Systematic evaluation of the adsorption of organic vapors onto a miniaturized cartridge device using breakthrough tests in parallel experiment with a full size respirator cartridge

Breakthrough experiments are essential for the characterization of the adsorption capacity and micropore volume of activated carbon respiratory cartridges and for the validation and determination of cartridge service life models. In an effort to gain better control over environmental conditions in breakthrough tests and to obtain reliable data, a novel experimental approach using a miniaturized (Mini) cartridge was designed to replicate a small section of a respiratory cartridge. The Mini device and the organic vapor respiratory cartridge were tested in single and parallel experiments where in the former, one filter was tested one at a time and in the latter both devices were exposed simultaneously to the same conditions. The Mini device gave comparable results to the 10% breakthrough times and adsorption capacities of the organic vapor cartridges. The reproducibility of the packed carbon bed of the Mini provided strong support for using the Mini in breakthrough experiments for the characterization of the activated carbon adsorption capacity and estimation of cartridge service life

How the activation process modifies the hydrogen storage behavior of biomass-derived activated carbons

Microporous activated carbons (ACs) derived from biomass residues, by virtue of their low-cost, good thermo-mechanical stability and easy adsorbent regeneration, are widely considered as hydrogen storage materials for near-term applications. The hydrogen uptake performance of activated carbons is known to depend on the pore-textural and surface characteristics, such as size and distribution of micropores and specific surface area. Here, we present a detailed investigation on how the activation processes using KOH, CO2, K2CO3, and H3PO4 modify the microstructure of olive stones-derived ACs and how they affect the ACs’ hydrogen storage behavior. The KOH-activation results in the formation of exfoliated graphene sheets, which are not common in lignocellulose-derived ACs. In addition, the KOH-activation forms supermicropores (1–2 nm) that enhance the hydrogen uptake capacity at high pressures (200 bar). The absolute hydrogen adsorption of KOH-activated sample at 200 bar and 77 K is 6.11 wt%, which is among the highest reported for activated carbon samples. The best hydrogen uptake density per surface area of the carbon we obtained is 2.1 × 10−3 wt% m−2 g which is very close to the theoretical maximum hydrogen uptake density on a single graphene sheet. CO2 and H3PO4 activations are more effective on the creation of ultramicropores (d ≤ 0.7 nm) in the carbon matrix. This order of pore size is useful when hydrogen adsorption is performed at sub-atmospheric pressures. Our study suggests that activated carbons with a homogenous pore size distribution centered at narrow range are not as efficient H2 adsorbents as the ACs with a bimodal PSD

Influence of Nanoconfinement on Reaction Pathways of Complex Metal Hydrides

AbstractNanoconfinement is receiving increasing interest in the field of energy storage and has been applied to different metal hydride systems in order to improve their properties for hydrogen storage. Modified hydrogen sorption kinetics and thermodynamics of metal hydrides have been achieved by nano size effects. In case of metal complex hydrides, in addition to kinetic limitations, competing side reactions and stable intermediates during de/rehydrogenation processes are obstacles for a practical utilization. The impacts of nanoconfinement on dehydrogenation reaction pathways of the eutectic borohydrides LiBH4–Mg(BH4)2 have been studied in the presented work