Zirconia‐Supported Cobalt Catalysts: Activity and Selectivity in NO Reduction by CO. Issue 35 (13th December 2017) - Lima, Thiago M.
Abstract: Cobalt catalysts supported on tetragonal and monoclinic zirconia were prepared using a one‐pot procedure through the incorporation of a Co3 O4 colloidal suspension during the support synthesis and evaluated in the reaction of NO reduction by CO. A better dispersion of the active phase was obtained by this method when compared to the conventional impregnation one. Furthermore, the crystalline phase of zirconia in the supports had a crucial effect in the dispersion of the cobalt species, being that the pure tetragonal phase led to a higher dispersion of the active phase. The one‐pot prepared tetragonal zirconia led to cobalt active species that consisted in well‐dispersed small agglomerates of Co3 O4 and Co 2+ species as oxo‐ions which displayed the best catalytic performance among the studied catalysts, with the highest NO conversion (75%) and high selectivity to N2 (85%) at 300 °C. These results show that the one‐pot methodology employed in this work has a strong potential to produce suitable catalysts for the abatement of NOx emissions. Abstract : Tuning N2 selectivity: The incorporation of a colloidal suspension of Co3 O4 in the ZrO2 preparation (one‐pot method) improved the Co dispersion as small agglomerates of cobalt oxide and cobalt species as oxo‐ions. These features led to a marked increase in the selective reduction of NO to N2 using CO as reducing agent. Better dispersion of Co3 O4 and selectivity to N2 was achieved combining the one‐pot method with a pure tetragonal zirconia phase.