High-Temperature Oxidation Mechanisms of m- and p-Xylene

Article abstract of DOI:10.1021/j100157a024

Mechanisms for the oxidation of m- and p-xylene were developed with the aid of atmospheric flow reactor tests at temperatures ranging from 1093 to 1199 K and equivalence ratios from 0.47 to 1.7.The experimental data suggested that m-xylene is oxidized by sequential oxidation and removal of the methyl side chains while p-xylene reacts through simultaneous, as well as sequential, oxidation of the side chains.The formation of p-xylylene (3,6-bis(methylene)-1,4-cyclohexadiene), postulated to occur during the oxidation of p-xylene, opens up the simultaneous oxidation route and leads to the formation of p-phthalaldehyde.The formation of m-xylylene during the oxidation of m-xylene was determined to be unfavorable.In order to better understand specific steps of the mechanisms, the oxidation of p-tolualdehyde and the pyrolysis of p-methylanisole were also studied. p-Tolualdehyde tests were used to show that the aldehydic side chain is consumed quicker than the methyl side chain.Because p-methylanisole decays quickly to methyl and p-methylphenoxy radical, it was used to determine the fate of methylphenoxy radical formed during the xylene tests.The results indicated that methylcyclopentadienyl and CO are formed from the methylphenoxy and that methylcyclopentadienyl rearranges quickly to benzene and hydrogen atom.