The Oxyiodination of Aromatic Compounds over Zeolite KX: The Case of Naphthalene

Article abstract of DOI:10.1006/jcat.1994.1129

Aromatic compounds, iodine, and oxygen react in the vapor phase over basic faujasite zeolites at 225-350 deg C to produce iodoaromatic compounds and water.When the aromatic compond is naphthalene and the reaction is conducted in the region of 250 deg C over KX zeolite, a shape-selective catalytic oxyiodination occurs, resulting in predominant iodination at the 2-position of naphthalene.Typical product mixtures contain approximately 10percent 1-iodonaphthalene, 65percent 2-iodonaphthalene, 19percent 2,6-diiodonaphthalene, 5percent other diiodonaphthalene isomers, and 1percent mixed triiodonaphthalene isomers at approximately 20percent naphthalene conversion and 80-99percent iodine conversion.Excessive conversion and excessive residence time reduce the selectivity to kinetic product, 2,6-diiodonaphthalene, but do not alter the selectivity for iodination in the 2-position.Selectivity for iodination in the 2-position is decreased by substituting sodium for potassium in the zeolite, by alterning the faujasite zeolite Si/Al ratio significantly above or below 1.25 and by increasing the amount of iodine in the reactant feed.