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Solar photo-thermal catalytic reactions to produce high value chemicals

Description: This report presents a summary of the research work accomplished to date on the utilization of solar photo-thermal energy to convert low cost chemical feedstocks into high $-value chemical products. The rationale is that the solar IR-VIS-UV spectrum is unique, supplying endothermic reaction energy as well as VIS-UV for photochemical activation. Chemical market analysis and product price distribution focused attention on speciality chemicals with prices >$1.00/lb, and a synthesis sequence of n-paraffins to aromatics to partial oxidized products. The experimental work has demonstrated that enhanced reaction effects result from VIS-UV irradiation of catalytically active V2O5/SiO2. Experiments of the past year have been on dehydrogenation and dehydrocyclization of n-paraffins to olefins and aromatics with preference for the latter. Recent results using n-hexane produced 95% conversion with 56% benzene; it is speculated that aromatic yield should reach {approximately}70% by further optimization. Pilot- and commercial-scale reactor configurations have been examined; the odds-on-favorite being a shallow fluid-bed of catalyst with incident radiation from the top. Sequencing for maximum cost effectiveness would be day-time endothermic followed by night-time exothermic reactions to produce the products.
Date: April 1, 1992
Creator: Prengle, H. W. Jr. & Wentworth, W. E.
Partner: UNT Libraries Government Documents Department

The role of the resid solvent in coprocessing with finely divided catalysts. Quarterly report, October--December 1993

Description: The reactions with anthracene as a hydrogen acceptor were performed to determine how much hydrogen could be transferred by the hexane soluble resid fraction and hydrogen atmosphere to anthracene. The product distributions obtained by anthracene are given in Table 4. The products obtained from anthracene (ANT) were dihydroanthracene (DHA) and hexahydroanthracene (HHA). When FHC-365 was the resid used in the reaction, very similar amounts of ANT, DHA, and HHA were present after the reaction in both the catalytic and noncatalytic reaction. The predominant product was DHA at 51 to 53 mol%. Slightly more than one-fourth of the ANT remained unreacted. The production of HHA was between 20 and 22%. The amount of H{sub 2} accepted by ANT was the same for both catalytic and noncatalytic reactions. For the reactions with Maya, ANT reacted differently under noncatalytic and catalytic conditions. The reaction products produced were DHA and HHA, with DHA being the predominant product. In the catalytic reaction, substantially more DHA was produced under catalytic conditions and substantially less ANT remained than in the noncatalytic reaction. Under both reaction conditions nearly the same amount of HHA was produced. Under catalytic conditions, nearly twice as much hydrogen was accepted by ANT than under noncatalytic conditions. The product distribution from ANT obtained for the noncatalytic reaction with Maya was similar to dig obtained from ANT when ANT was reacted with FHC-365. The catalyst only seemed to have an effect with Maya resid. The catalyst also had a strong effect on the GC fraction obtained from the reaction using hexane solubles of Maya with ANT. The average boiling point showed a substantial shift toward low boiling constituents.
Date: December 31, 1993
Creator: Curtis, C. W.
Partner: UNT Libraries Government Documents Department

Super critical water oxidation on energetic materials

Description: Supercritical water oxidation (SCWO) is an innovative process for the destruction of hazardous wastes that occurs above the critical temperature and pressure of water. In this paper we present results for the oxidation of simple organic wastes and the destruction of explosives. We have tested a 50 gal./day mobile tubular reactor using both acetone and hexane as surrogate aqueous wastes in reaction with excess oxygen. For acetone, our results indicate that the fuel and oxidant can be conveniently premixed before heating and the acetone effectively destroyed (>99.999%). By contrast, hexane, and likely other insoluble flammable organics must be separately preheated to above the critical temperature of water to avoid detonation. With regards to the treatment of explosives, we have demonstrated detection-sensitivity-limited destruction (typically >99.9%) of five explosives, HMX, RDX, TNT, NQ, and PETN, in a smaller scale SCWO reactor. Two alternative methods of increasing processing throughput for explosives, which have very low solubility in water at room temperature, were also investigated. They are the use of slurries and the SCWO postprocessing of the products of explosives hydrolyzed in low-temperature, basic solutions.
Date: April 1, 1993
Creator: Sanchez, J. A.
Partner: UNT Libraries Government Documents Department

