Pore engineering of ultramicroporous carbon from an N-doped polymer for CO2 adsorption and conversion

•N-doped porous carbon with an ultramicroporous structure was fabricated.•CO2 uptake of up to 6.95 mmol·g−1 was acquired at 1 bar and 0 °C.•NPC-700 combined with TBAB to fix CO2 into various cyclic carbonates.•Cyclic carbonates achieves the yield of up to 99% under solvent-free conditions.•Excellent stability and recyclability of NPC-700 for both CO2 adsorption and conversion. Microporous carbon materials are widely used in CO2 adsorption because of their unique structure and excellent stability. In this work, N-doped porous carbon (NPC) with an ultramicroporous structure was prepared through the carbonization of an N-doped polymer and KOH at 600 °C, 700 °C, and 800 °C, respectively. The prepared NPC exhibited excellent CO2 adsorption properties of up to 6.95 mmol·g−1 at 1 bar and 0 °C, and this value is considerably higher than that of the parent N-doped polymer. The excellent CO2 adsorption performance is due to the well-defined ultramicroporous structure and high specific surface area of NPC. Moreover, these porous carbons can be combined with tetrabutylammonium bromide (TBAB) to fix CO2 into various cyclic carbonates, with a yield of up to 99% without any solvent. Whether the cause is the adsorption or catalytic conversion of CO2, NPC-700 exhibits excellent stability and can be cycled multiple times without significant reduction in its performance. [Display omitted]