C. Cullis, A. Fish, D. Trimm
1963
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Influential Citations
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Abstract
Several researches are described in which the solution of combustion problems has been facilitated by the use of carbon-13 and carbon-14 tracer methods. One of the widest applications is in the elucidation of the mechanism of formation of combustion products and some work is described in which the position of the isotopic carbon has been determined in the principal products formed from [2-C14] and [4-C14]-2-methyl-but-2-enes. Another use is in the determination of the most probable points of oxidative attack of fuel molecules and in this connection 2-methylpentane has been labeled specifically in all its skeletal positions and the isotopic enrichment of the final combustion products has been measured. The technique of isotopic labeling has also been applied to discover which component of a mixed fuel is responsible for the formation of a given product; thus measurement of the activity of the carbon deposits formed from samples of gasoline containing each constituent labeled in turn with carbon-14 gives quantitative information about their deposit-forming tendency. The role of additives in fuel+oxygen systems may be elucidated by labeling either the additive or the fuel. If the additive is an intermediate combustion product, the origin of certain of the other intermediate and final products may be found; some work is described in which the mechanism of formation of certain products has been investigated by addition of [1,3-C14]-acetone to isobutane+oxygen mixtures. Another example of the power of tracer techniques is their use in the determination of the actual rates of formation and consumption of intermediates (as opposed to their net rate of accumulation) even when these two processes occur concurrently and work is discussed from which it has been possible to calculate the rates of certain elementary reactions occurring during the combustion of paraffins and olefins. Determination of the rates of competing processes has also been effected by the use of fuels and additives labeled with isotopic carbon; measurement of the total isotopic concentrations in the products enables their relative rates of formation from a given labeled intermediate to be determined irrespective of their concurrent production by other routes. Finally consideration is given to possible further applications of isotopic carbon in combustion research.