钴掺杂二氧化硅膜的制备、表征及氢气分离性能

采用正硅酸乙酯(TEOS)和Co(NO3)2.6H2O为前驱体通过溶胶-凝胶法制备掺钴微孔二氧化硅膜,研究钴在二氧化硅膜材料中的存在状态、膜材料孔结构以及膜材料的气体渗透和分离性能。结果表明钴元素以Si-O-Co的形式存在于SiO2骨架之中,掺杂Co 10%的微孔SiO2膜具有典型的微孔结构,其孔体积为0.119 cm3·g-1,平均孔径在0.52 nm左右且孔径主要分布在0.4～0.55 nm之间。氢气在膜材料中的输运低温下遵循Knudsen扩散机理,高于100℃时遵循活化扩散机理,300℃时膜材料的H2渗透率达到6.41×10-7 mol.m-2.s-1.Pa-1,H2/CO2分离系数达到6.61,高于Knudsen扩散的理想分离系数。

Preparation, Characterization and Hydrogen Separation of Cobalt-Doped Silica Membranes

Cobalt-doped silica membranes were prepared by the sol-gel technique using tetraethyl orthosilicate(TEOS) and nitrate hexahydrate(Co(NO3)2·6H2O) as precursors.The status of Co,the pore structure and the gas permeation and separation performance of the doped silica membranes were investigated in detail.The results show that cobalt atoms are covalently linked to oxygen atoms by replacing a fraction of silicon atoms in the framework.Silica membranes doped with 10% cobalt have a typical microporous structure with a pore size centered at 0.52 nm and mainly distributed between 0.4 nm and 0.55 nm,and a pore volume of 0.119 cm3·g-1.The hydrogen transport in the co-doped silica membranes was subjected to a Knudsen diffusion mechanism at low temperatures and complies with an activated diffusion mechanism at temperatures higher than 100 ℃.The membranes possess a H2 permeance of 6.41×10-7 mol·m-2·s-1·Pa-1 and a H2/CO2 permselectivity of 6.61 at 300 ℃,which is higher than that of Knudsen diffusion.