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Pathway and kinetic analysis on the iso-propyl radical + O{sub 2} reaction system

Description: We analyze the isopropyl + 02 reaction system using thermochemical Transition State Theory (TST), molecular thermodynamic properties, analysis (quantum RRK) for k(E) and modified strong collision analyze Cyclic transition states for both hydrogen transfer and concerted propylene from isopropylperoxy are calculated using semi-empirical theory in addition to transition states for H02 elimination from hydroperoxy-isopropyl. Computed rate constants are compared to constant measurements of for isopropyl + H02.
Date: April 7, 1997
Creator: Bozzelli, J. W. & Pitz, W. J.
Partner: UNT Libraries Government Documents Department

Development of a Gas-Promoted Oil Agglomeration Process

Description: Two series of agglomeration tests were conducted as part of an effort to find a suitable basis for size scale-up of the mixing system used for a gas-promoted oil agglomeration process. In the first series of tests the agitator impeller diameter and speed were varied among runs so as to vary impeller tip speed and agitator power independently while keeping other conditions constant. In the second series of tests the mixing tank size and agitator speed were varied while the ratio of tank diameter to impeller diameter were held constant. All tests were conducted with finely ground Pittsburgh No. 8 coal and with i-octane as the agglomerant. The results of these tests showed that the minimum time te required to produce spherical agglomerates was predominantly a function of the agitator power input per unit volume. In addition, the size of the agglomerates produced in a given time was also strongly dependent on power input. At lower power input levels, the mean size rose as power input increased until a point was reached where agglomerate breakage became important and the mean size decreased. The results also showed that the ash content of the agglomerates produced in a given time tended to decrease with increasing power input. On the other hand, the recovery of clean coal on a dry, ash-free basis was not greatly affected by power input.
Date: October 30, 1998
Creator: Shen, M.; Abbott, R. & Wheelock, T. D.
Partner: UNT Libraries Government Documents Department

Development of a Gas-Promoted Oil Agglomeration Process

Description: The preliminary laboratory-scale development of a gas-promoted, oil agglomeration process for cleaning coal was carried out with scale model mixing systems in which aqueous suspensions of ultrafine coal particles were treated with a liquid hydrocarbon and a small amount of air. The resulting agglomerates were recovered by screening. During a batch agglomeration test the progress of agglomeration was monitored by observing changes in agitator torque in the case of concentrated suspensions or by observing changes in turbidity in the case of dilute suspensions. Dilute suspensions were employed for investigating the kinetics of agglomeration, whereas concentrated suspensions were used for determining parameters that characterize the process of agglomeration. A key parameter turned out to be the minimum time te required to produce compact spherical agglomerates. Other important parameters included the projected area mean particle diameter of the agglomerates recovered at the end of a test as well as the ash content and yield of agglomerates. Batch agglomeration tests were conducted with geometrically similar mixing tanks which ranged in volume from 0.346 to 11.07 liters. Each tank was enclosed to control the amount of air present. A variable speed agitator fitted with a six blade turbine impeller was used for agitation. Tests were conducted with moderately hydrophobic Pittsburgh No. 8 coal and with more hydrophobic Upper Freeport coal using either n-heptane, i-octane, or hexadecane as an agglomerant.
Date: November 1997
Creator: Nelson, C.; Zhang, F.; Drzymala, J.; Shen, M.; Abbott, R. & Wheelock, T. D.
Partner: UNT Libraries Government Documents Department

Supplemental Material: Enthalpy of Solvation Correlations for Gaseous Solutes Dissolved in Linear Alkanes (C5 thru C16) Based on the Abraham Model

Description: This document includes supplemental material to an article titled "Enthalpy of solvation correlations for gaseous solutes dissolved in linear alkanes (C5 thru C16) based on the Abraham model," published in QSAR & Combinatorial Science.
Date: June 2007
Creator: Mintz, Christina; Burton, Katherine; Acree, William E. (William Eugene) & Abraham, M. H. (Michael H.)
Partner: UNT College of Arts and Sciences

