Highly coke-resistant Ni-La2O2CO3 catalyst with low Ni loading for dry reforming of methane with carbon dioxide

Abstract

A series of xNi-La2O2CO3 catalysts with Ni loadings of 0.5–5 wt%, composed of Ni components supported on lanthanum oxycarbonate, were constructed via a simple wet impregnation method and systematically investigated for the reaction of dry reforming of methane with carbon dioxide to syngas (DRM). The xNi-La2O2CO3 catalyst with Ni loading lower than 1 wt% was primarily composed of well-defined Ni-La interfaces after reduction. However, xNi-La2O2CO3 with Ni loading of 2–5 wt% mainly possessed isolated Ni nanoparticles and Ni-La interfaces after reduction. The process of coke formation was proposed that carbon deposition was quickly occurring around the isolated active Ni sites, and then gradually evolved into carbon nanotubes encapsulating Ni nanoparticles, which were finally exsolved from the catalyst surface as the reaction proceeded. Interestingly, no coke formation was observed on the Ni-La interfaces after the DRM reaction even for 300 h. Therefore, the creation of catalytically active Ni-La interfaces indeed significantly improved the coke-resistant performance of the catalyst and was responsible for the much higher catalytic durability of 1Ni-La2O2CO3 than 5Ni-La2O2CO3. Moreover, the catalyst model and its activation of CH4 and CO2 in the DRM reaction were tentatively proposed based on the structure-performance relationship. The current study not only guides for potential industrial pathways for the DRM reactions but also provides a simple and effective method for the design of coke-resistant catalysts for other challenging reactions.