In this study the catalytic pyrolysis and combustion characteristics of Turkish coal samples in O2/N2 and O2/CO2 (oxy-fuel conditions) ambient conditions were explored and the evolution of emissions during these tests was investigated using non-isothermal Thermo-gravimetric Analysis (TGA) technique combined with Fourier Transform Infrared (FTIR) spectroscopy. Potassium carbonate (K2CO3), calcium hydroxide (Ca(OH)2), iron (III) oxide (Fe2O3) and iron (III) chloride (FeCl3) were employed as precursors of catalysts to investigate the effects of potassium (K), calcium (Ca) and iron (Fe). Furthermore the effects of these catalysts on calorimetric tests of Turkish coal samples were investigated. TGA-FTIR pyrolysis tests were carried out in 100 % N2 and 100 % CO2 ambient conditions which are the main diluting gases in air and oxy-fuel conditions. Lignite pyrolysis tests revealed that the major difference between pyrolysis in these two ambient conditions was observed beyond 720

ABSRACT This study was to investigate the removal efficiency and kinetics in oxidation of ammonia solutions (NH3-N) in ranging from 400 mg/L to 1000 mg/L by adding Cu/La/Ce catalyst in process of Wet Air Oxidation (denoted by WAO). All experiments were conducted in semi-batch and continuous reactors in series. The major parameters included temperature, pressure, concentration and pH. In the semi-batch type of WAO experiments, the major parameters were performed at the following conditions: an initial concentration NH3-N of 400 mg/L, temperatures ranging from 423 K to 503 K, a total pressure of 4.0 Mpa, and a pH of 12.0. A removal efficiency of 32.7%was obtained in WAO process at 503 K for180 min, but it could be significantly promote to 95.1% after adding a catalyst of molar ratio 7:2:1.The kinetics of WAO with this catalyst in oxidation of NH3-N solutions, using a test of half-life, was developed nearly to a zero order. The reaction constants were 10.12 KJ/mol, 9.12 KJ/mol, and 6.57 KJ/mol at 503 K, 473 K and 423 K. In the continuous type of WAO experiments, the major parameters were performed at the following conditions: an initial concentration NH3-N of 400 mg/L, a temperature of 503 K, a total pressure of 2.0 Mpa, a pH of 12.0 and a liquid space velocity of 4.5 hr-1 (averagelyresidence time 14 min) . A removal efficiency of NH3-N of 6.5 % only was achieved in WAO process for a space velocity of 4.5 hr-1 (averagely residence time 14 min) , but after adding a catalyst of molar ratio 7:2:1 it increased to 72.3 % for a same residence time and a better efficiency of above 91 % was found for 1.5 hr-1 (averagely residence time 40 min) . For increasing the initial concentration of NH3-N into 600 mg/L, 800 mg/L, and 1000 mg/L the removal efficiency of NH3-N decreased with 85 %,75 % and 69 % for 1.5 hr-1 . Thus, the initial concentration of NH3-N in influent inhibits the removal efficiency in the oxidation process. The higher initial concentration the lower removal efficiency.

Complex reaction kinetics of the solid acid alkylation of isobutane with butenes over a proton-exchanged Y-zeolite has been modeled at the elementary step level. Starting with a computer algorithm that generated the reaction network based on the fundamentals of the carbenium ion chemistry, the formation of over 100+ product species has been modeled in order to gain understanding of the underlying phenomena leading to rapid catalyst deactivation and product selectivity shifts observed in experimental runs. An experimental investigation of the solid acid alkylation process was carried out in a fixed bed catalytic reactor operating with an excess of isobutane under isothermal conditions at moderate temperatures (353-393 K) in liquid phase. Experimental data varying with run-time for a set of butene space-times and reaction temperatures were collected for parameter estimation purposes. A kinetic model was formulated in terms of rate expressions at the elementary step level including a rigorous modeling of deactivation through site coverage. The single event concept was applied to each rate coefficient at the elementary step level to achieve a significant reduction in the number of model parameters. Based on the identification of structural changes leading to the creation or destruction of symmetry axes and chiral centers in an elementary step, formulae have been developed for the calculation of the number of single events. The Evans-Polanyi relationship and the concept of stabilization energy were introduced to account for energy levels in surface-bonded carbenium ions. A novel functional dependency of the stabilization energy with the nature of the carbenium ion and the carbon number was proposed to account for energy effects from the acid sites on the catalyst. Further reductions in the number of parameters and simplification of the equations for the transient pseudohomogeneous one-dimensional plug-flow model of the reactor were achieved by means of thermodynamic constraints. Altogether, the single event concept, the Evans-Polanyi relationship, the stabilization energy approach and the thermodynamic constraints led to a set of 14 parameters necessary for a complete description of solid acid alkylation at the elementary step level.

