College of Architecture and Environment, Sichuan University, Chengdu, People's Republic of China.
National Engineering Research Center for Flue Gas Desulfurization, Chengdu, People's Republic of China.
Environ Technol. 2020 Nov;41(27):3544-3553. doi: 10.1080/09593330.2019.1615131. Epub 2019 May 20.
In this study, nitrogen-tailored hierarchical meso-/micro-porous activated carbons were successfully fabricated from cypress sawdust by HPO activation with further nitrogen modification using three kinds of nitrogen source (i.e. nitic acid, urea and melamine). The produced carbons were used as adsorbents for CO capture. The physic-chemical properties of the produced carbons were characterized by N adsorption-desorption, fourier-transform infrared spectroscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. The effects of pore structure and nitrogen content on CO adsorption were investigated. It was found that HPO activation would turn cypress sawdust into mesoporous carbon (AC), nitrogen doping could induce the development of microporosity and also increase the basicity of the carbon framework, which favoured for CO adsorption. Among the nitrogen-tailed carbons, HNO-treated activated carbon (AC-N) showed the highest (0.127 cm/g), the largest CO adsorption capacity (2.8 mmol/g at 273 K, 1 bar) and the best CO/N selectivity as compared to urea and melamine treated ones. The adsorption experiments showed that the presence of microporosity and pyrrolic-N on the carbons were responsible for CO adsorption, the oxygen functional groups on AC-N might also contribute to higher CO uptake, and the mesoporous structure could favour for the fast mass transfer of CO. The results of CO adsorption heat confirmed the high affinity of the prepared carbons to CO. This study provides a strategy to produce hierarchical meso-/micro-porous activated carbons with enriched nitrogen functional groups, which favoured for CO adsorption.
在这项研究中，通过 HPO 活化，成功地从柏木锯末中制备了氮调谐的分级中孔/微孔活性炭，并用三种氮源（即硝酸、尿素和三聚氰胺）进一步进行氮改性。所制备的碳用作 CO 捕获的吸附剂。通过 N 吸附-解吸、傅里叶变换红外光谱、扫描电子显微镜和 X 射线光电子能谱对所制备的碳的物理化学性质进行了表征。考察了孔结构和氮含量对 CO 吸附的影响。结果表明，HPO 活化会将柏木锯末转化为中孔碳（AC），氮掺杂会诱导微孔的发展，并增加碳骨架的碱性，有利于 CO 吸附。在氮尾碳中，HNO3 处理的活性炭（AC-N）表现出最高的（0.127 cm/g），在 273 K、1 bar 下的最大 CO 吸附容量（2.8 mmol/g）和最好的 CO/N 选择性，优于尿素和三聚氰胺处理的碳。吸附实验表明，碳上微孔和吡咯氮的存在是 CO 吸附的原因，AC-N 上的含氧官能团也可能有助于提高 CO 吸收量，中孔结构有利于 CO 的快速传质。CO 吸附热的结果证实了所制备的碳对 CO 的高亲和力。这项研究提供了一种制备富含氮官能团的分级中孔/微孔活性炭的策略，有利于 CO 吸附。
