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Arctic Energy Technology Development Laboratory (Part 2)
Methane (CH{sub 4}) in natural gas is a major energy source in the U.S., and is used extensively on Alaska's North Slope, including the oilfields in Prudhoe Bay, the community of Barrow, and the National Petroleum Reserve, Alaska (NPRA). Smaller villages, however, are dependent on imported diesel fuel for both power and heating, resulting in some of the highest energy costs in the U.S. and crippling local economies. Numerous CH{sub 4} gas seeps have been observed on wetlands near Atqasuk, Alaska (in the NPRA), and initial measurements have indicated flow rates of 3,000-5,000 ft{sup 3} day{sup -1} (60-100 kg CH{sub 4} day{sup -1}). Gas samples collected in 1996 indicated biogenic origin, although more recent sampling indicated a mixture of biogenic and thermogenic gas. In this study, we (1) quantified the amount of CH{sub 4} generated by several seeps and evaluated their potential use as an unconventional gas source for the village of Atqasuk; (2) collected gas and analyzed its composition from multiple seeps several miles apart to see if the source is the same, or if gas is being generated locally from isolated biogenic sources; and (3) assessed the potential magnitude of natural CH{sub 4} gas seeps for future use …
Date:
December 31, 2008
Creator:
960443, See OSTI ID Number
Object Type:
Report
System:
The UNT Digital Library
Arctic Energy Technology Development Laboratory (Part 3)
Various laboratory tests were carried at the R & D facility of BJ Services in Tomball, TX with BJ Services staff to predict and evaluate the performance of the Ceramicrete slurry for its effective use in permafrost cementing operations. Although other standards such as those of the American Standard for Testing Materials (ASTM) and Construction Specification Institute (CSI) exist, all these tests were standardized by the API. A summary of the tests traditionally used in the cement slurry design as well as the API tests reference document are provided in Table 7. All of these tests were performed within the scope of this research to evaluate properties of the Ceramicrete.
Date:
December 31, 2008
Creator:
960443, See OSTI ID Number
Object Type:
Report
System:
The UNT Digital Library
[Account Statement for A-B-C Racket Store, December, 1948]
Account statement prepared for Jeane Bertig Kempner by A-B-C Racket Store for charges including itemized charges and balance.
Date:
December 31, 1948
Creator:
A-B-C Racket Store
Object Type:
Text
System:
The Portal to Texas History
[Concrete Footing Reinforcement]
Photograph of a footing reinforcement for a concrete pile cap in the Brownsville post office. It consists of a large square panel with four rows of four round objects covered with metal rods in a criss-cross pattern. A text on the front of the photograph reads "'Rogers' Photo 12-17-1931."
Date:
December 31, 1931
Creator:
A. Rogers Studio
Object Type:
Photograph
System:
The Portal to Texas History
Results from the Soviet-American gallium experiment
A radiochemical {sup 71}Ga-{sup 71}Ge experiment to determine the primary flux of neutrinos from the Sun has begun operation at the Baksan Neutrino Observatory. The number of {sup 71}Ge atoms extracted from thirty tons of gallium was measured in five runs during the period of January to July 1990. Assuming that the extraction efficiency for {sup 71}Ge atoms produced by solar neutrinos is the same as from natural Ge carrier, we observed the capture rate to be 20 + 15/{minus}20 (stat) {plus_minus} 32 (syst) SNU, resulting in a limit of less than 79 SNU (90% CL). This is to be compared with 132 SNU predicted by the Standard Solar Model.
Date:
December 31, 1991
Creator:
Abazov, A. I.; Anosov, O. L.; Faizov, E. L.; Gavrin, V. N.; Kalikhov, A. V.; Knodel, T. V. et al.
