Catalytic combustion of 1,2-dichlorobenzene at low temperature over Mn-modified Co3O4 catalysts

• Mn-modified Co3O4 catalysts with spinel structure with various Co/Mn ratios prepared by co-precipitation method.
• The incorporation of Mn into Co3O4 spinel structure greatly increases the dispersion of spinel.
• Substitute of Mn for Co3+ at octahedral sites with small amount can increase Co2+ concentration.
• Catalyst with high Co2+ amount and CoOCo species shows high activity for dichlorobenzene oxidation.
• The addition of Mn retards greatly the formation of 1,2,4-trichlorobenzene.

Mn-modified Co3O4 catalysts with spinel structure with various Co/Mn ratios prepared by co-precipitation method were characterized by XRD, Raman, TEM, HRTEM, XPS and H2-TPR, and used in catalytic combustion of 1,2-dichlorobenzene (o-DCB), as a model of dioxins. The results revealed that the catalyst with Co/Mn ratio of nine presented the highest activity with T90 of 347 °C and high stability at least 35 h at 3000 ppm o-DCB and 10% O2 at GHSV = 15,000 h−1. High activity could be ascribed to synergetic effect between activation of o-DCB on Co2+ sites and oxidation by surface active oxygen from Co3O4 nano-particles. Additionally, 1,2,4-trichloro- benzene was formed over Co3O4 to a significant extent through the reaction of adsorbed Cl species with o-DCB, while the incorporation of Mn in Co3O4 can effectively retard chlorination of o-DCB. A possible reaction pathway for the catalytic combustion of o-DCB on CoxMny catalysts was also investigated by in situ FTIR spectroscopy.

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