Synergistic regulation of H2 + CH4 hydrate formation kinetics, phase equilibrium, and heating-induced dissociation stability by C8F18 and 1,3-DIOX

H 2  + CH 4 hydrate is a promising solid state gas-storage medium, but its slow formation and limited stability under heating conditions restrict its practical application. In this study, 1,3-dioxolane (1,3-DIOX) and perfluorooctane (C 8 F 18 ) were used as single and combined additives for H 2  + CH 4 hydrate formation with a 25 mol% H 2  + 75 mol% CH 4 gas mixture. Their effects on phase equilibrium, nucleation, gas uptake, and heating-induced dissociation behavior were investigated. 1,3-DIOX acted as the dominant thermodynamic and kinetic promoter, yielding equilibrium temperatures of 291.05–293.75 K at pressures of 4.90–7.02 MPa and producing the highest gas uptake of 0.09781 mol/mol. In contrast, C 8 F 18 had limited influence on phase equilibrium and formation kinetics but delayed gas release during heating-induced dissociation. The combined system showed functional complementarity between formation promotion and dissociation-response regulation for H 2  + CH 4 hydrate storage.