Proton Transfer in Zeolites

Hydrogen-Transfer Reactions. Edited by J. T. Hynes, J. P. Klinman, H. H. limbadi, and R. L Schowen Copyright 2007 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-30777-7 

Si/Al ratio between 100000 and 20 [1], Two catalysts, H-FAU and H-MFI, with the same Si/Al ratio of 26 have nearly the same specific activities, 11.4 and 

There is a third possible variation for acidic zeolite catalysts - the composition of the framework. The active Si-0(H)-A103 site in a high-sUica zeolite is formally created from a nanoporous Si02 polymorph by replacing Si by Al/H. If we consider an AIPO4 framework instead of an Si02 framework (as we do when we go from the mineral quartz to berlinite) and then replace P by Si/H (see formula above), we obtain a catalyst with the same Si-0(H)-A103 active site but a different framework composition. 

Strictly, these catalysts are not zeolites (this name is reserved for aluminosilicates), but aluminumphosphates (AlPOs) or silicon-aluminumphosphates (SAPOs). It is indeed possible to synthesize acidic high-silica (H-SSZ-13) [3] and SAPO catalysts (H-SAPO-34) [4] with the same framework structure (CHA) [5]. 

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A Review of Ab Initio Calculations on Proton Transfer in Zeolites (M. Allavena D. White)... 

Allavena, M. and Kassab, E. (1993) Molecular interactions in solid state and quantum chemistry A model problem, the proton transfer in zeolites. Solid State Ionics, 61,33-39. 

Experimental Methods and Evidence for Proton Transfer in Zeolites... 

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