Spin crossover in metal–organic framework for improved separation of C2H2/CH4 at room temperature

Abstract

Abstract C2H2 is a very promising fuel substitute in the future, but it is often accompanied by the presence of CH4 in its production process, and high-purity C2H2 cannot be obtained. In this work, the mixed metal-organic framework (M’MOF), [Fe(pyz)Ni(CN)4] (FeNi-M’MOF, pyz\xa0\u200b=\xa0\u200bpyrazine), was used to induce changes in Fe–N bonds at room temperature using spin-crossover (SCO) properties, and highly selective adsorption of C2H2/CH4 was carried out. The MOFs has a high C2H2 adsorption capacity (96.5\xa0\u200bcm3\xa0\u200bg−1 for HS state; 96.1\xa0\u200bcm3\xa0\u200bg−1 for LS state), and has a remarkable selectivity for C2H2/CH4 (198.9 for HS state; 273.5 for LS state) at room temperature and standard atmospheric pressure. Under the condition that the C2H2 adsorption capacity is less affected, the selectivity of the polymer to C2H2/CH4 in the LS state is much higher than that in the HS state. Moreover, the preparation method of this material is simple and the performance after synthesis is stable, which indicates that FeNi-M’MOF is a promising C2H2/CH4 separation material.