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

Safe production and widespread application of AlH 3 are limited by unstable hydrogen evolution and explosion risk. Alkali (earth) metal compounds, A(E)MCs, are promising materials for inhibiting AlH 3 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 AlH 3 explosions using thermal properties of A(E)MCs to select inhibitors, and EIE of different groups on AlH 3 is analyzed. Notably, KH 2 PO 4 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 Al 2 O 3 , and preventing the formation of particle Al 2 O 3 can be effective in improving EIE. Combining characterizations and simulation results reveals that A(E)MCs inhibit AlH 3 explosions in both chemical and physical ways. Further, the synthesized composite inhibitor KH 2 PO 4 /SiO 2 , 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.