Hee Tae Beum

Micro- and mesoporous CuBTCs for CO2/CH4 separation

Micro- and mesoporous CuBTCs, referred to as micro- and meso-CuBTCs, were synthesized, and tested for their capacity to adsorptively remove CO2 from a binary mixture of CO2-CH4. Physicochemical analyses of the thermally treated Cu-BTCs were performed. The CO2 and CH4 adsorption isotherms for the Cu-BTCs at 25 °C in the pressure range 0-3MPa were experimentally measured and implemented for calculating the CO2/CH4 selectivity as a function of pressure and CO2 concentration using the ideal adsorbed solution theory (IAST). The CH4 adsorption capacity of meso-CuBTC at 3MPa was reduced to 43% of that of micro-CuBTC, whereas the CO2 adsorption capacity of meso-CuBTC at 3MPa was reduced to 27% of that of micro-CuBTCs. Consequently, meso-CuBTC shows a higher CO2/CH4 selectivity compared to micro-CuBTC. It was also found that the selectivity of the CuBTCs could be enhanced by lowering the partial pressure of CO2. This was ascribed to the larger abatement of the adsorption capacity for CH4 than for CO2, resulting from a reduction of the interaction of CH4 with the surface of pores of meso-CuBTC of which the pore size had been augmented.

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 (30wt% CuCl in total) thermally treated at 573K was the best optimized sample for CO separation. The CuCl/boehmite had a high capacity of CO adsorption (1.56mmolg-1) and an exceedingly low capacity of CO2 adsorption (0.13mmolg-1) under 100kPa of each gas at 293K. 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.