ELECTROSTATIC NATURE OF CATALYTIC EFFECTS RESULTING FROM SI GREATER-THAN AL SUBSTITUTIONS IN ZMS-5 ZEOLITE

Catalytic activity changes resulting from Si > Al substitution modelle d by corresponding ab initio cluster calculations have been compared w ith analogous perturbational values obtained from an atomic multipole expansion. Preliminary results indicate the dominant electrostatic nat ure of the long-range catalytic effects in cluster models of substitut ed zeolites. This opens the possibility to dissect catalytic effects i n modified zeolites into additive increments derived directly from an atomic multipole representation of the molecular charge redistribution . Such an approach may be potentially useful in the rational design of optimal catalysts of extensive size. (C) 1998 Elsevier Science B.V. A ll rights reserved.