Role of surface vanadium oxide coverage support on titania for the simultaneous removal of o-dichlorobenzene and NOx from waste incinerator flue gas

• VOx/TiO2 catalyst is able to remove NO and 1,2-dichlorobenzene simultaneously.
• Surface vanadia density on titania determines their reactivity toward the destruction of NO and 1,2-dichlorobenzene.
• Isolated surface vanadia species on titania are most efficient to destroy 1,2-dichlorobenzene.
• Polymeric surface vanadia species on titania are most efficient to destroy NO.

The catalytic activity of VOx species supported on TiO2 was investigated in the simultaneous destruction of NO and 1,2-dichlorobenzene (o-DCB), as typical pollutants molecules in the off-gases from municipal waste incinerator (MWI) plants. Catalysts with different vanadium loading were prepared in order to obtain different VOx species and characterized by ICP-AES, XPS, N2 adsorption at −196 °C, XRD, H2-TPR, Raman and UV–vis–NIR DRS spectroscopy. The characterization results show that molecularly dispersed isolated and polymeric vanadia species form below the dispersion limit loading (“monolayer coverage”), while crystalline species form above it. We used moderate HNO3 treatment to partially leach vanadium oxide species, creating a series of catalysts with variable vanadia loading. The catalytic activity of the VOx/TiO2 catalyst shows that it is able to catalyze the destruction of both pollutants, although higher temperature is required for o-DCB oxidation than for NO reduction. Surface vanadia coverage has a clear effect on TOF and activation energy values, which underline that isolated vanadia species are more efficient for o-DCB oxidation, while the polymeric ones are more efficient for NO reduction.

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