Stabilizing Ni-CeOx Bifunctional Nanoparticles on Activated Alumina to Enhance Carbon Resistance for Dry Reforming of Methane

Abstract

Syngas, an extremely meaningful chemical feedstock consisting of hydrogen and carbon monoxide, can be produced through methane dry reforming with carbon dioxide. The extensively utilized Ni-based catalysts usually suffer from coke-induced instability. Herein, we design Ni-CeO_x bifunctional catalysts with different proximity and explore the influence of proximity level on anticoking performance. Ni-CeO_x bimetallic nanoparticles with intimate contact are precisely regulated through the anchoring strategy of coordination unsaturated Al³⁺_penta, which undergoes the topotactic exsolution of a Ni–Ce–O quasi-solid solution into Ni-CeO_x bimetallic nanoparticles. A trend toward easier elimination and even the absence of graphitic carbon is observed with a decreasing spatial distance between Ni and CeO_x, which is attributed to the proximity between the dissociation and gasification sites of CH_x* intermediates. CH_x* species generated at Ni nanoparticles migrated to adjacent CeO_x oxygen carriers for Ni-CeO_x/Al₂O₃ catalyst gasification with Ni-CeO_x bimetallic nanoparticle interfaces, which undergo the Mars–van Krevelen (MvK) mechanism. The exploration of the Ni-CeO_x proximity provides guidance for developing efficient and durable Ni-based DRM catalysts.