Confinement effect and Hetero-interface enable High-Performing MnOx/CeO2 oxidation catalysts with exceptional sintering resistance:Morphology effect of ceria support

Abstract

Combining both low-temperature activity and sintering resistance to meet practical requirements is still a great challenge for the most of effective catalysts. Herein, nano ceria with different morphologies (nanosphere, nanorod, nanocube) were applied to construct novel MnOx/CeO2 catalysts by post impregnation method for catalytic combustion of carcinogenic benzene. Detail structural/physio-chemical characterizations and activity measurements were conducted to investigate the structure-dependent behavior and interfacial effect on catalytic performance and sintering resistance properties. Compared to blank ceria supports, the low-temperature activities of all MnOx/CeO2 catalysts are significantly improved, and the T90 of best-performed MnOx/CeO2 nanorods composite is only 225 °C which is 197 °C lower than that of pure ceria nanorods. Experimental studies indicate low-temperature reducibility, oxygen mobility and surface defects could be greatly promoted by introducing hetero-interface with synergistic effects between ceria and MnOx nanocrystals. Moreover, the morphology-effect on sintering resistance is dramatically different, and the T90 of spherical MnOx/CeO2 increased to only 270 °C from 245 °C after thermal ageing at 750 °C for 100 h while this value raised to 507 °C from 256 °C on MnOx/CeO2 nanocube catalyst. This exceptional sintering resistance over spherical MnOx/CeO2 can be attributed to confinement effect of Ceria nanosphere where the supported MnOx nanoparticles is trapped in the nanopores so that it’s difficult for MnOx particles to aggregate through thermal ageing treatment. In addition, due to the small contact area between the spherical particles, there is no obvious sintering phenomenon such as growth, aggregation and collapse of the spherical particles after thermal ageing, further leading to enhancement of sintering resistance. This work provides a versatile strategy for designing highly active thermal combustion catalysts with good low-temperature activities and sintering resistance for industrial applications.