Ultramicroporous Carbon Synthesis Using Lithium-Ion Effect in ZSM‑5 Zeolite Template

Zeolite templating is a versatile synthesis route to produce various types of ordered microporous carbon. However, the synthesis thus so far has been limited to the use of wide-pore zeolites with 12-membered ring (12MR) pore mouths or more because of the diffusion limitation of organic carbon precursors. Here, we report an extension of the carbon synthesis to a 10MR zeolite, through acetylene carbonization in Li+-ion-exchanged ZSM-5 zeolite. The promoting effect of the Li+ ions on the carbon synthesis could be relevant to the carbide-forming property of the element, similar to the recently reported cases of La3+, Y3+, and Ca2+ cations in 12MR zeolites. The resultant carbon exhibited an ordered array of ultramicropores of 0.5 nm diameter, which corresponded to the thickness of the zeolite framework. Because of the ultramicroporosity, the ZSM-5-templated carbon exhibited an anomalously high value of surface-area-normalized electrical double-layer capacitance.