Size, Shape, and Site Selectivities in the Photochemical Reactions of Molecules Adsorbed on Pentasil Zeolites

摘要

The photochemistry of dibenzyl ketones in the presence of pentasil zeolites follows strikingly different pathways depending on the location of the absorbed ketone. The product distribution or Cage Effect (vide infra) demonstrates the effects of sorption and diffusion on the radical species produced by photolysis. The difference in chemistry of these zeolites, expressed as the Si/Al ratio, does not affect the product distribution. By addition of a non-reactive titrant, such as water, after the ketone adsorption into the zeolite, the photolysis product distributions can be systematically varied depending upon the aluminum content of the framework. These results are completely described by considerations of (a) the size and shape sorption selectivity of the pentasil zeolites, (b) sorption of water by the hydrophilic sites of the pentasil zeolites (which depends upon the framework aluminum content), and (c) the hydrophobic characteristics of the pentasil channels which do not contain framework aluminum. Keywords: Zeolites, Photochemistry, Adsorption, Pentasil. (jes)