An In(III)-MOF based on pore engineering for efficient capture SF6 from SF6/N2 mixture

•A new In(III)-MOF (HBU-21) was designed and synthesized according to pore engineering.•HBU-21 shows higher IAST selectivity of SF6/N2 (SF6/N2, v/v 10:90, 184.05).•DFT calculations reveal the importance of OMS for selective adsorption.•The cyclic adsorption experiments show its potential application value.