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Steam gasification of carbon: Catalyst properties

Description: This research uses several techniques to measure the concentration of catalyst sites and determine their stoichiometry for the catalyzed gasification of carbon. Both alkali and alkaline earth oxides are effective catalysts for accelerating the gasification rate of coal chars, but only a fraction of the catalyst appears to be in a form that is effective for gasification, and the composition of that catalyst is not established. Transient techniques, with {sup 13}C labeling, are being used to study the surface processes, to measure the concentration of active sites, and to determine the specific reaction rates. We have used secondary ion mass spectroscopy (SIMS) for both high surface area samples of carbon/alkali carbonate mixtures and for model carbon surfaces with deposited alkali atoms. SIMS provides a direct measure of surface combination of these results can provide knowledge of catalyst dispersion and composition, and thus indicate the way to optimally utilize carbon gasification catalysts.
Date: September 16, 1991
Creator: Falconer, J.L.
Partner: UNT Libraries Government Documents Department

Methane conversion to methanol

Description: The objective of this research study is to demonstrate the effectiveness of a catalytic membrane reactor for the partial oxidation of methane. The specific goals are to demonstrate that we can improve product yield, demonstrate the optimal conditions for membrane reactor operation, determine the transport properties of the membrane, and provide demonstration of the process at the pilot plant scale. The last goal will be performed by Unocal, Inc., our industrial partner, upon successful completion of this study.
Date: January 1, 1992
Creator: Noble, R.D. & Falconer, J.L.
Partner: UNT Libraries Government Documents Department

Physics of correlated systems

Description: This report discusses the following topics: negative hydrogen ions doubly-excited state properties; spectra of heavy open-shell atoms; atomic hydrogen in a strong magnetic field. (LSP)
Date: January 1, 1991
Creator: Greene, C.H.
Partner: UNT Libraries Government Documents Department

Physics of correlated systems

Description: This report discusses hydrogen minus doubly-excited state properties; spectra of heavy open-shell atoms; atomic hydrogen in a strong magnetic field; and other simple atomic systems. (LSP)
Date: January 1, 1991
Creator: Greene, C.H.
Partner: UNT Libraries Government Documents Department

Steam gasification of carbon: Catalyst properties

Description: This research uses several techniques to measure the concentration of catalyst sites and determine their stoichiometry for the catalyzed gasification of carbon. Both alkali and alkaline earth oxides are effective catalysts for accelerating the gasification rate of coal chars, but only a fraction of the catalyst appears to be in a form that is effective for gasification, and the composition of that catalyst is not established. Transient techniques with {sup 13}C labeling, are being used to study the surface processes, to measure the concentration of active sites, and to determine the specific reaction rates. We have used secondary ion mass spectrometry (SIMS) for both high surface area samples of carbon/alkali carbonate mixtures and for model carbon surfaces with deposited alkali atoms. SIMS provides a direct measure of surface composition. The combination of these results can provide knowledge of catalyst dispersion and composition, and thus indicate the way to optimally utilize carbon gasification catalysts.
Date: December 13, 1991
Creator: Falconer, J.L.
Partner: UNT Libraries Government Documents Department

Steam gasification of carbon: Catalyst properties

Description: This research uses several techniques to measure the concentration of catalyst sites and determine their stoichiometry for the catalyzed gasification of carbon. Both alkali and alkaline earth oxides are effective catalysts for accelerating the gasification rate of coal chars, but only a fraction of the catalyst appears to be in a form that is effective for gasification, and the composition of that catalyst is not established. Transient techniques, with {sup 13}C labeling, are being used to study the surface processes, to measure the concentration of active sites, and to determine the specific reaction rates. We have used secondary ion mass spectrometry (SIMS) for both high surface area samples of carbon/alkali carbonate mixtures and for model carbon surfaces with deposited alkali atoms. SIMS provides a direct measure of surface composition. The combination of these results can provide knowledge of catalyst dispersion and composition, and thus indicate the way to optimally utilize carbon gasification catalysts.
Date: March 16, 1992
Creator: Falconer, J.L.
Partner: UNT Libraries Government Documents Department

