UiO-66及其官能化改性材料对C6烷烃吸附性能研究

Adsorption Properties of C6 Alkane on UiO-66 and Its Functionalized Materials

利用溶剂热法制备了UiO-66及其官能化改性的UiO-66-NH 2,UiO-66-(CF_(3))_(2)材料,均为微孔。40℃下测定正己烷(nC6)、3-甲基戊烷(3MP)、2,2-二甲基丁烷(22DMB)3种C6异构体分别在3种材料上的静态吸附速率曲线及等温线,并通过方程拟合研究其吸附行为。结果表明,改性的UiO-66-NH 2和UiO-66-(CF_(3))_(2)对nC6或3MP的吸附速率及平衡饱和吸附量均大于UiO-66;通过动力学拟合,UiO-66对nC6吸附符合一级动力学模型,反相吸附22DMB;而UiO-66-NH 2和UiO-66-(CF_(3))_(2)对3MP的吸附符合二级动力学模型,但均对动力学直径较小的nC6吸附量较大,更适合于从烷烃异构体中分离出具有高辛烷值的支链烷烃。通过等温线拟合,发现UiO-66和UiO-66-NH 2均符合Freundlich吸附等温方程,但UiO-66-NH 2与烷烃异构体的作用力更强;UiO-66-(CF_(3))_(2)对3MP的吸附行为更符合Langmuir方程,为单分子层吸附。

UiO-66 and functionalized UiO-66-NH_(2) and UiO-66-(CF_(3))_(2) materials were prepared by a solvothermal method.Nitrogen absorption/desorption isotherm indicated that the three materials are all microporous.The static adsorption rate curves and isotherms of n-hexane(nC6),3-methylpentane(3MP)and 2,2-dimethylbutane(22DMB)of the three C6 isomers were measured at 40℃,and their adsorption behaviors were studied by model fitting.The results showed that the adsorption rate and equilibrium saturation adsorption capacity of UiO-66-NH_(2) and UiO-66-(CF_(3))_(2) were higher than UiO-66 for nC6 or 3MP.By kinetic fitting,nC6 adsorption on UiO-66 was fitted to the First-order kinetic model with reverse adsorptions on 22DMB.The alkane of 3MP on the modified UiO-66-NH_(2) and UiO-66-(CF_(3))_(2) were fitted to second-order kinetic model,but,both of them showed large adsorption capacity for nC6 with a relative smaller kinetic diameter,which are more suitable for the separation of branched alkanes with high octane values from alkane isomers.Through isotherm fitting,it is found that UiO-66 and UiO-66-NH_(2) were fitted well with Freundlich adsorption isotherm equation,but UiO-66-NH_(2) has a stronger interaction force with alkane isomers.The adsorption behavior of UiO-66-(CF_(3))_(2) on 3MP was more in line with the Langmuir equation,which was monolayer adsorption.