Refining of fossil resin flotation concentrate from Western coal. Second quarterly final report, April 1, 1993--June 30, 1993

Description: Ultimate analysis was conducted for the fossil resin concentrate and results obtained are given in Table 2. Based on these results and other results from spectroscopic analysis it appears that the fossil resin from the Wasatch Plateau coal field consists mainly of aliphatic components and partially aromatized multicyclic terpenoids with a few oxygen functional groups. As compared with the parent high volatile bituminous coal, the resin has higher hydrogen and carbon content, low oxygen, nitrogen, and sulfur contents, and relatively low aromaticity. The values of the acid number and iodine number indicate that the fossil resins from the Wasatch Plateau coal field contain only a modest amount of oxygen functional groups and unsaturated carbon-carbon double-bonds in their molecular structures. Fossil resin is a complex mixture of sesquiterpenoids and the solubility of these resin compounds depends on the type of solvent used. The determination of the extractable resin content in the resin concentrate by different solvents provides an important control variable for selective solvent refining and purification. The data generated during preliminary solvent extraction tests are especially important for process design, control of the refined resin quality and prediction of the refined resin products. In this work, the extractable resin content was determined for each size fraction with four solvents: ethyl acetate (ACS grade), hexanes (ACS grade), heptane (98%, assay grade), and toluene (ACS grade). The extraction tests were conducted in TX-6 Soxhlet extraction units. Results are given in Table 5.
Date: July 10, 1993
Creator: Jensen, G. F. & Miller, J. D.
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

Fischer-Tropsch synthesis in supercritical reaction media. Progress report, October 1, 1993--December 31, 1993

Description: Construction of the automated high pressure reactor unit was completed. Testing of the reactor and trial runs are currently in progress. An HP 5890 GC/FID system interfaced with an BP 3365 Chemstation is now in place for analysis of F-T synthesis products. Calibration methods are currently under development. The pressure transducers were successfully calibrated using high precision Heise gauges. Figure 1 shows the linearity of the transducer response. The HPLC pump, used for pumping n-hexane was also tested and calibrated. The agitated sand bath surrounding the reactor (meant for absorbing the high heat of reaction produced in Fischer-Tropsch synthesis) was assembled in place and successfully tested. The entire system was tested to withstand the operating pressures and to be free of leaks. A cold wax trap was fabricated and added to the existing setup. This is similar in nature to the hot wax trap and will serve to collect condensables from the product stream not collected in the hot wax trap and from the GC exhaust stream. Pressure control (using the stepping-motor-driven micrometering valve) and temperature control tests are currently in progress aimed at establishing the control parameters. Thereafter, the experimental investigations consisting of the blank runs and sub-, near-, and supercritical experiments will be commenced. Progress was made in the development of both on-line and off-line analyses. Off-line analysis determines retention times (compound identification) and response factors (quantitative analysis).
Date: January 1, 1994
Creator: Subramaniam, B.; Bochniak, D. & Snavely, K.
Partner: UNT Libraries Government Documents Department

Investigation of coal structure. Quarterly report, October 1, 1992--December 31, 1992

