SHAPE-SELECTIVE DISPROPORTIONATION OF XYLENE OVER PARTIALLY CATION-EXCHANGED H-MORDENITE

The shape-selective disproportionation of xylene to form 1,2,4-trimethylbenzene over the partially exchanged H-mordenite catalysts by various cations has been studied. The catalysts were prepared by a conventional or rapid cation-exchange method. The shape selectivity depends on the ionic radius of exchanged cation. The most suitable ionic radius is nearly 0.096 nm. The most suitable catalyst is the H-mordenite exchanged by Cu cation. This catalyst has a high selectivity, not only because there is not enough space to form the transition state leading to 1,3,5-trimethylbenzene, but also because the diffusion of 1,3,5-trimethylbenzene is inhibited. The rapid cation exchange is more effective than the conventional one, because a smaller amount of cation controls the pore dimension and provides a high selectivity without a drop in activity. © 1979.