Impact of synthesis conditions of KOH activated carbons on their hydrogen storage capacities

39 activated carbons (ACs) were prepared by KOH activation of anthracite, using weight ratios KOH/anthracite (W) ranging from 1.5 to 7, activation temperatures (T) from 973 to 1073 K, and heating rates (Hr) from 1 to 5 K min−1. ACs with high apparent surface areas (>3400 m2 g−1), high micropore volumes (>1 cm3 g−1) and high hydrogen storage capacities (up to 6.6 wt. %) were obtained. A statistical study was carried out to clarify the impact of synthesis conditions on hydrogen storage capacities of the resultant ACs. Analysis of variance (ANOVA) showed that both W and T have a significant impact on hydrogen storage capacity, whereas Hr has not. A quadratic model was used to correlate W2, W, T2 and T to hydrogen storage capacities. The model adequately evaluated the impact of synthesis conditions on hydrogen storage capacities of the resultant ACs.

Hydrogen uptakes as a function of W and T, fitted by a 3D surface. Results corresponding to the 39 lab-made ACs are plotted as black points. Figure optionsDownload as PowerPoint slideHighlights
► Hydrogen storage on 39 activated carbons and impact of KOH synthesis conditions are reported.
► Heating rate has no impact on H2 uptake.
► Weight ratio KOH/anthracite (W) has a stronger impact than activation temperature (T) on H2 uptake.
► No interaction exists between W and T.
► A quadratic model correlated well W2, W, T2 and T to H2 storage capacities.