Experimental and kinetic modeling study of α-methyl-naphthalene pyrolysis: Part I. Formation of monocyclic aromatics and small species

α-Methyl-naphthalene is a very important intermediate in fuel oxidation and a raw material in industrial and scientific fields. Unraveling its detailed chemistry is important for its practical applications. Pyrolysis of α-methyl-naphthalene (C₁₁H₁₀) is studied in a flow reactor at low and atmospheric pressures (30 and 760 Torr) using synchrotron vacuum ultraviolet photoionization molecular beam mass spectrometry (SVUV-PI-MBMS). A kinetic model is developed to predict the decomposition of α-methyl-naphthalene under pyrolytic conditions. A general map of α-methyl-naphthalene thermal decomposition is presented according to the experimental observations and model analysis. Benzo[b]benzyl radical is the dominant primary product in α-methyl-naphthalene pyrolysis. Benzo[b]benzyl radical dissociates to monocyclic aromatics and small intermediates mainly via benzo-fulvenallene and ethynyl-indenyl. The yielded o-benzyne and cyclopent-1-en-3‑yne then contributes to the formation of C₅ – C₈ species. Phenylacetylene has a direct formation route from α-methyl-naphthalene by H-addition allyl-elimination. In addition to naphthalene (C₁₀H₈) and indene (C₉H₈) sub-mechanisms, C₁₁ sub-mechanism is shown to be critical to unveil the degradation from bicyclic to monocyclic aromatics.