Abstract
Mo/zeolites catalysts were investigated in ethane and ethylene ammoxidation into acetonitrile. The catalysts were prepared either in solid-solid or liquid-solid interface after varying different parameters. The stabilization of Mo species upon the exchange is dependent on the hydrophilic/hydrophobic character of the zeolite and the type of Mo precursor. In fact, zeolites with low Si/Al molar ratios should be avoided due to their higher dehydration enthalpy values (Δ dehyd .H). On the other hand, the use of MoOCl 4 , Mo(CO) 6 and MoCl 3 precursors and zeolites with high Si/Al ratios led to inefficient [Mo 7 O 24 ] 6species and amorphous MoO 3 which catalyzes the combustion reaction. Nevertheless, the use of MoCl 5 , MoO 3 and MoO 2 (C 5 H 7 O 2) 2 led to promising activities. In catalysis, [MoO 4 ] 2species are required to activate C 2 H 6 into C 2 H 4 , while [Mo x O3 x+1 ] 2-(x =1, 2) species catalyze the ammoniation of C 2 H 4 and the ethylamine dehydrogenation into CH 3 CN. Interestingly, active catalysts could be obtained by humid impregnation and a simultaneous oxidative treatment. Such a treatment improves the dispersion state of crystalline MoO 3 , which activate ethane molecules. It is judicious to perform C 2 H 6 oxidative dehydrogenation before ammoxidation since the interference between the different investigated parameters could be noted.