Metal-organic framework-based composites for biogas and natural gas uptake: An overview of adsorption and storage mechanisms of gaseous fuels

Biogas and natural gas are potential renewable energy sources. They primarily contain CH4, H2, CO2, CO, C2H6, C3H8, H2S, N2, and moisture. To be used as fuel, raw biogas and natural gas require upgrading to enrich the CH4 content (≥97 %). The development of a practical technique to effectively trap gas molecules in a limited space for a variety of uses has been acknowledged as a major technical difficulty. Among the various practical enrichment processes, the adsorption-based method is particularly attractive for upgrading because of its ease of use and economy. A new family of versatile porous solid-state materials, metal–organic frameworks (MOFs), possess controllable structures, tunable thickness and pore size, chemically adjustable architectures, vast surface areas, and favorable mechanical flexibility. Therefore, MOF-based adsorbents can play an exceptional role in the adsorption of gas molecules like CO2, CH4, H2, and C2H2 for gaseous fuel uptake and eliminating greenhouse gases from the atmosphere. The mechanism of gaseous molecule adsorption/separation using MOF materials was critically evaluated. Fluorinated MOFs, such as ZIF-8, ZIF-67, UiO-66, and nanosheets (2D MOFs), are considered potential adsorbents for moisture-stable, cost-effective, and efficient biogas and natural gas adsorption. Moreover, the prospects and further research ought to concentrate on comprehending the dynamics of gas adsorption and desorption in massive columns loaded with MOFs, effectively packing MOF particles, cost-effective manufacturing, and enhancing the reusable nature of MOFs. The comprehensive review provides an in-depth understanding of MOFs by focusing on the most recent advancements in gas storage and adsorption.