Two flow reactor studies, using an electrically heated laminar flow reactor over Vanadia based (V2O5-WO3/TiO2) honeycomb catalyst, were performed at 1 atm pressure and various temperatures. The experiments were conducted using simulated exhaust gas compositions for different exhaust gases. A quartz tube was used in order to establish inert conditions inside the reactor. The experiments utilized a Fourier transform infrared (FTIR) spectrometer in order to perform both qualitative and quantitative analysis of the reaction products. Urea-water solution decomposition was investigated over V2O5-WO3/TiO2 catalyst over the entire SCR temperature range using the temperature controlled flow reactor. The solution was preheated and then injected into pure nitrogen (N2) stream. The decomposition experiments were conducted with a number of oxygen (O2) compositions (0, 1, 10, and 15%) over the temperature range of 227oC to 477oC. The study showed ammonia (NH3), carbon-dioxide (CO2) and nitric oxide (NO) as the major products of decomposition along with other products such as nitrous oxide (N2O) and nitrogen dioxide (NO2). The selective catalytic reduction (SCR) of nitric oxide (NO) with urea-water solution over V2O5-WO3/TiO2 catalyst using a laboratory laminar-flow reactor was investigated. Urea-water solution was injected at a temperature higher than the vaporization temperature of water and the flow reactor temperature was varied from 127oC to 477oC. A FTIR spectrometer was used to determine the concentrations of the product species. The major products of SCR reduction were NH3, NO and CO2 along with the presence of other minor products NO2 and N2O. NO removal of up to 87% was observed. The aim of the urea-water decomposition experiments was to study the decomposition process as close to the SCR configuration as possible. The aim of the SCR experiments was to delineate the effect of various parameters including reaction temperature and O2 concentration on the reduction process. The SCR investigation showed that changing parameter values significantly affected the NO removal, the residual NH3 concentration, the temperature of the maximum NO reduction, and the temperature of complete NH3 conversion. In the presence of O2, the reaction temperature for maximum NO reduction was 377?C for ratio of 1.0.

No description available.

Doctor of Philosophy / Department of Chemical Engineering / Keith L. Hohn / To characterize surface properties by current techniques, metal oxides typically have to be pre-treated at high temperature to remove surface absorbents. Therefore, a new low temperature method which can provide information on the surface chemistry is desired. In this work, the surface properties of metal oxide samples were studied by tetrakis(dimethylamino)ethylene (TDE) chemiluminescence (CL). This chemiluminescent method was also employed in probing the properties of reversed microemulsions. It was found that the emission intensity vs. reaction time curve (I[subscript]t) of catalyzed TDE CL on MgO was affected by the distributions and types of surface hydroxyl groups. Isolated hydroxyls with lower coordination were found to have higher catalytic reactivity for the emission of TDE CL. Although hydrogen bonded hydroxyls also catalyze the TDE oxidation reaction, the influence on the light emission was negative. Because the properties of surface hydroxyls are associated with specific orientations of adjacent ions, information on surface hydroxyls can provide information about some general surface characteristics of a metal oxide. When characterizing surface hydroxyls on Al[subscript]2O[subscript]3 by TDE CL, it was found that the catalytic reactivity of isolated hydroxyl groups is strongly associated with the stretching frequency of isolated hydroxyl. The stretching frequency of an isolated hydroxyl group is related to the modification of the adjacent ions and the coordination of the isolated hydroxyl. The results showed that the blue-shifts in the stretching frequencies of isolated hydroxyls led to increases in the catalytic reactivity of Al[subscript]2O[subscript]3 surfaces for the emission of TDE CL. TDE CL was further applied in characterizing the surfaces of other metal oxides and chemically grafted Al[subscript]2O[subscript]3. The results indicated that the isolated hydroxyl groups with fewer adjacent ions likely have higher affinity for the binding of grafting agents. Higher emission intensities were obtained from catalyzed TDE CL on metal oxides featuring higher percentages of isolated hydroxyls. The determination of a surfactant’s critical micellar concentration was accomplished by measuring the decay rate of the emission of TDE CL in a reversed microemulsion system. In this study, the CMC values of non-ionic and ionic surfactants were measured in different non-polar solvents.

In laser wakefield acceleration, an ultra-short high-intensity laser pulse excites a plasma wave, which can sustain accelerating electric fields of several hundred GV/m. This scheme advances a novel concept for compact and less expensive electron accelerators, which can be hosted in a typical university size laboratory. Furthermore, laser wakefield accelerators (LWFA) feature unique electron bunch characteristics, namely micrometer size with duration ranging from several fs to tens of fs. Precise knowledge of the longitudinal profile of such ultra-short electron bunches is essential for the design of future table-top X-ray light-sources and remains a big challenge due to the resolution limit of existing diagnostic techniques. Spectral measurement of broadband coherent and incoherent transition radiation (TR) produced when electron bunches passing through a metal foil is a promising way to analyze longitudinal characteristics of these bunches. Due to the limited reproducibility of the electron source this measurement highly requires single-shot capability. An ultra-broadband spectrometer combines the TR spectrum in UV/NIR (200-1000 nm), NIR (0.9-1.7 µm) and mid-IR (1.6-12 µm). A high spectral sensitivity, dynamic bandwidth and spectral resolution are realized by three optimized dispersion and detection systems integrated into a single-shot spectrometer. A complete characterization and calibration of the spectrometer have been done concerning wavelengths, relative spectral sensitivities, and absolute photometric sensitivities, also taking into account for the light polarization. The TR spectrometer is able to characterize electron bunches with charges as low as 1pC and can resolve time-scales of 0.4 fs. Electron bunches up to 16 fs (rms width) can be reconstructed from their TR spectrum. In the presented work, the self-truncated ionization induced injection (STII) scheme has been explored to study the relevant beam parameters especially its longitudinal bunch profile and the resulting peak current.