Reversible hydrogen storage using a SAPO-34 layer

A SAPO-34 zeolite membrane was made essentially impermeable to high-pressure hydrogen at room temperature by adsorbing methanol in the SAPO-34 layer. Hydrogen permeance decreased 3 orders of magnitude when the methanol feed activity was ∼0.1, and it decreased more than 6 orders of magnitude when the methanol feed activity was higher than 0.85 at 293 K. The hydrogen permeance at 293 K was below ∼10-14 mol/m2·s·Pa for at least 5 days for a H2 feed pressure of 6.6 MPa. At higher temperatures, methanol desorbed and the H2 flux increased. The hydrogen permeance could be controlled by the activity of the methanol on the feed side. These results suggest that hydrogen could be stored at 7 MPa pressure or higher and ambient temperature in hydrogen-storage materials that are in the form of small spheres coated with a thin SAPO-34 layer. Hydrogen would be adsorbed at high pressure and then the spheres could be sealed by methanol adsorption. The high-pressure hydrogen would remain in the spheres after the external hydrogen pressure was reduced, and heating the spheres would release the hydrogen.