Promotion Effect of Ga−Co Spinel Derived from Layered Double Hydroxides for Toluene Oxidation

Considering the radius similarity of Al3+ (0.50 Å) and Ga3+ (0.62 Å), Al−Co and Ga−Co layered double hydroxides (LDH) was prepared as precursor to improve the synergetic interaction of the transition metals. The Al−Co and Ga−Co spinel catalysts were obtained by the following calcination for the toluene oxidation. The Ga−Co (Ea=79.5 kJ mol−1) showed higher activity than the Al−Co (Ea=95.4 kJ mol−1), and it exhibited excellent stability and resistance to carbon deposition during a 50 h reaction period at 300 °C. Characterization results indicated that the improved activity of Ga−Co spinel could be attributed to the higher reducibility (H2‐TPR), more surface Co3+ and adsorbed oxygen in quantity (XPS) and adsorbed toluene (Toluene‐TPD) than Al−Co spinel. Compared with traditional Ga−Co binary catalyst, the spinel structure possessed more B‐sites cations outermost of the surface and surface oxygen vacancies for the toluene adsorption and ring‐open reaction.