Influence of Ce/Cu ratio on the performance of ordered mesoporous CeCu composite oxide catalysts

• Ordered mesoporous CeCu oxide catalysts were synthesized by hard-template method.
• Effect of Ce/Cu molar ratio on the physicochemical properties of CeCu oxide catalyst was investated.
• Benzene, toluene, xylene, and ethylbenzene were used as the air pollutants to be studied.
• Catalytic activity is related to the surface active oxygen species and reducibility.

CeCu composite oxide catalysts were prepared by a hard-template method using different mole ratios of Ce/Cu (being designated as CeCu-HTx, where x is the Ce/Cu molar ratio). The prepared catalysts were characterized by XRD, TEM, AAS, XPS, and H2-TPR. The catalytic properties of the prepared CeCu composite oxide catalysts were also investigated by phenyl VOCs (benzene, toluene, xylene, and ethylbenzene) catalytic combustion in air. XRD results showed that the CuO species can fully dissolve into the CeO2 lattice to form CeCu solid solutions having the fluorite structure of crystal-phase CeO2. TEM and low-angle XRD results indicated that CeCu-HT3 had a well-ordered and developed mesoporous structure with uniform pore size, which is better than the CeCu-HT2 and CeCu-HT4. XPS and H2-TPR results showed that CeCu-HT3 had abundant active oxygen species and superior reducibility. CeCu-HT3 had higher toluene catalytic combustion activity than CeCu-HT2 and CeCu-HT4 in air. The minimum reaction temperature at which toluene conversion exceeded 90% on CeCu-HT3 was 225 °C. Toluene catalytic combustion conversion on CeCu-HT3 at 240 °C exceeded 99.3% with decreased toluene concentration in air to below 70 ppm. The phenyl VOCs catalytic combustion activity on the CeCu-HT3 catalyst follows the order ethylbenzene > toluene > xylene > benzene. The CeCu-HT3 catalyst shows high stability and efficiency for toluene catalytic combustion in air. And the CeCu-HT3 catalyst can be applied in purification treatments for air containing a wide range of toluene concentrations.