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

Designing a bifunctional catalyst to concurrently activate NO and O2 is of fundamental importance to the simultaneous catalytic removal of NOx 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 (O22-) 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 NOx and toluene than that of the CeTi catalyst.