Development of porous nickel catalysts by low-temperature Ni-Al chemical alloying and post selective Al leaching, and their application for ammonia decomposition

Abstract

Micron-sized Ni-Al alloy powders (Ni-x wt.%Al, x = 40, 50, 60) were synthesized using the low-temperature chemical alloying (LTCA) at 500 degrees C. The three different as-prepared Ni-Al alloy powders were composed of Ni2Al3 and/or NiAl3 phases while achieving thermodynamic equilibrium compositions (Ni-40 wt%Al, Ni2Al3; Ni-50 wt%Al, the coexistence of Ni2Al3 and NiAl3; Ni-60 wt%Al, NiAl3). The LTCA method demonstrates that it is capable of producing Al-rich Ni-Al alloy powders while maintaining a particle size similar to that of the starting Ni particles. The three Ni-Al alloy powders were used as precursor materials to fabricate porous nickel catalysts through a selective aluminum leaching process, followed by the enlargement of the surface area. Alteration of the material characteristics with respect to the leaching time was investigated using XRD, FESEM-EDS, TEM, XPS, TPR, BET, and particle size analysis. The nickel skeletal catalysts with the increased BET-surface areas (50-111 m(2)/g) displayed high reactivity toward ammonia decomposition. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.