有序氮掺杂介孔碳的水热自组装合成及其CO2吸附性能研究

Hydrothermal Self-Assembly Synthesis and CO2 Adsorption Property of Ordered Nitrogen-Doped Mesoporous Carbon

以Pluronic F127为软模板,三聚氰胺和尿素为氮源,通过无需预聚合的一步水热协同自组装法制备了有序氮掺杂介孔碳CO2吸附剂。采用N2吸附/脱附、X射线衍射仪(XRD)、透射电子显微镜(TEM)、傅里叶红外光谱仪(FT-IR)以及X射线光电子能谱仪(XPS)等多种表征手段考察了吸附剂的结构及表面特性。测定了不同温度下CO2和N2在有序氮掺杂介孔碳上的吸附等温线,应用多种吸附等温模型(Langmuir、Freundlich、Temkin、Dual-site Langmuir(DSL)模型)进行了拟合分析,并结合IAST模型预测了吸附剂在模拟烟气中的CO2/N2吸附选择性。结果表明,有序氮掺杂介孔碳具有较大的比表面积(可达498.6 m2/g)、高度有序的介观结构(P6mm空间群)以及较高的氮含量,其中氮元素以多种形式均匀掺杂在碳骨架中。研究发现,有序氮掺杂介孔碳对CO2和N2的吸附高度符合DSL吸附等温模型。此外,氮含量更高的NOMC-M具有更大的CO2吸附量(0℃,3.55 mmol/g;25℃,2.67 mmol/g)和CO2/N2吸附选择性(>40),且在连续CO2吸附/脱附循环测试后仍可保持良好的再生稳定性。

Ordered nitrogen-doped mesoporous carbon CO2 adsorbents were synthesized by a simple one-step hydrothermal self-assembly method using F127 as a soft template,melamine and urea as the nitrogen source without additional pre-polymerization steps.Characterization methods including N2 adsorption/desorption,XRD,TEM,FT-IR and XPS were taken to study the structure and surface properties of the adsorbents.Besides,the adsorption isotherms of CO2 and N2 on the ordered nitrogen-doped mesoporous carbon at different temperatures were determined,and the results were fitted and analyzed by various adsorption isotherm models(Langmuir,Freundlich,Temkin,Dual-site Langmuir(DSL)models),further combined with the IAST model,the CO2/N2 adsorption selectivity of adsorbents in simulated flue gas was predicted.The results indicate that the ordered nitrogen-doped mesoporous carbon exhibit large specific surface area(up to 498.6 m2/g),highly ordered mesostructure(P6mm space group)and high nitrogen content,and the nitrogen is uniformly doped in the carbon framework in various forms.It was found that the adsorption isotherms of CO2 and N2 on ordered nitrogen-doped mesoporous carbon were highly consistent with the DSL model.Moreover,NOMC-M with higher nitrogen content exhibit higher CO2 adsorption capacity(0℃,3.55 mmol/g;25℃,2.67 mmol/g)and CO2/N2 adsorption selectivity(>40),and can still maintain good regeneration stability after continuous CO2 adsorption/desorption cycle test.