Object Type:
Report
System:
The UNT Digital Library
An engineering and economic evaluation of the methane de-NOX{sup SM} technology
The Institute of Gas Technology (IGT) and Ogden Martin Systems, Inc. (OMS) are conducting joint engineering and economic evaluation of IGT`s METHANE de-NOX{sup SM} technology for its application to new, as well as retrofit, municipal waste combustors (MWCs). It is anticipated that this new technology offers a technically and economically attractive alternative to existing selective noncatalytic reduction (SNCR) systems for new facilities, as well as in retrofit applications. Consequently, IGT and OMS are considering pursuing a long-term demonstration of this technology on an OMS MWC. The METHANE de-NOX approach was developed based on extensive full-scale MWC infurnace characterization and pilot-scale testing using simulated combustion products. The approach involves injection of natural gas, together with recirculated flue gases (for mixing), above the grate to provide oxygen-deficient combustion conditions that promote the destruction of NO{sub x} precursors, as well as NO{sub x}. Extensive pilot-scale testing, using both simulated combustion products and actual municipal waste (MW), showed that significant NO{sub x} reduction could be achieved. The results were used to define the key operating parameters for a field evaluation of the process. A full-scale METHANE de-NOX system was designed and retrofitted to a 100-ton/day Riley/Takuma mass burn system at the Olmsted County Waste-to-Energy …
Date:
December 31, 1993
Creator:
Abbasi, H. A.; Khinkis, M. J. & Scherrer, R.
Object Type:
Report
System:
The UNT Digital Library
Development of novel copper-based sorbents for hot-gas cleanup. Technical report, September 1--November 30, 1991
The objective of this investigation is to evaluate several novel copper-based binary oxides for their suitability as regenerable sorbents for hot gas cleanup application in the temperature range of 650{degree} to 850{degree}C (1200{degree}--1550{degree}F). To achieve this objective, several novel copper-based binary oxide sorbents will be prepared. Experimental tests will be conducted at ambient pressure to determine the stability, sulfidation capacity, regenerability, and sulfidation kinetics of the novel sorbents. Tests will also be conducted at high pressure for the determination of the sulfidation reactivity, regenerability, and durability of the sorbents. The attrition characteristics of the sorbents will also be determined.
Date:
December 31, 1991
Creator:
Abbasian, J.
Object Type:
Report
System:
The UNT Digital Library
Stabilization and/or regeneration of spent sorbents from coal gasification. Technical report, September 1--November 30, 1991
The objective of this investigation is to determine the effects of SO{sub 2} partial pressure and reaction temperature on the conversion of sulfide containing solid wastes from coal gasifiers to stable and environmentally acceptable calcium-sulfate, while preventing the release of sulfur dioxide through undesirable side reactions during the stabilization step. An additional objective of this program is to investigate the use of the Spent Sorbent Regeneration Process (SSRP) to regenerate spent limestone, from a fluidized-bed gasifier with in-bed sulfur capture, for recycling to the gasifier. To achieve these objectives, selected samples of partially sulfided sorbents will be reacted with oxygen at a variety of operating conditions under sufficient SO{sub 2} partial pressure to prevent release of sulfur from the solids during stabilization that reduces the overall sorbent utilization. Partially sulfided limestone will also be regenerated with water to produce calcium hydroxide and release sulfur as H{sub 2}S. The regenerated sorbent will be dewatered, dried and pelletized. The reactivity of the regenerated sorbent toward H{sub 2}S will also be determined. During this quarter sulfidation tests were conducted in a quartz fluidized-bed reactor in which the selected calcium-based sorbents were first calcined and then were reacted with hydrogen sulfide at ambient pressure …
Date:
December 31, 1991
Creator:
Abbasian, J.
Object Type:
Report
System:
The UNT Digital Library
Sulfur removal in advanced two stage pressurized fluidized bed combustion. Technical report, March 1--May 31, 1995
The objective of this study is to obtain data on the rates and the extent of sulfation reactions involving partially sulfided calcium-based sorbents, and oxygen as well as sulfur dioxide, at operating conditions closely simulating those prevailing in the second stage (combustor) of Advanced Two-Stage Pressurized Fluidized-Bed Combustors. In these systems the CO{sub 2} partial pressure generally exceeds the equilibrium value for calcium carbonate decomposition. Therefore, calcium sulfate is produced through the reactions between SO{sub 2} and calcium carbonate as well as the reaction between calcium sulfide and oxygen. To achieve this objective, the rates of reaction involving SO{sub 2} and oxygen, calcium sulfide and calcium carbonate will be determined by conducting tests in a pressurized thermogravimetric analyzer unit. The sulfate tests conducted during this quarter, focused on the determination of the rate of sulfation reaction involving partially sulfided half-calcined dolomite and oxygen. The test parameters included CO{sub 2} and O{sub 2} concentrations, reaction temperature and pressure, as well as the sorbent particle size. The results obtained during this quarter suggest that the rate of sulfation reaction involving partially sulfided half-calcined dolomite and oxygen is very fast at temperatures above 850 C which rapidly increases with increasing temperature, achieving more …
Date:
December 31, 1995
Creator:
Abbasian, J.
