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Materials and Component Development for Advanced Turbine Systems

Description: In order to meet the 2010-2020 DOE Fossil Energy goals for Advanced Power Systems, future oxy-fuel and hydrogen-fired turbines will need to be operated at higher temperatures for extended periods of time, in environments that contain substantially higher moisture concentrations in comparison to current commercial natural gas-fired turbines. Development of modified or advanced material systems, combined with aerothermal concepts are currently being addressed in order to achieve successful operation of these land-based engines. To support the advanced turbine technology development, the National Energy Technology Laboratory (NETL) has initiated a research program effort in collaboration with the University of Pittsburgh (UPitt), and West Virginia University (WVU), working in conjunction with commercial material and coating suppliers as Howmet International and Coatings for Industry (CFI), and test facilities as Westinghouse Plasma Corporation (WPC) and Praxair, to develop advanced material and aerothermal technologies for use in future oxy-fuel and hydrogen-fired turbine applications. Our program efforts and recent results are presented.
Date: October 1, 2008
Creator: Alvin, M.A.; Pettit, F.; Meier, G.; Yanar, N.; Chyu, M.; Mazzotta, D. et al.
Partner: UNT Libraries Government Documents Department

Development of Novel Activated Carbon-Based Adsorbents for Control of Mercury Emission From Coal-Fired Power Plants

Description: The overall objective of this study is to evaluate pertinent design and operational parameters that would enable successful application of activated carbon adsorption for the reduction of mercury emissions from coal-fired power plants. The study will evaluate the most suitable impregnate such as sulfur, chloride and other chelating agents for its ability to enhance the adsorptive capacity of activated carbon for mercury vapor under various process conditions. The main process variables to be evaluated include temperature, mercury concentration and speciation, relative humidity, oxygen content, and presence of SO2 and NOx in the flue gas. The optimal amount of impregnate for each of these carbons will be determined based on the exhibited performance. Another important parameter which governs the applicability of adsorption technology for the flue gas clean up is the rate at which vapor phase mercury is being removed from the flue gas by activated carbon. Therefore, the second part of this study will evaluate the adsorption kinetics using the impregnated activated carbons listed above. The rate of mercury uptake will also be evaluated under the process conditions that are representative of coal-fired power plants. Concerned with the ability of the adsorbed mercury to migrate back into the environment once saturated adsorbent is removed from the system, the study will also focus on the mercury desorption rate as a function of the type of impregnate, loading conditions, and the time of contact prior to disposal.
Date: September 8, 1997
Creator: Vidic, Radisav D.
Partner: UNT Libraries Government Documents Department

Enhanced Sulfur Removal of Coal Via Carbon Fiber Production

Description: The characterization of highly graphitic vapor-grown carbon fiber (VGCF) produced by the floating catalyst method was determined to evaluate the effect of processing changes on the VGCF properties. Properties examined were bulk density, bulk resistivity of compressed fiber bundles, UV absorption of acetone extractables, graphitic index, pH value, and ASTM dibutyl phthalate absorption number. The data show the properties do not vary significantly from three different reactor tubes used to produce the fibers. Of the properties examined, only graphitic index, density and UV absorption of acetone extractables appear to be independent of sampling handling. Resistivity is directly correlated to the pressure exerted to from the fiber pellet due to the layering of the fiber bundles. The pH of fiber samples suspended in water does not vary significantly. The dibutyl phthalate absorption number is strongly affected by the compression of the material. Thus, only the graphitic index, the UV absorption of acetone extractables, and the apparent density will be used to aid in process quality control and to determine the process conditions required to produce carbon fiber with properties optimized for specific conditions using high sulfur coal dust.
Date: May 30, 1997
Creator: Patterson, Alesha; Grffith, David; Buffinger, Delbert; Asikele, Edward; Smitherman, Herbert & Evbuoma, Osagie
Partner: UNT Libraries Government Documents Department

Quarterly Technical Progress Report - Investigation of Syngas Interaction in Alcohol Synthesis Catalysts

