Regenerable Ni-Au/La2O3 catalysts for dry reforming of methane

Abstract

Dry reforming of methane (DRM) has been proposed as an effective way of converting CO2 and CH4, two major greenhouse gases, into synthesis gas (H2 + CO), a ubiquitous feedstock for various chemical industries. Ni-based bimetallic catalysts have been widely explored as an attractive route to improve DRM activity, selectivity, and stability. In this study, we synthesized LaNiO3 (LNO) and 1% Au-doped LaNiO3 (Au/LaNiO3 – A/LNO) using the modified sol-gel method. The material properties were studied using various characterization techniques, including XRD, BET, H2-TPR, TPO, STEM-HAADF with EDX mapping, Raman spectroscopy, and XPS. Ni nanoparticles with sizes ranging from 10 to 70 nm were successfully exsolved from the perovskite material after reduction at 800 °C. DRM activity of the reduced catalysts was probed from 400 to 800 °C. The Au-doped LNO exhibits significant enhancement in DRM activity at a lower temperature range (600–700 °C) compared to LNO. The A/LNO was also shown to retard coke formation and improve the selectivity for DRM. A computational study using density functional theory (DFT) reveals that the Ni3Au sites have a lower methane activation barrier due to the formation of NiAu alloy and the synergetic effect between Ni and Au.