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Articles 1 - 12 of 12
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Electrochemical Reduction Of Co2 On Supported Cu2o Catalysts, Joel Niño Galvez Bugayong
Electrochemical Reduction Of Co2 On Supported Cu2o Catalysts, Joel Niño Galvez Bugayong
LSU Doctoral Dissertations
We have examined Cu-based catalyst materials that enable the conversion of CO2 to useful products such as fuels and chemical feedstocks by electrochemical reduction. In particular, we compared the electrocatalytic activity of supported Cu2O particles prepared using electrodeposition and wet chemical methods. The particles had cubic structure, ranging in size from 40 nm to 900 nm and consisting of low index planes. We observed significantly different product distribution on these catalysts compared to polycrystalline Cu, specifically for methane and ethylene formation. While Cu particles showed higher faradaic efficiency for methane formation compared to ethylene formation, we observed that Cu2O particles …
Rare Earth/Transition Metal Oxides For Syngas Cleanup, Rui Li
Rare Earth/Transition Metal Oxides For Syngas Cleanup, Rui Li
LSU Doctoral Dissertations
Syngas from gasification of biomass or biomass and coal is a potential source of renewable energy. However, byproducts such as H2S and tars must be removed before further utilization or processing of syngas. Rare earth oxides (REOs, e.g., Ce/LaOx (1.7< x <2)) mixed with transition metals (e.g., Mn, Fe) were synthesized by various methods, and in some cases supported on a thermally stable alumina. Both desulfurization and tar reforming experiments were conducted at high temperatures under similar conditions with synthetic effluents in order to achieve better heat integration and higher yield to desired products CO and H2. The sulfur capacities at temperatures from 900-1025 K with air regeneration were measured for repeat cycles until a stable, reversible capacity was obtained. The oxidized and sulfided (reduced) sorbents were characterized by XRD, XANES, XAFS, TPR and BET. Density functional theory calculations were used to aid in interpreting characterization data and in explaining the enhanced S adsorption capacities. The results showed that mixed REOs, such as Ce/Tb, and Ce/La synthesized by a templated sol-gel approach do not have high sulfur capacities. The presence of either CO2 or H2O inhibits the adsorption of H2S. However, addition of Mn to REOs effectively increased the sulfur capacity, and Mn-REO sorbents are regenerable even in the presence of air, although there is some sulfate formation. The formation of elemental sulfur during regeneration could be related to the oxygen vacancies promoted by doping Mn into the ceria lattice. DFT calculations suggested doping Mn into CeO2 decreased the vacancy formation energies and lowered the H2S adsorption energy. In contrast, for MnO-doped REOs supported on ã-Al2O3, although their surface areas remained high after multi-cycle usage, the probable formation of MnAl2O4 as observed by XANES reduces the sulfur capacities. Reforming experiments were carried out using synthetic syngas mixtures with C10H8 as a tar model compound, both with and without H2S. The results showed that CO2 and H2O inhibit the reforming activities to some extent. Fe- or Mn-doped supported REOs are promising tar cleanup catalysts. They exhibited higher sulfur tolerance, less coking, and less methanation than typical Ni-based high temperature reforming catalysts. This behavior is in part attributed to enhanced generation of oxygen vacancies in the doped REOs.