Application of modern mathematical concepts to plasma confinement

Description: Progress in three research areas has been achieved. (1) A new expression for the trapping probability for transitioning particles in asymmetric toroidal plasma confinement devices (e.g., stellarators and rippled tokamaks) has been derived. Comparison with numerical integrations shows that this new expression is more accurate than those of previous workers. (2) Simulations show that the dynamical enhancement of the turbulent diffusion coefficient over quasilinear observed in test particle simulations occurs also in selfconsistent plasma turbulence. (3) The simple method for calculating magnetic island widths discussed in the previous report has been published.
Date: August 1, 1991
Creator: Cary, J.R.
Partner: UNT Libraries Government Documents Department

IUTAM symposium on hydrodynamic diffusion of suspended particles

Description: Hydrodynamic diffusion refers to the fluctuating motion of nonBrownian particles (or droplets or bubbles) which occurs in a dispersion due to multiparticle interactions. For example, in a concentrated sheared suspension, particles do not move along streamlines but instead exhibit fluctuating motions as they tumble around each other. This leads to a net migration of particles down gradients in particle concentration and in shear rate, due to the higher frequency of encounters of a test particle with other particles on the side of the test particle which has higher concentration or shear rate. As another example, suspended particles subject to sedimentation, centrifugation, or fluidization, do not generally move relative to the fluid with a constant velocity, but instead experience diffusion-like fluctuations in velocity due to interactions with neighboring particles and the resulting variation in the microstructure or configuration of the suspended particles. In flowing granular materials, the particles interact through direct collisions or contacts (rather than through the surrounding fluid); these collisions also cause the particles to undergo fluctuating motions characteristic of diffusion processes. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.
Date: December 31, 1995
Creator: Davis, R.H.
Partner: UNT Libraries Government Documents Department

Controlled production of cellulases in plants for biomass conversion. Progress report, June 15, 1996--March 10, 1997

Description: The goal of this project is to facilitate conversion of plant biomass to usable energy by developing transgenic plants that express genes for microbial cellulases, which can be activated after harvest of the plants. In particular, we want to determine the feasibility of targeting an endoglucanase and a cellobiohydrolase to the plant apoplast (cell wall milieu). The apoplast not only contains cellulose, the substrate for the enzymes, but also can tolerate large amounts of foreign protein. To avoid detrimental effects of cellulase expression in plants, we have chosen enzymes with high temperature optima; the genes for these enzymes are from thermophilic organisms that can use cellulose as a sole energy source.
Date: June 1, 1997
Creator: Danna, K.J.
Partner: UNT Libraries Government Documents Department

Finding four dimensional symplectic maps with reduced chaos: Preliminary results

Description: A method for finding integrable four-dimensional symplectic maps is outlined. The method relies on solving for parameter values at which the linear stability factors of the fixed points of the map have the values corresponding to integrability. This method is applied to accelerator lattices in order to increase dynamic aperture. Results show a increase of the dynamic aperture after correction, which implies the validity of the method.
Date: June 1, 1998
Creator: Wan, Weishi; Cary, J.R. & Shasharina, S.G.
Partner: UNT Libraries Government Documents Department

Controlled production of cellulases in plants for biomass conversion. Annual report, March 11, 1997--March 14, 1998

