State Key Laboratory for Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou, 310027, China.
State Key Laboratory for Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou, 310027, China.
Environ Pollut. 2021 Sep 1;284:117113. doi: 10.1016/j.envpol.2021.117113. Epub 2021 Apr 13.
Typical organic pollutants from coal-combustion flue gas such as volatile organic compounds (VOCs) need to be effectively controlled. This work synthesized a series of nitrogen-doped hierarchical porous carbons (NHPCs) by one-step activation with various proportions of cellulose, (NH)CO and KHCO/NaHCO. The NHPCs have a high specific surface area and pore volume up to 2816 m/g and 1.413 cm/g as well as a hierarchical porous structure with micro-meso-macropores distribution. The dynamic adsorption tests of toluene at 600 ppm showed that NHPCs have a high adsorption capacity up to 585 mg/g (NHPC(K)131), this was about 3 times more than that of AC (208 mg/g), and is a better absorbent compared to many other carbon adsorbents. The porous characteristics and toluene adsorption properties of NHPCs improved along with the fluctuation of the proportions of raw materials and active agents. The micropore size of the material is the main factor that affecting the toluene adsorption capacity. The analysis of toluene dynamic adsorption breakthrough curves revealed that NHPCs had great toluene adsorption kinetics with high adsorption rate constants and short mass transfer zone. The excellent toluene adsorption kinetics of NHPCs can be attributed to the hierarchical porous structure. The abundant 2-10 nm mesopores and macropores of NHPCs act as mass transfer channels for toluene molecules. The XPS analysis showed that the NHPCs have nitrogen doping up to 6.71% (NHPC(Na)161) and they effectively promote toluene adsorption. The nitrogen doping mechanism can be attributed to the reactions between cellulose pyrolysis substances and NH which decomposed from (NH)CO. Moreover, the pore forming reactivity of KHCO is better than that of NaHCO in the NHPCs activation process.
典型的燃煤烟气有机污染物，如挥发性有机化合物（VOCs），需要得到有效控制。本工作通过纤维素、（NH）CO 和 KHCO/NaHCO 不同比例的一步活化合成了一系列氮掺杂分级多孔碳（NHPCs）。NHPCs 具有高达 2816 m/g 和 1.413 cm/g 的比表面积和孔体积，以及具有微孔-介孔-大孔分布的分级多孔结构。600 ppm 下甲苯的动态吸附测试表明，NHPCs 具有高达 585 mg/g（NHPC(K)131）的高吸附容量，这大约是 AC（208 mg/g）的 3 倍，并且比许多其他碳吸附剂具有更好的吸附能力。NHPCs 的多孔特性和甲苯吸附性能随原料和活性剂比例的波动而提高。材料的微孔尺寸是影响甲苯吸附容量的主要因素。甲苯动态吸附穿透曲线的分析表明，NHPCs 具有很大的甲苯吸附动力学，具有高吸附速率常数和短的质量传递区。NHPCs 优异的甲苯吸附动力学性能可归因于分级多孔结构。NHPCs 丰富的 2-10nm 介孔和大孔作为甲苯分子的传质通道。XPS 分析表明，NHPCs 中的氮掺杂高达 6.71%（NHPC(Na)161），并能有效促进甲苯吸附。氮掺杂机制可归因于纤维素热解产物与 NH（由（NH）CO 分解）之间的反应。此外，在 NHPCs 活化过程中，KHCO 的造孔反应活性优于 NaHCO。