Volatile organic compounds (VOCs) can detrimentally affect human health directly and indirectly. However, the main environmental concern of VOCs involves the formation of smog. In the presence of nitrogen oxides, VOCs are the precursors to the formation of ground level ozone. Isopropyl alcohol (IPA) and toluene are extensively used in industry as solvents. They are all highly toxic to animals and humans. Accordingly, IPA and toluene are strongly associated with problems of VOCs. Catalytic incinerations and a regenerative catalytic oxidizer (RCO) were adopted to decompose VOCs herein. Various catalysts were prepared and developed in this study. The screening test of catalytic activity and the influences of the operational parameters on VOCs removal efficiencies were widely discussed through catalytic incinerations of VOCs. The more effective and cheaper catalysts through above discussions of catalytic incineration were selected. And they were utilized in an RCO to investigate their performance in VOCs oxidation and RCO operations. Experimental results demonstrate that 10 wt%CuCo/(G) catalyst performed well in an RCO because it has the excellent performance in incineration efficiency and economic efficiency. The achievements of this study are summarized as follows: (1) Treatment of isopropyl alcohol (IPA) using ceramic honeycomb(CH) catalyst The eighteen ceramic honeycomb catalysts we prepared by various methods (co-precipitation, wet impregnation and incipient impregnation), various metal weight loadings (5 ~ 20 wt %), and various metals (Cu and CuCe) were used in the experiment. The results indicate that 20 wt%CuCe/(CH) catalyst prepared by wet impregnation had the best performance in CO2 yield because TC50 and TC95 were 245¢J and 370¢J, respectively, under the following operating conditions; a space velocity of 12000 hr-1, an inlet IPA concentration of 1600 ppm, an oxygen concentration of 21%, and a relative humidity of 25%. Given the operational parameters of IPA oxidation experiments, the CO2 yields increased with higher temperature and oxygen concentration, but decreased with inlet IPA concentration, space velocity and the relative humidity increased. Moreover, the stability test results show that the 20 wt%CuCe/(CH) catalyst had excellent stability. (2) Treatment of toluene using molecular sieve(MS) catalyst Molecular sieve catalysts with various metals (Cu, Co, Mn, CuMn, CuCo, MnCo) and various loadings (5~10 wt %) were produced by wet impregnation to treat toluene. The results indicate that 10 wt%CuCo/(MS) had the best performance in toluene conversion because T50 and T95 were 295¢J and 425¢J, respectively, at an influent concentration of toluene of 900 ppm, an oxygen concentration of 21%, a space velocity of 12000 hr-1, and a relative humidity of 26%. The conversions of toluene increased with the reaction temperature and the influent concentration of oxygen, but decreased as the initial concentration of toluene and the space velocity increased. Moreover, we did not find any decay between the fresh and used catalysts using SEM and EDS. (3) Treatment of isopropyl alcohol (IPA) using Cu/(CH) and CuCo/(CH) catalysts We used the 20 wt% CuCo/(CH) and 20 wt% Cu/(CH) catalysts in a pilot RCO to test IPA oxidation performance under various conditions. The best catalyst was selected, and the economic efficiency of RCO and the phenomenon of RCO operations were more widely discussed. The results demonstrate that 20 wt% CuCo/(CH) catalyst performed well in an RCO because it was effective in treating IPA, with a CO2 yield of up to 95%. It also had the largest tolerance of variations in inlet IPA concentration and gas velocity. The 20 wt% CuCo/(CH) catalyst in an RCO also performed well in terms of TRE, pressure drop and selectivity to CO2. The thermal recovery efficiency (TRE) decreased as gas velocity increased. The temperature difference (Td) and pressure drop increased with gas velocity and heating zone temperature. The TRE range was from 87.8 to 91.2 % and the Td ranged from 22.1~35.1¢Junder various conditions. Finally, the stability test results indicate that the 20 wt% CuCo/(CH) catalyst was very stable at various CO2 yields and temperatures. (4) Treatment of toluene using CuCo/(CH) catalysts with various carriers In this work, three catalysts (10 wt%CuCo/(G)¡B10 wt%CuCo/(MS) and 20 wt% Cu/(CH)) were prepared by wet impregnation, and used in an RCO to test their performance in incineration efficiency and economic efficiency under various operational conditions. Then the best catalyst was selected and the phenomenons of RCO operations were further investigated. Experimental results demonstrate that 10 wt%CuCo/(G) catalyst performed well in an RCO because it is effective in treating toluene with a toluene conversion of up to 95% at the heating zone temperature (Tset) = 400¢J under various conditions. The 10 wt% CuCo/(G) catalyst had the greatest tolerance against the effects of inlet toluene concentration and gas velocity, and exhibited the best performance in terms of TRE , Td and pressure drop. The TRE range was from 90.2 to 92.9 % and Td ranged from 18.2 to 30.9¢J under various conditions at Tset = 300~400¢J. Moreover, when 10 wt% CuCo/(G) catalyst was used in an RCO, the results demonstrate that (1) high selectivity to CO2 ; (2) decrease in TRE and increase in Td as increasing the shifting time; (3) an insignificant effect of shifting time on pressure drop and (4) excellent stability of 10 wt% CuCo/(G) catalyst in a long period test.