Description: The goal of this project is to facilitate conversion of plant biomass to usable energy by developing transgenic plants that express genes for microbial cellulases, which can be activated after harvest of the plants. In particular, the feasibility of targeting an endoglucanase and a cellobiohydrolase to the plant apoplast (cell wall milieu) is to be determined. To avoid detrimental effects of cellulose expression in plants, enzymes with high temperature optima were chosen; the genes for these enzymes are from thermophilic organisms that can use cellulose as a sole energy source. During the past year (year 2 of the grant), efforts have been focused on testing expression of endoglucanase E{sub 1}, from Acidothermus cellulolyticus, in the apoplast of both tobacco suspension cells and Arabidopsis thaliana plants. Using the plasmids constructed during the first year, transgenic cells and plants that contain the gene for the E{sub 1} catalytic domain fused to a signal peptide sequence were obtained. This gene was constructed so that the fusion protein will be secreted into the apoplast. The enzyme is made in large quantities and is secreted into the apoplast. More importantly, it is enzymatically active when placed under optimal reaction conditions (high temperature). Moreover, the plant cells and intact plants exhibit no obvious problems with growth and development under laboratory conditions. Work has also continued to improve binary vectors for Agrobacterium-mediated transformation, to determine activity of E{sub 1} at various temperatures, and to investigate the activity of the 35S Cauliflower Mosaic Virus promoter in E. coli. 9 figs.
Date: June 1, 1998
Creator: Danna, K.J.
Partner: UNT Libraries Government Documents Department

An efficient strategy for the inversion of bidirectional reflectance models with satellite remote sensing data

Description: The angular distribution of radiation scattered by the earth surface contains information on the structural and optical properties of the surface. Potentially, this information may be retrieved through the inversion of surface bidirectional reflectance distribution function (BRDF) models. This report details the limitations and efficient application of BRDF model inversions using data from ground- and satellite-based sensors. A turbid medium BRDF model, based on the discrete ordinates solution to the transport equation, was used to quantify the sensitivity of top-of-canopy reflectance to vegetation and soil parameters. Results were used to define parameter sets for inversions. Using synthetic reflectance values, the invertibility of the model was investigated for different optimization algorithms, surface and sampling conditions. Inversions were also conducted with field data from a ground-based radiometer. First, a soil BRDF model was inverted for different soil and sampling conditions. A condition-invariant solution was determined and used as the lower boundary condition in canopy model inversions. Finally, a scheme was developed to improve the speed and accuracy of inversions.
Date: December 31, 1994
Creator: Privette, J.L.
Partner: UNT Libraries Government Documents Department

[Time-resolved FTIR emission studies of laser photofragmentation and radical reactions]

Description: Fourier transform infrared emission experiments were used to study photofragmentation processes, single collision reactions, energy transfer events, and laser-initiated radical-radical reactions: CH{sub 3} + O, Cl + C{sub 2}H{sub 5}, CF{sub 3}CH{sub 2} + D, H + H{sub 2}O, H + HF, and H + NH{sub 2}.
Date: December 31, 1994
Partner: UNT Libraries Government Documents Department

Mechanistic aspects of photoconversion at semiconductor-liquid junctions and in facilitated transport membranes. Final report, March 15, 1994--March 14, 1998

Description: A major portion of the research completed during this funding period involved the use of rotating ring-disk electrochemical techniques in conjunction with carefully chosen solution redox systems to investigate hot electron transfer reactions at the semiconductor electrolyte interface. This paper cover the following topics: photoreduction reactions at GaAs/AlGaAs superlattice electrodes; photoelectrochemistry at GaInP{sub 2} capped p-GaAs electrodes; further investigation of p-InP photocathodes; rotating ring disk photoelectrochemistry at TiO{sub 2} films; and photomodulation of interfacial mass transport rates.
Date: June 1, 1998
Creator: Koval, C.A.
Partner: UNT Libraries Government Documents Department

Neoclassical transport of energetic particles in asymmetric toroidal plasma. Progress report

Description: During the most recent funding period the authors obtained results important for helical confinement systems and in the use of modern computational methods for modeling of fusion systems. The most recent results include showing that the set of magnetic field functions that are omnigenous (i.e., the bounce-average drift lies within the flux surface) and, therefore, have good transport properties, is much larger than the set of quasihelical systems. This is important as quasihelical systems exist only for large aspect ratio. The authors have also carried out extensive earlier work on developing integrable three-dimensional magnetic fields, on trajectories in three-dimensional configurations, and on the existence of three-dimensional MHD equilibria close to vacuum integrable fields. At the same time they have been investigating the use of object oriented methods for scientific computing.
Date: October 1, 1997
Creator: Cary, J.R.
Partner: UNT Libraries Government Documents Department