Pathway and kinetic analysis on the propyl radical + 02 reaction system

Description: In this study of the reaction of alkyl radicals with molecular oxygen, we analyze the propyl + 02 reaction system using thermochemical kinetics, Transition State Theory (TST), molecular thermodynamic properties, quantum Kassel analysis (quantum RRK) for k(E) and modified strong collision analysis for fall off. Cyclic transition states for both hydrogen transfer and the H02 concerted elimination from propylperoxy are calculated using semi-empirical (MOPAC PM3) calculations [8] in addition to transition states for H02 elimination and epoxide formation from hydroperoxy-isopropyl. Computed rate constants for propyl + 02 are compared to the values of Gulati and Walker who measured the rate constants at 50 torr and over a temperature range of 653 to 773 K. Computed rate constants are also used in a detailed chemical kinetic mechanism and compared to the n- propyl + 02 data of Slagle. They measured the rate of disappearance of n-propyl by reaction with 02 over a temperature range of 297 to 635 K and a pressure range of 0.4 to 7 Torr, as well as the fall off data of the Kaiser and Wallington.
Date: May 1, 1997
Creator: Bozzelli, J.W. & Pitz, W.J.
Partner: UNT Libraries Government Documents Department

Development of high temperature catalytic membrane reactors. Final report

Description: Early efforts in 1992 were focused on relocating the membrane reactor system from Alcoa Separation Technology, Inc.`s Warrendale, PA facility to laboratory space at the University of Pittsburgh Applied Research Center (UPARC) in Harmarville, PA following the divestiture of Alcoa Separations to US Filter, Inc. Reconstruction was completed in March, 1992, at which time the reactor was returned to ethylbenzene dehydrogenation service. Efforts on ethylbenzene dehydrogenation to styrene focused on optimizing hybrid reactor performance relative to packed bed operation. Following this, the reactor system was converted to isobutane dehydrogenation. Experimentation on isobutane dehydrogenation focused on design of an inert reactor, evaluation of commercial light alkane dehydrogenation catalysts, and modeling of membrane reactor performance relative to the performance of a packed bed reactor. This report summarizes the effort in 1992 on the development of ceramic membranes as dehydrogenation reactors. In addition, outside interactions on behalf of this investigation are discussed.
Date: February 28, 1992
Creator: Gallaher, G.; Gerdes, T. & Gregg, R.
Partner: UNT Libraries Government Documents Department

BRANCHED ALKANES FROM BLUE-GREEN ALGAE

Description: Branched alkanes from blue-green algae were separated on a 750 feet high resolution capillary gas chromatographic column. The mixture was found to be 90% of 1:1 ratio 7-methyl, and 8-methyl-heptadecane, and 10% of 6-methylheptadecane. An optical rotation of +2.5 {+-} 0.5 was obtained on a 5 mg of mixture.
Date: August 1, 1970
Creator: Han, Jerry & Calvin, Melvin.
Partner: UNT Libraries Government Documents Department

FINAL TECHNICAL REPORT for grant DE-FG02-93ER14353 œ"Carbon-Hydrogen Bond Functionalization Catalyzed by Transition Metal Systems"

Description: Alkanes are our most abundant organic resource but are highly resistant to selective chemical transformations. Alkenes (olefins) by contrast are the single most versatile class of molecules for selective transformations, and are intermediates in virtually every petrochemical process as well as a vast range of commodity and fine chemical processes. Over the course of this project we have developed the most efficient catalysts to date for the selective conversion of alkanes to give olefins, and have applied these catalysts to other dehydrogenation reactions. We have also developed some of the first efficient catalysts for carbonylation of alkanes and arenes to give aldehydes. The development of these catalysts has been accompanied by elucidation of the mechanism of their operation and the factors controlling the kinetics and thermodynamics of C-H bond activation and other individual steps of the catalytic cycles. This fundamental understanding will allow the further improvement of these catalysts, as well as the development of the next generation of catalysts for the functionalization of alkanes and other molecules containing C-H bonds.
Date: May 21, 2012
Creator: Goldman, Alan S.
Partner: UNT Libraries Government Documents Department