Oil storage tanks and their pipelines are mostly constructed under the ground. If the leaches are occurred, the soil pollution and the contamination of groundwater quality will influenced seriously. The soil of oil polluted sites is usually containing the huge amounts of volatile organic compounds (VOCs) and other organics. These VOCs is uncomfortable on physical body when they spread into atmosphere not only to cause the harm of human health but also to react into photochemical smog. Besides, the VOCs are probably reacting with nitrogen oxides into the problems of high concentrations of ozone. In this study, we used a regenerative catalytic oxidizer (RCO) to deal with VOCs in soil of the oil polluted sites. The RCO system was packed with self-made catalyst of 20 wt%CuMn/£^-Al2O3. Experimental results revealed 90¡Ó5% of the influent VOCs (C0=450-10,000 ppm) was thermally destruction with no catalyst in beds operated with a valve shifting time (ts) of 2 min, superficial gas velocities (Ug) of 0.37 m/s (evaluated at an influent air temperature of around 30¢J) and present maximum destruction temperature (TS) of 800-900¢J. With the catalyst packings and operation conditions of Ug=0.37 m/s and C0=450~10,000 ppm, the destruction efficiency of 93.35 and 96.5% were observed, respectively in average at TS of 600 and 650¢J. When Ug=1.11 m/s and C0=450-10,000 ppm, the destruction efficiency of 87.51 and 93.75% were observed, respectively in average at TS of 600 and 650¢J. The destruction efficiency of RCO is high at higher influent concentration of VOCs and low gas velocities at TS=600-650¢J.

Hydrocarbon conversion and synthesis gas production are two components of the power production process that require significant development and exploration in the advanced energy arena. To remain within our current fueling infrastructure, it is imperative that an efficient and reliable mechanism to facilitate these components of the power production process is developed for automotive applications. A honeycomb monolith rhodium based catalyst has been identified as a potential fuel reformer element for use in automotive hydrocarbon fuel conversion. Using the novel and minimally invasive SpaciMS (Spatially resolved capillary inlet Mass Spectroscopy), developed at Oak Ridge National Laboratories, and an internal temperature acquisition system, the impact of fuel inlet space velocity on the operating rhodium based catalytic fuel reformer of interest was parametrically studied. In situ temperature and species profiles of the catalyst during steady state operation were produced. The data acquired through these experiments was then used to demonstrate analytic capability by conducting thermodynamic analyses on the operating fuel reformer. Experimental and analytical results can be used in development of design considerations for fuel conversion systems.

The distinct response of biological systems to the two enantiomers of a chiral chemical has led to a large market for enantiopure pharmaceuticals and raised fundamental issues about the origin of biological homochirality. It is therefore important to understand the interactions of chiral molecules with chiral environments. Chiral environments associated with solid surfaces could potentially play a useful role in chirally specific chemical processing. There are a variety of routes for creating chiral solid surfaces. Surfaces of materials whose bulk crystal structure is enantiomorphic can be used as one type of chiral solid surfaces. Metal surfaces that are intrinsically chiral due to the presence of kinked surface steps provide another route for creating chiral solid surfaces. Alternatively, we can impart chirality onto surfaces by attaching irreversibly adsorbing chiral organic species on otherwise achiral surfaces. Understanding and ultimately controlling enantiospecific interactions of molecules on this kind of surfaces requires detailed insight into the adsorption geometries and energies of these complex interfaces. To tackle these issues, we performed density functional theory (DFT) calculations that have proved to be a useful tool for quantitative prediction of these effects. Besides our main topic above, we theoretically examine the effects of K atoms as a promoter coadsorbed with small molecules on Mo2C surfaces, a promising catalyst for a range of chemicals applications. Our results in this thesis provide fundamental information about these systems and demonstrate that using DFT for this purpose can be a useful means of identifying the phenomena that control chiral surface chemistry.

