Molecular sieving of di‐branched hexane isomers in a self‐adaptive adsorbent for benchmark research octane number gasoline production

Effective separation of isomers is critical in various industrial applications, particularly in the production of high research octane number (RON) gasoline. This study introduces a novel flexible adsorbent, NCU‐542 ([Zn‐BTEC‐TEIB] [H4BTEC = pyromellitic acid, TEIB = 1,2,4,5‐tetra(1H‐imidazol‐1‐yl)benzene]), featuring self‐adaptive pore systems for the molecular sieving of di‐branched 2,3‐dimethylbutane (23DMB) and 2,2‐dimethylbutane (22DMB) isomers. The unique self‐adaptive framework of NCU‐542 selectively adsorbs 23DMB (RON = 101.7) while excluding 22DMB (RON = 91.8). Consequently, a record‐high adsorption capacity difference of 235.2 mg g−1 and an uptake ratio of 73.3 are achieved between 23DMB/22DMB. The diffusional time constant (D′, D/r2) for 23DMB (1.03 × 10−3 s−1) is 130‐fold higher than that of 22DMB (7.76 × 10−6 s−1) and benchmark rigid JNU‐2 (6.5 × 10−6 s−1). Furthermore, breakthrough experiments demonstrate the production of premium gasoline with a benchmark RON value of 99.2 from the equimolar mixture of n‐hexane/2‐methylpentane/3‐methylpentane/23DMB/22DMB. Within the liquid system, 23DMB can be completely removed from 23DMB/22DMB solutions for five consecutive cycles under ambient conditions.