Pt-Ni-CeZrO₂-CNT hybrid catalysts for stable low-temperature Dry reforming of methane (DRM)

Introduction. Dry reforming of methane (DRM) is an advantageous approach for the simultaneous utilization of greenhouse gases CH₄ and CO₂, while producing syngas, which can then be further used for ammonia/hydrogen synthesis, Fischer-Tropsch processes, methanol production, amongst others. However, DRM is yet to be industrialized due to deactivation of catalysts at high temperatures via coking or sintering. In this study, Pt-Ni-CeZrO₂-CNT catalysts were designed and prepared to improve catalytic performance, stability and resistance to deactivation in DRM.

Methods. The catalysts were synthesized using a coprecipitation-solvothermal route, and further characterized via X-ray diffraction (XRD), N₂ sorption, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The structural characterization confirmed successful deposition of active phases of metals Pt and Ni, and CeZrO₂ promoter species on the functionalized CNT support, with well-dispersed nanoparticles.

Results. Catalytic performance in DRM was evaluated at the temperatures of 500-600°C under gas hour space velocity of 10,000 h^-1. The catalysts achieved CH₄ conversions of up to 97% and CO₂ conversions of ~55% while maintaining stable activity under long term operation. Carbon balance calculations and H₂/CO ratios of approximately ~0.7 indicated the contribution of reverse water gas shift reaction, explaining the lower CO₂ conversions. Long term stability tests demonstrated catalytic performance for more than 100 h time on run, whereas a second batch maintained stable operation for over 75 h, confirming excellent reproducibility. Furthermore, the catalysts exhibited promising activity in partial oxidation of methane, reaching 97% CH₄ conversion and producing syngas with a H₂/CO ratio close to 2 at 700°C.

Conclusions. The developed catalysts exhibit excellent activity, stability and reproducibility in DRM under low temperature conditions. Their additional activity in partial oxidation of methane highlights the potential of these hybrid catalysts as versatile materials for durable syngas production through methane reforming.