Millisecond Oxidation of Alkanes

Description: This project was undertaken in response to the Department of Energy's call to research and develop technologies 'that will reduce energy consumption, enhance economic competitiveness, and reduce environmental impacts of the domestic chemical industry.' The current technology at the time for producing 140 billion pounds per year of propylene from naphtha and Liquified Petroleum Gas (LPG) relied on energy- and capital-intensive steam crackers and Fluidized Catalytic Cracking (FCC) units. The propylene is isolated from the product stream in a costly separation step and subsequently converted to acrylic acid and other derivatives in separate production facilities. This project proposed a Short Contact Time Reactor (SCTR)-based catalytic oxydehydrogenation process that could convert propane to propylene and acrylic acid in a cost-effective and energy-efficient fashion. Full implementation of this technology could lead to sizeable energy, economic and environmental benefits for the U. S. chemical industry by providing up to 45 trillion BTUs/year, cost savings of $1.8 billion/year and a combined 35 million pounds/year reduction in environmental pollutants such as COx, NOx, and SOx. Midway through the project term, the program directive changed, which approval from the DOE and its review panel, from direct propane oxidation to acrylic acid at millisecond contact times to a two-step process for making acrylic acid from propane. The first step was the primary focus, namely the conversion of propane to propylene in high yields assisted by the presence of CO2. The product stream from step one was then to be fed directly into a commercially practiced propylene-to-acrylic acid tandem reactor system.
Date: September 30, 2011
Creator: Han, Scott
Partner: UNT Libraries Government Documents Department

Fluorination Effect on the Conformational Properties of Alkanes

Description: A Series of fluorophores of the general formular P(CF2)nP and P(CF2)n-1CF3 has been synthesized. Copper catalyzed coupling of 1-bromopyrene and the corresponding mono and di-iodoperfluoroalkanes were used in most cases. For the n=3 dimer, a novel 1,w-perfluoroalkylation of pyrene via bis-decarboxylation of hexafluorogultaric acid was utilized. These compounds, along with suitable hydrocarbon analogs, are being used to study the flexibility of fluorocarbon chains using emission. We have found that the excimer formation for the fluorinated pyrene monomers is highly dependent on concentration and is less efficient than for pyene. Excimer formation for the fluorinated pyrene dimers is much more efficient than for the fluorocarbon monomers and is only slightly concentraion dependent. Steady-state emission spectra indicate hydrocarbon dimers-models form excimers more efficiently than the fluorinated dimers suggesting the fluorinated chains are stiffer than the hydrocarbons. We conducted the temperature-dependent studies and quantified the conformational difference.
Date: May 2002
Creator: Xu, Wenjian
Partner: UNT Libraries

Catalytic conversion of light alkanes phase II. Topical report, January 1990--January 1993

Description: The Topical Report on Phase II of the project entitled, Catalytic Conversion of Light Alkanes reviews work done between January 1, 1990 and September 30, 1992 on the Cooperative Agreement. The mission of this work is to devise a new catalyst which can be used in a simple economic process to convert the light alkanes in natural gas to oxygenate products which can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon transportation fuel. This Topical Report documents our efforts to design, prepare, characterize and test novel catalysts for the mild selective reaction of light hydrocarbons with air or oxygen to produce alcohols directly. These catalysts are designed to form active metal oxo (MO) species and to be uniquely active for the homolytic cleavage of the carbon-hydrogen bonds in light alkanes producing intermediates which can form alcohols. Research on the Cooperative Agreement is divided into three Phases relating to three molecular environments for the active catalytic species that we are trying to generate. In this report we present our work on catalysts which have oxidation-active metals in polyoxoanions (PHASE II).
Date: December 31, 1998
Partner: UNT Libraries Government Documents Department

Development of Vanadium Phosphaate Catalysts for Methanol Production by Selective Oxidation of Methane.

