for determination of non-solubilized starch in mash has to be developed.</p><p>Starch is a carbon reserve in plants. Starch granules are polymers of amylose and amylopectin which are polysaccharides of glucose. When a starch/water solution is heated the starch granules start to absorb water and swell, a process termed gelatinization. The swelling makes the granules susceptible to hydrolysis by enzymes such as alpha-amylase, this is called liquefaction. Eventually the granular structure is broken and the slurry contains solubilized starch which can be saccharified to glucose by glucoamylase. In the bioethanol production process, the milled grain is mixed with water and enzymes. The slurry is heated, gelatinization and liquefaction occurs. Saccharification occurs simultaneously to fermentation. Ethanol is purified from the fermented mash during downstream processing.</p><p>Starch in the form of starch granules cannot be quantified. The adopted principle for determination of non-solubilized starch in liquefied mash is to wash away the solubilized starch, then quantitatively hydrolyze non-solubilized starch to glucose and quantify glucose.</p><p>To find and optimize factors significant for yield of liquefaction multiple factor experiments were conducted where eight factors were studied. pH, temperature in mixtank and temperature in liquefaction tank 1 were the most significant factors. The temperature in liquefaction tank 1 should be kept as is is at 74°C. A small rise in pH should shorten the mean length of dextrins which is preferable. An increase of pH from 5.2 to 5.4 is therefore proposed. The temperature in mixtank should also be increased by a few degrees. The yield of the process should be carefully evaluated during the modifications.</p> / <p>Etanolproduktionen på Lantmännen Agroetanol AB i Norrköping började i December 2000. Målet med examensarbetet är att hitta och optimera faktorer som påverkar utbytet av likvifieringen i etanolproduktionen. För att studera utfallet av likvifieringen är det önskvärt att mäta hur mycket stärkelse som inte har löst sig, och därför måste en metod för att mäta olöst stärkelse i mäsk utvecklas.</p><p>Stärkelse utgör en kolreserv i växter. Stärkelsegranuler är polymerer av amylos och amylopektin, vilka i sin tur är polysackarider av glukos. När en stärkelse/vatten-blandning värms upp börjar stärkelsegranulerna att absorbera vatten och svälla, en process som kallas gelatinisering. Svällningen gör granulerna känsliga mot hydrolys av till exempel enzymet alfa-amylas, vilket kallas för likvifiering. Efter tillräckligt mycket gelatinisering och likvifiering förstörs hela den granulära strukturen och stärkelsen övergår till löst form. Löst stärkelse kan försockras till glukos med enzymet glukoamylas. I produktionen av bioetanol blandas malet spannmål med vatten och enzymer. Slurryn värms upp och gelatinisering och likvifiering sker. Försockring sker simultant med fermenteringen. Etanol renas fram från den fermenterade mäsken i nedströmsprocessen.</p><p>Stärkelse i granulform kan inte kvantifieras. Den valda metoden för mätning av olöst stärkelse i likvifierad mäsk innebär att den lösta stärkelsen tvättas bort, sedan hydrolyseras den olösta stärkelsen kvantitativt till glukos, vilken kan kvantifieras.</p><p>Flerfaktorförsök gjordes för att hitta och optimera faktorer signifikanta för utbytet av likvifiering. Åtta olika faktorer studerades. pH, temperatur i mixtank och temperatur i likvifieringstank 1 visade sig vara de tre mest signifikanta faktorerna. Temperaturen i likvifieringstank 1 ska bibehålla samma temperatur som idag, 74°C. En liten höjning av pH borde förkorta medellängden av dextrinerna, vilket är fördelaktigt. En ökning av pH från 5,2 till 5,4 är föreslås därför. Temperaturen i mixtanken ska ökas några få grader. Utbytet av processen måste noggrant utvärderas under modifieringarna.</p>

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (p. 447-462).

Thesis (M.U.D.)--University of Hong Kong, 1992. / Includes bibliographical references (leaves 261-264).

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 67-70).