(281b) High Severity Pyrolyses of C6 to C12 Cyclo-Alkanes Comprizing Unsubstituted and Methylated Moieties

High temperature, short residence time pyrolyses of cyclohexane, methyl-cyclohexanes, decalin and methyl-decalins were experimentally investigated. A coiled tube flow reactor was used at outlet temperatures about 1100 K and residence times of order 300 milliseconds with steam dilution to simulate commercial steam cracking conditions at severities ranging from 1 to 4. Decomposition kinetics and the major and minor product selectivities obtained from all substrates were interpreted in terms both of conventional Rice-Herzfeld free-radical pathways and a graph-theoretic ?moiety hypothesis?, according to which the selectivity to a particular pyrolysis product is a linear function of unsubstituted and methylated moieties in the substrate. Examples are presented for the yields of ethylene, propylene, butadiene and isoprene products, with possible applications of these results to the pyrolysis of heavy naphthenic feedstocks.