Description: The method was applied to standard polymers under the same condition above. The particle size distribution with volume diameters of polyvinylpyrrolidone (average molecular mass; 10,000) was measured at sample/solvent = 0.50 g/100 ml. This polymer readily dissolve in methanol and water, while the polymer does not dissolve in n-hexane and toluene, and toluene is a slightly better solvent than n-hexane. Figure 3 shows the particle size distributions in n-hexane (a) and toluene (b-1 and -2). The distribution in toluene changed time to time, and two representative distributions are shown. The mean volume diameters-were 14 {mu}m in n-hexane and 18 and 31 {mu}m in toluene. The particle size distribution of cross-linked polyvinylpyrrolidone was further examined in methanol and n-hexane. Figure 4 compares these distributions with scanned counts at sample/solvent = 0.50 g/100 ml. As a significant portion of particles was over 250 {mu}m with volume diameters, the distributions are presented with scanned counts. Figure 4 compared the specific swelling ratio (Q`) versus sample/solvent (w/w %) in the same solvents for this sample. It is seen that methanol is a good solvent than n-hexane and swells the sample. It is also seen that the swelling is dependent on the sample concentration. Therefore, the particle size in good solvent methanol is expected to be larger due to swelling. However, the particle size was smaller in methanol than in n-hexane (Figure 4). The dependence of sample concentration on solvent swelling in methanol (Figure 5) is interpreted as follows: Polymer particles disaggregated at low sample concentration and the interparticle voidage of the swollen polymer after centrifugation changed depending upon disaggregation.
Date: January 1, 1993
Partner: UNT Libraries Government Documents Department

NMR studies of molecules in liquid crystals and graphite

Description: NMR experiments to measure proton dipole couplings were performed on a series of n-alkanes (n-hexane through n-decane) dissolved in nematic liquid crystals. Computer modeling of the experimental NMR-spectra was done using several different models for intermolecular interactions in these systems. The model of Photinos et al. was found to be best in describing the intermolecular interactions in these systems and can provide a statistical picture of the conformation and orientation of the alkane molecules in their partially-oriented environment. Order parameters and conformational distributions for the alkanes can be calculated from the modeling. The alkanes are found to have conformational distributions very much like those found in liquid alkanes. Proton NMR spectra of tetrahydrofuran (THF) intercalated in two graphite intercalation compounds were also measured. Computer simulations of these spectra provide a picture of THF in the constrained environment between the graphene layers where the THF is oriented at a particular angle, can translate and rotate freely, but does not appear to pseudorotate.
Date: June 1, 1992
Creator: Rosen, M. E.
Partner: UNT Libraries Government Documents Department

Fischer-Tropsch synthesis in supercritical reaction media. Progress report, July 10, 1992--September 30, 1992

Description: The goal of this research is to thoroughly investigate the feasibility of using supercritical fluid (SCF) solvent medium for carrying out Fischer-Tropsch (FT) synthesis. Research will address the systematic experimental investigations of FT synthesis over supported Fe and Co catalysts in a CSTR and in a fixed-bed reactor at typical synthesis temperatures (240-260{degrees}C). The SCF medium to be employed is n-Hexane (P{sub c} = 29.7 bar; {Tc} = 233.7{degrees}C), while n-Hexadecane will be employed as the liquid reaction medium. Overall conversion, product distribution and catalyst deactivation will be measured in each case for various feed H{sub 2}/CO ratios ranging from 0.5 to 2. Product analyses will be carried out using GC/TCD, GC/FID and GC/MS systems. The fresh and used catalysts will be characterized with respect to active metal dispersion, surface area and pore size distribution.
Date: October 1, 1992
Creator: Subramaniam, B.
Partner: UNT Libraries Government Documents Department

Fischer Tropsch synthesis in supercritical fluids. Quarterly technical progress report, July 1, 1993--September 30, 1993

Description: During this quarter we have tested and calibrated six thermocouples of the temperature probe assembly. We obtained additional information on potential supercritical fluids from several vendors. We found out that all three potential supercritical solvents (propane, butane, and hexane) have less than 1 ppM sulfur impurities, whereas the maximum amount of sulfur in the feed should be less than 0.05 ppM. This remains to be a potential problem, since high levels of sulfur in the feed will result in catalyst poisoning. However, this would be the case with all three potential solvents, and thus we have decided to use propane as the supercritical fluid in our reaction studies based on its cost and favorable supercritical properties. In our shake down tests we will not use a catalyst guard bed for sulfur removal. If we experience problems with catalyst deactivation due to sulfur in feed, the guard bed will be installed in the propane feed line. We have ordered 1-tetradecene and will begin measuring diffusion coefficients of this compound in subcritical propane.
Date: December 31, 1993
Creator: Akgerman, A. & Bukur, D. B.
Partner: UNT Libraries Government Documents Department

