Producing ultrastable Ni-ZrO2 nanoshell catalysts for dry reforming of methane by flame synthesis and Ni exsolution

Abstract

Commercial dry reforming of methane (DRM) is limited by catalyst deactivation through metal sintering and coking. New catalyst synthesis methods are needed to overcome such challenges. Here, we report a unique flame aerosol synthesis and exsolution method for producing hollow Ni-Zr oxide nanoshells as a highly stable and efficient DRM catalyst. This process incorporates immiscible elements into single-phase hollow nanoshells by rapid particle formation and quenching. Ni nanoparticles are then uniformly exsolved from the metastable solid solution to provide strong metal-support interactions that limit metal sintering. Rapid synthesis under reducing conditions produces oxygen vacancies in ZrO 2 that favor carbon removal during the DRM reaction. As a result, our catalyst maintained 98% CH 4 conversion for more than 500 h, without sintering or coking, dramatically outperforming conventional catalysts. This method of metastable solid solution nanoshell formation followed by active site exsolution could provide durable catalysts for many high-temperature reactions. • Incorporation of NiO and ZrO 2 into a single phase by rapid flame synthesis • Exsolution of active Ni nanoparticles leads to stable catalyst formation • High sintering and coking resistance of Ni-ZrO 2 nanoshell catalyst • Maintains 98% CH 4 conversion over more than 500 h for dry reforming of methane Dry reforming of methane, which converts two greenhouse gases to useful chemical feedstocks, has been regarded as a promising strategy to address global climate change and sustainable energy development. Design of effective nonnoble metal catalysts is key to achieving its industrial implementation. However, conventional Ni-based catalysts often suffer from deactivation by carbon coking and metal sintering, while complex catalyst synthesis approaches inevitably lead to high cost. This work presents a continuous, one-step, vapor-phase synthesis route to produce a highly stable Ni/ZrO 2 nanoshell catalyst with excellent resistance to both coking and sintering. The methods proposed in this work are expected to expand routes to heterogeneous catalyst synthesis with impact on both scientific and industrial communities. A highly stable Ni-ZrO 2 nanoshell catalyst is produced by a continuous flame aerosol process and Ni exsolution. Its notable characteristics include abundant oxygen vacancies and strong metal-support interactions, which lead to both coking and sintering resistance, along with high activity, for dry reforming of methane.