Explicit photochemical mechanism for atmospheric oxidation of n-butane

Thesis/Dissertation · Tue Dec 31 23:00:00 EST 1991

OSTI ID:5509768

Wen, L

Alkanes, being an important component of atmosphere, serve as precursors to ozone formation in urban and rural air masses. An explicit photochemical oxidation mechanism for n-butane, which is the major hydrocarbon component of automobile exhaust, is created in this work. The yields of organic nitrates from n-butane, n-pentane, and methyl ethyl ketone photooxidations were studied in Teflon bag and smog chamber experiments. Comparing with the expression currently using the most atmospheric model studies, the total butyl nitrates yield obtained in this work is about 36% lower, and the ratio of primary to secondary butyl nitrates is slightly higher. It is shown in this work that the yields of hydroxyl and carbonyl butyl nitrates are very low, and can be ignored in the explicit photochemical mechanisms. The explicit photochemical oxidation mechanism for methyl ethyl ketone (MEK) was created first because it is the major product from photooxidation of n-butane. The explicit photochemical oxidation mechanism for n-butane, created later, draws on the MEK mechanism. The mechanisms were tested by comparing model predictions with experimental observations from smog chamber experiments. The comparisons were conducted for species which had experimental observation data, such as O[sub 3], NO, and NO[sub 2], n-butane, MEK, organic nitrates, and aldehydes species. The sixteen smog chamber experiments, used in model simulations, were conducted during 1978 to 1992. The mechanisms are mainly based on the available kinetic data in literature and the experimental result in this work. The rate constants for some reactions in the mechanisms were adjusted to make a better fit with the experimental observations. These reactions were: reaction of OH and n-butane to form secondary butyl peroxy radical, decomposition of secondary butoxy radical, and reaction of OH and MEK.

• Research Organization: North Carolina Univ., Chapel Hill, NC (United States)
• OSTI ID: 5509768
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500 -- Photochemistry
54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
ALDEHYDES
ALKANES
ATMOSPHERIC CHEMISTRY
AUTOMOBILES
BUTANE
CHEMICAL REACTIONS
CHEMISTRY
EXHAUST GASES
FLUIDS
GASEOUS WASTES
GASES
HYDROCARBONS
NITRATES
NITROGEN COMPOUNDS
ORGANIC COMPOUNDS
OXIDATION
OXYGEN COMPOUNDS
OZONE
PENTANE
PHOTOCHEMICAL OXIDANTS
PHOTOCHEMICAL REACTIONS
SMOG
VEHICLES
WASTES