氮掺杂的碳基吸附剂高效分离甲烷/氮气

Efficient separation of methane/nitrogen mixture over N-doped carbon

采用变压吸附(PSA)高效分离甲烷和氮气是实现甲烷富集和回收的重要手段之一,其核心是高性能吸附剂的制备。本研究以三聚氰胺(M)为氮源,采用水热法合成了五种不同三聚氰胺和间苯二酚(R)质量比的间苯二酚树脂基吸附材料MRF-AC_(n)。运用容量法测试303K,0~0.7MPa下甲烷和氮气的吸附性能,低温(77 K)氮吸脱附法对材料的孔结构进行表征,分别用Langmuir Freundlich(LF)模型和准二阶动力学(PSO)模型拟合甲烷和氮气的吸附等温线数据和动力学数据。结果表明,氮元素的引入调节了吸附材料的孔结构,不同程度增加了吸附材料的比表面积和微孔孔容,增加了吸附材料的极性,从而改变了甲烷和氮气的吸附量,其中样品MRF-AC_(2)表现出更好的甲烷和氮气吸附和分离性能,吸附量分别为45.20和22.23mL·g^(-1)分离比最高达到10以上。

The efficient separation of methane and nitrogen using pressure-variable adsorption(PSA)is one of the important means to achieve methane enrichment and recovery,and its core is the preparation of high-performance adsorbents.In this study,five resorcinol resin-based adsorbent materials MRF-ACn with different mass ratios of melamine(M)to resorcinol(R)were synthesized by a hydrothermal method using melamine(M)as the nitrogen source.The adsorption performances of methane and nitrogen on these five adsorption materials were tested at 303 K in the pressure range from 0 to 0.7 MPa through the volumetric method.The adsorption isotherm data and kinetic data of methane and nitrogen were fitted using the Langmuir Freundlich(LF)model and pseudo-second-or-der(PSO)model,respectively.This allowed the calculation of the ftting parameters corresponding to the equilibrium data.The results indicated that the pore size distribution of MRF-AC_(2)adsorbent material was mainly in the range of 0.45 to 2 nm.The addition of melamine significantly altered the pore size distribution of the adsorbent materials,and MRF-AC_(2)(M/R=0.2)exhibited a distinct pore size distribution range in the 0.45~0.55 nm interval compared to other materials.The introduction of nitrogen in melamine changed the pore size distribution and pore structure of the adsorbent material.The optimal effect for CH_(4) and N(2) separation occurred in the 0.45~0.8 nm range.The micropore volume showed a positive correlation with the adsorption and separation performance of the adsorbent material for CH_(4) and N.This resulted in MRF-AC_(2)material having the maximum CH_(4) and N adsorption performance and adsorption separation ratio,with adsorption capacities of 45.20 and 22.23 mL g,respectively,and a separation ratio exceeding 10.