Tailored ETS-4 Molecular Gate Thermal Contractibility via Crystallization Time for N2/CH4 Separation

The separation of methane and nitrogen is critical for upgrading low-grade natural gas. However, their similar physicochemical properties render efficient separation extremely challenging. This study explores the application of Engelhard titanosilicate-4 for N 2 /CH 4 separation. Framework thermal contractibility is tailored by regulating crystallization time. Thermal activation enables precise pore-size modulation, affording a superior separation selectivity of 15.1. Furthermore, the material properties are evaluated through structural characterization, adsorption isotherm measurements, and kinetic tests. Finally, in the simulation of a two-bed six-step vacuum pressure swing adsorption (VPSA) process, the obtained methane product has a purity exceeding 95%, validating the promising practical application potential of this adsorbent.