Trimetallic nanocatalysts to enhanced hydrogen production from hydrous hydrazine: The role of metal centers

摘要

A simple low-cost cetyltrimethylammonium bromide (CTAB) assisted step-wise metal displacement plating method was used to prepare noble-and noble-metal free Ni/Fe/Pd, Ni/Fe/Ag and Ni/Fe/Cu nickel based nanocatalysts for the hydrogen production from complete hydrazine decomposition in basic solution at mild temperature. Pd/Ag/Ni was prepared by seedless method. Compared to the mono-metallic (Ag-0, Pd-0, Fe-0, Ni-0 and Cu-0) and bimetallic (Pd/Ag, Ag/Ni and Ni/Fe), the tri-metallic catalyst exhibits higher catalytic performance towards hydrazine decomposition. The nessler's reagent was used to detect the formation of ammonia during hydrazine dehydrogenation. The effect of [catalyst], [hydrazine], [NaOH] and temperature were determined on hydrogen generation by using Ni/Fe/Pd. The generation of hydrogen follows excellent first-order kinetics with [hydrazine]. The activation energies were determined to be 32.1, 42.3, 44.6 and 75.9 kJ/mol for Ni/Fe/Pd, Ni/Fe/Ag, Ni/Fe/Cu and Pd/Ag/Ni, respectively. Noble-metal nickel based Ni/Fe/Pd nanocatalyst shows better catalytic efficiency and hydrogen selectivity. The durability of Ni/Fe/Pd provides evidence to excellent catalytic degree for five kinetic runs. The morphology of Ni/Fe/Pd was determined by using FESEM, EDX, TEM, XRD and UV-visible spectroscope. Hydrazine dehydrogenation mechanism proposed, which follows the following rate-law:- d[hydrazine]dt = k1K(ad)OH]Ni@Fe@Pd][NH2-NH2](T) 1+K-b/[OH]+K-ad[NH2-NH2](T)(C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.