Mg⁃Al⁃LDH对塔河沥青质及其亚组分的吸附研究

Study on the Adsorption of Asphaltenes and Their Sub⁃Components by Mg⁃Al⁃LDH in Tahe

采用pH恒定共沉淀法合成了双金属氢氧化物Mg⁃Al⁃LDH,采用X射线衍射(XRD)、扫描电镜(SEM)、能谱(EDS)及BET等手段对其微观形貌、结构和组成进行表征。结果表明,成功制备出具有层状结构且有序程度较高的LDHs,其孔径属于介孔范畴。采用甲苯⁃正庚烷法将塔河沥青质(T_(A))分离成重组分(A_(1))和轻组分(A_(2)),并对其进行元素分析,得知A_(1)的极性最大,其次依次为T_(A)和A_(2)。进一步考察了Mg⁃Al⁃LDH对塔河沥青质及其亚组分A_(1)、A_(2)的吸附性能,研究发现Mg⁃Al⁃LDH对T_(A)及其亚组分A_(1)、A_(2)的吸附可在2~3 h达到平衡,实验数据与准二级动力学拟合较好,所得吸附等温线符合Langmuir模型,Mg⁃Al⁃LDH对T_(A)及其亚组分A_(1)、A_(2)的吸附量分别为71.38、140.65、39.31 mg/g。

Mg⁃Al⁃LDH was synthesized by the constant pH co⁃precipitation method,and the micro⁃structure and composition of the layered bimetallic hydroxides were characterized by X⁃ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)and BET.The results show that LDHs were successfully prepared with a layered structure,a high degree of order,and mesopores.The toluene⁃n⁃heptane method was used to separate the asphaltenes in Tahe into heavy component A_(1) and light component A_(2).The elemental analysis indicates that A_(1) had the highest polarity,followed by the Tahe asphaltenes and A_(2).This paper further investigated the adsorption properties of Mg⁃Al⁃LDH for asphaltenes and their sub⁃components A_(1) and A_(2) in Tahe and found that the adsorption equilibrium can be reached within 2~3 h.The experimental data fitted well with the pseudo⁃second⁃order kinetics,and the adsorption isotherms followed the Langmuir model.The adsorption capacity of Mg⁃Al⁃LDH was 71.38,140.65 and 39.31 mg/g for asphaltenes in Tahe and their sub⁃components A_(1) and A_(2),respectively.