Low-Temperature and Single-Step Synthesis of N-Doped Porous

Sep 21, 2018 - Moreover, these lotus stalk-derived adsorbents exhibit a rapid CO2 adsorption rate, high CO2/N2 selectivity, moderate CO2 isosteric hea...
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Environmental and Carbon Dioxide Issues

Low-temperature and single-step synthesis of N-doped porous carbons with a high CO2 adsorption performance by sodium amide activation Linli Rao, Limin Yue, Linlin Wang, Zhenzhen Wu, Changdan Ma, Liying An, and Xin Hu Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.8b02659 • Publication Date (Web): 21 Sep 2018 Downloaded from http://pubs.acs.org on September 23, 2018

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Energy & Fuels

Low-temperature and single-step synthesis of N-doped porous carbons with a high CO2 adsorption performance by sodium amide activation Linli Raoa, Limin Yuea, Linlin Wangb, Zhenzhen Wua, Changdan Maa, Liying Ana, Xin Hu*,a, a

Key Laboratory of the Ministry of Education for Advanced Catalysis Materials,

Zhejiang Normal University, Jinhua 321004, China b

College of Engineering, Zhejiang Normal University, 688 Yingbin Ave. Jinhua

321004, PR China *

Corresponding author’s e-mail: huxin@zjnu.cn; phone: 86-151-0579-0257; fax:

86-579-8228-8269

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Abstract In this study, N-enriched porous carbons were prepared by a facile synthesis method at low temperatures ranging from 400-500°C. Sodium amide was used as both activator and nitridation reagent, and lotus stalk was used as the carbon precursor. The as-synthesized samples demonstrate the maximum CO2 uptake of 3.88 and 5.62 mmol/g at 25 and 0°C, respectively, at atmospheric pressure. Moreover, these lotus stalk-derived adsorbents exhibit rapid CO2 adsorption rate, high CO2/N2 selectivity, moderate CO2 isosteric heat of adsorption, stable cyclic ability and excellent dynamic CO2 capture capacity. Systematic research shows that besides the volume of narrow micropore and nitrogen content, the pore size distribution is also a non-negligible factor in determining CO2 adsorption capacity under ambient condition for these adsorbents. The good CO2 adsorption performance together with single-step and low temperature preparation indicate that these sorbents are very promising for CO2 capture from flue gas.

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Energy & Fuels

Introduction According to the Earth System Research Laboratory, the atmospheric CO2 concentration has reached 408.9 ppm by April 2018.1 It is urgent to control the emission of CO2 to improve the global climate. CO2 capture plays a critical role in reducing CO2 emissions and thus mitigating the greenhouse effect. For CO2 capture, a great variety of techniques have been researched including amine scrubbing,2 membrane separation,3 ionic liquid absorption4 and adsorption via solid adsorbents.5-8 Among these extensively-studied approaches, adsorption by solid adsorbents stands out because of its merits of low energy consumption, non-corrosiveness, low operation cost, high adsorption efficiency and good renewability, to name a few. The most important key for this technology is to synthesize solid materials having excellent CO2 adsorption properties such as high CO2 uptake, fast adsorption kinetics, high CO2/N2 selectivity, medium adsorption heat and superior chemical, thermal and mechanical stability. Up to now, different porous materials, for example porous metal oxide,9 zeolites,10 porous carbons,11-13 metal-organic frameworks (MOFs)14 and porous polymers15-18 have been broadly researched as CO2 sorbents. Among various solid adsorbents, porous carbons are promising because of their advantages of large surface area, low cost, easy steering of porosity, low chemical reactivity, easy regeneration and hydrophobicity. Currently, it has been well recognized that narrow micropore (