Conversion of ethanol over metal-exchanged zeolites.
The effects of metal exchange between zeolites and alkali metals (Li, Na, K; zeolite Y, ZSM-5, T), alk. earths (Mg, Ca, Sr, Ba; ZSM-5), transition metals (La, Ce, Cr, Mn, Fe, Co, Ni, Pd, Cu, Zn; ZSM-5) and Al (ZSM-5) on the conversion of EtOH were studied. Activities of the catalysts and selectivities for C2H4, C3+ olefins, paraffins, and arenes strongly depended on the cation chosen. Only C2H4 was formed by alkali-exchanged zeolites, the most active being LiY. This could be confirmed by a long-term ageing test with LiY pellets under semi-industrial conditions. The exchange of ZSM-5 with alk. earths or transition metals permitted the formation of a wide variety of products, ranging from high C2H4 to high arom. yields. A correlation between certain product selectivities and electronegativity was only possible in a rough approxn.
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