Two-dimensional synthesis: Ultrathin porous membranes. Final report, December 1, 1993--November 30, 1996

Description: The proposed proof of concept has been accomplished. We have synthesized an ultrathin (7 {angstrom}) covalent molecular grid of the proposed type, composed of 2.5 nm x 2.5 run squares with 1.5 nm x 1. 5 nm square openings, we have demonstrated that it is sturdy (boiling with alcoholic HCl and surface-to-surface transfer), and we have obtained its spectral and STM characterization. The synthesis was based on the originally proposed two-dimensional linear cross-coupling of oriented molecular connectors mounted on pedestals that were constrained to a two-dimensional liquid mercury surface, but the molecules actually used in the successful experiment were different from those intended originally. In this first attempt, only small sheets of the grid were made (up to 0.15 {mu} x 0.15 {mu}), and they did not have long-range order. Both of these problems were undoubtedly caused by the use of an irreversible coupling reaction in the polymerization process, and by the use of a coupler that was not strictly linear and thus permitted easy formation of defects (pentagons instead of squares, etc.). Neither of these limitations are inherent, and we have already submitted research proposals in which we outline how we propose to do the polymerization in a reversible way, yet produce a sturdy polymeric grid, and suggest chemical structures for linear couplers. Patent protection for these results has been applied for by the University of Colorado (following up on a previous conceptual patent already granted) and several publications have been written.
Date: May 28, 1997
Creator: Michl, J.
Partner: UNT Libraries Government Documents Department

Symposium on hydrodynamic diffusion of suspended particles. Final report

Description: The symposium brought together researchers from academic, government, and private laboratories interested in the interactions of particles in fluids and in granular media. There were 68 participants, including 24 students, currently residing In 12 countries. The participants represented a wide variety of fields, including applied mathematics, chemical engineering, computer science, fluid dynamics, materials science, mechanical engineering, physics, and theoretical and applied mechanics. There were 33 talks and 16 posters presented. The focus of the symposium was on multiparticle hydrodynamic interactions which lead to fluctuating motion of the particles and resulting particle migration and dispersion or diffusion. Implications of these phenomena were described for sedimentation, fluidization, suspension flows, granular flows, and fiber suspensions. Computer simulation techniques as well as experimental techniques were described.
Date: May 1, 1996
Partner: UNT Libraries Government Documents Department

Direct methane conversion to methanol. Final report, April 13, 1995--September 30, 1996

Description: We proposed to demonstrate the effectiveness of a catalytic membrane reactor (a ceramic membrane combined with a catalyst) to selectively produce methanol by partial oxidation of methane. Methanol is used as a chemical feed stock, gasoline additive, and turbine fuel. Methane partial oxidation using a catalytic membrane reactor has been determined as one of the promising approaches for methanol synthesis from methane. Methanol synthesis and separation in one step would also make methane more valuable for producing chemicals and fuels. Another valuable fuel product is H{sub 2}. Its separation from other gasification products would make it very valuable as a chemical feedstock and clean fuel for fuel cells. Gasification of coal or other organic fuels as a source of H{sub 2} produces compounds (CO, CO{sub 2}, and H{sub 2}O) that require high temperature (1000-1500 degrees F) and high pressure (600-1000 psia) separations. A zeolite membrane layer on a mechanically stable ceramic or stainless steel support would have ideal applications for this type of separation.
Date: January 1, 1998
Creator: Noble, R.D. & Falconer, J.L.
Partner: UNT Libraries Government Documents Department

