MoP-15


GAS PHASE REACTIONS OF SiO3- WITH METHANOL AND ETHANOL

Sejin Jeong, Keith J. Fisher, Russell F. Howe and Gary D. Willett

School of Chemistry, University of New South Wales, Sydney 2052


Infrared/visible laser ablation of zeolites, typically defined as microporous aluminosilicate minerals [1], produces three different series of anions: (SiO2)n-, (SiO2)nO-, and M(SiO2)nO- (n = 1, 2, 3..., M = H, AlO, or exchangeable metal atoms). [2] The study of the gas phase reactions of metal/non-metal oxide cluster anions with 'reactive' organic molecules may provide an insight into intrinsic reactivity of similar active sites on the surface of corresponding condensed-phase basic catalysts. [3] Gas-phase reactions of mass selected SiO3- with methanol and ethanol have been studied on a Fourier transform ICR mass spectrometer. Along with the aluminosilicate cluster anions, AlO(SiO2)nO-, the SiO3- produced the most diverse product anions upon reactions with the alcohols, while other larger silicate cluster anions gave mostly acid-base reaction product anions. [4]

Gaussian-94 and DMOL ab initio calculations are used to examine the potential energy surface for the reactions. Results will be presented on the thermochemistry and optimised ionic structures. Reaction pathways and possible mechanisms for the reactions will be discussed.


References

[1] J. V. Smith, Zeolites, 4 (1984) 309.

[2] S. Jeong, K. J. Fisher, R. F. Howe and G. D. Willett, Micropor. Mat., 4 (1995) 467.

[3] H. Hattori, Chem. Rev., 95 (1995) 537.

[4] S. Jeong, Ph. D. Thesis (1996) University of New South Wales.