Preparation and Pore Structure of Copper-doped Silica Membranes

doi:10.3724/SP.J.1077.2010.01047

Abstract

Abstract: Copper-doped silica membranes were prepared via Sol-Gel process with tetraethylorthosilicate(TEOS) and copper nitrate as precursors. The status of copper in the membranes was detected by means of FT-IR, XPS, XRD and the pore structure was determined by N₂ adsorption. The effects of copper dopant and H₂O/TEOS molar ratio on the pore structure were investigated and the stability of the pore structure under hydrothermal conditions was studied in detail. The results show that when the molar ratio of TEOS to H₂O is 0.5, it leads to microporous structure, with a pore volume of 0.155 cm³/g and a sharp pore size distribution centered at 0.5nm for the sample with a Cu/Si molar ratio of 0.8. A faction of copper is incorporated into silica framework by replacing silicon atoms, and the residual mainly exists as crystalline phase such as Cu and Cu₂O outside the framework. The microporous structure of the doped samples could be preserved for a short time (240h) under hydrothermal conditions but finally collapsed after further hydrothermal treatment.

Key words: silica membranes, copper-doped, pore structure, Sol-Gel process

CLC Number:

O484

WEI Na-Na, WEI Qi, LI Zhen-Jie, LI Qun-Yan, NIE Zuo-Ren. Preparation and Pore Structure of Copper-doped Silica Membranes[J]. Journal of Inorganic Materials, 2010, 25(10): 1047-1052.

References

[1] Turov V V, Mironyuk I F. Adsorption layers of water on the surface of hydrophilic, hydrophobic and mixed silicas. Colloids and Surfaces A:?Physicochemical and Engineering Aspects, 1998, 134(3): 257–263. [2] 韦奇, 李健林, 宋春林, 等（WEI Qi, et al）. 微孔二氧化硅膜的制备、氢气分离以及水热稳定性研究. 无机材料学报(Journal of Inorganic Materials), 2004, 19(1): 133–139. [3] Boffa V, Castricum H L, Garcia R, et al. Structure and growth of polymeric niobia-silica mixed-oxide sols for microporous molecular sieving membranes: a SAXS study. Chem. Mater., 2009, 21(9): 1822–1828. [4] Kanezashi M, Asaeda M. Hydrogen permeation characteristics and stability of Ni-doped silica membranes in steam at high temperature. J. Membr. Sci., 2006, 271(1/2): 86–93. [5] Boffa V, Blank D H A, Ten Elshof J E. Hydrothermal stability of microporous silica and niobia-silica membranes. J. Membr. Sci., 2008, 319(1/2): 256-263. [6] Uhlmann D, Liu S, Ladewig B P, et al. Cobalt-doped silica membranes for gas separation. J. Membr. Sci., 2009, 326(2): 316-321. [7] 王振余, 郭树才. 膜气体分离机理的初步探讨. 炭素技术, 1997(4): 7–10. [8] 余锡宾, 吴虹(YU Xi-Bin, et al). 正硅酸乙酯的水解、缩合过程研究. 无机材料学报(Journal of Inorganic Materials), 1996, 11(4): 703–707. [9] 李进军, 郝郑平, 赵伟, 等. 弱酸性条件下合成大孔容介孔氧化硅. 第四届全国环境催化与环境材料学术会议论文集, 中国北京, 2005: 68. [10] Kaneko K. Determination of pore size and pore size distribution: adsorbents and catalysts. J. Membr. Sci., 1994, 96(1/2): 59–89. [11] Horvath G, Kawazoe K. Method for the calulation of effective pore-size distribution in molecular-sieve carbon. J. Chem. Eng. Jpn., 1983, 16(6): 470–475. [12] Olejniczak Z, Leczka M, Cholewa-Kowalska K. 29Si: MAS NMR and FTIR study of inorganic-organic hybrid gels. J. Mol. Struct., 2005, 744–747: 465–471. [13] Tsvetkova I N, Shilova O A, Shilov V V, et al. Sol–Gel synthesis and investigation of hybrid organic–inorganic borosilicate nanocomposites. Glass Phys. Chem., 2006, 32(2): 218–227. [14] Vinogradova E, Estrada M, Moreno A. Colloidal aggregation phenomena: spatial structuring of TEOS-derived silica aerogels. J. Colloids Interface Sci., 2006, 298(1): 209–212. [15] Beck J S, Vartuli J C, Roth W J, et al. A new family of mesoporous molecular sieves prepared with liquid crystal templates. J. Am. Chem. Soc., 1992, 114(27): 10834–10843. [16] Hoque E, DeRose J A, Houriet R, et al. Stable perfluorosilane self-assembled monolayers on copper oxide surfaces: evidence of siloxy-copper bond formation. J. Chem. Mater., 2007, 19(4): 798–804. [17] 刘芬, 赵志娟, 邱丽美, 等. XPS光电子峰和俄歇电子峰峰位表. 分析测试技术与仪器, 2009, 15(1): 1–17. [18] Duke M C, da Costa J C D, Do D D, et al. Hydrothermally robust molecular sieve silica for wet gas separation. Adv. Funct. Mater., 2006, 16(9): 1215–1220. [19] Wei Q, Wang Y L, Nie Z R, et al. Facile synthesis of hydrophobic microporous silica membranes and their resistance to humid atmosphere. Microp. Mesop. Mater., 2008, 111(1/2/3): 97–103.