Object Type:
Report
System:
The UNT Digital Library
Stabilization and/or regeneration of spent sorbents from coal gasification. Final technical report, September 1, 1991--August 31, 1992
The objective of this investigation was to determine the effects of SO{sub 2} partial pressure and reaction temperature on the conversion of sulfide containing solid wastes from coal gasifiers to stable and environmentally acceptable calcium sulfate, while preventing the release of sulfur dioxide during the stabilization step. An additional objective of this study was to investigate the use of the Spent Sorbent Regeneration Process (SSRP) to regenerate spent Ca-based sorbent, from a fluidized-bed gasifier with in-bed sulfur capture, for recycling to the gasifier. To achieve these objectives, selected samples of partially sulfided sorbents were reacted with oxygen and SO{sub 2} at various operating conditions and the extent of CaS and CaO conversion were determined. Partially sulfided dolomite was used in sulfidation/regeneration over several cycles and the regeneration efficiency and sorbent reactivity were determined after each cycle. The results of the stabilization tests show that partially sulfided Ca-based sorbents (both limestone and dolomite) can be sulfated at temperatures above 1500{degrees}F resulting in high CaS conversion without release of SO{sub 2} producing environmentally acceptable material for disposal in landfills. The results also indicate that spent dolomite can be regenerated in the SSRP process, in successive cycles, with high regeneration efficiency without loss …
Date:
December 31, 1992
Creator:
Abbasian, J.; Hill, A. H. & Wangerow, J. R.
Object Type:
Report
System:
The UNT Digital Library
Stabilization of spent sorbents from coal gasification. Final technical report, September 1, 1992--August 31, 1993
The objective of this investigation was to determine the rates of reactions involving partially sulfided dolomite and oxygen, which is needed for the design of the reactor system for the stabilization of sulfide-containing solid wastes from gasification of high sulfur coals. To achieve this objective, samples of partially sulfided dolomite were reacted with oxygen at a variety of operating conditions in a fluidized-bed reactor. The effect of external diffusion was eliminated by using small quantities of the sorbent and maintaining a high flow rate of the reactant gas. The reacted sorbents were analyzed to determine the extent of conversion as a function of operating variables including sorbent particle size, reaction temperature and pressure, and oxygen concentration. The results of sulfation tests indicate that the rate of reaction increases with increasing temperature, increasing oxygen partial pressure, and decreasing sorbent particle size. The rate of the sulfation reaction can be described by a diffuse interface model where both chemical reaction and intraparticle diffusion control the reaction rate. The kinetic model of the sulfation reaction was used to determine the requirements for the reactor system, i.e., reactor size and operating conditions, for successful stabilization of sulfide-containing solid wastes from gasification of high sulfur …
Date:
December 31, 1993
Creator:
Abbasian, J.; Hill, A. H.; Rue, D. M. & Wangerow, J. R.
Object Type:
Report
System:
The UNT Digital Library
Development of novel copper-based sorbents for hot-gas cleanup. Final technical report, September 1, 1991--August 31, 1992
The objective of this investigation was to evaluate several novel copper-based binary oxides for their suitability as regenerable sorbents for hot gas cleanup application in the temperature range of 650{degree} to 850{degree}C. To achieve this objective, several novel binary oxides of copper were systematically evaluated and ranked in terms of their high-temperature stability against reduction to metal, sulfidation reactivity, and regenerability. The sorbents studied included oxides of chromium, cerium, aluminum, magnesium, manganese, titanium, iron, and silicon. The results of initial testing indicated that mixed binary oxides of copper with chromium (CuCr{sub 2}O{sub 4}) and cerium (CuO{circle_dot}CeO{sub 2}) were the most promising sorbents for such high temperature gas cleanup applications. These two sorbents were further evaluated in cyclic sulfidation/regeneration tests in 10--15 cycles to determine the effect of operating conditions on their performance. The results of this investigation indicate that the two selected sorbents, copper-chromium and copper-cerium, are capable of removing H{sub 2}S from the hot fuel gas to very low levels (<10 ppmv) at temperatures as high as 850{degree}C with good sorbent regenerability in cyclic process. These sorbents should be further studied to achieve optimum sorbent composition for hot gas cleanup application.
