28 Matching Results

Search Results

Advanced search parameters have been applied.

Development of a gas-promoted oil agglomeration process. Quarterly technical progress report, July 1, 1995--September 30, 1995

Description: The preliminary laboratory-scale development of a gas-promoted, oil agglomeration process for cleaning coal advanced in three major research areas. One area of research resulted in the development of a method for measuring the rate of agglomeration of dilute particle suspensions and using the method to relate the rate of agglomeration of coal particles to various key parameters. A second area of research led to the development of a method for monitoring a batch agglomeration process by measuring changes in agitator torque. With this method it was possible to show that the agglomeration of a concentrated coal particle suspension is triggered by the introduction of a small amount of gas. The method was also used in conjunction with optical microscopy to study the mechanism of agglomeration. A third area of research led to the discovery that highly hydrophobic particles in an aqueous suspension can be agglomerated by air alone.
Date: December 31, 1995
Creator: Wheelock, T.D.
Partner: UNT Libraries Government Documents Department

The Effect of Surface Contamination on Adhesive Forces as Measured by Contact Mechanics

Description: The contact adhesive forces between two surfaces, one being a soft hemisphere and the other being a hard plate, can readily be determined by applying an external compressive load to mate the two surfaces and subsequently applying a tensile load to peel the surfaces apart. The contact region is assumed the superposition of elastic Hertzian pressure and of the attractive surface forces that act only over the contact area. What are the effects of the degree of surface contamination on adhesive forces? Clean aluminum surfaces were coated with hexadecane as a controlled contaminant. The force required to pull an elastomeric hemisphere from a surface was determined by contact mechanics, via the JKR model, using a model siloxane network for the elastomeric contact sphere. Due to the dispersive nature of the elastomer surface, larger forces were required to pull the sphere from a contaminated surface than a clean aluminum oxide surface.
Date: December 18, 2000
Creator: EMERSON,JOHN A.; GIUNTA,RACHEL K.; MILLER,GREGORY V.; SORENSEN,CHRISTOPHER R. & PEARSON,RAYMOND A.
Partner: UNT Libraries Government Documents Department

Atmospheric aerosol microphysics: Formation, characterization, and interaction. Progress report, September 1, 1991--February 28, 1994

Description: This project conducts theoretical and computational studies of the physical transformation processes of aerosols which underlie their atmospheric formation, interaction, transport, and removal and derives results that contribute to improved capabilities for modelling aerosol physical and chemical evolution in support of the environmental component of the National Energy Strategy. The subject of study is submicrometer aerosol particles with primary focus upon the ultrafine fraction. This report summarizes technical progress during the first two and one-half years of the project. Results of calculations of equilibrium vapor pressures over adhering pairs of 50, 100, and 200 nm particles are reported showing substantial depression of equilibrium vapor pressure relative to isolated spheres. Calculations are given of collective, long-range intermolecular energies for irregular particles to be used for growth rate calculations for realistic particles. Molecular dynamic simulations of thermal collisions of small clusters with each other and with single atoms are presented as a function of cluster size in the range from 1 to 8 atoms. Calculations of aerosol condensation in which vapor depletion and heating effects are taken into account for atmospheric cloud nucleation modelling are reported.
Date: December 31, 1994
Creator: Marlow, W.H.
Partner: UNT Libraries Government Documents Department

Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, October 1995--December 1995

Description: The goal of this research is to develop a methodology for analyzing the reactivity of cyclic olefins in situ in a high temperature and high pressure infrared cell. Cyclic olefins, such as 1,4,5,8-tetrahydronaphthalene (isotetralin) and 1,4,5,8,9,10-hexahydroanthracene (HHA), are highly reactive donor compounds that readily donate their hydrogen to coal and model acceptors when heated to temperatures of 200{degrees}C and above. These donors are active donors in the low severity liquefaction of coal at 350{degrees}C as shown in the research performed in this project. The infrared studies are being performed in a high temperature infrared cell that was obtained from AABSPEC. Modifications to that cell have been made and have been reported in previous progress reports. During this last quarter the useful temperature range of the high temperature infrared cell was extended to 230{degrees}C through the use of a high-boiling perfluorocarbon solvent. The solvent used was an Air Products and Chemicals Company proprietary product trade named Multifluor APF-240. Solubilities of aromatics and cyclic olefins were quite low in APF-240, usually less than 0.1 wt% at room temperature, but were found to be a strong function of temperature, increasing markedly when the mixtures were heated to 65{degrees}C. Spectra have been obtained of n-hexadecane and naphthalene at temperatures of 65, 100, 125, 150, 175, 200 and 230{degrees}C. This demonstration of the safe operation of the high temperature IR cell and the acquisition of spectra at elevated temperatures paves the way for kinetic studies of the hydrogen donor capability of isotetralin. A perfluoroether has been obtained from Dupont which should extend the useful temperature range of the high temperature IR cell to 350{degrees}C.
Date: December 31, 1995
Creator: Curtis, C.W.
Partner: UNT Libraries Government Documents Department

