A Kinetic Study of the Inhibition Mechanism of 2,3,3,3-Tetrafluoropropene on Hydrogen Combustion

2,3,3,3-Tetrafluoropropylene (HFO-1234yf) has attracted considerable attention as an environmentally friendly fire suppressant because of its low global warming potential and excellent flame inhibition potential. In this study, the gas-phase inhibition mechanism of HFO-1234yf was systematically investigated by combining high-level quantum chemical calculations with RRKM/master equation analysis. The unimolecular decomposition of HFO-1234yf and its reactions with H atoms and OH radicals, including hydrogen abstraction, substitution, and addition pathways, were characterized over wide temperature and pressure ranges. The kinetic results indicate that the R5 channel dominates the unimolecular decomposition of HFO-1234yf over the investigated temperature and pressure ranges, with the R1 and R2 channels serving as secondary pathways. However, the rates of all unimolecular decomposition reactions are negligibly small below 800 K, indicating that unimolecular decomposition is unlikely to play a significant role in combustion inhibition under these conditions. As the temperature increases, the decomposition rates increase markedly, highlighting the critical role of high-temperature conditions in promoting the thermal decomposition of HFO-1234yf. Among the bimolecular reactions, OH-abstraction reactions, particularly the R8 pathway, represent the primary OH-radical consumption route, while substitution reactions contribute negligibly because of their substantially lower reaction rates. Furthermore, the presence of the CC double bond enables rapid radical addition reactions, which become the dominant inhibition pathway. OH addition predominates under low-temperature conditions, whereas H addition becomes increasingly important at elevated temperatures, together forming a synergistic radical-scavenging mechanism over a broad temperature range. Elevated pressures significantly promote radical addition by enhancing collision stabilization of the reaction intermediates, thereby further improving the radical-scavenging efficiency of HFO-1234yf. The present work provides reliable kinetic parameters and mechanistic insights for the development of detailed combustion inhibition mechanisms involving HFO-1234yf and facilitates the rational design of environmentally benign flame suppressants.