Promotional role of gallium in an eco-friendly synthesized CuZnAlGa catalyst for low-temperature methanol steam reforming

Abstract

Methanol steam reforming (MSR) is an effective method for producing high-purity hydrogen for polymer electrolyte membrane fuel cells. However, this technology still faces challenges, including high reaction temperatures and excessive CO formation. Gallium (Ga) plays a beneficial role in modulating the performance of Cu-based catalysts. In this study, a Ga-promoted quaternary CuZnAlGa catalyst, synthesized via an eco-friendly co-precipitation method, significantly enhances hydrogen production via MSR at 220 °C while effectively suppressing CO generation. Characterization results revealed that Ga contributes to reduced particle size and promotes heterometallic microcrystal doping, thereby increasing the number of dehydrogenation active sites with abundant oxygen vacancies at the interfaces. Moreover, Ga introduces new dehydrogenation sites that facilitate H* recombination and H₂ release, and modulates the surface acidity of the catalyst to promote CO₂ desorption. As a result, Ga suppresses CO formation by inhibiting the reverse water–gas shift reaction. The synergistic effects induced by Ga lead to high methanol conversion and low CO selectivity in the MSR reaction over the CuZnAlGa catalyst.