Deactivation and Regeneration Study of a Co-Promoted MoO₃ Catalyst in Hydrogenolysis of Dibenzofuran

Abstract

The efficient hydrogenolysis of dibenzofuran (DBF) was investigated at 360 °C and atmospheric hydrogen pressure with Co/MoO3 catalysts. All catalysts selectively cleaved the C–O bond and thus effectively transformed DBF to biphenyl (BP) at relatively moderate conditions. A strong promotional effect in the catalytic activity was observed over the Co/MoO3 catalyst with the optimal Co content of 3 wt %, as evidenced by the decreasing activation barrier which was resulted from Co-facilitated increase of active Mo species and acidic sites. The best catalytic activity was realized with almost 100% yield of BP over Co/MoO3. During 300 h of catalyst life test, the MoO3 and Co/MoO3 catalysts underwent a gradual deactivation because of the over-reduction of Mo species and carbon deposition as evidenced by the characterization of X-ray diffraction, X-ray photoelectron spectroscopy, Raman, thermogravimetric analysis–mass spectrum, and transmission electron microscopy. However, the deactivated catalyst can be regenerated with simple calcination using O2, without losing its initial activity. Characterization studies demonstrated that the formation of MoOxCyHz played an important role in stabilizing Mo species by preventing over-reduction to inactive Mo4+ species.