Mn-Promoted Co3O4/TiO2 as an efficient catalyst for catalytic oxidation of dibromomethane (CH2Br2)

Brominated hydrocarbon is the typical pollutant in the exhaust gas from the synthesis process of Purified Terephthalic Acid (PTA), which may cause various environmental problems once emitted into atmosphere. Dibromomethane (DBM) was employed as the model compound in this study, and a series of TiO2-supported manganese and cobalt oxide catalysts with different Mn/Co molar ratio were prepared by the impregnation method and used for catalytic oxidation of DBM. It was found that the addition of Mn significantly enhanced the catalytic performance of Co/TiO2 catalyst. Among all the prepared catalysts, Mn(1)-Co/TiO2 (Mn/Co molar ratio was 1) catalyst exhibited the highest activity with T-90 at about 325 degrees C and good stability maintained for at least 30 hat 500 ppm DBM and 10% O-2 at GHSV = 60,000 h(-1), and the final products in the reaction were COx, HBr and Br-2, without the formation of Br-containing organics. The high activity and high stability might be attributed to the redox cycle (Co2+ + Mn4+ <-> Co3+ + Mn3+) over Mn-promoted Co3O4/TiO2 catalyst. Based on the results of in situ DRIFT studies and analysis of products, a plausible reaction mechanism for catalytic oxidation of DBM over Mn-Co/TiO2 catalysts was also proposed. (C) 2016 Elsevier B.V. All rights reserved.