An Evaluation of the Fuel Factor Through Direct Measurement of Photochemical Reactivity of Emissions

The Reactivities of Gasoline Vapors in Photochemical Smog

“…Dimitriades and coworkers 6 developed empirical correlation equations which enabled them to predict the behavior expected in their smog chamber from a hydrocarbon mixture when the mole fractions of paraffins, olefins, benzene, and other aromatics were known, but the coefficients used in the equations are of empirical meaning only and do not reflect the actual contributions made by the various hydrocarbons to smog production. 6 Linear summation techniques and reactivity scales are frequently applied, with varying degrees of success, to predict the reactivity of a mixture. Our results with whole gasolines, along with Glasson and Tuesday's 14 observations, indicate that the relative NO2 formation rates of gasolines can be predicted with accuracy by linear additivity.…”

“…The olefins are completely consumed in each experiment, and the presence of olefin invariably retards the disappearance of the saturated hydrocarbons, clearly indicating that reactive intermediates generated from the olefin preferentially attack remaining olefin, nitrogen oxides, molecular oxygen, or hydrocarbon oxidation products (such as aldehydes). In short, no major synergistic effects are observed between olefins and saturates, and d~C 6 saturates remain relatively unreactive in all the hydrocarbon blends investigated. …”

“…Thus, several laboratories and cooperative study groups (Coordinating Research Council and American Petroleum Institute) have investigated the ways in which fuel properties (especially the amounts and types of C4-C5 hydrocarbons) influence both the amount and the potential atmospheric reactivity of evaporative emissions. 1 "" 6 But fuel evaporation accounts for only a small portion of the total hydrocarbons emitted by automobiles, and gasoline modifications (such as volatility reductions) that reduce evaporative losses can lead to higher levels of hydrocarbons in automobile exhaust. 4 " 6 A joint undertaking by the California Air Resources Board, Los Angeles County Air Pollution Control District, and Western Oil and Gas Association recently evaluated the possibility of reducing photochemical smog in Los Angeles by either lowering gasoline volatility or by removing C4 and C 5 olefins from automotive fuels.…”

“…1 "" 6 But fuel evaporation accounts for only a small portion of the total hydrocarbons emitted by automobiles, and gasoline modifications (such as volatility reductions) that reduce evaporative losses can lead to higher levels of hydrocarbons in automobile exhaust. 4 " 6 A joint undertaking by the California Air Resources Board, Los Angeles County Air Pollution Control District, and Western Oil and Gas Association recently evaluated the possibility of reducing photochemical smog in Los Angeles by either lowering gasoline volatility or by removing C4 and C 5 olefins from automotive fuels. This joint study worked with composite gasoline samples (prepared by combining the blends supplied by major gasoline companies in the Los Angeles area) which included 1968 commercial gasolines as well as prototype blends designed to give reductions in volatility or light-olefin content.…”

Organic Compounds in Urban Atmospheres: A Review of Distribution, Collection and Analysis

“…51 Some workers have preferred to classify organic pollutants by a scale of reactivities. 52 The scale adopted by Pitts is specifically based on reaction with hydroxyl radicals. 53 The California State Air Resources Board 54 approved a three class scheme of reactivities in 1976.…”