63 research outputs found
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Advanced thermally stable jet fuels: Technical progress report, October 1994--December 1994
There are five tasks within this project on thermally stable coal-based jet fuels. Progress on each of the tasks is described. Task 1, Investigation of the quantitative degradation chemistry of fuels, has 5 subtasks which are described: Literature review on thermal stability of jet fuels; Pyrolytic and catalytic reactions of potential endothermic fuels: cis- and trans-decalin; Use of site specific {sup 13}C-labeling to examine the thermal stressing of 1-phenylhexane: A case study for the determination of reaction kinetics in complex fuel mixtures versus model compound studies; Estimation of critical temperatures of jet fuels; and Surface effects on deposit formation in a flow reactor system. Under Task 2, Investigation of incipient deposition, the subtask reported is Uncertainty analysis on growth and deposition of particles during heating of coal-derived aviation gas turbine fuels; under Task 3, Characterization of solid gums, sediments, and carbonaceous deposits, is subtask, Studies of surface chemistry of PX-21 activated carbon during thermal degradation of jet A-1 fuel and n-dodecane; under Task 4, Coal-based fuel stabilization studies, is subtask, Exploratory screening and development potential of jet fuel thermal stabilizers over 400 C; and under Task 5, Exploratory studies on the direct conversion of coal to high quality jet fuels, are 4 subtasks: Novel approaches to low-severity coal liquefaction and coal/resid co-processing using water and dispersed catalysts; Shape-selective naphthalene hydrogenation for production of thermally stable jet fuels; Design of a batch mode and a continuous mode three-phase reactor system for the liquefaction of coal and upgrading of coal liquids; and Exploratory studies on coal liquids upgrading using mesopores molecular sieve catalysts. 136 refs., 69 figs., 24 tabs
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Advanced thermally stable jet fuels: Technical progress report, July 1994--September 1994
There are five tasks within this project on thermally stable coal-based jet fuels. Progress on each of the tasks is described. Task 1, Investigation of the quantitative degradation chemistry of fuels, has 3 subtasks which are described: Pyrolysis of n-alkylbenzenes; Thermal decomposition of n-tetradecane in near-critical region; and Re-examining the effects of reactant and inert gas pressure on tetradecane pyrolysis--Effect of cold volume in batch reactor. Under Task 2, Investigation of incipient deposition, the subtask reported is Uncertainty analysis on growth and deposition of particles during heating of coal-derived aviation gas turbine fuels; under Task 3, Investigation of the quantitative degradation chemistry of fuels, is subtask, Effects of high surface area activated carbon and decalin on thermal degradation of jet A-1 fuel and n-dodecane; under Task 4, Coal-based fuel stabilization studies, is subtask, Screening potential jet fuel stabilizers using the model compound dodecane; and under Task 5, Exploratory studies on the direct conversion of coal to high quality jet fuels, is subtask, Shape-selective naphthalene hydrogenation for production of thermally stable jet fuels. 25 refs., 64 figs., 22 tabs
Early above- and below-ground responses of subboreal conifer seedlings to various levels of deciduous canopy removal
We examined the growth of understory conifers, following partial or complete deciduous canopy removal, in a field study established in two regions in Canada. In central British Columbia, we studied the responses of three species (Pseudotsuga menziesii var. glauca (Beissn.) Franco, Picea glauca (Moench) Voss x Picea engelmannii Parry ex Engelm., and Abies lasiocarpa (Hook.) Nutt.), and in northwestern Quebec, we studied one species (Abies balsamea (L.) Mill.). Stem and root diameter and height growth were measured 5 years before and 3 years after harvesting. Both root and stem diameter growth increased sharply following release but seedlings showed greater root growth, suggesting that in the short term, improvement in soil resource capture and transport, and presumably stability, may be more important than an increase in stem diameter and height growth. Response was strongly size dependent, which appears to reflect greater demand for soil resources as well as higher light levels and greater tree vigour before release for taller individuals. Growth ratios could not explain the faster response generally attributed to true fir species or the unusual swift response of spruces. Good prerelease vigour of spruces, presumably favoured by deciduous canopies, could explain their rapid response to release
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Effects of surface chemistry on the porous structure of coal. Quarterly technical progress report, October 1995--December 1995
