Enhanced dehydrogenation of nanoscale MgH2 confined by ordered mesoporous silica

Nanoscale MgH2 was synthesized through loading di-n-butylmagnesium (MgBu2) solution into the pores of ordered mesoporous silicas (SBA-15) with a pore diameter in a range of 5–10 nm, followed by freeze drying and hydrogenation treatment. The MgBu2 inside the pore channels of SBA-15 decomposed into MgH2 upon hydrogenation at 493 K under 6 MPa hydrogen. The nanoconfined MgH2 exhibited greatly decreased desorption temperature of 540 K, a reduction of 146 K in comparison with that of commercial MgH2, or 65 K reduction relative to that of MgH2 obtained from MgBu2 without confinement. Moreover, lower desorption temperature for the MgH2 supported by SBA-15 with smaller pore diameter. The improvement on the dehydrogenation properties of MgH2 was attributed to the nanosizing effect induced by the nanoconfinement of mesoporous silica.