1-PENTENE OXIDATION AND ITS INTERACTION WITH NITRIC-OXIDE IN THE LOW AND NEGATIVE TEMPERATURE-COEFFICIENT REGIONS

The oxidation of l-pentene and the effect of nitric oxide (NO) on this oxidation has been examined in a pressurized flow reactor facility. T he experiments were conducted at 6 atmospheres over the temperature ra nge of 600-800 K and an equivalence ratio of 0.4. l-Pentene showed alk ane type behavior exhibiting low temperature reactivity and strong neg ative temperature coefficient behavior. An examination of stable speci es composition revealed that hydrogen abstraction reactions leading to allyl radicals are more important than radical addition to the double bond. This is in contrast to previous studies on terminal olefins whe re the addition route was proposed as the dominant fuel consumption pa thway. We believe that as carbon number of the terminal olefin increas es alkane type reaction behavior occurs at the other end of the molecu le and this is the reactivity observed under our experimental conditio ns. The presence of small concentrations of nitric oxide (0-500 ppm mo le fraction) significantly altered l-pentene oxidation at these temper atures. The effect of NO is a result of the competition between its pr omoting effect through reaction with HO2. radicals and its retarding e ffect through reaction with OH. radicals. Thus the effect depends stro ngly on the underlying fuel oxidation chemistry which generates the HO 2. and OH. radicals and the concentration of the nitric oxide added. A n explanation for this behavior is presented in the paper.