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Dissertation
Effects of pressure on hydrocarbon oxidation chemistry
Doctor of Philosophy (Ph.D.), Drexel University
Dec 1990
DOI:
https://doi.org/10.17918/00009409
Abstract
A turbulent flow reactor has been constructed for chemical kinetic studies of hydrocarbon oxidation in the low to intermediate temperature regimes. The flow reactor enables the study of gas-phase kinetics from 2 to 20 atm. Experiments studying the effect of pressure on the oxidation chemistry during the transition from low to intermediate temperature have been conducted. Experimental conditions cover temperatures from 600 to 900 K, pressures from 5 to 15 atm and equivalence ratios from 0.4 to 2.8 using ethylene/air, ethane/air and propane/air mixtures. In these experiments, gas samples were extracted along the reactor centerline with a water-cooled probe. Species measurements were made using gas chromatography and reactivity mapping was conducted using CO measurements as an indicator of extent of reaction. Results for propane/air experiments indicate typical NTC behavior which manifests as a narrow temperature range (640 to 770 K) in which the rate of hydrocarbon oxidation peaks. The NTC region temperature range shifts to higher temperatures and broadens with increasing pressure. This behavior contrasts with Dryer's 1990 prediction suggesting that the NTC region narrows and disappears as pressure increases. Several changes in the major reaction products occur as temperature is varied indicating changes in the dominant branching agent. Below approximately 690 K, CO₂ is the major product. Above 690 K, CO is the major product. Above 740 K, propylene becomes the major product. The temperatures at which these transitions occur are observed to change with pressure. The pressure dependent shift in the NTC region temperature range is compared to Benson's 1981 analysis which is found to accurately predict the shift. Transition in the CO and propylene yields is explained by considering the fate of energetically unstable propylperoxy radicals in the coupled reaction mechanism of Slagle et al. (1985). The low temperature region in which CO₂ is the major product is explained by aldehyde and acylhydroperoxide branching.
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Details
- Title
- Effects of pressure on hydrocarbon oxidation chemistry
- Creators
- David Niel Koert
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xv, 576 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Engineering; Drexel University
- Other Identifier
- 991021888789504721