A nonequilibrium molecular dynamics study of the rheology of alkanes

Description: We examine the rheological properties of four different alkanes: n-decane, n-hexadecane, n-tetracosane, and squalane. Simulations of Couette flow are performed for a range of shear rates with 100 molecules in each case using a replicated data version of our code. Number of interaction sites ranges from 1000 to 3000. We have performed extremely long simulations required to obtain acceptable statistics at low shear rates. The alkanes show a transition from non-Newtonian to Newtonian behavior as the shear rate decreases to low values. 1 tab, 1 fig, 17 refs.
Date: May 1, 1996
Creator: Gupta, S.A.; Cui, S.T.; Cummings, P.T. & Cochran, H.D.
Partner: UNT Libraries Government Documents Department

THE IMPACT OF TRACE ADDITIVES ON THE APPARENT SOLUBILITY OF HYDROGEN IN HEAVY OIL AND RELATED FEEDSTOCKS AT LOW AND HIGH TEMPERATURES

Description: A systematic investigation was conducted to provide an accurate determination of hydrogen solubility in liquid media in temperatures in the range of 25-250 C and pressures in the range of 0.5-8 MPa. Results were obtained by an indirect gas solubility measurement method. The method was intended for use with high-resolution camera. The hydrogen solubility measurements were indirect and were based on pressure changes at constant temperature and measured volumes. Since the volume of the view cell was fixed the volume available for the vapor phase could be determined by measuring the location of the liquid-vapor interface. The interface was located to within the height of one pixel using high-resolution camera, which added {+-} 0.4 ml to the uncertainty of the vapor volume. Liquid-liquid interface locations were measured with equal precision. The accuracy of the method was illustrated through hydrogen solubility measurements in hexadecane and tetralin, which were in close agreement with the values available in the literature. Hydrogen solubilities in Athabasca bitumen vacuum bottoms (ABVB) were reported over a broad range of temperatures (80-250 C) and pressures (0.5-8 MPa).
Date: September 1, 2002
Creator: Abedi, Jalal
Partner: UNT Libraries Government Documents Department

Liquid fuel reformer development: Autothermal reforming of Diesel fuel

Description: Argonne National Laboratory is developing a process to convert hydrocarbon fuels to clean hydrogen feeds for a polymer electrolyte fuel cell. The process incorporates an autothermal reforming catalyst that can process hydrocarbon feeds at lower temperatures than existing commercial catalysts. The authors have tested the catalyst with three diesel-type fuels: hexadecane, certified low-sulfur grade 1 diesel, and a standard grade 2 diesel. Hexadecane yielded products containing 60% hydrogen on a dry, nitrogen-free basis at 850 C, while maximum hydrogen product yields for the two diesel fuels were near 50%. Residual products in all cases included CO, CO{sub 2}, ethane, and methane. Further studies with grade 1 diesel showed improved conversion as the water:fuel ratio was increased from 1 to 2 at 850 C. Soot formation was reduced when the oxygen:carbon ratio was maintained at 1 at 850 C. There were no significant changes in hydrogen yield as the space velocity and the oxygen:fuel ratio were varied. Tests with a microchannel monolithic catalyst yielded similar or improved hydrogen levels at higher space velocities than with extruded pellets in a packed bed.
Date: July 24, 2000
Creator: Pereira, C.; Bae, J-M.; Ahmed, S. & Krumpelt, M.
Partner: UNT Libraries Government Documents Department

Liquid fuel reformer development.

