from first principles PP-I-1

PP-II-16Clean Synthesis of Adipic Acid Catalyzed by Keggin-Type PolyoxometalateTahar A., Benadji S., Mazari T., Dermeche L., Rabia C.Laboratoire de Chimie du Gaz Naturel, Faculté de Chimie, Université des Sciences et de laTechnologie Houari Boumediène (USTHB), BP 32, El-Alia, 16111 Bab-Ezzouar, Alger, Algériec_rabia@yahoo.fr/crabia@usthb.dzThe adipic acid is a valuable raw material, used in the production of nylon-6, 6, and foodadditives. Its industrial production, based on the oxidation of a mixture of cyclohexanol andcyclohexanone with nitric acid, leads to NO x , pollutant gas, as by-products. An alternativesynthetic pathway to this process for an environmentally more friendly is the use of Keggintypepolyoxometalates (POMs) as catalysts which offer a unique structural versatility thatmakes them possible to tune the composition in function of the requirements of thereaction [1,2] . In the present work, we report the catalytic performance of Keggin-type POMsof formula M x PMo 12 O 40 (M: H, Ni, Co, Fe) for the liquid-phase oxidation of cyclohexanol toadipic acid in the presence of aqueous hydrogen peroxide (30%).The M x PMo 12 O 40 salts were prepared, characterized by BET method, IR and UV-Visspectroscopies and XRD and tested in the liquid-phase oxidation of cyclohexanol by H 2 O 2(30%) at 90°C.Among the POMs studied, FePMo 12 has no catalytic activity. For other POMs, the obtainedcatalytic results showed that both amounts and nature of counter–ion influence the adipic acidyields. With an amount of POM varying from 0.031 g to 0.250 g, the highest adipic acidyields, 19.3% for CoPMo 12 , 16.4% for NiPMo 12 and 13.2% for HPMo 12 were obtained with amass of 0.125, 0.062, and 0.125 g, respectively. The high catalytic activity observed in thepresence of CoPMo 12 with respect to adipic acid could be attributed to the simultaneouspresence of redox couples Co(III)/Co(II) and Mo(VI)/Mo(V). The mechanism of the liquidphase cyclohexanol oxidation can be similar to that of Mars-van KrevelenThis study showed the efficient POMs Keggin for the direct catalytic oxidation ofcyclohexanol to adipic acid with hydrogen peroxide.References:[1] I.V. Kozhevnikov, Russ. Rev. 62 (1993) 437.[2] N. Mizuno, K. Kamata, Coord. Chem. Rev. 255 (2011) 2358-2370.147