Process and analytical studies of enhanced low severity co-processing using selective coal pretreatment. Quarterly technical progress report, June--August 1991

Description: This report describes progress on research during the 12th and final quarter of this contract dealing with applications of coal pretreatment techniques in coal/oil co-processing and direct hydroliquefaction. The overall objectives of the project are to investigate various coal pretreatment techniques and to determine the effect of these pretreatment procedures on the reactivity of the coal. Reactivity enhancement will be evaluated under both direct hydroliquefaction and co-processing conditions. Coal conversion utilizing low rank coals and low severity conditions (reaction temperatures generally less than 350{degree}C) is the primary focus of the liquefaction experiments, as it is expected that the effect of pretreatment conditions and the attendant reactivity enhancement will be greatest for these coals and at these conditions.
Date: December 31, 1991
Creator: Baldwin, R. M.; Gaur, S. & Miller, R. L.
Partner: UNT Libraries Government Documents Department

Fischer-Tropsch synthesis in supercritical reaction media. [Quarterly] progress report, July 1, 1993--September 30, 1993

Description: Figure 1 shows the physical appearance of the reactor and analytical units. The feed preparation section consists of a mass flow controller for syngas introduction, the BPLC pump for n-hexane introduction, preheaters, check valves, static mixer, and safety head has been completed. The stainless steel reactor was fabricated and was alonized to passivate the stainless steel surface. The fluidized sand bath surrounding the reactor was fabricated in house. Aluminum oxide (120 mesh) will be used as the fluidized medium. Stepping-motor-driven micrometering (Autoclave{reg_sign}) valves have been installed for pressure control of the reactor and of the syngas feed stream. The sample transfer lines connected to the gas sampling valves in the GC will be routed inside the valve oven and out through the front top of the GC, where they will be connected with the heated sample transfer lines from the reactor. The sample outlet line will be routed through a cold trap operated at 20{degrees}C or lower and the gases from the cold trap will be exhausted to the roof vent. The reactor unit is versatile and permits us to investigate the effect(s) of any of the following variables on syngas conversion, selectivity and reaction rate maintenance: (1) pressure (25--70) bars, (2) syngas flowrate (30--150) cc/min/g{center_dot}cat, (3) syngas ratio (H{sub 2}/CO of 0.5, 1.0 or 2.0) (4) ratio of syngas to reaction media (0.2--5.0), (5) catalyst type (Fe or Co), (6) direction of cocurrent flow (upflow or downflow), (7) cosolvent effects (such as n-pentane), and (8) sulfur content (1--50 mg{center_dot}/g{center_dot}Fe). Based on a literature review (Pennline et al., 1987; Baltrus et al., 1989; Bukur et al., 1990), the pretreatment of Fe catalysts will be performed with flowing CO at low pressure ({approximately}1 atm) and high temperatures ({approximately}280{degrees}C).
Date: October 1, 1993
Creator: Subramaniam, B.
Partner: UNT Libraries Government Documents Department

An investigation of catalytic active phase-support interactions by IR, NMR and x-ray absorption spectroscopies. Progress report, January 15, 1992--September 15, 1992

Description: Active catalytic phases (metal, mixed metals, oxide or mixed oxides) interacting with oxide support on which the active phase is dispersed can affect the percentage exposed, the morphology of supported particles, the degree of reducibility of cations, etc., in a variety of ways. Our objective is to characterize the physical chemistry of the active phase-oxide support interaction by spectroscopic methods and to correlate this structure with catalytic function. Two catalytic systems and their associated techniques (x-ray absorption and NMR) are discussed in this progress report. Firstly, the interaction of Pt-Ni supported on silica and L-zeolite are characterized and compared by x-ray absorption spectroscopy (EXAFS). Secondly, we present both experimental and calculational developments of NMR for the investigation of amorphous silica-alumina catalysts and/or supports.
Date: September 1, 1992
Creator: Haller, G. L.
Partner: UNT Libraries Government Documents Department

Process and analytical studies of enhanced low severity co-processing using selective coal pretreatment. Quarterly technical progress report, June--August 1990

