Synthesis of Ni–Co bimetallic catalyst with high activity and coking resistance for simulated biogas dry reforming in a constant alkaline chemical environment

Abstract

The biogas dry reforming (BDR) process has emerged as a pivotal carbon-neutral technology for converting greenhouse gases (CH₄ and CO₂) into high-purity syngas. While nickel-based catalysts exhibit intrinsic catalytic potential, their industrial application is hindered by rapid deactivation due to coking and metal sintering. To address these challenges, we synthesized a homogeneous NiCo bimetallic catalyst using an innovative ammonia cycling methodology. Systematic characterization revealed that ammonia reflux condensation significantly enhances the dispersion of NiCo active sites while establishing robust metal–carrier interfacial interactions. Most importantly, the 8Ni2Co/NH₃–SiO₂ catalyst exhibited the greatest activity and carbon deposition resistance during the 6-hour evaluation compared to the 8Ni/SiO₂ and 8Ni/NH₃–SiO₂ counterparts, achieving CH₄ and CO₂ conversion rates of 45.43% and 90.42% respectively. In addition, the carbon deposition on 8Ni2Co/NH₃–SiO₂ measured 0.23%, markedly lower than the 6.11% observed in the isovolumetric impregnation-prepared 8Ni/SiO₂ catalyst. Mechanistic analysis demonstrates that the synergistic coordination between Ni–Co bimetallic centers, combined with the ammonia-mediated synthesis protocol, effectively suppresses carbon nucleation while maintaining redox activity. These findings provide a strategic framework for designing coke-resistant catalysts in sustainable syngas production systems.