Hydrogen sorption in transition metal modified NaETS-4

Transition metals nickel (Ni), rhodium (Rh) and palladium (Pd) both exchanged and in situ loaded in NaETS-4 samples were synthesized and characterized. Hydrogen adsorption studies in the synthesized NaETS-4 samples were performed at 77.4 K up to 1 bar and at 303 K up to 40 bar pressure. The reversible adsorption isotherms at 77.4 K showed physisorption of hydrogen but at 303 K chemisorption was the major mechanism for hydrogen uptake, which is clear from the irreversible nature of adsorption isotherms at 303 K. Rhodium loaded NaETS-4 showed the highest hydrogen adsorption capacity of 66 cc/g at 77.4 K and 35 cc/g at 303 K. The hydrogen adsorption in transition metal modified NaETS-4 at 303 K is driven by the chemical interactions leading to the formation of transition metal hydrides inside the micropores of NaETS-4. The absorbed hydrogen at 303 K can be desorbed by heating the modified titanosilicates up to 423 K.