Description: This DOE sponsored study of methane partial oxidation was initiated at Amax Research and Development in Golden, CO in October of 1993. Shortly thereafter the management of Amax closed this R&D facility and the PI moved to the Colorado School of Mines. The project was begun again after contract transfer via a novation agreement. Experimental work began with testing of vandyl pyrophosphate (VPO), a well known alkane selective oxidation catalyst. It was found that VPO was not a selective catalyst for methane conversion yielding primarily CO. However, promotion of VPO with Fe, Cr, and other first row transition metals led to measurable yields for formaldehyde, as noted in the summary table. Catalyst characterization studies indicated that the role of promoters was to stabilize some of the vanadium in the V{sup 5+} oxidation state rather than the V{sup 4+} state formally expected for (VO){sub 2}P{sub 2}O{sub 7}.
Date: October 1, 1997
Creator: McCormick, R.L.
Partner: UNT Libraries Government Documents Department

Analysis of Steam Heating of a Two-Layer TBP/N-Paraffin/Nitric Acid Mixtures

Description: This report presents an analysis of steam heating of a two-layer tri-n-butyl phosphate (TBP)/n-paraffin-nitric acid mixture.The purpose of this study is to determine if the degree of mixing provided by the steam jet or by bubbles generated by the TBP/nitric acid reaction is sufficient to prevent a runaway reaction.
Date: July 22, 1998
Creator: Laurinat, J.E.; Hassan, N.M.; Rudisill, T.S. & Askew, N.M.
Partner: UNT Libraries Government Documents Department

Nanorheology of Liquid Alkanes

Description: We report molecular dynamics simulations of liquid alkanes, squalane and tetracosane, confined between moving walls to which butane chains are tethered, effectively screening the details of the wall. As in an experiment, heat is removed by thermostatting the tethered molecules. Results obtained at high strain rates, typical of practical applications, suggest little or no difference between the bulk rheology and confined flow, and the occurrence of a high degree of slip at the wall-fluid interface at the conditions studied. At relatively low velocities and high densities, tetracosane shows the formation of fully-extended chains at certain wall spacings.
Date: September 1, 1997
Creator: Gupta, S.A., Cochran, H.D., Cummings, P.T.
Partner: UNT Libraries Government Documents Department

Dynamics of intermediate-length alkane films absorbed on graphite

Description: The dynamics of flexible chain molecules near a solid interface is of fundamental interest in polymer science. This paper makes a preliminary report on a quasielastic neutron scattering study of the dynamics of monolayer films of C{sub 24}H{sub 66} adsorbed on graphite. Quasielastic scattering was observed at temperatures as low as {approximately}180 K, well below the monolayer melting temperature of 340 K. Preliminary analysis of the data indicates that at 230 K the entire molecule executes a rolling motion about its long axis while the terminal methyl groups exhibit relatively rapid reorientation.
Date: January 28, 2000
Creator: Herwig, K. W.; Fuhrmann, D.; Criswell, L.; Taub, H.; Hansen, F. Y.; Dimeo, R. et al.
Partner: UNT Libraries Government Documents Department

The effects of pressure, temperature and concentration on the reactivity of alkanes; experiments and modeling in a rapid compression machine

Description: Experiments in a rapid compression machine have examined the influences of variations in pressure, temperature, and equivalence ratio on the autoignition of n-pentane. Equivalence ratios included values from 0.5 to � 2.0, compressed gas initial temperatures were varied between 675K and 980K, and compresed gas initial pressures varied from 8 to 20 bar. Numerical simulations of the same experiments were carried out using a detailed chemical kinetic reaction mechanism. The results are interpreted in terms of a low temperature oxidation mechanism involving addition of molecular oxygen to alkyl and hydroperoxyalkyl radicals. Idealized calculations are reported which identify the major reaction paths at each temperature. Results indicate that in most cases, the reactive gases experience a two-stage autoigni tion. The first stage follows a low temperature alkylperoxy radical isomerization pathway that is effectively quenched when the temperature reaches a level where dissociation reactions of alkylperoxy and hydroperoxyalkylperoxy radicals are more rapid than the reverse addition steps. The second stage is controlled by the onset of dissociation of hydrogen peroxide. Results also show that in some cases, the first stage ignition takes place during the compression stroke in the rapid compression machine, making the interpretation of the experiments somewhat more complex than generally assumed. At the highest compression temperatures achieved, little or no first stage ignition is observed.
Date: January 8, 1998
Creator: Curran, H J; Griffiths, J F; Mohamed, C; Pitz, W J; Westbrook, C & Wo, S K
Partner: UNT Libraries Government Documents Department