Description: At Argonne National Laboratory we are developing a process to convert hydrocarbon fuels to a clean hydrogen feed for a fuel cell. The process incorporates a partial oxidation/steam reforming catalyst that can process hydrocarbon feeds at lower temperatures than existing commercial catalysts. We have tested the catalyst with three diesel-type fuels: hexadecane, low-sulfur diesel fuel, and a regular diesel fuel. We achieved complete conversion of the feed to products. Hexadecane yielded products containing 60% hydrogen on a dry, nitrogen-free basis at 800 C. For the two diesel fuels, higher temperatures, >850 C, were required to approach similar levels of hydrogen in the product stream. At 800 C, hydrogen yield of the low sulfur diesel was 32%, while that of the regular diesel was 52%. Residual products in both cases included CO, CO{sub 2}, ethane, ethylene, and methane.
Date: July 30, 1999
Creator: Ahmed, S.; Krumpelt, M.; Pereira, C. & Wilkenhoener, R.
Partner: UNT Libraries Government Documents Department

VLE MEASUREMENTS FOR ASYMMETRIC MIXTURES OF FISCHER-TROPSCH HYDROCARBONS

Description: The ability to model the thermodynamic phase behavior of long-chain and short-chain alkane mixtures is of considerable industrial and theoretical interest. However, attempts to accurately describe the phase behavior of what we call asymmetric mixtures of hydrocarbons (AMoHs) have met with only limited success. Vapor-liquid equilibrium (VLE) data are surprisingly scarce, and the limited data that are available suggest that cubic equations of state may not be capable of fitting (much less predicting) the phase behavior of AMoHs. The following tasks, which address the problems described above, were accomplished during the one-year period of this Phase I UCR grant: (1) A continuous-flow apparatus was modified for the measurement of AMoHs and used to measure VLE for propane + hexadecane mixtures at temperatures from 473 to 626 K and pressures up to the mixture critical pressures of about 100 bar. (2) The extent to which cubic vs. modern, statistical mechanics-based equations of state (EoS) are applicable to AMoHs was evaluated. Peng-Robinson (PR) was found to be a surprisingly accurate equation for fitting AMoHs, but only if its pure component parameters were regressed to liquid densities and vapor pressures. However, even this form of PR was still not a predictive equation, as there was a significant variation of kij with temperature. In spite of its deficiencies in terms of vapor-phase predictions and modeling of the critical region, PC-SAFT was found to be the most appropriate EoS for truly predicting the phase behavior of highly asymmetric mixtures of alkanes. (3) Finally, a dense-gas extraction (DGE) apparatus was designed and constructed for the fractionation of F-T waxes into cuts of pure oligomers. Such oligomers are needed in g-sized quantities to perform VLE measurements with long-chain alkanes with carbon numbers greater than 40. The dense gas and the solute mixture to be extracted are contacted ...
Date: January 12, 2004
Creator: Thies, Mark C.
Partner: UNT Libraries Government Documents Department

Low severity upgrading of F-T waxes with solid superacids. Quarterly report, January 1995--March 1995

Description: In this quarter we studied the effect of hydrogen pressure, and of sulfur and nitrogen containing compounds on the isomerization and hydrocracking of n-hexadecane using a Pt/ZrO{sub 2}/SO{sub 4} catalyst. The reactions were carried out at 300{degrees}C and hydrogen pressures between 50 and 500 psig. Increasing hydrogen pressure resulted in increased conversion and increased hydrocracking. Nitrogen containing compounds had a greater inhibiting effect on the conversion of n-hexadecane than sulfur-containing compounds. The reaction of diphenylmethane in air at 25{degrees}C and in the presence of sulfated zirconia was studied as a possible means to characterize the protonic acidity of solid superacids.
Date: April 6, 1995
Creator: Tierney, J. W. & Wender, I.
Partner: UNT Libraries Government Documents Department

Fischer-Tropsch synthesis in supercritical reaction media. Progress report, October 1, 1992--December 31, 1992

Description: Our goals for this quarter were to complete construction of the reactor and analytical units for carrying out Fischer-Tropsch (F-T) synthesis in liquid (n-hexadecane) and in supercritical n-hexane phases. Progress during this quarter was slower than expected.
Date: January 1, 1993
Creator: Subramaniam, B.; Bochniak, D. & Snavely, K.
Partner: UNT Libraries Government Documents Department

