A novel Cu(I) loading method, which includes the reduction of CuCl2 to CuCl without an external reducing agent and high-temperature calcination, was developed using the redox properties of coordinatively unsaturated Fe(II) sites in MIL-100(Fe). The successful loading of Cu(I) ions and their redox-couple reactions are supported by various methods such as TEM/EDS, XPS, PXRD, and ICP-AES techniques, as well as N2 adsorption isotherms at 77 K. Compared to Cu loaded into isostructural MIL-100(Al) devoid of redox active sites, Cu(I)-loaded MIL-100(Fe) exhibits higher C3H6/C3H8 selectivity and superior air stability. This indicates that the Fe(II) sites in MIL-100(Fe) act as antioxidants that protect the resultant Cu(I) species, as well as reducing agents for CuCl2. Remarkably, in the typical pressure-swing adsorption (PSA) range (1–5 bar), the Cu(I)-loaded MIL-100(Fe) exhibits a large C3H6 working capacity as well as very high C3H6/C3H8 selectivities that are superior to those of the benchmark adsorbents, zeolite-13X and HKUST-1. Moreover, this material is easily regenerated under mild conditions and exhibits good separation performance under dynamic mixed-flow conditions. This facile method for loading Cu(I) can be applied to other adsorbents containing redox-active sites.
Bibliographical noteFunding Information:
We would like to acknowledge the National Research Council of Science & Technology (NST) grant by the Korea government (MSIP) (No. CRC-14-1-KRICT ). This work was also supported by In-house Research and Development Program of the Korea Institute of Energy Research (KIER) ( B7-2437-03 ).
© 2017 Elsevier B.V.
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering