Superior Capture of CO2 Achieved by Introducing Extra-framework Cations into N-doped Microporous Carbon
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- 作者：Yunfeng Zhao ; Xin Liu ; Ke Xin Yao ; Lan Zhao ; Yu Han
- 刊名：Chemistry of Materials
- 出版年：2012
- 出版时间：December 21, 2012
- 年：2012
- 卷：24
- 期：24
- 页码：4725-4734
- 全文大小：589K
- 年卷期：v.24,no.24(December 21, 2012)
- ISSN：1520-5002
文摘
We 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鈥? at 25 掳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 CO2/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 CO2 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 CO2 adsorption, which contradicts the conventional wisdom that the neutralization of basic sites by acids diminishes the adsorption of acidic CO2 gas.