Epoxidation of limonene over low coordination Ti in Ti-SBA-16

Epoxidation of limonene was studied over Ti-SBA-16 catalysts prepared using two different post grafting techniques. The first one consisted of an in-situ synthesis of a titanium acetylacetone (ACAC) precursor and the other one used directly TiO(ACAC)(2). Reaction conditions such as temperature, concentration of TBHP and solvent polarity were examined. The reaction should be carried out at 75 degrees C in acetonitrile using a TBHP/Iimonene molar ratio of 11/6.The conversion of limonene reached 80% with a 1,2-limonene oxide selectivity of 79% for both impregnation methods using Ti-SBA-16 with a Ti/Si atomic ratio of 7.3%. Under the same conditions the 3D pore structure of SBA-16 support favors reactants and products mass transfer compared to the 2D pore structure of SBA-15. No differences in catalytic activity were observed as atomic ratio Ti/Si was varied from 5 to 13.4% in Ti-SBA-16. Repeated catalytic tests showed no change in activity over three process cycles. 2017 Elsevier B.V. All rights reserved.