Keywords: Hydrogen storage, Carbon nanotubes, …show more content…
In case of single walled carbon nanotubes (SWCNT), hydrogen can be stored in the inside area of the cylindrical layer, or amid the nanotubes in case of multi walled CNTs. There are three different places for hydrogen bonding. One being on top of the carbon atom, the others being in the middle of C – C bridge and in the center of hexagonal carbons. SWCNTs have hydrogen storage capacity in the range of 2 and 4 wt% at room temperature and a pressure of 12 MPa, where these SWCNTs are produced by hydrogen arc discharge method and are post treated with HCl. In case of MWCNTs that are produced by catalytic decomposition of 〖 C〗_2 H_2 and hydrogen mixture at〖 900〗^o C, hydrogen storage is found to be up to 5 wt% at room temperature and a pressure of 100atm.
The inconsistency regarding the hydrogen storage capacity of CNTs is associated with the models used to describe the gas – solid interaction, various experimental conditions, and different methods of production of CNTs, for instance carbon nanotubes produced by chemical vapour deposition is having a carbon content of 83 wt.% (95 vol.%) and a specific surface area equal to 790 m2/g[3]. Pre-treatment of obtained CNTs, different tube diameters and tube lengths, inner spacing, different process of purification of CNTs. This article studies the parameters …show more content…
This process is followed by desorption while linearly increasing temperature at a specific rate. Quantity of hydrogen adsorbed at various flow conditions and flow times is measured and are plotted in fig.4[1]. From the results, it is evident that a minimum adsorption time of 60 minutes is required to achieve equilibrium adsorption. Upon further investigation, it is observed that desorption temperature is inversely proportional to the hydrogen adsorption capacity. The peak values of desorption temperatures can be used to estimate the activation energy of desorption from the following