Pressure dependent kinetic analysis of pathways to naphthalene from cyclopentadienyl recombination

Abstract

Cyclopentadiene (CPD) and cyclopentadienyl radical (CPDyl) reactions are known to provide fast routes to naphthalene and other polycyclic aromatic hydrocarbon (PAH) precursors in many systems. In this work, we combine literature quantum chemical pathways for the CPDyl + CPDyl recombination reaction and provide pressure dependent rate coefficient calculations and analysis. We find that the simplified 1-step global reaction leading to naphthalene and two H atoms used in many kinetic models is not an adequate description of this chemistry at conditions of relevance to pyrolysis and steam cracking. The C10H10 species is observed to live long enough to undergo H abstraction reactions to enter the C10H9 potential energy surface (PES). Rate coefficient expressions as functions of T and P are reported in CHEMKIN format for future use in kinetic modeling.

Modeling of aromatics formation in fuel-rich methane oxy-combustion with an automatically generated pressure-dependent mechanism

“…For most of the ten pathways, the PESs reported by Mebel et al 51 were used in this work. The difference was the newly reported calculations for C 5 H 5 + C 5 H 5 recombination and C 5 H 5 + C 5 H 6 reaction, where previously published C 10 H 9 and C 10 H 10 PESs were combined and rates evaluated by Long et al, 60 and rates on the C 10 H 11 surface were calculated by Vervust et al 59 The first step to generating pressure-dependent kinetics of the ten pathways is to identify the PES that each pathway belongs to. There were multiple pathways sharing the same potential surface, and some species and elementary steps are in common.…”

“…48 This approach was used instead of calculating pressure-dependent rates directly using quantum chemistry output because some combined PESs came from more than one literature source using different levels of theory for quantum chemistry calculations. For example, the C 10 H 9 PES is composed of reaction networks including 54 ), and 60 ). Inconsistencies in species (e.g.…”

“…(N1) Hydrogen abstraction acetylene addition (HACA) 52,53 sequences, 54,55 (N2) Addition of vinylacetylene to phenyl radical, 51,56 (N3) Recombination of two cyclopentadienyl radicals and the reaction of cyclopentadienyl with cyclopentadiene, [57][58][59][60] (N4) Reactions of propargyl radical with benzyl radical, 61 (N5) Addition of 1,3-butadiene to phenyl radical, 62 (N6) Conversion of indene or indenyl radical to naphthalene via methylation. 63 Four pathways for indene include: (I1) Reactions of phenyl radical with allene and propyne, 63 (I2) Reactions of propargyl radical with benzene and phenyl radical, 63 (I3) A reaction of benzyl radical with acetylene, 64 (I4) Reactions of phenyl radical with propene and allyl radical.…”

An experimental study of indene pyrolysis with synchrotron vacuum ultraviolet photoionization mass spectrometry

“…Cavallotti and Polino studied the combination of two C 5 H 5 and its subsequent reactions; 57 and Long et al recently revisited this reaction by quantum chemical tools and reached similar conclusions. 58 Six different C 5 H 5 C 5 H 5 isomers are considered in their study, 57,58 including 1,1-, 2,2-, 3,3-, 1,2-, 2,3-, and 1,3-C 5 H 5 C 5 H 5 . Among all the C 5 H 5 C 5 H 5 isomers, the energies of 2,2-, 2,3-, and 3,3-C 5 H 5 C 5 H 5 are more than 6 kcal mol À1 lower than those of the other isomers.…”

“…Among all the C 5 H 5 C 5 H 5 isomers, the energies of 2,2-, 2,3-, and 3,3-C 5 H 5 C 5 H 5 are more than 6 kcal mol À1 lower than those of the other isomers. 58 The isomerization among these isomers is very easy, which only needs to overcome a small energy barrier of about 21.5 kcal mol À1 . 58 As suggested by Lu and Mulholland, a cyclopentadienyl-to-naphthalene scheme could be extended to the indenyl radical via a 9-step elementary reaction to C 18 H 12 .…”