Description: This report describes progress on research during the seventh quarter of this contract dealing with applications of coal pretreatment techniques in coal hydroliquefaction. The objectives of the project are to investigate various coal pretreatment techniques and to determine the effect of these pretreatment procedures on the reactivity of the coal. Reactivity enhancement will be evaluated under both direct hydroliquefaction and co-processing conditions. Coal conversion utilizing low rank coals and low severity conditions (reaction temperatures generally less than 350 {degrees}C) are the primary focus of the liquefaction experiments, as it is expected that the effect of pretreatment conditions and the attendant reactivity enhancement will be greatest for these coals at these conditions.
Date: December 31, 1990
Creator: Baldwin, R. M. & Miller, R. L.
Partner: UNT Libraries Government Documents Department

The effect of rhenium, sulfur and alumina on the conversion of hydrocarbons over platinum single crystals: Surface science and catalytic studies

Description: Conversion reactions of hydrocarbons over Pt-Re model catalyst surfaces modified by sulfur and alumina have been studied. A plasma deposition source has been developed to deposit Pt, Re, and Al on metal substrates variable coverage in ultrahigh vacuum without excessive heating. Conversion of n-hexane was performed over the Re-covered Pt and Pt-covered Re surfaces. The presence of the second metal increased hydrogenolysis activity of both Pt-Re surfaces. Addition of sulfur on the model Catalyst surfaces suppressed hydrogenolysis activity and increased the cyclization rate of n-hexane to methylcyclopentane over Pt-Re surfaces. Sulfiding also increased the dehydrogenation rate of cyclohexane to benzene Over Pt-Re surfaces. It has been proposed that the PtRe bimetallic catalysts show unique properties when combined with sulfur, and electronic interactions exist between platinum, rhenium and sulfur. Decomposition of hydrocarbons on the sulfur-covered Pt-Re surfaces supported that argument. For the conversion of 1-butene over the planar Pt/AlO{sub x}, the addition of Pt increased the selectivity of hydrogenation over isomerization.
Date: April 1, 1992
Creator: Kim, C.
Partner: UNT Libraries Government Documents Department

Electron attachment as a probe of photoionization processes in liquid media

Description: The effects of electron attaching additives on the photoionization threshold of pyrene in seven liquid media comprising a dielectric hydrocarbon liquid and an electron attaching additive, A, were studied. The photoionization threshold, I/sub L/, was found to be independent of the dielectric hydrocarbon liquid and the concentration of each A used. On the basis of these data it was concluded that in the presence of an efficient A at high concentrations, the photoejected electron is captured by A at times shorter than those required for electron solvation (or any possible trapping by the solvent) and that the photoionization process for a solute molecule in these dielectric liquids is probably completed at times less than or equal to 10/sup -14/ and greater than or equal to 10/sup -16/ s and its energetics are rather independent of the bulk properties of these liquids.
Date: January 1, 1981
Creator: Siomos, K.; Kourouklis, G.A. & Christophorou, L.G.
Partner: UNT Libraries Government Documents Department

Geothermal direct-contact heat exchange. Final report

Description: A glass direct contact heat exchange column was operated in the laboratory at atmospheric pressure using hot water and normal hexane. Column internals tested included an empty column, sieve trays, disk-and-doughnut trays, and two types of packing. Operation was very smooth in all cases and the minimum temperature approaches varied from less than 1{sup 0}C for packing to 13{sup 0}C for the empty column. High heat transfer rates were obtained in all cases, however, columns should be sized on the basis of liquid and vapor traffic. The solubilities of hydrocarbons were determined for normal hexane, pentane and butane in water and sodium chloride and calcium chloride brines at various temperatures. The values seem to be internally consistent and salt content was found to depress hydrocabon solubility. Laboratory stripping tests showed that gas stripping can be used to remove hydrocarbon from reject hot water from the direct contact heat exchange column. Although the gas volumes required are small, stripping gas requirements cannot be accurately predicted without testing. A computer program was used to study the effect of operating variables on thermodynamic cycle efficiencies. Optimum efficiencies for the moderate brine conditions studied were obtained with isopentane as working fluid and relatively low operating pressure. A preliminary design for a 50 MWe plant was prepared and plant capital cost and operating cost were estimated. These costs were combined with previously developed brine production and power transmission costs to provide an estimate of the cost of delivered power for a geothermal field at Heber, California. A pilot plant program is described that would be suitable for continuing the investigation of the direct contact process in the field. The program includes a suggested schedule and the estimated cost.
Date: June 10, 1976
Creator: Sims, A.V.
Partner: UNT Libraries Government Documents Department

