Development and Evaluation of Ni–Cu–Pt Monolithic Catalysts for Improved Ethanol Autothermal Reforming and Hydrogen Production

Abstract

This study investigates the development and characterization of Ni-based catalytic monoliths for ethanol reforming, focusing on the effects of incorporating Cu and Pt as promoters. Al₂O₃ monoliths were coated with α-Al₂O₃ and impregnated with Ni, Cu, and Pt by using a wet impregnation method. The catalysts were characterized by field-emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and temperature-programmed reduction (TPR). The multitechnique characterization results revealed differences between the monometallic Ni/α-Al₂O₃ catalyst and the trimetallic Ni-Cu-Pt/α-Al₂O₃ catalyst. A unique flower-like structure was identified in the trimetallic catalyst, formed due to acid leaching during the Pt impregnation step. The metal impregnation process did not alter the crystalline structure of the Al₂O₃ substrate with both catalysts primarily exhibiting oxide phases. The Ni-Cu-Pt/α-Al₂O₃ catalyst has surface concentrations of Cu and Pt around 1.3% or lower, while Ni concentration exceeds 4.8%, confirming the presence of all three metals at the catalyst surface, despite the acid leaching caused by the Pt impregnation. TPR analysis indicated complex metal-support interactions in the trimetallic catalyst, with distinct reduction peaks compared with the monometallic Ni/α-Al₂O₃ catalyst. Catalytic evaluation revealed that the trimetallic catalyst achieved similar ethanol conversion in comparison with the monometallic Ni/α-Al₂O₃ catalyst but exhibited lower hydrogen selectivity due to reduced C–C bond breaking, likely influenced by the presence of Cu. These findings highlight the potential and challenges of using trimetallic catalysts in ethanol reforming, with implications for optimizing catalyst composition and reaction conditions for hydrogen production.