Description: This report presents the work done on " Investigation of Syngas Interaction in Alcohol Synthesis Catalysts" during the last quarter. The major activity during this period is on FTIR absorption studies of Co/Cr catalysts using CO as a probe molecule. Transition metals cobalt and copper play significant roles in the conversion of syngas (CO + H2 ) to liquid fuels. With a view to examine the nature of interaction between CO and metal, the FTIR spectra of CO adsorbed on Co-Cr2 O3 composites were investigated. The results indicate that as cobalt loading increases, the intensity of the CO adsorption bands increase and several vibrational modes seem to be promoted. Heat treatment of the sample revealed two distinct processes of adsorption. Bands due to physisorption disappeared while bands due to chemisorption not only increased in intensity but persisted even after desorption. It seems that the physisorption process is more active when the catalyst is fresh and is hindered when carbidic/carbonyl formations occur on the metal surfaces.
Date: November 10, 1998
Creator: Akundi, Murty A.
Partner: UNT Libraries Government Documents Department

Hydrogen chemisorption on diamond surfaces. Final report

Description: Previously we demonstrated the ability to measure submonolayer quantities of surface hydrogen on insulating glasses. The present study builds on this by examining hydrogen coverages on another insulating material: the technologically important diamond (100) surface. The information to be obtained in the present study will allow us to deduce the correct structures for the diamond (100)-(1X1) and -(2X1) surface phases and provide information on the kinetics of hydrogen desorption from the (100) surface. Such experiments are essential for a complete understanding of hydrogen surface chemistry during the chemical vapor deposition of thin diamond films. This report summarizes progress made in FY93 for measuring surface hydrogen concentrations on the diamond (100) surface. Although the available LDRD resources were insufficient to finish this study in FY93, completion of the study is planned using other resources and this detailed report as a reference.
Date: September 1, 1994
Creator: Daley, R. & Musket, R.
Partner: UNT Libraries Government Documents Department

On the behavior of Bronsted-Evans-Polanyi Relations for Transition Metal Oxides

Description: Versatile Broensted-Evans-Polanyi (BEP) relations are found from density functional theory for a wide range of transition metal oxides including rutiles and perovskites. For oxides, the relation depends on the type of oxide, the active site and the dissociating molecule. The slope of the BEP relation is strongly coupled to the adsorbate geometry in the transition state. If it is final state-like the dissociative chemisorption energy can be considered as a descriptor for the dissociation. If it is initial state-like, on the other hand, the dissociative chemisorption energy is not suitable as descriptor for the dissociation. Dissociation of molecules with strong intramolecular bonds belong to the former and molecules with weak intramolecular bonds to the latter group. We show, for the prototype system La-perovskites, that there is a 'cyclic' behavior in the transition state characteristics upon change of the active transition metal of the oxide.
Date: August 22, 2011
Creator: Vojvodic, Aleksandra
Partner: UNT Libraries Government Documents Department

Modeling of Syngas Reactions and Hydrogen Generation Over Sulfides

Description: The objective of the research is to analyze pathways of reactions of hydrogen with oxides of carbon over sulfides, and to predict which characteristics of the sulfide catalyst (nature of metal, defect structure) give rise to the lowest barriers toward oxygenated hydrocarbon product. Reversal of these pathways entails the generation of hydrogen, which is also proposed for study. In this first year of study, adsorption reactions of H atoms and H{sub 2} molecules with MoS{sub 2}, both in molecular and solid form, have been modeled using high-level density functional theory. The geometries and strengths of the adsorption sites are described and the methods used in the study are described. An exposed MO{sup IV} species modeled as a bent MoS{sub 2} molecule is capable of homopolar dissociative chemisorption of H{sub 2} into a dihydride S{sub 2}MoH{sub 2}. Among the periodic edge structures of hexagonal MoS{sub 2}, the (1{bar 2}11) edge is most stable but still capable of dissociating H{sub 2}, while the basal plane (0001) is not. A challenging task of theoretically accounting for weak bonding of MoS{sub 2} sheets across the Van der Waals gap has been addressed, resulting in a weak attraction of 0.028 eV/MoS{sub 2} unit, compared to the experimental value of 0.013 eV/MoS{sub 2} unit.
Date: September 17, 2002
Creator: Klier, Kamil; Spirko, Jeffery A. & Neiman, Michael L.
Partner: UNT Libraries Government Documents Department

