Metallic Honeycomb Catalysts for Methane Steam Reforming: Effect of the Bimetallic Surface Coating on Catalytic Properties

Abstract

Metallic honeycomb catalysts are promising candidates for fuel cell and small-scale onsite hydrogen production applications. In this study, high-cell-density Ni honeycomb catalysts coated with a series of bimetallic surface layers were synthesized. Their catalytic performance for CH₄ steam reforming was investigated under a low steam-to-carbon ratio of 1.36 and a gas hourly space velocity of 6400 h⁻¹ in the temperature range of 400–700°C. The catalysts coated with Ni–Mg and Ni–Zr showed excellent catalytic performance, reaching a high CH₄ conversion and CO selectivity close to the equilibrium values within the test temperature range. The enhanced catalytic performance of the Ni–Mg and Ni–Zr coatings was attributed to the formation of oxide-supported fine Ni particles. In contrast, the catalysts coated with Ni–Fe and Ni–Sn exhibited an extremely low activity, which was lower than that of the catalyst coated with only Ni. The low activity of the Ni–Fe and Ni–Sn coatings is supposed to be due to the formation of aggregated Ni₃Fe, Ni₃Sn, and Ni₃Sn₂ phases.