Liquid phase isophorone oxide rearrangement over mesoporous Al-MCM-41 materials

Abstract

The rearrangement of isophorone oxide has been investigated over Al-MCM-41 type mesostructured catalysts having different Si/Al molar ratios. The main rearrangement products are the ¿-diketone and the keto aldehyde, whereas the product coming from the decarbonylation of the latter is detected in minor amounts. The textural properties and the number of acid sites of Al-MCM-41 materials influence the extent of isophorone oxide rearrangement reaction. The best catalytic performance in regards to epoxide conversion is obtained for a catalyst having a molar Si/Al ratio around 40 due to a right contribution of acid site concentration and pore size. However, irrespective to the aluminium content of the catalysts and the reaction temperature, the selectivity to the desired keto aldehyde was around 80%. Al-MCM-41 materials are superior catalysts compared to zeolites in terms of both activity and aldehyde selectivity. As a consequence of its large pore size, the use of Al-containing mesostructured materials as catalyst in isophorone oxide rearrangement allows the diffusional problems present in zeolites to be avoided.