Two dimensional NMR of liquids and oriented molecules

Description: Chapter 1 discusses the quantum mechanical formalism used for describing the interaction between magnetic dipoles that dictates the appearance of a spectrum. The NMR characteristics of liquids and liquid crystals are stressed. Chapter 2 reviews the theory of multiple quantum and two dimensional NMR. Properties of typical spectra and phase cycling procedures are discussed. Chapter 3 describes a specific application of heteronuclear double quantum coherence to the removal of inhomogeneous broadening in liquids. Pulse sequences have been devised which cancel out any contribution from this inhomogeneity to the final spectrum. An interpretation of various pulse sequences for the case of /sup 13/C and /sup 1/H is given, together with methods of spectral editing by removal or retention of the homo- or heteronuclear J coupling. The technique is applied to a demonstration of high resolution in both frequency and spatial dimensions with a surface coil. In Chapter 4, multiple quantum filtered 2-D spectroscopy is demonstrated as an effective means of studying randomly deuterated molecules dissolved in a nematic liquid crystal. Magnitudes of dipole coupling constants have been determined for benzene and hexane, and their signs and assignments found from high order multiple quantum spectra. For the first time, a realistic impression of the conformation of hexane can be estimated from these results. Chapter 5 is a technical description of the MDB DCHIB-DR11W parallel interface which has been set up to transfer data between the Data General Nova 820 minicomputer, interfaced to the 360 MHz spectrometer, and the Vax 11/730. It covers operation of the boards, physical specifications and installation, and programs for testing and running the interface.
Date: February 1, 1987
Creator: Gochin, M.
Partner: UNT Libraries Government Documents Department

Picosecond dynamics of reactions in the liquid phase: studies of iodine photodissociation and development of new laser techniques

Description: Iodine photodissociation and recombination was studied as a model for processes common to chemical reaction in the liquid phase. Picosecond transient absorption measurements from 1000 to 295 nm were used to monitor the dynamics in a variety of solvents. Most of the atoms which undergo geminate recombination were found to do so in less than or equal to 15 ps, in agreement with the results of existing molecular dynamics simulations. Vibrational relaxation times vary from approx.15 ps near the middle of the ground state well to approx.150 ps for complete relaxation to v = 0. The prediction of strong resonant vibrational energy transfer to chlorinated methane solvents was not supported, but some evidence for this mechanism was found for alkane solvents. Current theory is unable to explain the large variation (65 to 2700 ps) of the excited A'-state lifetime in various solvents. The 10-Hz amplified, synchronously-pumped dye laser which was used in these studies is described and characterized. SERS (Stimulated Electronic Raman Scattering) and difference frequency mixing were used in the generation of the infrared and far-infrared, respectively. 54 refs., 38 figs., 3 tabs. (WRF)
Date: September 1, 1985
Creator: Berg, M.A.
Partner: UNT Libraries Government Documents Department

Picosecond pulse radiolysis studies to understand the primary processes in radiolysis

Description: The use of pulse radiolysis to learn about processes which occur before the beginning of chemical times is discussed. Two examples, the distance distribution of positive and negative ions in hydrocarbons, and the state of the dry electron are discussed in detail.
Date: January 1, 1984
Creator: Jonah, C.D. & Lewis, M.A.
Partner: UNT Libraries Government Documents Department

