Silver and copper modified zeolite imidazole frameworks as sustainable methane storage systems

The effective sorption of methane with mesoporous adsorbents is one of the most sought-after methods of energy storage. The constant development of organometallic networks and the synthesis of new materials increases the efficiency of methane sorption, reaching new record amounts of gas adsorbed per gram of adsorbent. In this study, we present the optimised in-situ synthesis preparation method of Ag and Cu-modified zeolite imidazole frameworks by using ultrasonic irradiation. We proved that silver is present in ZIFs in the form of nanoparticles in the case of silver-modified materials. In contrast, in the case of copper-modified materials, the copper is present in ionic form. We also found that incorporating PVP as a stabilising agent and the modification with Ag and Cu changes the structural parameters of the prepared materials. The methane sorption results confirmed that the developed materials exhibit enhanced sorption capacity by over 100% (based on ZIF-8) and by 20% (based on ZIF-67). The highest methane adsorption at 1.6 MPa was achieved by Cu-PVP/ZIF-8 and Cu-PVP/ZIF-67, and Ag-PVP@ZIF-67 samples, and was equal to 112 cm3 CH4/g, 96 cm3 CH4/g and 97 cm3 CH4/g, respectively. The developed sonochemically assisted synthesis method allowed to obtain Ag and Cu modified zeolite imidazole frameworks which may be considered as efficient materials for sustainable methane storage systems.