Date:
December 31, 1992
Creator:
Abbasian, J.; Hill, A. H.; Wangerow, J. R.; Flytzani-Stephanopoulos, M.; Bo, Luhong; Patel, C. et al.
Object Type:
Report
System:
The UNT Digital Library
Advanced Low-Temperature Fluid Bed Sorbents
This paper discusses the results obtained in an ongoing study geared towards developing advanced mixed-metal oxide sorbents for desulfurization of coal-derived fuel gases in the temperature range of 350 to 550{degrees}C. The paper focuses on the study related to the development of durable sorbents suitable for fluidized-bed application and addresses thermodynamic considerations, sulfidation kinetics, regenerability, and the physical and chemical characteristics of a number of novel sorbents.
Date:
December 31, 1996
Creator:
Abbasian, J.; Slimane, R. B. & Wangerow, J. R.
Object Type:
Article
System:
The UNT Digital Library
Development of regenerable copper-based sorbents for hot gas cleanup. Technical report, September 1, 1995--November 30, 1995
The overall objective of this study is to determine the effectiveness of the copper-chromite sorbent (developed in previous ICCI-funded projects) for longer duration application under optimum conditions in the temperature range of 550{degrees}-650{degrees}C to minimize sorbent reduction and degradation during the cyclic process. To achieve this objective, several formulations of copper chromite sorbents are prepared. These sorbent formulations are screened for their desulfurization and regeneration capability at predetermined temperatures and gas residence times. The durability of the best sorbent formulation identified in the screening tests is evaluated in ``long-term`` durability tests conducted at the optimum operating conditions. This includes testing the sorbent in pellet and granular forms in packed- and fluidized-bed reactors. During this quarter, twenty one copper chromite-based sorbent formulations were prepared. Two sorbent formulations that have acceptable crush strength, designated as CuCr-10 and CuCr-21, were tested over 5 and 6 cycles respectively. The results indicate that both sorbents are reactive toward H{sub 2}S at 650{degrees}C and that the reactivity of the sorbents are relatively constant over the first 5 to 6 cycles. The H{sub 2}S prebreakthrough concentrations were generally about 20 to 30 ppm, making them suitable for IGCC application.
Date:
December 31, 1995
Creator:
Abbasian, J.; Slimane, R.B. & Hill, A.H.
Object Type:
Report
System:
The UNT Digital Library
Sulfur removal in advanced two stage pressurized fluidized bed combustion. Technical report, September 1--November 30, 1994
The objective of this study is to obtain data on the rates and the extent of sulfation reactions involving partially sulfided calcium-based sorbents, and oxygen as well as sulfur dioxide, at operating conditions closely simulating those prevailing in the second stage (combustor) of Advanced Two-Stage Pressurized Fluidized-Bed Combustors (PFBC). In these systems the CO{sub 2} partial pressure generally exceeds the equilibrium value for calcium carbonate decomposition. Therefore, calcium sulfate is produced through the reactions between SO{sub 2} and calcium carbonate as well as the reaction between calcium sulfide and oxygen. To achieve this objective, the rates of reaction involving SO{sub 2} and oxygen (gaseous reactant); and calcium sulfide and calcium carbonate (solid reactants), will be determined by conducting tests in a pressurized thermogravimetric analyzer (HPTGA) unit. The effects of sorbent type, sorbent particle size, reactor temperature and pressure; and O{sub 2} as well as SO{sub 2} partial pressures on the sulfation reactions rate will be determined. During this quarter, samples of the selected limestone and dolomite were sulfided in the fluidized-bed reactor. These tests were conducted in both calcining and non-calcining operating conditions to produce partially-sulfided sorbents containing calcium oxide and calcium carbonate, respectively. These samples which represent the carbonizer …
Date:
December 31, 1994
Creator:
Abbasian, Javad; Hill, Andy; Wangerow, James R. & Honea, Franklin I.
