A comparative study of bulk and 3DOM-structured Co3O4, Eu0.6Sr0.4FeO3, and Co3O4/Eu0.6Sr0.4FeO3: Preparation, characterization, and catalytic activities for toluene combustion

Three-dimensionally ordered macroporous (3DOM) and bulk Co3O4, Eu0.6Sr0.4FeO3 (ESFO), and 3 wt% Co3O4/Eu0.6Sr0.4FeO3 (3Co3O4/ESFO) were fabricated using the PMMA-templating (3DOM-Co3O4 and 3DOM-ESFO), citric acid-assisted hydrothermal (Co3O4-bulk and ESFO-bulk), and incipient wetness impregnation (3Co3O4/3DOM-ESFO and 3Co3O4/ESFO-bulk) methods, respectively. Physicochemical properties of these materials were characterized by means of various techniques, and their catalytic activities were evaluated for toluene combustion. Compared to the nonporous Co3O4 and ESFO samples, the 3DOM-Co3O4, 3DOM-ESFO, and 3Co3O4/3DOM-ESFO samples exhibited higher oxygen adspecies concentrations and better low-temperature reducibility. The 3Co3O4/3DOM-ESFO sample showed the best catalytic activity for toluene combustion, giving the T50% and T90% of 251 and 269 °C at 20,000 mL/(g h), respectively. The apparent activation energies of these samples were in the range of 72–88 kJ/mol. We believe that the higher oxygen adspecies concentration, better low-temperature reducibility, and synergistic action between Co3O4 and 3DOM-structured ESFO were responsible for the excellent catalytic performance of 3Co3O4/3DOM-ESFO.

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► 3DOM-structure and bulk Co3O4, Eu0.6Sr0.4FeO3, and Co3O4/Eu0.6Sr0.4FeO3 are prepared.
► Porous samples are higher than bulk samples in Oads content and better reducibility.
► The porous samples exhibit higher catalytic performance than the bulk samples.
► There is a synergistic effect between Co3O4 and Eu0.6Sr0.4FeO3.
► Catalytic activity is governed by Oads content, reducibility, and synergistic action.