氢同位素在线分析用MnCl_2\γ-Al_2O_3色谱填料的制备与性能

Preparation and Characterization of Gas Chromatography Using MnCl_2\\γ-Al_2O_3 Stationary Phase for On-line Hydrogen Isotopes Analysis

吸附活性太强的γ-Al2O3将导致氢同位素各组分保留时间延长、色谱峰拖尾、选择性差异不明显,从而无法满足快速在线分析需求。为此,采用锰盐浸渍沉积法改性γ-Al2O3,制备了一种可在液氮温度下分析氢同位素的MnCl2\γ-Al2O3色谱填料,并对其形貌、比表面积、孔径、孔体积、吸附性能及氢氘分离性能进行研究。与改性前的γ-Al2O3填料相比,本填料吸附活性适中,表面均匀,具有优良的孔结构和选择吸附性能,堆密度增大了44.8%,比表面积减小了11.4%,孔径在0.7～4.0nm分布,改善了单纯γ-Al2O3表面有序度、孔结构和吸附性质,降低了表面活性。MnCl2非均匀磁场的存在加速了正仲氢转化,使正仲氢合二为一,能够有效分离He,H2,HD和D2混合气体,谱图中各组分峰型对称,接近标准高斯分布;H2与HD分离度达到0.94,HD与D2分离度达到1.78,对稳定氢同位素的保留时间在2min内,分离度和柱效均优于未经改性的γ-Al2O3。

γ-Al2O3 has strong activated adsorption capacity,which would induce long retention time and asymmetry peak,thus is not suitable for on-line hydrogen isotopes analysis.On basis of chemical deposition methods,one kind of gas chromatography packing was prepared by using γ-Al2O3,reacted with MnCl2,as base material.This packing was used to analyze hydrogen isotopes at liquid nitrogen temperature.The surface topography of MnCl2/γ-Al2O3 prepared by this method was characterized.The specific surface area,pore volume and pore size were measured.The hydrogen isotopes adsorption capacity of this packing was researched with static volume device.Compared with γ-Al2O3,MnCl2/γ-Al2O3 has moderate adsorption activity and its surface is uniformly.Also it has excellent pore size distributing and selectivity of adsorption performance.It was calculated that bulk density of this packing increased by 44.8%,and specific surface area decreased by 11.4%.The pore size distribution was 0.7-4.0 nm.The modification improved the surface orderly degrees and pore structure of γ-Al2O3,changed the adsorption properties and lowered the surface activity.The column packed with MnCl2/γ-Al2O3 restrained the split of para-and ortho-hydrogen,separated He,H2,HD and D2 gas mixture successfully.The separation factors are 0.94 and 1.78 for H2/HD and HD/D2 respectively.The retention time of hydrogen isotopes are in 2 min.The separation factor and column efficiency are better than conventional γ-Al2O3 column.