Influencia del tratamiento con diborano sobre la actividad catalítica de óxidos metálicos

Abstract

In a previous work a relationship was found between the amount of OH groups at the surface of TiO2 and Cr203 catalysts, and their activity in fortnic acid dehydration. In this paper the effect of the treatment with diborane on the activity of those catalyst has been studied. The activation energy and frequency factor for dehydration reaction are largely afected in this way, but no change was recorded in the activity of the oxides toward dehydrogenation. From the I.R. study of the treated surfaces, the presence of = B - OH has been stablisbed. Tbese groups must be help to the surface on the same possitions that the OH in the untreated oxides, and can be removed when the sample is washed with hot water. This restores the OH groups and the catalytic activity of the sample to its original value. Cbanges in EH2 tor the set of Cr203 oxides, sintered between 400 and 1000 ºC, are explained as due to Cr6+ in tetrahedral interstices at the Cr203- corundum lattice.