High-pressure hydrogen storage on modified MIL-101 metal-organic framework.

Porous chromium(III) oxoterephthalate MIL-101 possesses an MTN zeolite-type framework with tetrahedral micropores (diameter ∼0.8 nm) and two types of mesopores (diameter ∼3.0 and 2.8 nm, respectively). The hybrid MIL-101/Pt/C composite materials were produced by a bridge building technique by grinding of ternary mixtures of MIL-101, glucose, and Pt-catalyst, followed by a bridge formation via a carbonization of glucose at 160 °C. The hydrogen adsorption properties of porous materials were investigated at pressures up to 1000 bar. Excess adsorption isotherms measured volumetrically at temperatures of 81 and 298 K evidence a remarkable effect of the catalyst on the material behaviors under high hydrogen pressure. There is no saturation at room temperature within the studied pressure range as the excess hydrogen sorption capacity increases gradually with pressure and reaches 1.5 wt.%instead of maximum 0.4 wt.% for the pristine MIL-101. The maximum total H₂ uptake at 298 K is estimated to be 6.1 wt.% that leads to a shift of the upper limit of the efficiency of the storage system from 25 to 250 bar as compared with the unmodified metal-organic framework. The results obtained demonstrate feasibility of advanced high-pressure hydrogen storage systems based on hybrid technology. [ABSTRACT FROM AUTHOR]