Enhanced dual-catalytic elimination of NO and VOCs by bimetallic oxide (CuCe/MnCe/CoCe) modified WTiO2 catalysts: Boosting acid sites and rich oxygen vacancy

Abstract

It remains challenging to remove nitrogen oxides (NOx), benzene (C6H6), and toluene (C7H8) simultaneously under conditions of low oxygen and high SO2 concentration. Herein, CuCe, MnCe, and CoCe doped WTiO2 catalysts were designed. The prepared CuCe-WTiO2 catalyst consistently maintained more than 85% NO, 92% C6H6, and 91% C7H8 removal in 260–420 °C under 3.33% O2 and 1000 ppm SO2. The adequate charge flow between the catalyst surface and the gas molecules was enhanced, promoting SO2 tolerance of CuCe-WTiO2. More NH3, NH4+, and -NH2 were adsorbed with acid sites on the CuCe-WTiO2 surface. The high concentration of adsorption centers and superior redox properties effectively improved the co-catalytic efficiency. The primary intermediates in the reduction processes via the Langmuir-Hinshelwood and Eley-Rideal mechanisms were NO2, bridged nitrite (NO2–), and monodentate nitrite (NO2–). The generation of reactive chemisorbed oxygen (Oα) becomes more accessible with the transfer of electrons from Ce4+ to adsorbed O2. C6H6 and C7H8 are progressively oxidized by Oα and eventually completely mineralized to CO2 and H2O. This study is anticipated to offer a new option for co-catalytic removal of NO, C6H6, and C7H8.