New vistas in zeolite and molecular sieve catalysis

Abstract

Zeolites and zeolite-like molecular sieves are able to \nrecognize, discriminate, and organize molecules with \nprecisions that can be less than 1 Å. Because these structures (Figure 1) contain uniformly sized pores in the range of 4-13 Å, they have been exploited by the petrochemical industries to perform many large-scale, \nshape-selective hydrocarbon reactions. Further information \non the materials listed in Figure 1 is provided in Table I. The pore sizes listed are the crystallographic free diameters from each structure. Additionally, the dimensionality of the pore systems is provided. (A simple way to think about the dimensionality of the pore system is to place an organic molecule into the void space and observe in how many different directions it can move. For example, an n-hexane molecule can move in one direction in the channels of VPI-5 whereas it can travel in all three directions in NaX.) For more details on the structures of zeolites and molecular sieves, see ref 3.