Benzene and higher hydrocarbon formation during allene pyrolysis

Abstract

Pyrolysis of allene in a microjet reactor at millisecond to second reaction times from 500 K to 1700 K was used to study higher hydrocarbon growth processes from C3 hydrocarbon species. Low temperature benzene formation likely occurs through the molecular channel consisting of allene dimerization to a mixture of dimethylenecyclobutane isomers (DMCB) and subsequent isomerization and hydrogen loss to form benzene. At higher temperatures and longer residence times, the benzene production rate shows a change in formation mechanism. Higher hydrocarbon growth to multiple ring compounds was observed at longer residence times, with growth initially consistent with acetylene and possibly other small hydrocarbon addition to PAH radicals followed by reactive dimerization of small PAH compounds.