Cellulose-type binder enabling CuCl2 supported on nanoporous bayerite to have high CO adsorption ability via reduction of Cu²⁺ to Cu⁺

초록

Previously, we developed a powder-form nanoporous CO-selective adsorbent synthesized via thermal monolayer dispersion of CuCl on bayerite, showing high CO adsorption capacity (48.5 cm(3) g(-1)) and a high CO/CO2 selectivity (12.4). For its industrial applications, it is necessary to pelletize it, avoiding pressure-drop problems. Here, we demonstrate a facile three-step method of pelletizing a CuCl/bayerite: 1) physical mixing of CuCl, methyl-cellulose, inorganic-binder, and bayerite, 2) pelletizing, and 3) thermal treatment at 573 K under vacuum. The pelletized adsorbent shows high CO adsorption capacity (42 cm(3) g(-1)), CO/CO2 selectivity (12), and commercial-level mechanical strength (1.3 kg(f)). Notably, the added methyl-cellulose binder has reducing role that maintains the initial CO adsorption capacity for 100 days' exposure to humid air-condition, although CuCl-based adsorbent easily lost CO adsorption ability owing to oxidation of Cu+ to Cu2+. CuCl2, showing no specific interaction with CO, was converted to Cu+ by the methyl-cellulose. Thus, adsorbent prepared using CuCl2 instead of CuCl with the methyl-cellulose also showed high CO adsorption capacity (31.6 cm(3) g(-1)) and maintained the initial capacity after seven days' exposure. The reducing role of the methyl-cellulose binder allows inexpensive and feasible synthesis of the CO-adsorbent using CuCl2 that can be easily dispersed on bayerite, without additional reduction treatment.

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