Low severity upgrading of F-T waxes with solid superacids. Quarterly report, December 1, 1992--February 28, 1993

Description: In the last quarters a new class of solid superacids, including sulfated zirconium-hafnium oxides and ZrO{sub 2}/SO{sub 4} modified by Mn and Fe, were synthesized and shown to be active for isomerization and hydrocracking of hexadecane (n-C{sub 16}H{sub 34}). The reaction was carried out in a tubing bomb under mild conditions: 2.5 MPa and 433 K. Pt/HfO{sub 2}S0{sub 4} catalyst exhibited a low activity for hydrocracking of n-C{sub 16}, but the addition of ZrO{sub 2} to the sulfated hafnium improved its activity considerably. An 85 wt % conversion level was achieved when the molar ratio of ZrO{sub 2} to HfO{sub 2} reached 1:1, indicating the possibility of a synergistic effect between zirconium and hafnium. It has recently been reported that Mn,Fe/ZrO{sub 2}/SO{sub 4} is about three orders of magnitude more active than ZrO{sub 2}/SO{sub 4} for isomerizing n-butane. As a result, an 0.5%Mn1.5%Fe/ZrO{sub 2}/SO{sub 4} catalyst was prepared according to a procedure given in a patent. It was found that, without Pt, the catalyst was inactive for hydrocracking of n-C{sub 16}, possibly by deactivation due to coking. It is interesting that a 68 wt % conversion level was achieved after incorporation of Pt along with a product distribution that was shifted towards longer chain paraffins. ZrO{sub 2}/SO{sub 4}has been reported to be a superacid with H{sub 0} < {minus}16 as measured by the Hammett indicator method. However, the acid strength of some ZrO{sub 2}/SO{sub 4} based catalysts, such as the mentioned catalysts, could not be measured by using Hammett indicators because the catalysts are colored gray. We successfully modified an in situ FT-IR analytical system to characterize the acidity of these catalysts. We have applied the method using pyridine as adsorbate to demonstrate their acid strength. Preliminary results indicated a level of acidity of our catalysts which is consistent with ...
Date: March 26, 1993
Creator: Tierney, J. W. & Wender, I.
Partner: UNT Libraries Government Documents Department

Basic principles and mechanisms of selective oil agglomeration. Fossil energy interim report, October 1, 1983--September 30, 1992

Description: Numerous agglomeration tests were conducted with several types of low-ash coal and graphite, high grade mineral pyrite, and other materials. Relatively pure hydrocarbons, including heptane and hexadecane, were used as agglomerants. Access of air to the system was controlled. Particle recovery by agglomeration was observed to depend on a number of system parameters. Among the most important parameters are the hydrophobicity of the particles and the oil dosage, so that the, recovery of solids per unit of oil administered is proportional to the hydrophobicity. The pH and ionic strength of the aqueous suspension affect particle recovery in different ways depending on the surface properties of the particles. On the other hand, the presence of air in the system generally improves particle recovery. The greatest effect of air was observed in a closely related study which showed that air had to be present to produce good agglomerates from a moderately hydrophobic coal in a mixer producing a lower shear rate. The rate of agglomeration was found to be much greater for a strongly hydrophobic coal than for a moderately hydrophobic coal, and the rate was observed to be proportional to the oil dosage. Also the rate was enhanced by the presence of air in the, system. For hydrophobic coals, the rate increased with increasing ionic strength of the aqueous medium, but it was not affected greatly by pH over a wide range. The separation of coal and pyrite particles by selective agglomeration was found to depend on the relative hydrophobicity of the materials, the oil dosage, and the properties of the aqueous medium.
Date: December 31, 1992
Creator: Wheelock, T. D.
Partner: UNT Libraries Government Documents Department

Fischer-Tropsch synthesis in supercritical reaction media

Description: Our goals for this quarter were to complete construction of the reactor and analytical units for carrying out Fischer-Tropsch (F-T) synthesis in liquid (n-hexadecane) and in supercritical n-hexane phases. Progress during this quarter was slower than expected.
Date: January 1, 1993
Creator: Subramaniam, B.; Bochniak, D. & Snavely, K.
Partner: UNT Libraries Government Documents Department

