Enhancing coking resistance of nickel-based catalysts for dry reforming of methane via nitric oxide abatement: a support study†

Abstract

Coking poses a significant challenge to the longevity and efficacy of catalysts in dry reforming of methane (DRM), particularly for nickel-based catalysts, which are widely used for their affordability and high catalytic activity. This study explores a recent approach integrating DRM with NO reduction to address coking-related deactivation, aiming to gasify carbon deposits and reduce NO simultaneously. Therefore, herein, NO conversion is achieved using the carbon undesired by-product of the DRM reaction, avoiding the use of valuable resources for NO conversion (such as NH₃), via an approach “from waste to value” that enhances the sustainability of the process. Four nickel-impregnated oxide supports (γ-Al₂O₃, MgAl₂O₄ coated γ-Al₂O₃, CaZrO₃, and LaFeO₃) were compared to understand the key properties of catalyst design. The best performances were obtained for supports with a high surface area and high interaction with metal particles (95% reactant conversion for Ni/γ-Al₂O₃) as they allowed stable activity and protection from NO oxidation. Supports with a lower surface area suffered from coke blockage of active sites, whereas no protection from oxidation led to complete deactivation of the active phase. The LaFeO₃ support stood out for its ability to protect Ni from NO oxidation by reducing NO. Overall, this study showed the importance of balancing NO oxidative power and coking issues, emphasizing the relevance of catalyst design in both protecting Ni from NO oxidation and avoiding coke blockage of the active sites via high surface area supports.