"Ab initio" synthesis of zeolites for preestablished catalytic reactions

[EN] Unlike homogeneous catalysts that are often designed for particular reactions, zeolites are heterogeneous catalysts that are explored and optimized in a heuristic fashion. We present a methodol. for synthesizing active and selective zeolites by using org. structure-¿directing agents that mimic the transition state (TS) of preestablished reactions to be catalyzed. In these zeolites, the pores and cavities could be generated approaching a mol.-¿recognition pattern. For disproportionation of toluene and isomerization of ethylbenzene into xylenes, the TSs are larger than the reaction products. Zeolite ITQ-¿27 showed high disproportionation activity, and ITQ-¿64 showed high selectivity for the desired para and ortho isomers. For the case of a product and TS of similar size, we synthesized a catalyst, MIT-¿1, for the isomerization of endo-¿dicyclopentane into adamantane.