Non-thermal plasma enabled catalytic dry reforming of methane over a ceria nanorod supported NiO catalyst: the role of Ru as a coke resistant active site†

Abstract

This study reports that a 14 wt% Ni–1 wt% Ru bimetallic catalyst supported on ceria (CeO₂) nanorods (NRs) synthesized via wet impregnation can offer superior conversion and stability against coking during non-thermal plasma (NTP)-assisted dry reforming of methane (DRM) compared to monometallic Ni or Ru catalysts. This study revealed that when Ru was introduced as a promoter into the CeO₂ NR supported Ni catalyst, the DRM conversion percentage increased significantly under NTP (CH₄: 92% and CO₂: 70%) at 450 °C. Unlike thermal catalysis, plasma catalysis resulted in high yield (46% CO and 40% H₂) and selectivity (62% CO and 42% H₂) at 450 °C. Additionally, the durability (60 minutes) of the catalyst was tested at 350 °C. The bimetallic synergy and formation of CeO₂ NR supported Ni–O–Ru solid solution are believed to be the main causes of the significantly improved CH₄ and CO₂ conversions. The high coking resistance of the CeO₂-NR supported Ni–Ru bimetallic catalyst is attributed to three major factors: (1) the role of Ru in weakening the bond between Ni sites and carbon; (2) the higher dispersion of Ni over the CeO₂ NR surface; and (3) the accessibility of surface and lattice oxygen over the CeO₂ NR support, which promotes excellent redox properties and carbon oxidation. The proposed non-equilibrium and bimetallic synergy approach paves the way for cost-efficient and durable DRM catalysts for scalable syngas production from two potent greenhouse gases, which could potentially apply to future energy-efficient industrial processes such as the production of syngas and other value-added chemicals.