Inhibition mechanism and effect assessment of alkali (Earth) metal compound-based inhibitors on aluminum hydride explosion

Abstract

Safe production and widespread application of AlH₃ are limited by unstable hydrogen evolution and explosion risk. Alkali (earth) metal compounds, A(E)MCs, are promising materials for inhibiting AlH₃ explosions due to abundant reserves, low toxicity, and environmentally friendly. Currently, systematic evaluation of explosion inhibition effect (EIE) and understanding of inhibition mechanism is lacking. This study examines the inhibition behavior of 16 A(E)MCs for AlH₃ explosions using thermal properties of A(E)MCs to select inhibitors, and EIE of different groups on AlH₃ is analyzed. Notably, KH₂PO₄ effectively reduces explosion intensity to 0.53 MPa·m/s, with the maximum pressure and maximum pressure rise rate of 0.68 MPa and 4.63 MPa/s. EIE can be quantitatively described by relative changes in particle Al₂O₃, and preventing the formation of particle Al₂O₃ can be effective in improving EIE. Combining characterizations and simulation results reveals that A(E)MCs inhibit AlH₃ explosions in both chemical and physical ways. Further, the synthesized composite inhibitor KH₂PO₄/SiO₂, which adsorbs flame radicals, reduces explosion intensity by 92.23 % and enhances EIE by 4.33 %. We hope our work can provide theoretical support for the safe application of hydrogen storage materials and the quantitative assessment of EIE.