Superior capture of CO2 achieved by introducing extra-framework cations into N-doped microporous carbon
KAUST DepartmentAdvanced Membranes and Porous Materials Research Center
Physical Sciences and Engineering (PSE) Division
KAUST Catalysis Center (KCC)
Water Desalination and Reuse Research Center (WDRC)
Biological and Environmental Sciences and Engineering (BESE) Division
Chemical Science Program
Imaging and Characterization Core Lab
Advanced Nanofabrication, Imaging and Characterization Core Lab
Nanostructured Functional Materials (NFM) laboratory
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AbstractWe designed and prepared a novel microporous carbon material (KNC-A-K) for selective CO2 capture. The combination of a high N-doping concentration (>10 wt %) and extra-framework cations, which were introduced into carbonaceous sorbents for the first time, endowed KNC-A-K with exceptional CO2 adsorption capabilities, especially at low pressures. Specifically, KNC-A-K exhibited CO2 uptake of 1.62 mmol g -1 at 25 C and 0.1 bar, far exceeding the CO2 adsorption capability of most reported carbon material to date. Single component adsorption isotherms indicated that its CO2/N2 selectivity was 48, which also significantly surpasses the selectivity of conventional carbon materials. Furthermore, breakthrough experiments were conducted to evaluate the CO2 separation capability of KNC-A-K on CO2/N2 (10:90 v/v) mixtures under kinetic flow conditions, and the obtained CO 2/N2 selectivity was as high as 44, comparable to that predicted from equilibrium adsorption data. Upon facile regeneration, KNC-A-K showed constant CO2 adsorption capacity and selectivity during multiple mixed-gas separation cycles. Its outstanding low-pressure CO 2 adsorption ability makes KNC-A-K a promising candidate for selective CO2 capture from flue gas. Theoretical calculations indicated that K+ ions play a key role in promoting CO2 adsorption via electrostatic interactions. In addition, we found that HCl molecules anchored in N-doped carbon have a similar promotion effect on CO 2 adsorption, which contradicts the conventional wisdom that the neutralization of basic sites by acids diminishes the adsorption of acidic CO2 gas. © 2012 American Chemical Society.
SponsorsThis research was supported by baseline funding and an AEA research grant from KAUST to Yu Han.
PublisherAmerican Chemical Society (ACS)
JournalChemistry of Materials