活化时间诱导沥青基活性炭结构演化与吸附性能研究

Study on the Activation Time-Induced Structural Evolution and Adsorption Performance of Pitch-Based Activated Carbon

摘要: 活性炭因具有高比表面积、可控孔径分布及优异的化学表面可调性，是高效吸附挥发性有机物(VOCs)的理想材料。本研究以乙烯焦油沥青(ETP)为原料，采用预氧化结合水蒸气活化法制备富氧球形活性炭(SAC)，并通过单因素实验探究活化时间对其结构演化与吸附性能的影响。傅里叶变换红外光谱(FT-IR)证实预氧化处理提升了沥青中的含氧官能团含量；热重分析表明预氧化增强了沥青的热稳定性，为后续结构调控奠定了基础。X射线衍射(XRD)和拉曼光谱(Raman)结果表明，当活化时间达到90 min时，所制备活性炭的缺陷密度为7.64，层间距d₀₀₂为0.39 nm。高缺陷密度与扩大的层间距产生协同作用，使得该材料在常温下对甲醇的平衡吸附量达307 mg/g。经历4次再生后，其脱附率仍保持91.3%。本研究明确了活化时间对沥青基活性炭结构及其VOCs吸附性能之间的构效关系，为高效VOCs吸附材料的制备工艺优化提供了实验依据。

Abstract: Activated carbon is an ideal material for efficiently adsorbing volatile organic compounds (VOCs) due to its high specific surface area, controllable pore size distribution, and excellent chemical surface tunability. In this study, ethylene tar pitch (ETP) was used as the raw material to prepare oxygen-rich spherical activated carbon (SAC) through a combination of pre-oxidation and steam activation. The influence of activation time on the structural evolution and adsorption performance of the pitch-based activated carbon was systematically investigated via single-factor experiments. Fourier transform infrared spectroscopy (FT-IR) confirmed that pre-oxidation treatment increased the content of oxygen-containing functional groups in the pitch, while thermogravimetric analysis indicated that pre-oxidation enhanced the thermal stability of the pitch, laying the foundation for subsequent structural regulation. X-ray diffraction (XRD) and Raman spectroscopy results showed that when the activation time reached 90 min, the defect density of the prepared activated carbon was 7.64, with an interlayer spacing (d002) of 0.39 nm. The synergistic effect of high defect density and enlarged interlayer spacing enabled the material to achieve an equilibrium adsorption capacity of 307 mg/g for methanol at room temperature. After four regeneration cycles, the desorption rate remained as high as 91.3%. This study clarifies the structure–activity relationship between activation time and the structure and VOC adsorption performance of pitch-based activated carbon, providing experimental insights for the optimization of preparation processes for efficient VOC adsorption materials.