Surface acidity and cumene conversion. I. A study of γ-alumina containing fluoride, cobalt, and molybdenum additives

Authors:

• P.M. Boorman,
• R.A. Kydd,
• Zenon Sarbak,
• A. Somogyvari

Abstract

A series of catalysts containing fluoride, cobalt, and molybdenum as additives to γ-alumina both individually and in combination has been prepared and studied. The surface acidity has been studied by infrared spectroscopy of adsorbed pyridine and correlated with reactivity for cumene conversion. After preheating to 400 °C in vacuo, only Lewis acidic sites are present on the surface of γ-Al₂O₃, but the addition of fluoride ion initiates some Brønsted acidity and enhances the strength of the Lewis acidic sites. The presence of MoO₃ introduces another group of Brønsted acidic sites, but CoO, as a single additive, has little effect on either the Brønsted or Lewis acidity. As expected, the presence of fluoride ion enhances the activity of all the catalysts for the cracking of cumene to benzene. Although MoO₃ enhances the Brønsted acidity of γ-Al₂O₃, rather surprisingly this increased acidity did not enhance significantly the activity of the catalyst for cumene cracking to benzene. © 1985.