Highly CO selective Cu(I)-doped MIL-100(Fe) adsorbent with high CO/CO2 selectivity due to Π complexation: Effects of Cu(I) loading and activation temperature

Abstract

Abstract Cu(I) doping of octahedral MIL-100(Fe) was successfully performed by means of impregnation and consequent reduction under vacuum conditions. Although MIL-100(Fe) adsorbed CO2 better than CO, Cu(I)@MIL-100(Fe) showed selective CO adsorption compared to CO2 owing to π complexation between CO and Cu(I). Effects of Cu(I) loading concentration, activation temperature, and adsorption temperature upon CO/CO2 adsorption properties were systematically investigated. The adsorption behaviors of CO and CO2 on MIL-100(Fe) and Cu(I)@MIL-100(Fe) were well described by the dual-site Langmuir–Freundlich (DSLF) model. Ideal adsorbed solution theory (IAST) was used to predict adsorption isotherms of equimolar CO and CO2 mixtures and to predict CO/CO2 selectivities as a function of bulk pressure. The obtained results showed that 45\u202fwt% Cu(I)-doped MIL-100(Fe) had CO adsorption capacity of 3.10\u202fmmol\u202fg−1 and CO/CO2 selectivity of 420\u202fat 298\u202fK and 1\u202fbar. In addition, a large CO working capacity of 1.39\u202fmmol\u202fg−1 was observed for 45\u202fwt% Cu(I)-doped MIL-100(Fe) in the pressure range of 10–100\u202fkPa. Cu(I)-doped MIL-100(Fe) thus appears promising as an adsorbent material for effective CO/CO2 separation.