2-Methylnaphthalene disproportionation shape selectivity

The catalytic isomerization of 1-methylnaphthalene and all lation of 2-methylnaphtha-lene with methanol were studied at ambient pressure in a flow-type fixed bed reactor. Acid zeolites with a Spaciousness Index between ca. 2 and 16 were found to be excellent isomerization catalysts which completely suppress the undesired disproportionation into nwhthalene and dimethylnaphthalenes due to transition state shape selectivity. Examples are HZSM-12, H-EU-1 and H-Beta. Optimum catalysts for the shape selective methylation of 2-methylnaphthalene are HZSM-5 and HZSM-li. All experimental finding concerning this reaction can be readily accounted for by conventional product shape selectivity combined with coke selectivation, so there is no need for invoking shape selectivity effects at the external surface or "nest effects", at variance with recent pubhcations from other groups. 

Disproportionation of 2-methylnaphthalene over ZSM-5 zeolite to dimethylnapthalenes (DMN) has recently been reported to be shape selective by... 

Kikuchi, E., Y. Mogi and T. Matsuda. Shape Selective Disproportionation of Methylnaphthalene on ZSM-5 Catalyst. Collect. Czech. Chem. Comm., 1992, 57, 909-919. 

Lin, S.D., and C. Song. Noble Metal Catalysts for Low-Temperature Naphthalene Hydrogenation in the Presence of Benzothiophene. Catalysis Today, 1996, 31 (1), 93-104. Matsuda, T., K. Yogo, Y. Mogi and E. Kikuchi. Shape Selective Catalysis by ZSM-5 in Disproportionation of 2-Methylnaphthalene. Chemistry Letters, 1990, 1085-1088. 

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