A new nanoporous nitrogen-doped highly-efficient carbonaceous CO 2 sorbent synthesized with inexpensive urea and petroleum coke Ruizhu Bai a , Mingli Yang a , Gengshen Hu b , Leqiong Xu a , Xin Hu a, * , Zhiming Li a , Sunli Wang a , Wei Dai a , Maohong Fan c, * a College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, PR China b Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, PR China c Department of Chemical and Petroleum Engineering, University of Wyoming, Laramie, WY 82071, USA ARTICLE INFO Article history: Received 11 July 2014 Accepted 25 September 2014 Available online 2 October 2014 ABSTRACT The objective of this research is to develop a cost-effective carbonaceous CO 2 sorbent. Highly nanoporous N-doped carbons were synthesized by KOH activation of urea-modified petroleum coke. The resulting carbons show highly developed porosity and different amounts of nitrogen, depending on preparation conditions. This series of carbons exhibits high CO 2 adsorption capacities ranging from 3.69 to 4.40 mmol/g and 5.69 to 6.75 mmol/g at 25 °C and 0 °C under atmospheric pressure, respectively. Specifically, the sample UC-650-2 prepared at 650 °C with KOH/precursor ratio of 2 shows the highest CO 2 uptake of 4.40 mmol/g at 25 °C, which is among the best of the known nitrogen-doped porous car- bons. This high CO 2 capture capacity is due to the synergy of the sorbent’s high micropo- rosity and nitrogen content. In addition, the CO 2 /N 2 selectivity of the sorbent is 17, higher than that of many reported CO 2 sorbents. The multi advantages of the sorbent including its easy synthesis, low cost, high CO 2 uptake capacity and selectivity as well as regenerability demonstrates that the nanoporous nitrogen-doped carbon is promising for CO 2 capture. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction The concentration of CO 2 in the atmosphere has increased currently to 402 ppmv [1], a level 122 ppmv higher than the preindustrial period. This has caused serious concerns for cli- mate change, since CO 2 is generally recognized as a green- house gas and therefore a major contributor to global warming. To mitigate CO 2 emissions, carbon capture and sequestration (CCS) is considered to be one of the most promising solutions [2]. Among all CO 2 emission sources, fos- sil fuel-burning power plants are the single largest anthropo- genic sources globally, accounting for approximately one- third of CO 2 emissions [3]. Accordingly, capture of CO 2 from flue gas streams in fossil fuel based power plants has been considered one of the major strategies for reducing anthropo- genic CO 2 emissions. CO 2 concentration of flue gas typically accounts for 10–15% in coal-fired power plants [4]. Effective capture of CO 2 under http://dx.doi.org/10.1016/j.carbon.2014.09.079 0008-6223/Ó 2014 Elsevier Ltd. All rights reserved. * Corresponding authors: Fax: +86 579 8228 8269 (X. Hu), +1 307 766 6777 (M. Fan). E-mail addresses: huxin@zjnu.cn (X. Hu), mfan@uwyo.edu (M. Fan). CARBON 81 (2015) 465 – 473 Available at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/carbon