H. Hoser, S. Krzyzanowski
Jun 23, 1975
Citations
0
Influential Citations
11
Citations
Journal
Journal of Catalysis
Abstract
Abstract Isomerization of cis -2-butene, 1-butene, and 3,3-dimethyl-1-butene was studied over CoX zeolites, degassed at various temperatures. Activity of these catalysts was found to be affected by the degree of exchange of Na + for Co 2+ ions. The initial rise in the Co 2+ ion content in the zeolite lattice is accompanied by a very small increase in catalytic activity. It is only after the exchange of Na + for Co 2+ has exceeded ~ 28% that the catalytic activity increases rapidly, in a nearly direct relation to the degree of exchange. Also, the catalytic activity of the zeolites proved to be in a clear-cut correlation with the “concentration” of tetrahedral-coordinated Co 2+ ions in the zeolite lattice. It was postulated that, in the systems investigated, the active centers consist of the hydroxyl groups that arise by residual water molecules being split on the tetrahedral-coordinated Co 2+ ions, Co(OH 2 ) 2+ CoOH + + H + , and subsequently lattice oxygen atoms being immediately protonated to reconstitute new hydroxyl groups. A mechanism has been suggested involving a secondary carbonium-ion intermediate.