In the semiconductor industry, recovering and capturing SF6gas from the SF6/N2gas mixture has significant environmental and economic benefits. In this work, two Ni-based metal-organic frameworks (MOFs), Ni(ina)(bdc)0.5(ina = isonicotinic acid, bdc = terephthalic acid) and methyl-functionalized Ni(3-min)(bdc)0.5(3-min = 3-methylisonicotinic acid), are constructed for SF6capture. Ni(ina)(bdc)0.5and Ni(3-min)(bdc)0.5are both highly stable nine-connected porous materials. The pore sizes of these two materials are similar, but the pore environments are different, which has a bearing on the performance of SF6/N2separations. Ni(3-min)(bdc)0.5exhibits higher SF6adsorption capacity (50.5 cm−3g−1) and IAST (ideal adsorbed solution theory) SF6/N2selectivity (91) owing to its smaller window diameter and suitable pore chemistry. Theoretical calculations indicate that the SF6and N2molecules interact with the framework at different cages, which reduces their competition for adsorption sites. The remarkable separation performance of Ni(ina)(bdc)0.5and Ni(3-min)(bdc)0.5is further verified by dynamic breakthrough experiments. Thus, these two adsorbents have the potential to be utilized in industrial applications due to their excellent structural stability and recyclability.