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Policicchio A.,University of Calabria | Policicchio A.,Cnism Consiglio Nazionale Interuniversitario Of Science Fisiche Della Materia | Vuono D.,University of Calabria | Rugiero T.,University of Calabria | And 2 more authors.
Journal of CO2 Utilization | Year: 2015

Carbon nanotubes are very interesting materials, with a wide range of applications. Their use as adsorbents represents a method of gas purification which can find various applications; an example is the industrial processes for the production of methane (CH4), where the purification of the same from the carbon dioxide (CO2) and/or nitrogen (N2) has always been one of the main objectives. In this work, carbon nanotubes (CNTs) produced through a process of catalytic chemical vapor deposition (CCVD) are analyzed in view of this application. For this reason, the initial physical-chemical properties of the as-made, purified and oxidized CNTs, together with CH4, N2 and CO2 adsorption/desorption tests at room temperature, have been considered to optimize the best material and the best operative condition for a potential application in adsorption and/or purification processes. © 2015 Elsevier Ltd.All rights reserved. Source

Minuto F.D.,University of Calabria | Policicchio A.,University of Calabria | Policicchio A.,Cnism Consiglio Nazionale Interuniversitario Of Science Fisiche Della Materia | Aloise A.,University of Calabria | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2015

The hydrogen adsorption properties of commercial activated carbon (aC) samples, in particular Nuchar SA-1500, Filtercarb GCC 8x30 and Filtercarb PHA, are evaluated at different temperatures (77K, 196K and ambient temperature) and pressure up to 80bar. A comprehensive characterization is carried out by means of a volumetric Sieverts-type apparatus for hydrogen adsorption measurements and helium picnometry for the skeletal density evaluation, by nitrogen adsorption measurement for the evaluation of the surface area (BET) and pore size distribution (NLDFT), by Scanning Electron Microscopy (SEM) for morphology. All the adsorption data are evaluated by Langmuir/Tóth isotherm model with a very high accuracy and the enthalpy of adsorption is calculated through the Clausius-Clapeyron equation. Comparison between the different samples is shown. The probed aC samples show interesting hydrogen storage capacity and reversible behavior up to many cycles with and without any thermal treatment in between. Our data point out the crucial role of the microporosity and ultra-microporosity in the adsorption process at low H2 pressures. The surfaces exhibit an average adsorption enthalpy around 6.5kJ/mol while for the ultra-microporous sites a 14kJ/mol value is found. The observed trapping behavior at 77K is attributed to the ultra-microporous morphology of the porous structure in GCC and PHA samples. A further result is the evaluation of the hydrogen molar density in the micropores with size below 10Å, which is 30mmol/cm3, a value very close to the liquid hydrogen one. These results could represent an interesting starting point for a real and efficient alternative method to the hydrogen storage using cheap and easy scalable materials. © 2015 Hydrogen Energy Publications, LLC. Source

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