Separation of Fischer-Tropsch wax from catalyst by supercritical extraction. Quarterly report, July 1, 1996 - September 30, 1996

Description: The objective of this research projects is to evaluate the potential of SCF extraction for separating the catalyst slurry of a Fischer- Tropsch (F-T) slurry bubble column (SBC) reactor into two fractions: (1) a catalyst-free wax containing less than 10 ppm particulate matter and (2) a concentrated catalyst slurry that is ready for recycle or regeneration. The wax will be extracted with a hydrocarbon solvent that has a critical temperature near the operating temperature of the SBC reactor, i.e. 200-300{degrees}C. Initial work is being performed using n-hexane as the solvent. The success of the projects depends on two major factors. First, the supercritical solvent must be able to dissolve the F-T wax; furthermore, the must be accomplished without entraining the solid catalyst. Second, the extraction must be controlled so as not to favor the removal of the low molecular weight wax compounds, i.e., a constant carbon-number distribution of the alkanes in the wax slurry must be maintained at steady-state column operation. The project includes three tasks (1) equilibrium solubility measurements, (2) thermodynamic modeling, and (3) process design studies.
Date: December 31, 1996
Creator: Joyce, P. C.; Thies, M. C.; Sherrard, D.; Biales, J.; Kilpatrick, P. & Roberts, G.
Partner: UNT Libraries Government Documents Department

Low severity upgrading of F-T waxes with solid superacids. Quarterly report, September 1, 1993--November 30, 1993

Description: During the last quarter we characterized the acidity of platinum-promoted solid superacids by TPD (temperature-programmed desorption) and investigated the effect of sulfate concentration on the activity of Pt/ZrO{sub 2}/SO{sub 4} catalysts for isomerization and hydrocracking of n-hexadecane. The activities of Pt/ZrO{sub 2} promoted by different anions (SO{sub 4}{sup 2 {minus}}, MoO{sub 4}{sup 2{minus}} and WO{sub 4}{sup 2{minus}}), to give Pt/ZrO{sub 2}/SO{sub 4}, Pt/ZrO{sub 2}/MoO{sub 4} and Pt/ZrO{sub 2}/WO{sub 4}, were compared and the results related to their acidity and acid strength determined by TPD. TPD was an effective tool for the rapid evaluation of the acidity of metal-promoted solid superacids; this technique provided a good indication of the activity of the bifunctional solid superacids. The activity of the Pt/ZrO{sub 2}/SO{sub 4} catalyst at 160{degrees}C was compared with a Pt/{gamma}-Al{sub 2}O{sub 3} reforming catalyst at 160{degrees}C and also at 400{degrees}C (350 psig H{sub 2}), respectively. The Pt/{gamma}-Al{sub 2}O{sub 3} catalyst was not effective at 160{degrees}C but gave a 6.2 wt% conversion of the n-hexadecane to isomerized and cracked products at 400{degrees}C. The isomerization and hydrocracking of long-chain paraffins over metal-promoted solid superacids were carried out in the presence of selected aromatic compounds. It appears that the presence of aromatics changes the surface acidity of the catalyst, resulting in higher molecular weight products (from C{sub 4}{minus}C{sub 9} to C{sub 10}{minus}C{sub 16}) from n-hexadecane. This finding is important in obtaining a more desirable product distribution from hydrocracking of F-T waxes.
Date: January 31, 1994
Creator: Tierney, J. W. & Wender, I.
Partner: UNT Libraries Government Documents Department

Circulation and coalescence within a vaporizing emulsified fuel droplet

Description: A droplet of emulsified fuel (hexadecane, with 30% dispersed water and 2% surfactant) was supported by a vapor film between the droplet and a polished hot surface. Overlighting with a laser was used. During vaporization of approx. 2000 ..mu..m droplet, rapid internal circulation caused coalescence of the dispersed water droplets. Convective velocities are 0.2 to 0.5 m/s. During circulation, these droplets move directly along the fuel surface and are not preferentially distilled from the droplet. Coalescence of the water continues until all the water is in a single lump, and then this lump falls to the base of the droplet. (DLC)
Date: January 1, 1980
Creator: Baer, M.R.; Sheffield, S.A. & Denison, G.J.
Partner: UNT Libraries Government Documents Department

