Role of Ultra-micropores in CO₂ Adsorption on Highly Durable Resin-Based Activated Carbon Beads by Potassium Hydroxide Activation

Abstract

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.

Rational Design of Carbon-Based Porous Aerogels with Nitrogen Defects and Dedicated Interfacial Structures toward Highly Efficient CO2 Greenhouse Gas Capture and Separation

“…It has been well recognized that human emissions of carbon dioxide and other greenhouse gases are a primary driver of climate change, which is one of the world’s most critical challenges. Hence, seeking a highly efficient fixing and capturing strategy of CO 2 using adsorption and conversions under mild conditions seems to be the most attractive option. − Generally, this requires the adsorbent to have marvelous adsorption kinetics, high adsorption capacity, good selectivity, and long-term stability under actual working conditions. − Currently, rationally designing carbon-based absorbents with interfacial structures, abundant activation sites, and specific adsorptions characteristics has attracted enormous scientific attention.…”