SURFACE EFFECTS IN THE UNINHIBITED AND THE INHIBITED PYROLYSES OF ISOMERIC HEXANES: PARTS I-III. n-HEXANE, 2-METHYL PENTANE, 3-METHYL PENTANE

Abstract

The rates of pyrolysis of n-hexane, 2-methyl pentane, and 3-methyl pentane decrease with increasing S/V ratio in the pressure range of 15 to 90 mm at temperatures around 520 °C. The partial pressure of nitric oxide required for maximum inhibition which appears to be independent of the hydrocarbon pressure and is approximately constant for all isomers, namely 12–14 mm, for hydrocarbon ranging from 50 to 100 mm, increases slightly with increasing S/V ratio. Nitric oxide affects the product distribution markedly. The simultaneous increase in the yield of C2H4 and decrease in the yield of C2H6 with increasing NO pressure can be attributed to the set of competitive reactions[Formula: see text][Formula: see text]Similarly, the slight decrease in the yield of C3H8 with increasing NO pressure can be accounted for by the competition[Formula: see text][Formula: see text]Increased S/V ratios favor the formation of C2H6 in both the uninhibited and the inhibited pyrolyses, but has no effect on the yields of such products as C3H6, 1-C4H8, and i-C4H8. The analytical balance becomes less complete at higher NO pressures for the inhibited decomposition, which can be attributed to the formation of some nitrogen-containing compounds undetectable by the analytical methods used. Mechanisms are proposed accounting qualitatively for the products of the uninhibited and the inhibited pyrolyses.