High-pressure methane storage on metal-organic frameworks

Methane storage performance of a series of metal-organic frameworks (MOFs) has been thoroughly examined over a wide pressure range up to 750 bar. Based on volumetric adsorption measurements, crystal structure and porous texture characterization, excess, total and working adsorption capacities, and heat of adsorption as functions of pressure have been evaluated. It has been found that the use of MOFs demonstrates a significant advantage in methane storage capacity over compressed gas, and the Gain can reach 300% to 400% depending on the pressure-temperature operating conditions. However, the benefit of adsorption storage drops with increasing pressure. Even for the best MOF adsorbent, this methane storage method becomes technologically unreasonable above 280 bar. The data obtained allowed us to conclude that conventionally reported excess adsorption does not give a complete picture of the effectiveness of MOFs. Besides high specific surface area, optimal density of the skeleton and moderate heat of adsorption are required for the best storage performance. Based on experimental adsorption measurements for a series of MOFs, the efficiency of their use in high-pressure methane storage systems was assessed.image