Metal–Organic Framework Membranes and Adsorbents for Biogas Upgrading: A Critical Narrative Review of Process Readiness

Metal–organic frameworks (MOFs) have tunable adsorption and transport properties, but the fact that a material performs well does not mean that the process is ready for implementation. This critical narrative review examines membrane and adsorbent results regarding CO₂/CH₄ separation and methane delivery. Literature up to 21 August 2026 has been selected and analysed according to measurement, device architectures, operating conditions and process boundaries. Membrane benefits are dependent on formulation, fabrication, pressure, humidity and contaminants. The practical value of equilibrium uptake and selectivity can be altered by the way the adsorbent is shaped, the feed and regeneration. Laboratory cycling and process modelling relate material properties to purity, recovery and energy requirements; industrial-scale and multibed scenarios remain modelled outcomes. Material composites, sequential adsorbers and membrane–adsorption trains need to be interpreted separately. Among the studies reviewed, there is no evidence of continuous household operation of an integrated MOF membrane–adsorption system. A qualitative framework links process readiness to matched controls, realistic feed conditions, complete-cycle balances and service requirements. Generalisation is limited by selection bias, shared data, incomplete reporting and unresolved source conflicts. Development should prioritise testing the intended device, durability under relevant regeneration conditions, and transparent assessment of net methane delivery, utilities and replacement.