Optimization of activated carbons for hydrogen storage

Activated carbons (ACs) having hydrogen storage performances among the highest reported so far (i.e. 6.6 wt. % at 77 K and 4 MPa) are presented. These materials were prepared by chemical activation of anthracite with KOH. The effects of two experimental parameters: KOH/anthracite weight ratio (W) and activation temperature (T), on the hydrogen storage capacity were studied by application of central composite design and response surface methodology. A quadratic model was developed for correlating W and T to the hydrogen storage capacity. The analysis of variance showed that W the only significant parameter in the range of the experimental conditions tested. Our optimized AC showed higher hydrogen capacity in terms of absolute and excess storage properties than the well-known MAXSORB-3.

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► 6.6 wt. % H2 storage obtained onto ACs (4 MPa and 77 K) using experimental design and statistical tools.
► Only the KOH/anthracite weight ratio (W), from 2 to 4, was significant between 725 and 775 K.
► H2 storage was adequately fitted by H2 (wt. %) = −1.39 + 3.82 × W – 0.456 × W2.