Al2O3-modified CuO-CeO2 catalyst for simultaneous removal of NO and toluene at wide temperature range

A series of Al2O3-modified CuO-CeO2 (CuCeAlx) was synthesized to reveal the effect of Al2O3 addition on catalytic performance and the proposed mechanism for simultaneous removal of NO and toluene at a broad temperature range. BET, XRD, TEM, XPS, NH3-TPD, H2-TPR, and in situ DRIFTS were used to characterize these catalysts. Results demonstrated that Al2O3-modified CuO-CeO2 catalysts showed the excellent NH3-SCR performance at a broad temperature range (200–400 °C) and good low-temperature activity for toluene oxidation. The modification of Al2O3 significantly tunes the physical and textural properties and induces the formation of oxygen vacancies via the interaction between Ce4+/Ce3+ and Cu2+/Cu+ (Ce4+ + Cu+ ↔ Ce3+ + Cu2+). Besides, the inhibition effect of NH3 on toluene oxidation was confirmed in that the active oxygen species reacted preferentially with NH3 rather than the oxidation intermediates of toluene, while NO had a promotional effect on toluene oxidation owing to the reaction of C7H8 + 18NO = 9 N2 + 7CO2 + 4H2O. At the same time, toluene could also be reducing agents of NO, which was beneficial to NH3-SCR reaction, Based on the results, the proposed mechanism for simultaneous removal of toluene and NO over Al2O3-modified CuO-CeO2 catalysts was revealed.