The major goals of this thesis were to (1) design and synthesize a supported catalyst with well-defined monodisperse palladium nanoparticles evenly distributed throughout an inorganic oxide substrate with tunable porosity characteristics, (2) demonstrate the catalytic activity of this material in the decarboxylation of long chain fatty acids and their derivatives to make diesel-length hydrocarbons, (3) elucidate the deactivation mechanism of supported palladium catalysts under decarboxylation conditions via post mortem catalyst characterization and develop a regeneration methodology thereupon, and (4) apply this catalytic system to a real low-value biofeedstock. In an effort to maximize loading and minimize mass transfer limitations, mesoporous silica MCF was synthesized as catalyst support. Functionalization with various silane ligands facilitated even distribution of palladium precursor salts throughout the catalyst particle, and, after reduction, monodisperse palladium nanoparticles approximately 2 nm in diameter. The Pd-MCF catalyst showed high one-time activity in the decarboxylation of fatty acids to hydrocarbons in dodecane at 300 °C. Subsequent reactions were performed on acid derivatives to elucidate a decarboxylation reaction pathway. The catalyst experienced severe deactivation after only one use and substantial effort was put into elucidating the nature of this deactivation via post mortem catalyst characterization. The deactivation was found not to be caused by nanoparticle sintering, agglomeration or ripening, but instead by organic deposition, mainly of reactant acid. A regeneration methodology was developed and subsequent catalyst reuse exhibited high activity. Finally, the Pd-MCF catalyst was applied to a wastewater-derived brown grease from a poultry rendering facility, in an unpolished and polished form. The latter was successfully decarboxylated to diesel-length hydrocarbons with high conversion and selectivity.

<p>Catalytic combustion is an environmentally friendlytechnique to combust fuels in e.g. gas turbines. Introducing acatalyst into the combustion chamber of a gas turbine allowscombustion outside the normal flammability limits. Hence, theadiabatic flame temperature may be lowered below the thresholdtemperature for thermal NO_Xformation while maintaining a stable combustion.However, several challenges are connected to the application ofcatalytic combustion in gas turbines. The first part of thisthesis reviews the use of catalytic combustion in gas turbines.The influence of the fuel has been studied and compared overdifferent catalyst materials.</p><p>The material section is divided into two parts. The firstconcerns bimetallic palladium catalysts. These catalysts showeda more stable activity compared to their pure palladiumcounterparts for methane combustion. This was verified both byusing an annular reactor at ambient pressure and a pilot-scalereactor at elevated pressures and flows closely resembling theones found in a gas turbine combustor.</p><p>The second part concerns high-temperature materials, whichmay be used either as active or washcoat materials. A novelgroup of materials for catalysis, i.e. garnets, has beensynthesised and tested in combustion of methane, a low-heatingvalue gas and diesel fuel. The garnets showed some interestingabilities especially for combustion of low-heating value, LHV,gas. Two other materials were also studied, i.e. spinels andhexaaluminates, both showed very promising thermal stabilityand the substituted hexaaluminates also showed a good catalyticactivity.</p><p>Finally, deactivation of the catalyst materials was studied.In this part the sulphur poisoning of palladium, platinum andthe above-mentioned complex metal oxides has been studied forcombustion of a LHV gas. Platinum and surprisingly the garnetwere least deactivated. Palladium was severely affected formethane combustion while the other washcoat materials were mostaffected for carbon monoxide and hydrogen.</p><p><b>Keywords:</b>catalytic combustion, catalyst materials,palladium, platinum, bimetallic, garnet, spinel, hexaaluminate,deactivation, sulphur, poisoning, diesel, methane,hydrocarbons</p>

Title from PDF of title page. / Document formatted into pages; contains 73 pages. / Thesis (M.S.E.E.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: The goals of this research project were the design and construction of a carbon nanotube (CNT) reactor based on the plasma enhanced chemical vapor deposition (PECVD) principle and the development of a method for directed assembly of CNTs by catalyst patterning. PECVD was selected as the growth method due to the requirement of a catalyst for the growth process, thereby facilitating directed assembly and controlled diameter CNT growth at well-defined locations. The reactor was built in accord with horizontal flow design using standard ultra high vacuum components. The controllable parameters of the reactor include sample temperature, DC plasma intensity, chamber pressure, gas flow ratios, and total gas flow. The most favorable parameters for growing CNTs of well defined length, diameter, and separation were obtained by initially using parameter values obtained from literature, then optimized by changing a parameter and noting the effect on CNT growth. / ABSTRACT: Catalyst patterns for the directed assembly of CNTs were prepared by electron-beam lithography (EBL). Experiments were performed that demonstrated the feasibility of using lithographic methods to achieve directed assembly of carbon nanotubes for the manufacture of CNT devices. Experiments focusing on growth interruption and regrowth of CNTs were conducted to investigate methods of introducing tailored branching points into carbon nanotubes during the growth process. These experiments clearly demonstrate that growth interruption increases the occurrence of CNT branching. An analysis of the relationships between CNT diameter, branching points, and the number of growth steps was conducted. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.