Cost‐Effective Scalable Production of Ultra‐Stable Alkyl MOF Featuring Single‐Molecule C ₃ H ₆ Trap for Record Capture of Trace C ₃ H ₆ from C ₂ H ₄

Abstract Highly efficient capture of trace C 3 H 6 from C 2 H 4 by physisorbents remains an enormous challenge to combine top‐rank separation performance with excellent stability and economical scalability. We, herein, built a single‐molecule C 3 H 6 trap that bears an opposite series of oxygen and dense alkyl groups distributed in an ultramicroporous [Al(OH)(trans‐CDC)] (Al‐CDC, trans‐H 2 CDC = trans‐1,4‐cyclohexanedicarboxylic acid). The ultra‐stable trap with well‐matched pore size and pore chemistry enables a record uptake (40.8 cm 3 (STP) g −1 ) at ultralow concentration, Henry coefficient (12685.5 cm 3 (STP) g −1 bar −1 ), initial adsorption heat difference (27.2 kJ mol −1 ), adsorption kinetic (0.49 min −1 ) and kinetic selectivity (3.1) for C 3 H 6 with one of the highest initial C 3 H 6 adsorption heats (50.5 kJ mol −1 ) and selectivity (16.3), establishing a novel benchmark for capture of trace C 3 H 6 . The C 3 H 6 adsorption mechanism is deciphered to be thermodynamically driven owing to the synergism of multiple hydrogen‐bonding and van der Waals (vdW) forces. Breakthrough tests validate that Al‐CDC owns a record C 2 H 4 productivity (≥99.999%) of 410.5 cm 3 (STP) g −1 for trace C 3 H 6 capture with excellent reproducibility. The cost‐effective scalable production with the cheapest cost (508.9 $ kg −1 ) and highest space‐time yield (4564.8 kg m −3 day −1 ) and shaping of Al‐CDC is realized with unaffected structural property and capture performance.