ENANTIOSELECTIVE DEHYDRATION OF BUTAN-2-OL USING ZEOLITE-Y MODIFIED WITH DITHIANE OXIDES - COMMENTS ON THE NATURE OF THE ACTIVE-SITE

Modification of zeolite H-Y by dithiane oxides (2-R-1,3-dithiane 1-oxi de, R = H, CH3, C6H5) is shown to enhance significantly its activity f or the acid-catalysed gas phase dehydration of butan-2-ol. The rate en hancement is observed for catalysts that are prepared using two commer cial samples of zeolite H-Y. The origin of this effect is examined usi ng in situ FTIR spectroscopy and Al-27 and Si-29 MAS NMR spectroscopy studies of the modified zeolite. The rate enhancement is considered to result from a specific interaction between the dithiane oxide modifie r with both the extra-framework and framework aluminium in the zeolite .