Catalytic conversion of light alkanes-proof-of-concept stage - Phase IV. Topical report, February 1, 1994--January 31, 1995

Description: This report details the research performed on Phase IV of the extended Cooperative Agreement. This Phase, entitled C{sub 1}-C{sub 4} Research, provides the research support which accompanies the C{sub 4} Proof-of-Concept Phase (Phase V) as the two major activities of the Cooperative Agreement during calendar 1993. It is the objective of this phase to understand the nature of the catalysts and catalytic activity of perhaloporphyrin complexes uncovered during Phases I-III in order that superior catalytic materials can be made and tested which meet commercial criteria for the oxidation of the C{sub 1}-C{sub 4} light alkane gases found in natural gas and other available hydrocarbon streams. During Phase IV, we have examined the physical and electronic structures of the very active perhaloporphyrin catalysts which we have developed, and have gained an understanding of the properties which make them active. This has led us to design and synthesize materials which are cheaper, more active, more robust and, in general superior for carrying out practical catalysis. Our early generation perhaloporphyrin catalysts, while exhibiting unprecedented catalytic activity, were far too expensive for use in converting natural gas or its C{sub 1}-C{sub 4} components.
Date: December 31, 1998
Partner: UNT Libraries Government Documents Department

Catalytic conversion of light alkanes: Proof of concept stage

Description: During the stage at which this work ended, our program consisted of two phases which were running concurrently, a research phase and a proof-of-concept phase. The function of the research phase is to design synthesize and perform laboratory tests on new materials in order to enhance the catalytic properties of the suprabiotic systems generated in our laboratories. Increases in catalytic activity and process selectivity as well as extensions of structure-activity relationships are examined. The research phase is intended to provide the process development phases with catalysts having superior properties for light alkane oxidation. The second concurrent phase, is the proof-of-concept phase. In this phase process development of oxidations which have succeeded in the research phase are carried out in a pre-pilot PDU. At the conclusion of the cooperative agreement we were developing a process for the conversion of isobutane to (TBA), We have identified two routes for this transformation: a one-step route directly from isobutane to TBA, and a two-step route in which the isobutane is oxidized first to tert-butyl hydroperoxide and then transformed into TBA catalytically. This paper presents the results of these activities.
Date: June 1, 1995
Creator: Lyons, J.E.
Partner: UNT Libraries Government Documents Department

Gallium Zeolites for Light Paraffin Aromatization

Description: The primary original goal of this project was to investigate the active state of gallium-containing MFI catalysts for light paraffin aromatization, in particular the state of gallium in the active material. Our original hypothesis was that the most active and selective materials were those which contained gallium zeolitic cations, and that previously reported conditions for the activation of gallium-containing catalysts served to create these active centers. We believed that in high silica materials such as MFI, ion-exchange is most effectively accomplished with metals in their 1+ oxidation state, both because of the sparsity of the anionic ion-exchange sites associated with the zeolite, and because the large hydration shells associated with aqueous 3+ cations hinder transport. Metals such as Ga which commonly exist in higher oxidation states need to be reduced to promote ion-exchange and this is the reason that reduction of gallium-containing catalysts for light paraffin aromatization often yields a dramatic enhancement in catalytic activity. We have effectively combined reduction with ion-exchange and we term this combined process ''reductive solid-state ion-exchange''. Our hypothesis has largely been proven true, and a number of the papers we have published directly address this hypothesis.
Date: February 10, 1999
Creator: Price, G.L. & Dooley, K.M.
Partner: UNT Libraries Government Documents Department