Object Type:
Report
System:
The UNT Digital Library
Stabilization of spent sorbents from coal-based power generation processes. Technical report, September 1, 1995--November 30,1995
The overall objective of this study is to determine the effect of implementation of the new and more stringent EPA Protocol Test Method involving sulfide containing waste, on the suitability of the oxidized spent sorbents from gasification of of high sulfur coals for disposal in landfills, and to determine the optimum operating conditions in a ``final`` hydrolysis stage for conversion of the residual calcium sulfide in these wastes to materials that are suitable for disposal in landfills. An additional objective is to study the effect of ash on the regeneration and ash-sorbent separation steps in the Spent Sorbent Regeneration Process (SSRP). To achieve these objectives, a large set of oxidized samples of sulfided calcium-based sorbents (produced in earlier ICCI-funded programs) as well as oxidized samples of gasifier discharge (containing ash and spent sorbent) are tested according to the new EPA test protocol. Samples of the oxidized spent sorbents that do not pass the EPA procedure are reacted with water and carbon dioxide to convert the residual calcium sulfide to calcium carbonate. During this quarter, samples of oxidized sulfided calcium-based sorbents, including untreated calcium sulfide-containing feed materials, were analyzed using both weak acid and more stringent strong acid tests. Preliminary analysis …
Date:
December 31, 1995
Creator:
Abbassian, J. & Hill, A.H.
Object Type:
Report
System:
The UNT Digital Library
Functionally Graded Cathodes for Solid Oxide Fuel Cells
One primary suspected cause of long-term performance degradation of solid oxide fuels (SOFCs) is the accumulation of chromium (Cr) species at or near the cathode/electrolyte interface due to reactive Cr molecules originating from Cr-containing components (such as the interconnect) in fuel cell stacks. To date, considerable efforts have been devoted to the characterization of cathodes exposed to Cr sources; however, little progress has been made because a detailed understanding of the chemistry and electrochemistry relevant to the Cr-poisoning processes is still lacking. This project applied multiple characterization methods - including various Raman spectroscopic techniques and various electrochemical performance measurement techniques - to elucidate and quantify the effect of Cr-related electrochemical degradation at the cathode/electrolyte interface. Using Raman microspectroscopy the identity and location of Cr contaminants (SrCrO{sub 4}, (Mn/Cr){sub 3}O{sub 4} spinel) have been observed in situ on an LSM cathode. These Cr contaminants were shown to form chemically (in the absence of current flowing through the cell) at temperatures as low as 625 C. While SrCrO{sub 4} and (Mn/Cr){sub 3}O{sub 4} spinel must preferentially form on LSM, since the LSM supplies the Sr and Mn cations necessary for these compounds, LSM was also shown to be an active site for …
Date:
December 31, 2006
Creator:
Abernathy, Harry & Liu, Meilin
Object Type:
Report
System:
The UNT Digital Library
The role of catalyst precursor anions in coal gasification. Eighth quarterly report, [July--September 1993]
This project investigates the roles of various aqueous soluble catalyst precursor anions, specifically acetate, chloride, nitrate, sulfate, and carbonate anions on the surface electrical properties of coal and seeks to understand the effects of these anions on the adsorption, dispersion and activities of calcium and potassium. The effects of the various anions on coal char gasification is currently under investigation. The influence of acetate, chloride and nitrate ions, when using the corresponding potassium compounds, are discussed in this report. The thermograms for the char preparation in nitrogen show that rapid devolatilization of moisture and other volatile materials occurs in the first 30 min. The rate of weight loss decreases significantly thereafter up to about 70 min. when char preparation was complete. Introduction of carbon dioxide after this time resulted in only a small amount of carbon gasification of the unloaded, demineralized coal. However, the chars containing the acetate, chloride or nitrate of potassium gave reactivities of 24.8, 30.4 or 24.3 %wt., respectively. The catalysts were ion-exchanged with the salt solutions and the corresponding potassium content were 2.9, 2.6 and 2.3 %wt. The higher reactivities of the catalyzed chars compared to the unloaded char correlates the high degree of demineralization and …
Date:
December 31, 1993
Creator:
Abotsi, G. M. K.
