Control of pore environment in nickel-based metal-organic frameworks for SF_(6)/N_(2) separation

In the semiconductor industry,recovering and capturing SF_(6)gas from the SF_(6)/N_(2)gas mixture has significant environmental and economic benefits.In this work,two Ni-based metal-organic frameworks(MOFs),Ni(i-na)(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 SF_(6)capture.Ni(ina)(bdc)_(0.5)and Ni(3-min)(bdc)_(0.5)are 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 SF_(6)/N_(2)separations.Ni(3-min)(bdc)0.s exhibits higher SF_(6)adsorption capacity(50.5 cm^(3)g^(-1))and IAST(ideal adsorbed solution theory)SF_(6)/N_(2)selectivity(91)owing to its smaller window diameter and suitable pore chemistry.Theoretical calculations indicate that the SF_(6)and N_(2)molecules interact with the framework at different cages,which reduces their competition for adsorption sites.The remarkable separation performance of Ni(ina)(bdc)_(0.5)and Ni(3-min)(bdc)_(0.5)is 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.