Promotional effect of Mn in nickel catalysts supported on MgO: Engineering Ni-oxygen vacancy interfaces to boost glycerol dry reforming

Ni-based catalysts are promising for glycerol dry reforming (GDR) to produce renewable hydrogen but are prone to deactivation by coking and sintering. Here, we report the Ni/MgO catalyst promoted with Mn featuring Ni 0 species stabilized by Ni 2+ ions on the defect-rich combined support. Characterization analyses reveal that the Ni/MgMn 0.2 O x catalyst possesses the most abundant oxygen vacancies, which facilitates CO 2 dissociation and the formation of reactive oxygen species, thereby enhancing catalytic activity and reducing coke formation during GDR reaction. Ni binding environment sensitive experiments demonstrate that introducing Mn with a Mn/Mg:0.2 molar ratio suppressed the formation of the NiO-MgO solid solution, known for its excessively strong interaction between metal and support. Consequently, the Ni/MgMn 0.2 O x catalyst, featuring an adequate amount of metallic Ni⁰ with moderated metal-support interaction (MSI), played a key role in enhancing catalytic performance. This catalyst demonstrates high catalytic activity and excellent stability during the GDR reaction, achieving conversions of 70.13 % and 28.93 %, with low deactivation rates of 0.63 %/h and 0.86 %/h for glycerol and CO 2 , respectively. • Defect-rich Ni/MgMn 0.2 O x catalyst with tuned MSI is efficient for GDR. • Surface defects generate reactive oxygen species by CO 2 dissociation. • Mn combined with Ni/MgO also moderates MSI, increasing Ni° accessibility for GDR. • 70.1 % of glycerol conversion with excellent stability was seen over Ni/MgMn 0.2 O x .