Pore Engineering of IL@MOF-Derived Carbons via IL-Assisted Double Templating for CO2 Separation

Abstract

The mitigation of carbon dioxide (CO2) emissions requires adsorbent materials with tunable pore structures capable of balancing adsorption capacity and selectivity under postcombustion conditions. In this work, a proof-of-concept IL-assisted double-templating strategy is presented to engineer porosity in IL@MOF-derived carbons. The metal–organic framework (MOF) Cu-BTC was used as both carbon precursor and primary template, while the ionic liquid (IL) [C6MIM][B(CN)4] was used as a secondary sacrificial template at low loadings (1–10 wt %). IL@MOF composites with varying IL contents were prepared, carbonized, and subsequently acid-washed to remove residual copper-containing phases formed during carbonization. This enabled the evaluation of how IL loading influences the resulting carbon pore structure and adsorption behavior. Porosimetric characterization shows that IL incorporation promoted the development of additional (ultra)microporosity while simultaneously reducing total accessible pore volume at higher loadings, strongly influencing gas adsorption behavior. CO2 and N2 adsorption–desorption measurements at 303 K revealed a nonmonotonic dependence of CO2 adsorption capacity on IL loading, with a maximum at 2 wt % IL. At higher IL contents, the reduction in accessible pore volume limited adsorption capacity. In contrast, ideal CO2/N2 selectivity at 1 bar increased progressively with IL loading. These results show that even small amounts of IL can systematically tune pore architecture and adsorption performance in IL@MOF-derived carbons. Overall, IL-assisted double templating was validated as a versatile approach for pore engineering in carbon adsorbents, providing a framework for the rational design of materials for CO2 separation applications.