Enhanced coking resistance in methane dry reforming using anti-sintering Ni nanoparticles and atomically re-dispersed oxygen vacancy-rich CeOx on MgAl2O4 support

Abstract

The dry reforming of methane (DRM) with carbon dioxide offers a sustainable approach for producing valuable syngas (H 2 + CO); however, its industrial implementation remains constrained by the challenge of developing robust catalysts capable of efficiently cracking C–H bonds and activating C O bonds. In this study, we demonstrate that precise control over the geometric exposure and chemical states of Ni and Ce species on MgAl 2 O 4 support significantly enhances DRM performance and stability under relevant conditions, with no observed sintering or coke formation. Through a combination of catalyst testing and detailed characterization—including HAADF/STEM-EDX, H 2 -XRD, H 2 -XPS, H 2 -TPR, and CO 2 -TPD analyses —we reveal a regioselective reconstruction of MgAl 2 O 4 cross-border crystallites with CeO x atoms or clusters after reduction in H 2 flow or exposure to the DRM reaction at 750 °C. These atomically re-dispersed CeO x sites on MgAl 2 O 4 , along with residual non-stoichiometric NiAl 2 O x , act as oxygen vacancy sinks, promoting further CO 2 activation, while anti-sintering Ni particles (sub-7.5 nm) efficiently crack CH 4 . This synergistic catalysis between Ni and CeO x species effectively suppresses coke accumulation, ensuring prolonged stability of the Ni x /Ce-MA catalysts. Notably, a Ni (2 wt%)-based CeO x (5 wt%)-MgAl 2 O 4 catalyst achieved stable syngas production with an H 2 /CO molar ratio of ∼0.76–0.93 at 750 °C for up to 100 h on-stream. This study provides valuable insights into the design of more efficient DRM catalysts and underscores the potential of multivalent oxides for enhancing atom economy in catalysis. • Tailored Ni and Ce exposure and states improve catalytic efficiency in methane dry reforming. • Highly reactive, anti-sintering sub-7.5 nm Ni particles promote effective CH 4 decomposition. • Atomically re-dispersed CeO x on MgAl 2 O 4 interfaces act as oxygen vacancy sinks, aiding CO 2 activation. • Ni and Ce δ+ redox species interact synergistically to suppress coke formation effectively.