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. (C) 2012 Elsevier B.V. All rights reserved.