Synthesis of CuCl/Boehmite adsorbents that exhibit high CO selectivity in CO/CO2 separation

We developed nanoporous adsorbent exhibiting unprecedented performance in separation of toxic carbon monoxide (CO). The adsorbent was prepared by dispersing CuCl on mesoporous boehmite via thermal monolayer dispersion route. A key point of the present synthesis is dispersing optimized amount of CuCl on the boehmite at a moderate temperature to maintain the characteristics of the boehmite. We performed a systematic study to reveal that a CuCl/boehmite composite (30 wt% CuCl in total) thermally treated at 573 K was the best optimized sample for CO separation. The CuCl/boehmite had a high capacity of CO adsorption (1.56 mmol g−1) and an exceedingly low capacity of CO2 adsorption (0.13 mmol g−1) under 100 kPa of each gas at 293 K. The CO/CO2 separation factor was 12.4. To the best of our knowledge, this value is the best on record. The achievement of this work is attributed to finding a new type of suitable supporting material: boehmite. The boehmite has a high affinity to CuCl, exhibits excellent dispersion of the CuCl, and achieves a superior CO adsorption capacity. However, it has a weak interaction with CO2. The CuCl/boehmite composite is a promising adsorbent for selective separation of CO from combustion exhaust and industrial off-gas streams.