Promoting effect of Ti on MnTiOx catalysts for benzene highly efficient oxidation

Abstract

MnTiOx catalysts with different quantities of Ti are synthesized with a hydrothermal method and employed in the catalytic oxidation of benzene. By controlling the relative content of Mn and Ti, the effect of Ti content has been investigated from physicochemical properties and activity points of view. Ti enables the formation of Lewis acid with electrophilic properties and simultaneously leads to the increase of Mn4+ and surface lattice oxygen numbers. Additionally, it is established that the addition of Ti4+ can lead to the partial substitution of Mn3+ in MnTiOx to create the Mn-O-Ti structure, improving the active oxygen transfer capacity, which is crucial for catalytic activity. After optimization, the best catalytic performance sample is MnTiOx-0.33 with the T90 = 258 oC at GHSV = 45000 ml·g-1·h-1. It is proposed that the catalytic oxidation of benzene takes place on the surface of MnTiOx-0.33 through the MVK mechanism.