Development of Superior Sorbents for Separation of CO2 from Flue Gas at a Wide Temperature range during Coal Combustion

Description: A number basic sorbents based on CaO were synthesized, characterized with novel techniques and tested for sorption of CO{sub 2} and selected gas mixtures simulating flue gas from coal fired boilers. Our studies resulted in highly promising sorbents which demonstrated zero affinity for N{sub 2}, O{sub 2}, SO{sub 2}, and NO very low affinity for water, ultrahigh CO{sub 2} sorption capacities, and rapid sorption characteristics, CO{sub 2} sorption at a very wide temperature range, durability, and low synthesis cost. One of the 'key' characteristics of the proposed materials is the fact that we can control very accurately their basicity (optimum number of basic sites of the appropriate strength) which allows for the selective chemisorption of CO{sub 2} at a wide range of temperatures. These unique characteristics of this family of sorbents offer high promise for development of advanced industrial sorbents for the effective CO{sub 2} removal.
Date: September 17, 2002
Creator: Smirniotis, Panagiotis
Partner: UNT Libraries Government Documents Department

Hanford single shell tank saltcake cesium removal test plan

Description: This document provides the test preparation and conduct of a cesium removal test using Hanford Single Shell Tank Saltcake from tanks 241-BY-110, 241-U-108, 241 U 109, 241-A-101, and 241-S-102 in a benchscale column. The cesium sorbent to be tested is crystalline silicotitanate
Date: December 11, 1996
Creator: Duncan, J.B., Westinghouse Hanford
Partner: UNT Libraries Government Documents Department

Fundamental studies of hydrogen chemisorption on supported monometallic and bimetallic catalysts using microcalorimetry

Description: Highly dispersed transition metal catalysts are used in numerous commercial processes such as hydrocarbon conversions. For example, the use of Pt supported on acidic alumina or silica-alumina for reforming of naphtha in the production of gasoline is well known. Another use of supported catalysts is in automobile emission control where supported Pt-Rh bimetallic catalysts are used. Supported Ru can be used in Fischer-Tropsch synthesis for the production of higher hydrocarbons from synthesis gas. While many of these catalyst systems have been in commercial operation for several decades there is still a lack of consensus regarding the exact role of the catalyst on a molecular level. In particular, little is known about the mechanisms operating on the catalyst surface at the high pressure and high temperature conditions typically used in commercial operations. This report contains the general introduction and conclusions and an appendix containing the operating instructions for a microcalorimeter. Three chapters have been processed separately. They are: the effect of K on the kinetics and thermodynamics of hydrogen adsorption on Ru/SiO{sub 2}; hydrogen adsorption states on silica supported Ru-Ag and Ru-Cu bimetallic catalysts investigated via microcalorimetry; a comparative study of hydrogen chemisorption on silica supported Ru, Rh, and Pt.
Date: June 24, 1997
Creator: Narayan, R.L.
Partner: UNT Libraries Government Documents Department

Electrochemical and scanning probe microscopic characterization of spontaneously adsorbed organothiolate monolayers at gold

Description: This dissertation presented several results which add to the general knowledge base regarding organothiolates monolayer spontaneously adsorbed at gold films. Common to the body of this work is the use of voltammetric reductive resorption and variants of scanning probe microscopy to gain insight into the nature of the monolayer formation process as well as the resulting interface. The most significant result from this work is the success of using friction force microscopy to discriminate the end group orientation of monolayer chemisorbed at smooth gold surfaces with micrometer resolution (Chapter 4). The ability to detect the differences in the orientational disposition is demonstrated by the use PDMS polymer stamp to microcontact print an adlayer of n-alkanethiolate of length n in a predefine pattern onto a gold surface, followed by the solution deposition of a n-alkanethiol of n {+-} 1 to fill in the areas on the gold surface intentionally not coated by the stamping process. These two-component monolayers can be discriminated by using friction force microscopy which detects differences in friction contributed by the differences in the orientation of the terminal groups at surfaces. This success has recently led to the detection of the orientation differences at nanometer scale. Although the substrates examined in this work consisted entirely of smooth gold films, the same test can be performed on other smooth substrates and monolayer materials.
Date: December 10, 1999
Creator: Wong, Sze-Shun Season
Partner: UNT Libraries Government Documents Department

