Dual Activation of Molecular NO and O2 on a Pr-Doped CeO2-TiO2 Catalyst for the Simultaneous Catalytic Purification of NOx and Toluene

Abstract

Designing a bifunctional catalyst to concurrently activate NO and O₂ is of fundamental importance to the simultaneous catalytic removal of NO_x and VOCs. During this process, sufficient electron transfer from the catalyst surface to the antibonding π* orbitals of adsorbed NO and O₂ is necessary to facilitate the adsorption and subsequent bond cleavage. Herein, an electronic orbital coupling strategy is applied by doping praseodymium (Pr) into a CeO₂-TiO₂ (CeTi) composite oxide to obtain a PrCeTi bifunctional catalyst, which has a strong interaction with NO to form NO⁺, further splitting with N³⁺ production and thereby enhancing NH₃-SCR performance following the Langmuir–Hinshelwood mechanism. Meanwhile, O₂ adsorbs on the PrCeTi catalyst surface to produce superoxide (O₂^–) and further transforms into peroxide (O₂^2–) which, along with increased temperature, boosts the PhCH₃ total oxidation. Finally, the coactivation of NO and O₂ over the PrCeTi catalyst contributes to its better simultaneous removal efficiency of NO_x and toluene than that of the CeTi catalyst.