Enhanced NH3 decomposition for H2 production over bimetallic M(M=Co, Fe, Cu)Ni/Al2O3.

Ammonia (NH 3) 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 NH 3 where the decomposition rates, can be further tailored by adding other metals. Herein, we synthesized bimetallic M(M = Co, Fe, Cu)Ni/Al 2 O 3 catalysts delivering superior catalytic performance at a wide temperature range of 350–750 °C. Co-Ni/Al 2 O 3 demonstrated nearly 100% conversion of NH 3 decomposition to H 2 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/Al 2 O 3. 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 N 2 was the rate-determining step of the NH 3 decomposition reactions. NH 3 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 N 2. This study provides new insights in designing diverse catalysts for efficient NH 3 decomposition for controllable H 2 production. • Various biometallic M(M = Co, Fe, Cu)Ni/Al 2 O 3 catalysts were developed for NH 3 decomposition. • The associative decomposition of N to form N 2 was determined to be the rate-limiting step. • Co dopant lowered the energy barrier for the associative decomposition of N in Ni/Al 2 O 3 • Enhanced NH 3 decomposition performance was obtained by using CoNi/Al 2 O 3. [ABSTRACT FROM AUTHOR]