Numerical Investigation Of Cryopreserved Zebrafish Sperm Cell Activation In Microchannels, Thomas Foster Scherr
Numerical Investigation Of Cryopreserved Zebrafish Sperm Cell Activation In Microchannels, Thomas Foster Scherr
LSU Doctoral Dissertations
This aim of this research project is to probe the activation process of zebrafish spermatozoa. Zebrafish are a model species for biological engineering applications, and the cryopreservation of their reproductive cells allows for inexpensive cataloging and maintenance of valuable biological material. Evaluation of cryopreservation protocols for aquatic sperm cells is typically accomplished by motility analysis after subjecting cells to a cryopreservation treatment. In zebrafish sperm cells, motility is initiated when cells come into contact with a hypo-osmotic environment. Subsequent activation analysis is currently done manually and brings with it an inherent difficulty and error. This process is slow and not …
Poroelastic Inhomogeneities: Applications In Reservoir Geomechanics, Houman Bedayat
Poroelastic Inhomogeneities: Applications In Reservoir Geomechanics, Houman Bedayat
LSU Doctoral Dissertations
The scarce amount of conventional hydrocarbon reservoirs and increase of fuel consumption in the world have made production from unconventional hydrocarbon resources inevitable. Because of the low permeability of unconventional formations, fractures are the main paths for the fluid to flow. Therefore, detailed knowledge of the size, orientation, and permeability of the fracture systems are essential for reservoir engineers. Permeability of the fractures is function of their volume and opening, and stress and fluid pore pressure distribution in the formation. Since reservoir pressure may change over the production life of the reservoir, studying stress redistribution and mechanical behavior of the …
Applications Of Cfd Simulations On Studying The Multiphase Flow In Microfluidic Devices, Yuehao Li
Applications Of Cfd Simulations On Studying The Multiphase Flow In Microfluidic Devices, Yuehao Li
LSU Doctoral Dissertations
Microfluidics has been extensively investigated as a unique platform to synthesize nanoparticles with desired properties, e.g., size and morphology. Compared to the conventional batch reactors, wet-chemical synthesis using continuous flow microfluidics provides better control over addition of reagents, heat and mass transfer, and reproducibility. Recently, millifluidics has emerged as an alternative since it offers similar control as microfluidics. With its dimensions scaled up to millimeter size, millifluidics saves fabrication efforts and potentially paves the way for industrial applications. Good designs and manipulations of microfluidic and millifluidic devices rely on solid understanding of fluid dynamics. Fluid flow plays an important role …
Advanced And Novel Modeling Techniques For Simulation, Optimization And Monitoring Chemical Engineering Tasks With Refinery And Petrochemical Unit Applications, Gregory M. Robertson
Advanced And Novel Modeling Techniques For Simulation, Optimization And Monitoring Chemical Engineering Tasks With Refinery And Petrochemical Unit Applications, Gregory M. Robertson
LSU Doctoral Dissertations
Engineers predict, optimize, and monitor processes to improve safety and profitability. Models automate these tasks and determine precise solutions. This research studies and applies advanced and novel modeling techniques to automate and aid engineering decision-making. Advancements in computational ability have improved modeling software’s ability to mimic industrial problems. Simulations are increasingly used to explore new operating regimes and design new processes. In this work, we present a methodology for creating structured mathematical models, useful tips to simplify models, and a novel repair method to improve convergence by populating quality initial conditions for the simulation’s solver. A crude oil refinery application …
Image-Based Pore-Scale Modeling Of Inertial Flow In Porous Media And Propped Fractures, Yijie Shen
Image-Based Pore-Scale Modeling Of Inertial Flow In Porous Media And Propped Fractures, Yijie Shen
LSU Doctoral Dissertations
Non-Darcy flow is often observed near wellbores and in hydraulic fractures where relatively high velocities occur. Quantifying additional pressure drop caused by non-Darcy flow and fundamentally understanding the pore-scale inertial flow is important to oil and gas production in hydraulic fractures. Image-based pore-scale modeling is a powerful approach to obtain macroscopic transport properties of porous media, which are traditionally obtained from experiments and understand the relationship between fluid dynamics with complex pore geometries. In image-based modeling, flow simulations are conducted based on pore structures of real porous media from X-ray computed tomographic images. Rigorous pore-scale finite element modeling using unstructured …
