We report a molecular simulation study to screen 4764 computation-ready, experimental metal–organic frameworks (CoRE-MOFs) for CO₂ separation from flue gas (CO₂/N₂) and natural gas (CO₂/CH₄). Quantitative relationships are established, for the first time, between the metal type and adsorbent evaluation criteria (adsorption selectivity and capacity, working capacity and regenerability). It is found that alkalis exist in 75% of alkali-MOFs as nonframework ions or open metal sites, and 75% of alkaline-MOFs contain alkalines as open metal sites; thus alkali- and alkaline-MOFs exhibit high adsorption selectivity and large capacity. Combining selectivity, working capacity and regenerability, however, alkali- and alkaline-MOFs possess the lowest performance for CO₂ separation. Among ∼1000 lanthanide-based CoRE-MOFs, 50% contain lanthanides as open metal sites and have the highest performance. The best 30 CoRE-MOFs are identified for CO₂/N₂ and CO₂/CH₄ separation, and they mostly contain lanthanides. Furthermore, we predict the breakthrough curves in two identified CoRE-MOFs and demonstrate their superior separation performance. This modeling study highlights the central importance of adsorbent evaluation by holistic criteria, and suggests that lanthanides could be interesting metals in the design of new MOFs for CO₂ separation.