Theoretical studies of the structure and properties of cobalt-substituted aluminophosphates

Description: There has been considerable debate regarding the structure and properties of cobalt-substituted aluminophosphate catalysts. In particular, the coordination environment, Co-O bond lengths and oxidation state are all thought to have important effects on the catalytic effectiveness of the material. This paper uses both atomistic modeling and quantum mechanical based methods to probe the local structure both of possible framework and extra-framework cobalt sites. The authors find that in the case of tetrahedral geometries, the bond lengths are similar to those found in cobalt oxides and measured from EXAFS experiments. The attractiveness of the cobalt sites for the direct binding of molecular oxygen is also investigated to assess the likelihood of the use of this oxidant in a catalytic process. In order to benchmark the computational methods calculations are also performed on a model biological system which is known to bind molecular oxygen reversibly. The authors find no evidence for direct oxygen binding in the zeolite models for a five coordinated framework cobalt center.
Date: July 1998
Creator: Henson, N. J.; Hay, P. J. & Redondo, A.
Partner: UNT Libraries Government Documents Department

Alloy Thin-films and Surfaces for New Materials. Final Report

Description: Within the framework of a DOE National Laboratory/EPSCoR state partnership, investigations by researchers at Louisiana State University and Oak Ridge National Laboratory were focused on revealing the unique nanophase properties of alloy thin-films and bimetallic surfaces. Employing a number of experimental preparation techniques and characterization probes (synchrotron-based angle-resolved and valence/core-level PES and variable-temperature STM/STS), the goal of this program was to elucidate of the interconnecting physical and chemical properties of a variety of alloy surfaces and thin-films, specifically, determining the correlation between atomic structure/composition, electronic structure, and catalytic/chemisorption properties of these nanoscale.
Date: August 10, 2003
Creator: Sprunger, P. T.
Partner: UNT Libraries Government Documents Department

Correlation of Chemisorption and Electronic Effects for Metal/Oxide Interfaces: Transducing Principles for Temperature-Programmed Gas Microsensors

Description: This Report discusses progress and accomplishments during the initial 8 months (October 1, 1998 through May 31, 1999) of a 3-year project. Work is being performed through a collaboration between NIST and the Institute for Systems Research at the University of Maryland (PI: Professor T. J. McAvoy). This three year project has a goal of producing a scientific database for conductometric sensing materials and using this information to advance gas microsensor technology. The technology will use arrays of miniature solid state devices in which adsorption of target analytes produces measurable and quantifiable changes in conductance on a suitably chosen collection of sensing materials. Microsensor development evolving from this work would allow monitoring devices to be tailored for a range of Department of Energy hazardous waste sites (and for other applications). The primary project objectives for this three year program, summarized below, have not changed from those described in our proposal document.
Date: June 1, 1999
Creator: Semancik, Steve; Tarlov, Michael; Cavicchi, Richard; Suehle, John S. & McAvoy, Thomas J.
Partner: UNT Libraries Government Documents Department

Evaluation of Heat Shields from RTS Wright Industries Magnesium and Uranium Beds

Description: Heat shields from a factory test of the furnaces that will be used to heat the magnesium and uranium beds for the tritium extraction facility (TEF) were examined to determine the cause of discoloration. The samples were examined using visual, optical microscopy, electron microscopy, x-ray spectroscopy, and Auger electron spectroscopy.
Date: October 29, 2002
Creator: Korinko, P.S.
Partner: UNT Libraries Government Documents Department

EXAFS and activity studies of the poisoning effect on Cl on Pt/Al{sub 2}O{sub 3} catalysts during oxidation reactions.