Object Type:
Report
System:
The UNT Digital Library
The role of catalyst precursor anions in coal gasification. Fourth quarterly report
The aims of the proposed project are to enrich our understanding of the roles of various aqueous soluble catalyst precursor anions on the surface electrical properties of coal and to ascertain the influence of the surface charge on the adsorption, dispersion, and activities of calcium and potassium. These goals will be achieved by impregnating a demineralized North Dakota lignite (PSOC 1482) with calcium or potassium catalyst precursors containing acetate (CH{sub 3}COO{sup {minus}}), chloride (CI{sup {minus}}), nitrate (NO{sub 3}{sup {minus}}), sulfate (SO{sub 4}{sup 2{minus}}), and carbonate (CO{sub 3}{sup 2{minus}}) anions. In the past quarter, the effects of (CH{sub 3}COO{sup {minus}}), CI{sup {minus}}, (NO{sub 3}{sup {minus}}), (CO{sub 3}{sup 2{minus}}) or (CO{sub 3}{sup 2{minus}}) on the surface charge properties of the coal has been initiated using the calcium salts of these anions. Like the corresponding potassium compounds investigated previously, increasing anion concentrations produce less negative charge on the coal surface through the interaction of calcium ions with the surface. This was confirmed by metal adsorption and chemical analysis of the filtered coal particles. The extent of metal adsorption was strongly dependent on the catalyst precursor. For potassium, maximum metal uptake from solution was obtained using potassium carbonate, followed by potassium acetate, while the …
Date:
December 31, 1992
Creator:
Abotsi, G. M. K.
Object Type:
Report
System:
The UNT Digital Library
A novel approach to highly dispersing catalytic materials in coal for gasification. Eighth quarterly report, July 1, 1991--September 30, 1991
This project seeks to develop a technique, based on coal surface properties, for highly dispersing catalysts in coal for gasification and to investigate the potential of using potassium carbonate and calcium acetate mixtures as catalyst for coal gasification. The lower cost and high catalytic activity of the latter compound will produce economic benefits by reducing the amount of K{sub 2}CO{sub 3} required for high coal char activities. The effects of potassium impregnation conditions (pH and coal surface charge) on the reactivities, in carbon dioxide, of chars derived from demineralized lignite, subbituminous and bituminous coals have been determined. Impregnation of the acid-leached coal with potassium from strongly acidic solutions resulted in initial slow char reactivity which progressively increased with reaction time. Higher reactivities were obtained for catalyst (potassium) loaded at pH 6 or 10. The dependence of char gasification rates on catalyst addition pH increased in the order: pH 6 {approximately} pH 10 {much_gt} pH 1.
Date:
December 31, 1991
Creator:
Abotsi, G. M. K. & Bota, K. B.
Object Type:
Report
System:
The UNT Digital Library
A novel approach to highly dispersing catalytic materials in coal for gasification. First quarterly report, October 1, 1989--December 31, 1989
This project seeks to develop a technique, based on coal surface properties, for highly dispersing catalysts in coal for gasification and to investigate the potential of using potassium carbonate and calcium acetate mixtures as catalysts for coal gasification. The lower cost and high catalytic activity of the latter compound will produce economic benefits by reducing the amount of K{sub 2}CO{sub 3} required for high coal char reactivities. The work is focused on the elucidation of coal-catalyst precursor interactions in solution and the variables which control the adsorption and dispersion of coal gasification metal catalysts. In order to optimize coal-metal ion interactions and hence maximize catalyst activity, the study examines the surface electrochemistry of a lignite, a subbituminous, and a bituminous coals and their demineralized and oxidized derivatives prior to loading with the catalytic materials. The surface electrical properties of the coals are investigated with the aid of electrophoresis, while the effects of the surface charge on the adsorption of K{sup +} and Ca{sup 2+} are studied by agitating the coals with aqueous solutions of potassium and calcium. A zeta meter, a tube furnace, and other equipment required for the investigation have been acquired and installed. Preliminary work shows that the …
Date:
December 31, 1989
Creator:
Abotsi, G. M. K. & Bota, K. B.
