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 CoCeAlOx catalyst achieved 94.3% and 65.3% NH3 conversion at 550 °C and 500 °C (GHSV = 30 000 mL gcat−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 CoCeAlOx. 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.