Investigation of coal structure

Description: The method was applied to standard polymers under the same condition above. The particle size distribution with volume diameters of polyvinylpyrrolidone (average molecular mass; 10,000) was measured at sample/solvent = 0.50 g/100 ml. This polymer readily dissolve in methanol and water, while the polymer does not dissolve in n-hexane and toluene, and toluene is a slightly better solvent than n-hexane. Figure 3 shows the particle size distributions in n-hexane (a) and toluene (b-1 and -2). The distribution in toluene changed time to time, and two representative distributions are shown. The mean volume diameters-were 14 [mu]m in n-hexane and 18 and 31 [mu]m in toluene. The particle size distribution of cross-linked polyvinylpyrrolidone was further examined in methanol and n-hexane. Figure 4 compares these distributions with scanned counts at sample/solvent = 0.50 g/100 ml. As a significant portion of particles was over 250 [mu]m with volume diameters, the distributions are presented with scanned counts. Figure 4 compared the specific swelling ratio (Q') versus sample/solvent (w/w %) in the same solvents for this sample. It is seen that methanol is a good solvent than n-hexane and swells the sample. It is also seen that the swelling is dependent on the sample concentration. Therefore, the particle size in good solvent methanol is expected to be larger due to swelling. However, the particle size was smaller in methanol than in n-hexane (Figure 4). The dependence of sample concentration on solvent swelling in methanol (Figure 5) is interpreted as follows: Polymer particles disaggregated at low sample concentration and the interparticle voidage of the swollen polymer after centrifugation changed depending upon disaggregation.
Date: January 1, 1993
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

Measurement and prediction of aromatic solute distribution coefficients for aqueous-organic solvent systems. Final report

Description: Experimental and modeling activities were performed to assess techniques for measurement and prediction of distribution coefficients for aromatic solutes between water and immiscible organic solvents. Experiments were performed to measure distribution coefficients in both clean water and wastewater systems, and to assess treatment of a wastewater by solvent extraction. The theoretical portions of this investigation were directed towards development of techniques for prediction of solute-solvent/water distribution coefficients. Experiments were performed to assess treatment of a phenolic-laden coal conversion wastewater by solvent extraction. The results showed that solvent extraction for recovery of phenolic material offered several wastewater processing advantages. Distribution coefficients were measured in clean water and wastewater systems for aromatic solutes of varying functionality with different solvent types. It was found that distribution coefficients for these compounds in clean water systems were not statistically different from distribution coefficients determined in a complex coal conversion process wastewater. These and other aromatic solute distribution coefficient data were employed for evaluation of modeling techniques for prediction of solute-solvent/water distribution coefficients. Eight solvents were selected in order to represent various chemical classes: toluene and benzene (aromatics), hexane and heptane (alkanes), n-octanol (alcohols), n-butyl acetate (esters), diisopropyl ether (ethers), and methylisobutyl ketone (ketones). The aromatic solutes included: nonpolar compounds such as benzene, toluene and naphthalene, phenolic compounds such as phenol, cresol and catechol, nitrogenous aromatics such as aniline, pyridine and aminonaphthalene, and other aromatic solutes such as naphthol, quinolinol and halogenated compounds. 100 references, 20 figures, 34 tables.
Date: June 1, 1984
Creator: Campbell, J.R. & Luthy, R.G.
Partner: UNT Libraries Government Documents Department

NMR studies of molecules in liquid crystals and graphite

Description: NMR experiments to measure proton dipole couplings were performed on a series of n-alkanes (n-hexane through n-decane) dissolved in nematic liquid crystals. Computer modeling of the experimental NMR-spectra was done using several different models for intermolecular interactions in these systems. The model of Photinos et al. was found to be best in describing the intermolecular interactions in these systems and can provide a statistical picture of the conformation and orientation of the alkane molecules in their partially-oriented environment. Order parameters and conformational distributions for the alkanes can be calculated from the modeling. The alkanes are found to have conformational distributions very much like those found in liquid alkanes. Proton NMR spectra of tetrahydrofuran (THF) intercalated in two graphite intercalation compounds were also measured. Computer simulations of these spectra provide a picture of THF in the constrained environment between the graphene layers where the THF is oriented at a particular angle, can translate and rotate freely, but does not appear to pseudorotate.
Date: June 1, 1992
Creator: Rosen, M. E.
Partner: UNT Libraries Government Documents Department