Preparation of CuCl@AC with high CO adsorption capacity and selectivity from CO/N2 binary mixture

Abstract

The objective of this work is to develop CuCl@AC adsorbent with high CO capacity and selectivity from CO/N2 binary gas mixture. A series of CuCl@AC adsorbents were prepared by a solid-state auto dispersion method, and then characterized by N2 adsorption test, XRD and XPS. CO and N2 adsorption isotherms on the adsorbents were measured by a volumetric method. The adsorption isotherms and selectivities of CuCl@AC adsorbents for CO/N2 binary mixture were estimated on the basis of ideal adsorbed solution theory (IAST). Results showed that (a) CO uptakes of CuCl@AC increased with CuCl loading in the loading range of 0–1.2 g/g. The maximal CO adsorption capacity of the CuCl@AC with CuCl loading of 1.2 g/g reached 38 cc/g at the P/P0 of 0.40, around 8 times of that over the original AC; (b) calcination time for the preparation of Cu(I)@AC had significantly impact on CO adsorption of the adsorbents due to valence change of Cu species on carbon surfaces. XPS analysis indicated that when the calcination time was optimized to be 1 h at 350 °C under argon, the prepared Cu(I)@AC had the highest percentage of Cu+ species on its surfaces, and consequently it had the highest CO capacity among the adsorbents since adsorptive species responsible for CO adsorption is Cu+; (c) The IAST-predicted CO/N2 adsorption selectivities of 1.2CuCl/AC decreased with pressure. Its CO/N2 selectivity was up to 100–450 at low pressure range of 0–10 kPa, and it remained in the range of 50–100 at higher pressure range of 20–100 kPa. The high adsorption capacity and selectivity of Cu(I)@AC adsorbents made it a promising adsorbent for CO/N2 mixture separation.