H2 adsorption on Cu(I)-ZSM-5: Exploration of Cu(I)-exchange in solution

Abstract

A new Cu(I)-exchange method for zeolites in liquid media (acetonitrile) was developed with Cu/Al ratios surpassing 0.5 with ZSM-5 crystals containing pure Cu(I) cations without impurities such as Cl ions. The method resulted in a higher Cu/Al ratio (0.78) for mesoporous [B]-ZSM-5 when compared to microporous [Al]-ZSM-5 and [B]-ZSM-5 (0.55 and 0.66 respectively). H2 storage capacities of these Cu(I)-exchanged zeolites were investigated at 323 K along with their differential heat of H2 adsorption using adsorption calorimetry. H2 storage capacities as high as 0.03 wt. % at 323 K and 40 kPa were achieved on [Al] and [B]-ZSM-5 and mesoporous [B]-ZSM-5 showed an outstanding H2/Cu ratio of 1.03 at 323 K and below 100 kPa. Coverage-dependent differential adsorption heats were found to be ranging from 95 kJ/mol to 5 kJ/mol with observed values of 30–10 kJ/mol for H2/Cu ratios between 0.05 and 0.15.