Facile Synthesis of Ultramicroporous Carbon Adsorbents with Ultra-high
CH4 Uptake by In Situ Ionic Activation
Abstract
We introduce a straightforward method for the preparation of novel
starch-based ultramicroporous carbons (SCs) that demonstrate high CH4
uptake and excellent CH4/N2 selectivity. These SCs are derived from a
combination of starch and 1-6 wt. % of acrylic acid, and the resulting
materials are amenable to surface cation exchangeability as demonstrated
by the formation of highly dispersed K+ in carbon precursors. Following
activation, these SCs contain ultramicropores with narrow pore-size
distributions of <0.7 nm, leading to porous carbon-rich
materials that exhibit CH4 uptake values as high as 1.86 mmol/g at 100
kPa and 298 K, the highest uptake value for CH4 to date, with the
IAST-predicted CH4/N2 selectivity up to 5.7. Both the potential
mechanism for the formation of narrow pores and the origin of the
favorable CH4 adsorption properties are discussed and examined. This
work may potentially guide future designs for carbon-rich materials with
excellent gas adsorption properties.