Enhanced NH3 decomposition for H2 production over bimetallic M(M=Co, Fe, Cu)Ni/Al2O3
2021
Fu, Enkang | Qiu, Yu | Lu, Huaichang | Wang, Sijun | Liu, Lishan | Feng, Hanjun | Yang, Yanxin | Wu, Zizhan | Xie, Yunlong | Gong, Feng | Xiao, Rui
Ammonia (NH₃) has been regarded as an attractive energy source for hydrogen production via catalytic decomposition, especially over non-noble metal catalysts. Owing to the decent performance and low cost, nickel (Ni) based catalysts have been widely studied for catalytic decomposition of NH₃ where the decomposition rates, can be further tailored by adding other metals. Herein, we synthesized bimetallic M(M = Co, Fe, Cu)Ni/Al₂O₃ catalysts delivering superior catalytic performance at a wide temperature range of 350–750 °C. Co-Ni/Al₂O₃ demonstrated nearly 100% conversion of NH₃ decomposition to H₂ at 700 °C and the gas hourly space velocity of 30,000 ml g⁻¹ min⁻¹, which was ~20.85% higher than that of intrinsic Ni/Al₂O₃. The structural characterizations indicated that Co could decrease the particle size and enhance the dispersion of active sites. The density functional theory calculations substantiated that the associative decomposition of N to generate N₂ was the rate-determining step of the NH₃ decomposition reactions. NH₃ Temperature Programmed Desorption (TPD) results suggested that the enhanced catalytic performance was predominantly attributed to the Co that decreases the energy barrier for the associative decomposition of N to form N₂. This study provides new insights in designing diverse catalysts for efficient NH₃ decomposition for controllable H₂ production.
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