Electrodeposition of a Li-Al Layered Double Hydroxide (LDH) on a Ball-like Aluminum Lathe Waste Strips in Structured Catalytic Applications: Preparation and Characterization of Ni-Based LDH Catalysts for Hydrogen Evolution

A functionally structured catalyst was explored for ethanol steam reforming (ESR) to generate H-2. Aluminum lathe waste strips were employed as the structured catalytic framework. The mixed metal oxide (Li-Al-O) was formed on the surface of Al lathe waste strips through calcination of the Li-Al-CO3 layered double hydroxide (LDH), working as the support for the formation of Ni catalyst nanoparticles. NaOH and NaHCO3 titration solutions were, respectively, used for adjusting the pH of the NiCl2 aqueous solutions at 50 degrees C when developing the precursors of the Ni-based catalysts forming in-situ on the Li-Al-O oxide support. The Ni precursor on the Al structured framework was reduced in a H-2 atmosphere at 500 degrees C for 3 h, changing the hydroxide precursor into Ni nanoparticles. The titration agent (NaOH or NaHCO3) effectively affected the physical and chemical characterizations of the catalyst obtained by the different titrations. The ESR reaction catalyzed by the structured catalysts at a relatively low temperature of 500 degrees C was studied. The catalyst using NaHCO3 titration presented good stability for generating H-2 during ESR, achieving a high rate of H-2 volume of about 122.9 L/(g(cat)center dot h). It also had a relatively low acidity on the surface of the Li-Al-O oxide support, leading to low activity for the dehydration of ethanol and high activity to H-2 yield. The interactions of catalysts between the Ni precursors and the Li-Al-O oxide supports were discussed in the processes of the H-2 reduction and the ESR reaction. Mechanisms of carbon formation during the ESR were proposed by the catalysts using NaOH and NaHCO3 titration agents.

Automated summary

This study explores a functionally structured catalyst for ethanol steam reforming, aiming to generate H-2 at a relatively low temperature. Aluminum lathe waste strips are used as the structured catalytic framework, with a mixed metal oxide (Li-Al-O) formed on their surface to support the formation of Ni catalyst nanoparticles. The choice of titration agent for adjusting the pH of the NiCl2 aqueous solutions has a significant impact on the physical and chemical characteristics of the catalyst. The catalyst using NaHCO3 titration shows good stability and high H-2 yield during ESR.