Selective oxidation of ethane over hydrothermally synthesized Mo–V–Al–Ti oxide catalyst

Abstract

Mo–V-based oxide catalysts are known highly active for various hydrocarbon selective oxidations. Particularly those which are monophasic giving XRD diffraction at d=4 Å are extremely active for alkane oxidations. We succeeded to synthesize this unique monophasic material by hydrothermal method and obtained Mo 6V 2Al 1O x mixed oxide catalysts which showed activities for gas-phase ethane oxidation to ethene and acetic acid. The addition of titanium to the Mo 6V 2Al 1O x oxide catalyst was found to result in a marked increase of the activity for the ethane selective oxidation, which was due to the morphological change of the catalyst particles and the increase of surface area by the addition of titanium. During the heat-treatment above 550°C under a nitrogen stream, the structural phase of the Mo 6V 2Al 1Ti 0.5O x catalyst giving the XRD diffraction at d=4 Å transferred to (Mo 0.93V 0.07) 5O 14-like phase with drastic decreases of the oxidation activity and the surface area. On the basis of kinetic data and the fact that the lower reaction temperature and the existence of water vapor in the feed facilitated the formation of acetic acid, it is concluded that the breaking of C–H bond of ethane is the rate determining of the oxidation and acetic acid do not form through ethene.