Highly efficient cobalt catalysts promoted by CeO2–Al2O3 for ammonia decomposition†

Abstract

Hydrogen production by ammonia decomposition reveals great advantages in the utilization of hydrogen. Low-cost, efficient and stable transition metal catalysts are the key for the ammonia decomposition reaction. Using multi-component promoters adjust the electronic and geometric structures of bulk catalysts, which might be an effective approach for obtaining non-noble metal catalysts with excellent performance. In this work, CeO₂–Al₂O₃ bi-promoters were used and significantly improved the catalytic performance of bulk cobalt catalysts. The optimized CoCeAlO_x catalyst achieved 94.3% and 65.3% NH₃ conversion at 550 °C and 500 °C (GHSV = 30 000 mL g_cat⁻¹ h⁻¹), respectively, and exhibited strong stability within 200 h. It was found that the interaction between Co–CeO₂–Al₂O₃ effectively inhibited the aggregation of the Co⁰ active species, which enormously promoted the catalytic activity and stability of CoCeAlO_x. CeO₂–Al₂O₃ bi-promoters adjusted the surface properties of catalysts, bringing suitable NH₃ adsorption and N₂ desorption, and suppressing the hydrogen poisoning significantly. This work provided a reliable strategy for the construction of high-efficiency catalysts working under the harsh conditions for ammonia decomposition.