Carbon monoxide (CO) is a key material in C1 chemistry for chemical production and CO2 reduction, whereas in applications, such as H2 for fuel cells, its concentration must be kept below 0.2 ppm. Adsorption technology is useful for both CO removal and production to provide environmental sustainability for the energy and chemical industries. In this review, the CO adsorption performances of various adsorbents, such as activated carbons, zeolites, metal–organic frameworks, activated alumina, mesoporous silicas, and their modified adsorbents, are collected, and their physical and chemical properties and CO selectivities are summarized. Cu+ impregnation is a powerful and widely used modification method to enhance the CO adsorption of adsorbents. Therefore, the preparation methods and their effects on CO adsorption are also compared and reviewed. The data and analysis in this review can provide insights for the development of novel adsorbents and processes for CO removal and production.

Resin-based activated carbon beads through KOH activation (KRACs; 400−450 μm) were studied to elucidate the role of ultra-micropores in CO 2 adsorption and separation. The improved textural properties resulted in an enhancing CO 2 adsorption of 55.4% (10.0 wt % at 303 K and 101.3 kPa), showing excellent cyclic stability. The change in CO 2 adsorption capacity correlated well with ultra-micropore properties. However, it was noteworthy that excessive developed ultra-micropores reduced the CO 2 adsorption rate. In the breakthrough experiments using CO 2 /N 2 and CO 2 /CH 4 mixtures, KRAC with the most developed ultra-micropores showed the highest CO 2 adsorption capacity, but the tailing was higher. As CO 2 concentration increased in the CO 2 /N 2 mixture, the difference in adsorption capacity from other KRACs was highly reduced. Furthermore, the breakthrough time of the KRAC in the CO 2 /CH 4 mixture was even shorter than other KRACs due to the preoccupied CH 4 despite the highest adsorption capacity of CO 2 . The ultra-micropores should be carefully controlled for separation efficiency, considering adsorbates in mixtures.