Dual-ligand tuned ZIF-8-IM for cyclically stable, high-selectivity separation of C6 alkane isomers: Experiment-simulation convergence

DLA-ZIF-8-IM and SALE-ZIF-8-IM with identical imidazolate (IM) ratios were synthesized via dual-ligand confined regulation using delayed ligand exchange (DLA) and solvent-assisted ligand exchange (SALE), respectively. Their dynamic separation performance for C6 alkane isomers (n-hexane (nHEX), 3-methylpentane (3 ​MP), and 2,3-dimethylbutane (23DMB)) was evaluated at 303 ​K through experiments and Aspen Adsorption simulations, employing a Particle MB diffusion kinetic model and Extended Langmuir-Freundlich isotherm. Concentration-dependent selectivity was observed: DLA-ZIF-8-IM achieved a 3.39 separation factor for 3MP/23DMB at 21 ​% total C6 isomer concentration, while SALE-ZIF-8-IM showed 2.25 selectivity for nHEX/3 ​MP at 3 ​% concentration. Notably, DLA-ZIF-8-IM exhibited an exceptional 8.45 separation factor for 3MP/23DMB under an 8:1:1 ​M ratio (80 ​% 23DMB). Both materials maintained >99 ​% desorption rates for branched isomers and >98 ​% for nHEX over six cycles, demonstrating high stability. This study provides a novel approach for designing precise adsorbents for C6 alkane isomer separation, offering valuable insights for petrochemical refining. • A combination strategies of experimental and model simulation on the dynamic separation properties of C6 alkane isomers. • Simulation of dynamic adsorption/desorption cycling processes for equimolar nHEX, 3 ​MP and 23DMB mixture systems. • The adsorption separation factor of 3MP/23DMB on DLA-ZIF-8-IM was 8.45. • Desorption efficiencies of 23DMB and 3 ​MP on DLA-ZIF-8-IM exceeded 99 ​%.