金属改性SBA-15介孔分子筛水热稳定性研究

EFFECT OF METAL MODIFICATION ON THE HYDROTHERMAL STABILITY OF SBA-15 MESOPOROUS MOLECULAR SIEVE

采用X射线粉末衍射(XRD)、N_2吸附-脱附等分析手段研究了金属离子(Ce、Zr、Al、Fe、Co)对介孔分子筛SBA-15水热稳定性的影响。结果表明,金属离子Al、Fe水解能力较强,在水热环境中形成的羟基水合配离子与Si-OH脱羟基形成M-O-Si,Al、Fe被禁锢在介孔表面,对骨架硅起到保护作用,显著提高了分子筛的水热稳定性;金属离子Zr、Ce水解能力弱,主要以离子形式存在,难以进入骨架,不能很好的稳定分子筛的骨架结构,对提高介孔分子筛的水热稳定性效果不明显;金属离子Co水解能力介于两者之间,能够提高介孔分子筛水热稳定性。Al、Zr同时引入到SBA-15中,离子的协同作用使得介孔分子筛Al-Zr-SBA-15水热稳定性得到进一步提高。

The effect of metal element（Ce, Zr, A1, Fe, Co）modification on the hydrothermal stability of SBA-15 mesoporous molecular sieves was studied by X-ray diffraction（XRD）, N2 adsorption-desorption. The results showed that,metal ion A1, Fe hydrolysis ability is strong, in the environment of water and heat formation of hydroxy and hydrous complex ion and Si-OH dehydroxylation form M- O-Si, A1, Fe were imprisoned in the mesoporous surface and protect the silicon skeleton, and significantly improve the hydrothermal stability of molecular sieves; metal ion Zr, Ce hydrolysis ability is weak, mainly existed in the form of ions, it is difficult to enter the skeleton, cannot stabilize the molecular sieve framework structure, to improve the effect of hydrothermal stability of mesoporous molecular sieves was not obvious; metal ions co hydrolysis ability between them to improve mesoporous molecular sieve hydrothermal stability. The simultaneous introduction of A1 and Zr into SBA-15, the synergistic effect of ions on the hydrothermal stability of mesoporous molecular sieve AI-Zr-SBA-15 has been further improved.