A new study on the kinetics of Stöber synthesis by in-situ liquid 29Si NMR
- 274 Downloads
Liquid-state 29Si NMR was used to investigate the hydrolysis and condensation kinetics of ammonia-catalyzed tetraethoxysilane (TEOS) in methanol system. The reactive rate constants were calculated by applying first-order reaction approximation and the steady state approximation theory. The reaction orders with respect to TEOS, ammonia and water were derived, as well as the activation energies and the Arrhenius constants. It was found that the formation of intermediate species Si(OH)(OEt)3 was the rate-limiting step and its reaction rate equation was r TEOS=7.41×10−3[TEOS][NH3]0.333[H2O]0.227. Higher reactive temperature benefited the hydrolysis of TEOS. The results presented here indicated quantificationally that the formation of colloidal SiO2 particles was controlled by the initial hydrolysis of TEOS.
KeywordsStöber synthesis Reaction kinetics Nuclear magnetic resonance
The financial support from the National Key Native Science Foundation (No. 20133040) was gratefully acknowledged.
- 1.Shingo K, Ikuko Y, Noriko Y (1997) In: Dunn BS, Mackenzzie JD, Pope EJ, Schmidt HK, Yanane M (eds) Sol-Gel Optics IV, SPIE vol. 3136. The international society for optical engineering, Bellingham, WashingtonGoogle Scholar
- 8.Sadasivan S, Duber AK, Li Y, Rasmussen DH (1998) J Sol-Gel Sci Tech 5:12Google Scholar
- 10.Bailey JK, McCartney ML (1992) Colloids Surf 151:63Google Scholar
- 13.Brinker CJ, Scherer GW (1990) Sol-gel science: the physics and chemistry of sol-gel processing. Academic Press, San DiegoGoogle Scholar
- 16.David Cater E (1983) J Chem Educ 60:109Google Scholar
- 18.Parker AJ (1969) Chem Rev 1:69Google Scholar
- 19.Iler RK (1979) The chemistry of silica. Wiley, New YorkGoogle Scholar
- 20.Keefer KD (1984) In: Brinker CJ, Clark DE Ulrich DR (eds) Better ceramics through chemistry. North-Holland, New York, p 15Google Scholar