(631a) Flame Aerosol Synthesis of Stable Ni/ZrO2 Nanocatalyst for Dry Reforming of Methane

Dry reforming of methane (CH₄ + CO₂ → 2H₂ + 2CO) simultaneous converts two greenhouse gases into syngas and has been considered as a promising method to address challenges of global warming and an effective way to utilize the abundant natural gas resource produced from the U.S. Shale Revolution. However, industrial implementation of this reaction is seriously limited by catalyst deactivation by coking and sintering. Here, we present a stable Ni/ZrO₂ nanocatalyst that can maintain 98% CH₄ conversion for over 500 hours at 800 °C, produced using an advanced flame aerosol process. In this process, an aqueous precursor solution containing nickel nitrate and zirconium nitrate is injected into the throat of a converging-diverging nozzle placed downstream of a hydrogen-oxygen flame. The precursor solution is atomized by the hot gases as they are accelerated to sonic or supersonic velocity. The ZrO₂ support grows within each droplet, ultimately as hollow microspheres. Simultaneously Ni nanoparticles deposit and grow on the ZrO₂ surface, finally forming a supported catalyst structure. Our analysis suggests that the superior stability of the flame produced Ni/ZrO₂ catalyst results from its resistance to carbon formation; the spent catalyst showed no carbon deposition after 500 hours of reaction. Some sintering was evident, but isolated small nickel particles also remained after 500 hours on stream. The flame-based aerosol synthesis may yield abundant oxygen vacancies in ZrO₂ which play a role in strong metal-support interactions and in suppressing carbon formation. Further investigation of the coking resistance and high stability is ongoing. Whatever the mechanism, we can clearly conclude that this gas-phase based flame aerosol method can produce an extremely stable and active Ni/ZrO₂ nanocatalyst in a single-step, continuous, and scalable process.