Strategy for the enhancement of H2 uptake in porous materials containing TiO2

• TiO2-coated SBA-15 of up to 802 m2/g was prepared.
• 4.5% TiO2 doubles the H2 uptake (1.4% @ 1 bar, 77 K) of SBA-15.
• TiO2 is finely dispersed on the mesopores of SBA-15.
• Excess TiO2 (7.3%) forms plugs in the mesopores.

The good affinity of TiO2 surface for hydrogen sorption has prompted in the past the synthesis of high specific surface area, Ti-doped mesoporous silicas. Since most TiO2 is buried in the pore walls of the silicas, such materials did not express their full potential H2 uptake. In order to overcome this limitation, different amounts of titania were deposited on the pore surface of a pre-formed SBA-15 of 704 m2/g, and the resulting oxides were calcined at 300 or 500 °C. The hydrogen sorption–desorption isotherms of the materials prepared in this study, at 77.4 K and up to 100 kPa, reveal that a small amount of titania doubles the hydrogen storage capacity of SBA-15, provided that the materials are calcined at least at 300 °C. Reproducible H2 uptakes up to 1.4 wt.% at 77.4 K and 100 kPa have been measured. The optimal amount of TiO2 is 4.5% in moles, leading to a uniform dispersion in the mesopores. A higher loading (7.3%) brings about the formation of large titania particles that tend to block the lumen of the mesopores, with no gain in the H2 sorption capacity.