Description: The effect of Cl on the activity of Pt/Al{sub 2}O{sub 3} catalysts for methane oxidation has been studied by H{sub 2} and CO chemisorption, O{sub 2} isotopic exchange, kinetic studies and EXAFS spectroscopy. Catalysts containing 1.5% pt/Al{sub 2}O{sub 3} were prepared by incipient wetness from H{sub 2}PtCl{sub 6} and Pt(NH{sub 3}){sub 4}(NO{sub 3}){sub 2} precursors. Both reduced catalysts have similar dispersion (0.8) as determined by H{sub 2} chemisorption. At low methane concentration (0.3 vol.% CH{sub 4}, 16 vol.% O{sub 2}) the Cl-free catalyst was about 20 times more active during complete methane oxidation than the Cl-containing catalyst. Both CO chemisorption and oxygen exchange were observed on the Cl-free catalyst, whereas they were not detected on the Cl-containing catalyst. On the Cl-free catalyst, only Pt-Pt and Pt-O bonds were detected from the EXAFS results, while on the Cl-containing catalyst additional Pt-Cl bonds were present. The effect of chlorine on activity strongly depended on the reactant concentration. Exposure of the Cl-free catalyst to higher concentrations of methane (3 vol.% CH{sub 4}) reduced the activity to a level similar to that of the Cl-containing catalyst. Addition of HCl to the Cl-free catalyst rendered the activity identical to the catalyst prepared from Cl-containing precursors. A model is proposed to explain the mechanism of chloride poisoning, which appears to be site blocking.
Date: April 5, 2001
Creator: Gracia, F.; Wolf, E. E.; Miller, J. T. & Kropf, A. J.
Partner: UNT Libraries Government Documents Department

Correlation of Chemisorption and Electronic Effects for Metal/Oxide Interfaces: Transducing Principles for Temperature-Programmed Gas Microsensors

Description: This research project seeks to produce, and demonstrate the utility of, a scientific database for oxide conductometric sensing materials that relates materials performance (sensitivity, selectivity and stability) to composition, microstructure and temperature. This information and the capabilities derived from it would be applied to developing a robust, low cost and application tunable chemical monitoring technology based on micromachined platforms.
Date: June 1, 2000
Creator: Semancik, Steve; Cavicchi, Richard E. & McAvoy, Thomas J.
Partner: UNT Libraries Government Documents Department

Solid Sorbents for Removal of Carbon Dioxide from Gas Streams at Low Temperatures

Description: New low-cost CO2 sorbents are provided that can be used in large-scale gas-solid processes. A new method is provided for making these sorbents that involves treating substrates with an amine and/or an ether so that the amine and/or ether comprise at least 50 wt. percent of the sorbent. The sorbent acts by capturing compounds contained in gaseous fluids via chemisorption and/or physisorption between the unit layers of the substrate's lattice where the polar amine liquids and solids and/or polar ether liquids and solids are located. The method eliminates the need for high surface area supports and polymeric materials for the preparation of CO2 capture systems, and provides sorbents with absorption capabilities that are independent of the sorbents' surface areas. The sorbents can be regenerated by heating at temperatures in excess of 35 degrees C.
Date: June 21, 2005
Creator: Sirwardane, Ranjani V.
Partner: UNT Libraries Government Documents Department

Hydrogen storage on activated carbon. Final report

Description: The project studied factors that influence the ability of carbon to store hydrogen and developed techniques to enhance that ability in naturally occurring and factory-produced commercial carbon materials. During testing of enhanced materials, levels of hydrogen storage were achieved that compare well with conventional forms of energy storage, including lead-acid batteries, gasoline, and diesel fuel. Using the best materials, an electric car with a modern fuel cell to convert the hydrogen directly to electricity would have a range of over 1,000 miles. This assumes that the total allowable weight of the fuel cell and carbon/hydrogen storage system is no greater than the present weight of batteries in an existing electric vehicle. By comparison, gasoline cars generally are limited to about a 450-mile range, and battery-electric cars to 40 to 60 miles. The project also developed a new class of carbon materials, based on polymers and other organic compounds, in which the best hydrogen-storing factors discovered earlier were {open_quotes}molecularly engineered{close_quotes} into the new materials. It is believed that these new molecularly engineered materials are likely to exceed the performance of the naturally occurring and manufactured carbons seen earlier with respect to hydrogen storage.
Date: November 1, 1994
Creator: Schwarz, J. A.
Partner: UNT Libraries Government Documents Department