Development of technology for entrainer-enhanced CO sub 2 flooding

Description: The results of studies conducted to evaluate the development of the technology for utilizing entrainers for carbon dioxide (CO{sub 2}) flooding are described. Experiments were conducted to determine the extent of the fluid-property enhancement (gas-phase density and viscosity) of CO{sub 2} + hydrocarbon and CO{sub 2} + crude oil systems in the presence of selected entrainers (cosolvents). The improvement in CO{sub 2}-rich phase hydrocarbon extraction capacity was also determined in the presence of added cosolvents. The hydrocarbon systems used in the study were n-hexadecane and a crude oil sample from Bloomington (TX) field with an API gravity of 22.7{degree}. Preliminary entrainer screening studies were conducted utilizing gas and liquid chromatographic approaches to determine relative affinities of certain cosolvents with target high-molecular-weight hydrocarbon solutes. These solutes ranged in molecular weights from n-decane (n-C{sub 10}) up to n-tetracontane (n-C{sub 40}). These qualitative screening methods were useful in identifying potential cosolvents that may be used for future study. A method of utilizing entrainers to enhance the extraction of polymeric materials into the CO{sub 2}-rich phase was also investigated. This approach utilized a simple extraction apparatus to determine relative degrees of polymer extraction in CO{sub 2}as a function of pressure and the degree of enhancement of extraction in the presence of added cosolvent. 10 refs., 15 figs., 2 tabs.
Date: September 1, 1989
Creator: Llave, F.M.
Partner: UNT Libraries Government Documents Department

High-pressure solvent extraction of methane from geopressured brines: technical evaluation and cost analysis

Description: Solvent extraction is proposed as a means of recovering dissolved methane from geopressured-geothermal brines at high pressures. The assessment shows that additional investment in a high pressure solvent extraction plant preceding direct injection disposal of brines into isolated aquifers can be profitable. The technical and economic issues are discussed, and compared with other injection methods such as complete depressurization for methane recovery followed by conventional mechanical pumping. The contributions of hydraulic (pressure) energy recovery and geothermal power production are also assessed. For deep injection into the producing formation, it is concluded that methane extraction processes are not applicable, insofar as maintenance of high surface pressures provides no clear-cut energy benefits. As a first step in the evaluation of solvent extraction, the solubility of a promising solvent candidate, n-hexadecane, was measured in 15 wt % NaCl solutions at temperatures up to 150/sup 0/C. The solubility of a potential low cost solvent, No. 2 Diesel fuel, was also measured.
Date: July 1, 1981
Creator: Quong, R.; Otsuki, H.H. & Locke, F.E.
Partner: UNT Libraries Government Documents Department

Solvent extraction of methane from simulated geopressured-geothermal fluids: sub-pilot test results

Description: The extraction of methane dissolved in 15 wt % sodium chloride solution at 150/sup 0/C and 1000 psi has been demonstrated using n-hexadecane as the solvent in a sub-pilot scale extraction column operated in a continuous, countercurrent flow mode. Greater than 90% recovery of methane was obtained with solvent/brine mass flow ratios in the range of .040 to .045. The height of an ideal stage in this experimental Elgin-type spray column is estimated to be 1.5 ft. Application of this process on actual geopressured fluids is technically feasible, and when combined with direct drive injection disposal is economically attractive. Design and operation of a methane saturated-brine supply system to provide simulated geopressured fluid continuously at 150/sup 0/C and 1000 psi are also described.
Date: January 14, 1982
Creator: Quong, R.; Otsuki, H.H. & Locke, F.E.
Partner: UNT Libraries Government Documents Department