Continuous Reservoir Modeling Updating By Integrating Experimental Data Using An Ensemble Kalman Filter, Ting Sun
LSU Doctoral Dissertations
The continuous researvoir model updating is widely used to calibrate reservoir simulation models to production data, but many challenges remain. First, few real field data are available to test the new history matching method, and most of the data sets are synthetic cases. Second, computational cost may be high when using non-Gaussian priors or nonlinear models. Third, with large complex models, the simulation runs and history matching method require huge memory allocations. This dissertation achieves a continuous reservoir model updating workflow with a meter-scale , two-phase flow experiment. Both production and seismic data are collected in the experiment. Because the …
Catalytic Active Site, Mechanistic And Kinetic Studies Of Dry (Co2) Reforming Of Methane Over Lanthanum Zirconate (La2zr2o7) Pyrochlores, Devendra Pakhare
Catalytic Active Site, Mechanistic And Kinetic Studies Of Dry (Co2) Reforming Of Methane Over Lanthanum Zirconate (La2zr2o7) Pyrochlores, Devendra Pakhare
LSU Doctoral Dissertations
Dry (CO2) reforming of CH4 (DRM) produces commercially important synthesis gas (H2 and CO) with H2/CO ≤ 1, which can be used for synthesis of higher alkanes and oxygenates. DRM is highly endothermic and requires temperatures as high as 800°C-1000°C to attain high equilibrium conversions. A major problem associated with DRM is catalyst deactivation due to carbon deposition. Thus it is imperative that the catalyst used for DRM must resist deactivation due to sintering and carbon deposition. DRM is well studied in the literature over various catalysts, however, there is no literature, except the Ashcroft (1993) article, for DRM over …
Multiscale Estimation Of Inertial Effects For Frac-Pack Completed Gas Reservoirs, Sultan Anbar
Multiscale Estimation Of Inertial Effects For Frac-Pack Completed Gas Reservoirs, Sultan Anbar
LSU Doctoral Dissertations
Accurate estimation of production from frac-pack completed gas wells requires reliable estimation of flow properties from reservoir rocks and proppants. This study is composed of three parts: core-scale, pore-scale and reservoir-scale analyses of this problem. In the core-scale analysis, simultaneous estimation of permeability, non-Darcy, and Klinkenberg coefficients of reservoir rock is conducted from steady-state and pulse-decay experiments. Confidence intervals of the estimated parameters are determined from the Bootstrap method. The duration of pulse-decay experiments has a large impact on confidence intervals; therefore, correlations are developed to estimate the experimental duration for both 1-tank and 2-tank set-ups from the core properties …
Analysis Of Hydrodynamic Drag Forces Acting On Suspended Fine Particle In Porous Media, Seyed Amin Mirsaeidi Farahani
Analysis Of Hydrodynamic Drag Forces Acting On Suspended Fine Particle In Porous Media, Seyed Amin Mirsaeidi Farahani
LSU Doctoral Dissertations
An important class of flow and transport problems occurring in porous media involves the interactions between suspended fine particles and the moving fluid at Stokes limit. Historically, due to the complicated geometries of porous media, researchers have had to resort to simplifying assumptions to conceptualize the underlying physics. However, the advent of high performance computing, in recent decades, has made it possible to vigorously investigate this problem at the streamline scale level. In this work, the flow problem is solved by means of a finite-element model. The simulations results are used to compute the drag forces experienced by suspended fine …
Modeling Of Foam Flow In Porous Media For Subsurface Environmental Remediation, Seungjun Lee
Modeling Of Foam Flow In Porous Media For Subsurface Environmental Remediation, Seungjun Lee
LSU Doctoral Dissertations
Among numerous foam applications in a wide range of disciplines, foam flow in porous media has been spotlighted for improved/enhanced oil recovery processes in petroleum-bearing geological formations and shallow subsurface in-situ NAPL (non-aqueous phase liquid) environmental remediation in contaminated soils and aquifers. In those applications, foams are known to reduce the mobility of gas phase by increasing effective gas viscosity and improve sweep efficiency by mitigating subsurface heterogeneity. This study investigates how surfactant/foam process works fundamentally for environmental remediation purpose by using MoC (Method of Characteristics) based foam modeling and simulation techniques. It consists of two main parts: Part 1, …