Investigation of oxygen mobility on LaNi-Zn perovskite catalyst for carbon inhibition in dry reforming of methane

Abstract

Carbon formation is one of the major problems in methane reforming reactions, mainly in dry reforming of methane (DRM), limiting its industrial competitiveness. Thus, in this work, we investigate the oxygen mobility and carbon resistance of the LaNi-Zn perovskite in the DRM reaction. The catalysts LaNiO3 (LN) and LaNi0.5Zn0.5O3-δ (LNZn) were synthesized and characterized by XRD, H2-TPR, CH4-TPSR-MS, H2-TPHR-MS, XPS, TGA, Raman, HRTEM, and quasi-in-situ DRIFTS-MS, aiming to understand the role of the promoter in coke suppression. The CH4-TPSR-MS, H2-TPHR-MS, and Raman analyses revealed that the Zn-substituted catalyst exhibited higher oxygen mobility compared to the LN catalyst, attributed to the oxophilicity of Zn2+, which facilitates carbon gasification. XPS and HRTEM analyses of reduced samples confirmed the presence of metallic Zn0 on the surface as Ni-Zn alloying. 30 h of TOS showed higher activity for the LN catalyst than the LNZn. However, post-reaction analysis indicated that the addition of Zn increased carbon resistance by 5 times. The formation of the Ni-Zn alloying effectively prevented the removal of Ni particles from the support and their encapsulation by carbon nanotubes. Quasi-in-situ DRIFTS-MS has revealed that the LNZn catalyst promotes the formation of intermediate species responsible for carbon oxidation (CHxO, HCOO⁻, and HCO3⁻), clearing the anti-carbon behavior of the Zn-substituted catalyst.