Object Type:
Report
System:
The UNT Digital Library
Surface modified coals for enhanced catalyst dispersion and liquefaction. Quarterly report, 1996
The aim of this work is to enhance catalyst loading and dispersion in coal for improved liquefaction by preadsorption of surfactants onto coal. The application of surfactants to coal beneficiation and coal-water slurry preparation is well known. However, the effects of surfactants on catalyst loading and dispersion prior to coal conversion processes have not been investigated. The current work is focused on the influence of the cationic surfactant dodecyl dimethyl ethyl ammonium bromide (DDAB) and sodium dodecyl sulfate (SDS, anionic) on the surface properties of a bituminous coal and its molybdenum and iron uptake from solution. In the previous report, it was shown that molybdenum loading onto the coal was enhanced by preadsorption of DDAB. The optimum concentration of this surfactant for effective adsorption of molybdenum at the natural pH of the coal slurry has been determined to be in the 0.1 to 0.25 M range. Preadsorption of SDS onto the coal was found to increase the uptake of iron by the coal; iron loading increased with increase in the concentration of the catalyst precursor. This observation is attributed to the increase in the negative surface charge properties of the coal with increase in the concentration of the surfactant. The …
Date:
December 31, 1996
Creator:
Abotsi, G.M.K.
Object Type:
Report
System:
The UNT Digital Library
A novel approach to highly dispersing catalytic materials in coal for gasification. Second quarterly report, January 1, 1990--March 31, 1990
This project seeks to develop a technique, based on coal surface properties, for highly dispersing catalysts in coal for gasification and to investigate the potential of using potassium carbonate and calcium acetate mixtures as catalysts for coal gasification. The work is focused on the elucidation of coal-catalyst precursor interactions in solution and the variables which control the adsorption and dispersion of coal gasification metal catalysts. In order to optimize coal-metal ion interactions and hence maximize catalyst activity, the study examines the surface electrochemistry of a lignite, a subbituminous, and a bituminous coals and their demineralized and oxidized derivatives prior to loading with the catalytic materials. The surface electrical properties of the coals are investigated with the aid of electrophoresis, while the effects of the surface charge on the adsorption of K{sup +} and Ca{sup 2+} are studied by agitating the coals with aqueous solutions of potassium and calcium. Zeta potential studies show that the surfaces of the lignite are negatively charged between about pH2 to 11, the negative charge density increasing with increase in pH. Highly alkaline media promoted calcium adsorption due to high negative charge on the coal, while calcium uptake was inhibited in strongly acidic solutions.
Date:
December 31, 1990
Creator:
Abotsi, M. K. & Bota, K. B.
Object Type:
Report
System:
The UNT Digital Library
Transport and Reaction Kinetics at the Glass:Solution Interface Region: Results of Repository-Oriented Leaching Experiments
Repository-oriented leaching experiments involving Savannah River Laboratory (SRL) 165 type glass under a {gamma}-radiation field (1 = 0.2 x 10{sup 4} R/h) have been performed by the Nevada Nuclear Waste Storage Investigations (NNWSI) project. In this communication, we discuss glass surface analyses obtained by SEM, nuclear resonance profiling, and SIMS together with leachate solution data in relation to a mechanism that couples diffusion, hydrolysis (etching and gelation), and precipitation to qualitatively describe the release of different glass components to the leachant solutions. The release of mobile (e.g., Li) and partly mobile (e.g., B) species is controlled primarily by interdiffusion with water species across the interdiffusion zone. Glass components that are immobile in the interdiffusion zone are released to the solution by etching. For prediction of long-term steady-state concentrations of glass components with low solubility, the relative rates of release from the glass and secondary mineral precipitation must be taken into account.
Date:
December 31, 1986
Creator:
Abrajano, T. A., Jr. & Bates, J. K.
Object Type:
Report
System:
The UNT Digital Library