Equivalence-ratio effects on the persistence of aromatic suppression by n-butanol in a kerosene surrogate

The persistence of aromatic suppression by n-butanol was examined using a homogeneous isothermal kinetic model for an 80/20 wt% n-decane/1,2,4-trimethylbenzene surrogate at 1 atm, 1200–1800 K, equivalence ratios of 2.0–3.0, and 0–80 wt% n-butanol. Carbon-normalized yields were interpreted using composition controls, integrated carbon flows, and paired rate perturbations. At 1800 K, the predicted B80 reduction in tracked one- to three-ring aromatic yield increased from 61.24% to 73.00% between 20 and 100 ms at an equivalence ratio of 2.5, but decreased from 32.66% to 5.88% at 3.0. At the richer condition, the tracked polycyclic yield remained 16.54% lower at 100 ms. Composition controls showed that initial carbon loading alone did not explain the stronger suppression at 2.5. Integration refinement of six 1800 K anchors changed paired suppression by at most 6.03 × 10−7 percentage points. An n-butanol JSR comparison assessed component oxidation and identified larger discrepancies for oxygenated intermediates. The results connect suppression persistence to competing aromatic formation and consumption within the selected kinetic framework and concern gas-phase precursors rather than soot emissions.