Direct methane conversion to methanol. Final report, July 19, 1990--May 18, 1996

Description: One objective of this project was to demonstrate the effectiveness of a catalytic membrane reactor (a ceramic membrane combined with a catalyst) to selectively produce methanol by partial oxidation of methane. Methanol is used as a chemical feed stock, gasoline additive, and turbine fuel. Methane partial oxidation using a catalytic membrane reactor has been determined as one of the promising approaches for methanol synthesis from methane. Methanol synthesis and separation in one step would also make methane valuable for producing chemicals and fuels. Another valuable fuel product is H{sub 2}. Its separation from other gasification products would make it very valuable as a chemical feedstock and clean fuel for fuel cells. Gasification of coal or other organic fuels as a source of H{sub 2} produces compounds (CO, CO{sub 2}, and H{sub 2}O) that require high temperature (1000-1500{degrees}F) and high pressure (600-1000 psia) separations. A zeolite membrane layer on a mechanically stable ceramic or stainless steel support would have ideal applications for this type of separation. Separations using zeolite membrane was also evaluated for use in the production in the above fuels. 20 refs., 20 figs., 1 tab.
Date: December 31, 1998
Partner: UNT Libraries Government Documents Department

A theoretical analysis of the extraction of heterocyclic organic compounds from an organic phase using chemically mediated electrochemically modulated complexation in ion exchange polymer beads

Description: A cyclical electrochemical process for the removal of heterocyclic organic compounds (pollutants) from an organic solvent using an ion-exchange polymer is analyzed. In this analysis, there are three main steps: In the first step, the polymer beads containing the active form of the complexing agent are contacted with the contaminated (feed) hydrocarbon phase. The pollutant diffuses into the beads and binds with the complexing agent which is in the reduced state. It is a fast reversible reaction. For the second step, the beads which contain a pollutant are contacted with a waste (receiving) phase and a chemical mediator is then used to oxidize the complexing agent and to reduce its affinity towards the pollutant so that it can be released. The oxidation of the complexing agent is an irreversible reaction. This is a moving boundary problem with countercurrent diffusion. For each mole of mediator that goes into the bead, one mole of pollutant exits since each complexing agent binds one pollutant. In the third step, the waste hydrocarbon phase is removed and a second chemical mediator is then used to reduce the complexing agent. The reduction of the complexing agent is also an irreversible reaction. Partial differential equations are used to analyze this process. 26 refs., 9 figs.
Date: January 1, 1991
Creator: Ozekin, K.; Noble, R.D. & Koval, C.A.
Partner: UNT Libraries Government Documents Department

Reaction kinetics and product distributions in photoelectrochemical cells

Description: Hot electron reaction studies at p-InP/CH[sub 3]CN interface revealed essential/desirable features for redox systems used to investigate hot carriers in photoelectrocehmical cells. Reduction of dibromoethylbenzene (DBEB) in presence of metallocene couples is being studied using rotating rink disk electrodes of n-and p-InP disks and Pt rings. At highly doped p-InP electrodes, reduction of DBEB can be very efficient (>30%). A minielectrochemical cell was used to investigate electron transfer at nonilluminated n-WSe[sub 2]/dimethylferrocene[sup +/0] interfaces.
Date: January 1, 1992
Creator: Koval, C.A.
Partner: UNT Libraries Government Documents Department

Thermohaline circulations and global climate change. Final report

Description: This research is ultimately concerned with investigating the hypothesis that changes in surface thermal and hydrological forcing of the North Atlantic, changes that might be expected to accompany CO2-induced global warming, could result in ocean-atmosphere interactions` exerting a positive feedback on the climate system. This report concerns research conducted with funding from the Carbon Dioxide Research Program (now the Global Climate Change Program) of the US Department of Energy via grant no. DE-FG02-90ER61019 during the period 15 July 1990 - 14 July 1994. This was a three-year award, extended to a fourth year (15 July 1993 - 14 July 1994) via a no-cost extension. It is important to emphasize that this award has been renewed for an additional two years (15 July 1993 - 14 July 1995) via grant no. DE-FG03-93ER61646 (with the same title). Because the project was originally envisioned to be a five-year effort, many of the important results and conclusions will be available for the Final Report of that second award. This report therefore concerns mainly preliminary conclusions and a discussion of progress toward understanding the central hypothesis of the research.
Date: September 1, 1994
Creator: Hanson, H. P.
Partner: UNT Libraries Government Documents Department