Hydrogen Storage Properties of Ball Milled MgH 2 with Additives- Ni, V and Activated Carbons Obtained from Different By-Products.

The hydrogen sorption of materials based on 80 wt.% MgH 2 with the addition of 15 wt.% Ni or V and 5 wt.% activated carbons synthesized from polyolefin wax, a waste product from polyethylene production (POW), walnut shells (CAN), and peach stones (CPS) prepared by milling under an inert Ar atmosphere for a period of 1 h, is investigated. All precursors are submitted to pyrolysis followed by steam activation in order to obtain the activated carbons. The hydrogen sorption evaluations are carried out for absorption at 473 and 573 K with pressure of 1 MPa and for desorption at 623 and 573 K with pressure of 0.15 MPa. The composition of the samples after milling and hydrogenation is monitored by X-ray diffraction analyses. The 80 wt.% MgH 2 -15 wt. %Ni-5 wt.% POW or CAN after absorption-desorption cycling and in a hydrogenated state at 573 K and 1 MPa are analyzed by TEM.