Monolithic catalysts based on cobalt/eggshells for toluene combustion. Synthesis and characterization

DEHARBE, M. DE LOS MILAGROS; GÓMEZ, LETICIA E.; SERRA, RAMIRO M.; BOIX, ALICIA V.

Materials Today Chemistry

Elsevier

Año: 2025 vol. 47

2468-5194

Chicken eggshell waste was employed as a sustainable alternative to traditional calcium sources to develop monolithic cobalt–calcium (M-CoxCa) catalysts for toluene oxidation. This green, low-cost route is promising for industrial applications. The catalytic behavior of structured catalysts was better than that of their precursor powders. The best catalyst, with 16 wt % of cobalt (M−Co16Ca) achieved total toluene conversion (T100 %) at 240 °C. Remarkably, M−Co8Ca, with half the cobalt content, reached T100 % at only 10 °C higher, highlighting the high catalytic performance even at low cobalt loadings. In addition, the catalytic response to variations in toluene and oxygen concentration in the feed demonstrated the operational flexibility of these materials. The XRD, Raman, and XPS characterization techniques allowed identifying cobalt spinel as the active phase, promoted by calcium carbonate. TPR analysis revealed a synergistic interaction between Ca and Co species, while SEM-EDS confirmed their homogeneous distribution on the monolith surface. These results position eggshell-derived cobalt-calcium structured catalysts as robust, efficient, and sustainable materials for hydrocarbons control.