Pinecone-Derived Activated Carbons as an Effective Medium for Hydrogen Storage

Abstract

Pinecones, a common biomass waste, has an interesting composition in terms of cellulose and lignine content that makes them excellent precursors in various activated carbon production processes. The synthesized, nanostructured, activated carbon materials show textural properties, a high specific surface area, and a large volume of micropores, which are all features that make them suitable for various applications ranging from the purification of water to energy storage. Amongst them, a very interesting application is hydrogen storage. For this purpose, activated carbon from pinecones were prepared using chemical activation with different KOH/precursor ratios, and their hydrogen adsorption capacity was evaluated at liquid nitrogen temperatures (77 K) at pressures of up to 80 bar using a Sievert’s type volumetric apparatus. Regarding the comprehensive characterization of the samples’ textural properties, the measurement of the surface area was carried out using the Brunauer–Emmett–Teller method, the chemical composition was investigated using wavelength-dispersive spectrometry, and the topography and long-range order was estimated using scanning electron microscopy and X-ray diffraction, respectively. The hydrogen adsorption properties of the activated carbon samples were measured and then fitted using the Langmuir/ Töth isotherm model to estimate the adsorption capacity at higher pressures. The results showed that chemical activation induced the formation of an optimal pore size distribution for hydrogen adsorption centered at about 0.5 nm and the proportion of micropore volume was higher than 50%, which resulted in an adsorption capacity of 5.5 wt% at 77 K and 80 bar; this was an increase of as much as 150% relative to the one predicted by the Chahine rule.

The Deltah Lab, a New Multidisciplinary European Facility to Support the H2 Distribution & Storage Economy

“…Storage of H 2 in LSMs and SSMs is considered as an alternative safest method [22,23]. Specifically, different solid materials have been proposed as new H 2 storage systems, including metalorganic frameworks (MOFs) [39], zeolites [40], metal hydrides [41], polymers [42], hollow glass microspheres [43], and carbon-based materials [44]. Depending on the type of H 2material interaction, the storage method is defined as physisorption, when the interaction depends on physical forces such as in the case of MOF or carbon-based materials, or chemisorption when there are chemical forces between H 2 and material such as in the case of metal hydrides [45].…”

Hydrogen storage characteristics of bio‐based porous carbons of different origin: A comparative review

“…Hydrogen could add its contribution as an energy carrier and energy storage medium, nonetheless, developing appropriate, safe, and cost‐effective storage ways and means is the basic impedimentation for adapting hydrogen as fuel 2,3 . The key technology of hydrogen vehicles, which has been an active research area is the storage of hydrogen 8,18 …”

“…This limited potential is as a result of the lower hydrogen volumetric density, which requires much bulkier and weigher storage tanks. Storage of hydrogen as cryogenic liquids allows higher energy densities, however it requires larger energy inputs and is not cost‐effective 8,21 . In addition, such kind of systems require extremely low temperature (20 K) and have the potential of evaporative hydrogen losses.…”

“…It is commonly found out that ACs should contain micropores with sizes in the range 0.6‐0.8 nm for effective storage of hydrogen at either moderate or higher process pressures. Consequently, pore structure tailoring of material surface is necessary 3,8 . Physisorption is attractive as it does not involve any chemical bonding between the carbon surface and hydrogen, being completely a reversible process with an adsorption energy ranging 4‐8 kJ/mol 7 .…”

“…Commonly, ACs are produced through a progressive pulverization treatment followed by the carbonization of the precursor under an inert gas at an optimum temperature, and then the employment of a physical or a chemical activation process 13 . Physical activation could be carried out using steam or carbon dioxide, whereas chemical activation could be accomplished mixing the precursor with an active chemical agent such as certain alkaline earth hydroxides, salts, or some acids 8,31 . Among the various chemical agents, potassium hydroxide (KOH) is one of the most extensively employed one for the activation of carbon yielding a very high SSA (≤3000 m 2 /g), with a well‐defined micropore size distribution, and giving rise to very good hydrogen storage results 8 …”