The primary objective of this work is to use {sup 129}Xe NMR to characterize the microporous structure of coals. As an aide in this characterization, which is by no means straightforward, another objective is to combine this technique with volumetric adsorption techniques and track the effect of controlled opening of the micropores in a microporous carbon by oxygen chemisorption/desorption. The primary goal of the NMR work is to measure the micropore sizes in coal; more broadly, it is to better tailor the {sup 129}Xe NMR method for use with coal, and to investigate other ways it may be used to describe pore structure in coal, with emphasis on determining whether micropores in coal are connected or isolated. In terms of the primary objectives of the project, the {sup 129}Xe NMR spectra with pressure variation have been obtained for two more coals, completing this task for the sample set of six coals. In terms of the broad objectives of the project, examination of the influence on the xenon signal of packing the powdered coal has been undertaken. These data are of potential value for the determination of whether the porosity is open or closed. Results of powder density and related experiments will be used in the final interpretation of our current data, including the determination of whether, in the NMR of loose powdered, the chemical shift is indicative of the ``true`` gas-solid interaction
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Effects of surface chemistry on the porous structure of coal. Quarterly technical progress report, April 1996--June 1996
Objective is to use {sup 129}Xe NMR to study the microporous structure of coals. During this quarter, we have: performed a presaturation experiment on Wyodak subbituminous coal, monitored the progress of Xe adsorption in an anthracite, focusing on the changes observed in the external-surface adsorbed gas signal, used an echo sequence to obtain {sup 129}Xe NMR spectra of Blind Canyon hvAb coal, and improved and repeated the successive oxygen adsorption and desorption experiment on a microporous carbon
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Effects of surface chemistry on the porous structure of coal. Quarterly technical progress report, July 1996--September 1996
The primary objective of this project is to use {sup 129}Xe NMR to characterize the microporous structure of coals. We will use direct information on pore size, as well as indirect information from adsorption rates and evidence for intra/extraparticle diffusion, to characterize the connectivity of the micropore network. A second objective is to use {sup 129}Xe NMR to describe the effect of controlled opening of the micropores in a microporous carbon by oxygen chemi-sorption/desorption. Our experimental focus in this quarter has been the low power presaturation of the NMR signal of {sup 129}Xe adsorbed in coal. Preliminary work on this experiment was reported in the last quarter. Low power presaturation of {sup 129}Xe adsorbed in two coals produces a hole-burning effect in the adsorbed xenon NMR signals, indicating that these signals are broad due to overlap of a series of chemical shifts. Saturation transfer to the entire adsorbed xenon signal and to the extraparticle gas is observed with increasing presaturation time. Differences in timing of saturation transfer to the external gas have implications for the nature of the connectivity of the pore structures in coal
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Effects of surface chemistry on the porous structure of coal. Quarterly technical progress report, October 1996--December 1996
Selective presaturation and saturation transfer {sup 129}Xe NMR experiments were performed on a high volatile C bituminous coal and an anthracite. The experiments detect the movement of xenon atoms among different regions of the internal surface, and to the external surface of the coal particles. The results indicate that adsorbed xenon atoms can move to the external surface of the bituminous coal significantly faster than in the anthracite. The results are interpreted in terms of the porous structure of the coals
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Effects of surface chemistry on the porous structure of coal. Quarterly technical progress report, January 1996--March 1996
The primary objective of this work is to use {sup 129}Xe NMR to characterize the microporous structure of coals. Another objective is to use this technique to describe the effect of controlled opening of the micropores in a microporous carbon by oxygen chemisorption/desorption. The primary goal of the NMR work is to measure the micropore sizes in coal; more broadly, it is to better tailor the {sup 129}Xe NMR method for use with coal, and to investigate other ways it may be used to describe pore structure in coal, with emphasis on determining whether micropores in coal are connected or isolated. During this quarter, we have: (i) investigated particle size effect on the chemical shift of xenon adsorbed in a set of size-graded vitrinites; (ii) tracked the progress of xenon adsorption via xenon NMR, including particle size effect on the adsorption process; (iii) completed a preliminary test for chemical shift anisotropy in coal; and (iv) examined a microporous carbon by {sup 129}Xe NMR after two cycles of oxygen chemisorption/desorption
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