Low severity upgrading of F-T waxes with solid superacids

Description: In the last quarters a new class of solid superacids, including sulfated zirconium-hafnium oxides and ZrO[sub 2]/SO[sub 4] modified by Mn and Fe, were synthesized and shown to be active for isomerization and hydrocracking of hexadecane (n-C[sub 16]H[sub 34]). The reaction was carried out in a tubing bomb under mild conditions: 2.5 MPa and 433 K. Pt/HfO[sub 2]S0[sub 4] catalyst exhibited a low activity for hydrocracking of n-C[sub 16], but the addition of ZrO[sub 2] to the sulfated hafnium improved its activity considerably. An 85 wt % conversion level was achieved when the molar ratio of ZrO[sub 2] to HfO[sub 2] reached 1:1, indicating the possibility of a synergistic effect between zirconium and hafnium. It has recently been reported that Mn,Fe/ZrO[sub 2]/SO[sub 4] is about three orders of magnitude more active than ZrO[sub 2]/SO[sub 4] for isomerizing n-butane. As a result, an 0.5%Mn1.5%Fe/ZrO[sub 2]/SO[sub 4] catalyst was prepared according to a procedure given in a patent. It was found that, without Pt, the catalyst was inactive for hydrocracking of n-C[sub 16], possibly by deactivation due to coking. It is interesting that a 68 wt % conversion level was achieved after incorporation of Pt along with a product distribution that was shifted towards longer chain paraffins. ZrO[sub 2]/SO[sub 4]has been reported to be a superacid with H[sub 0] < [minus]16 as measured by the Hammett indicator method. However, the acid strength of some ZrO[sub 2]/SO[sub 4] based catalysts, such as the mentioned catalysts, could not be measured by using Hammett indicators because the catalysts are colored gray. We successfully modified an in situ FT-IR analytical system to characterize the acidity of these catalysts. We have applied the method using pyridine as adsorbate to demonstrate their acid strength. Preliminary results indicated a level of acidity of our catalysts which is consistent with ...
Date: March 26, 1993
Creator: Tierney, J.W. & Wender, I.
Partner: UNT Libraries Government Documents Department

Solvent tailoring in coal liquefaction. Quarterly report, May 1982-August 1982. [Comparison of subcritical and supercritical conditions]

Description: The initial objective of this work was to study the phase distribution of donor solvents and solvent mixtures during the liquefaction of coal, to investigate the effects of phase distribution on coal conversion, and to determine the advantages, if any, of operating at subcritical and/or supercritical conditions. Computer simulations were used to predict the phase distribution, for various binary systems, as a function of temperature. The FLASH program was used to theoretically predict phase distribution for various model systems. Due to limitations in the computer program, success was achieved only in a few cases. Even in these cases, the existence of two-phase regions was observed only at temperatures and pressures far below normal liquefaction conditions. An extensive review of the literature was carried out in order to survey methods of experimentally studying vapor-liquid equilibria. Finally, some preliminary laboratory studies were carried out with the use of benzothiophene-dodecane as the model reaction system. It was felt that the study of the effect of reactor configuration on conversion would provide insight into whether phase distribution or mass transfer was the limiting consideration for coal conversion. However, no conclusive results were obtained from these studies.
Date: January 1, 1982
Creator: Tarrer, A.R.; Guin, J.A.; Curtis, C.W. & Williams, D.C.
Partner: UNT Libraries Government Documents Department

Potential methods for methane extraction from geopressured brine at high temperature and pressure

Description: Recovery of methane from Gulf Coast geopressured-geothermal reservoirs does not appear to be profitable without a rise in natural gas prices to offset high production costs. If injection into the production reservoir becomes necessary to maintain productivity and to minimize subsidence, the injection pumping costs approach and even exceed the value of the recoverable methane. An option aimed at reducing the injection pump operating costs is to maintain a higher than normal pressure at the production wellhead to reduce the injection-pumping work load. This option, however, is considerably less attractive if that portion of methane still dissolved at elevated pressure cannot be recovered. Therefore, there is a strong incentive to devise methods for extracting methane at high pressures and temperatures. Liquid extraction with a very low water-soluble organic is a technically feasible method and looks promising as an applicable process. A candidate solvent is hexadecane, a paraffinic hydrocarbon with the necessary phase-equilibrium thermodynamic properties to satisfy the technical requirements for such an operation, without any obvious economic barriers. Gas stripping is another technically feasible method, but the economics do not look favorable because of gas dissolution losses. Freon refrigerants were considered because of their ease of product-stripping gas separation and nitrogen was considered because of its low cost. Brine-driven positive displacement pumps with provisions for methane exsolution are technically feasible concepts and could eliminate or greatly reduce pump power costs. These extraction operations will not preclude the option of recovering the thermal energy component, if desired.
Date: June 2, 1980
Creator: Quong, R.; Owen, L.B. & Locke, F.E.
Partner: UNT Libraries Government Documents Department