Improving Jet A-1 Thermal-Oxidative Stability through Selective Removal of Unwanted Trace Species via 3.7 Å Chabazite Filtration

Abstract

The thermal stability of Jet A-1 fuel is strongly affected by trace heteroatomic species that promote thermal oxidative deposit formation, as well as antioxidant additives such as butylated hydroxytoluene, which preserve fuel stability. 3.7 Å chabazite is a tunable microporous adsorbent, but optimizing its composition requires balancing promoter removal against antioxidant loss. Here, we use density functional theory and \textit{ab initio} molecular dynamics (AIMD) to evaluate this trade-off using two compositional descriptors: framework acidity (Si/Al $= 35$--$8$) and bimetallic substitution (Co, Mg, Zn) at fixed Al content. Lowering Si/Al strengthens adsorption of all species, including BHT, confirming an intrinsic selectivity penalty for acidity-only tuning. In contrast, bimetallic substitution introduces chemically selective behavior, strengthening uptake of specific promoters while either suppressing or enhancing antioxidant adsorption depending on dopant identity. AIMD simulations at 400 K further show that adsorption energy alone is insufficient to describe calculated trends, because molecular mobility inside chabazite can influence residence time and effective capture during fuel treatment. Analysis of the density of states and the participating wavefunctions reveals signatures that are consistent with dopant-dependent adsorption shifts. These results establish a unified adsorption--transport--electronic screening framework for selecting chabazite compositions that remove deposit promoters while preserving antioxidant functionality in Jet A-1 treatment.