I have synthesized mesoporous silica and I would like to load some metal on it, I don't want my oxygen atom of mesoporous silica to react with metal to form metal oxide. Even though I use reducing environment during synthesis like use of H2, and use of reducing agent. There is always formation of metal oxide. Can I poison the oxygen atoms of mesoporous silica by some route during synthesis? If yes, how? I feel the strong reducing agent may affect the mesoporosity of silica. Can I know the mild reducing agents in this process for the synthesis?
You can make a previous organic modification of mesoporous pure silica phases by “grafting” (postsynthetic functionalization) with terminal organosilanes of the type (R’O 3SiR, with R= organic functional group. So, OH on the surface are "grafted" forming Si-R-O.
Some literature:
-M. E. McGovern, K. M. R. Kallury y M. Thompson, “Role of solvent on the silanization of glass with octadecyltrichlorosilane”, Langmuir 10 (1994) 3607-3614
-J. B. Brzoska, N. Shahidzadeh y F. Rondelez, “Evidence of a transition temperature for the optimum deposition of grafted monolayer coatings”, Nature 360 (1992) 719-721
- J. D. Le Grange, J. L. Markham y C. R. Kurkjian, “Effects of surface hydration on the deposition of silane monolayers on silica”, Langmuir 9 (1993) 1749-1753
Alkali Metal-Silica Gel (M-SG) are stable industrial products http://signachem.com/industrial-chemistry/industrial-chemistry-products/
Most undesirable things are Si-OH groups on surface. Silanation (as Maria pointed) is good solution but it prevent stable deposition of metal. More suitable is convertation to Si-ONa or Si-OK by treatmet with corresponding tert-alcoholate or naphthalide.
onlly way is functionalization with organic compond. while you have -OH on the surfacr of , you should expect to obtain metal oxide and more specially withh hard metal ions.
Best way to resolve this cognitive dissonance is to poison for yourself instead of oxygen ;-)
Because all has understood that the problem is not in oxygen from silica gel because it does not react with alkali metals. Of course it is true for less reactive metals
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