Defect-Rich and Boron-Doped Al₂O₃-Supported Ru Nanocatalyst for Enhanced CO₂ Methanation Activity

Abstract

Presently, fabricating a stable and high-performance noble metal catalyst is still a challenging task due to the easy aggregation and growth of metal particles during heterogeneous catalysis reactions. In this regard, catalyst supports always can profoundly impact the metal dispersion and electronic interaction with active metal species, thereby significantly regulating the catalytic performance of catalysts. Herein, a new strategy for fabricating boron-doped alumina support with coordinatively unsaturated penta-coordinated Al 3+ (Al penta 3+ ) sites via a micro-liquid-film reactor-assisted coprecipitation approach was developed. Accordingly, as-formed alumina could efficiently immobilize Ru atoms via the anchoring effect of the Al penta 3+ site to construct a supported Ru catalyst for CO 2 methanation. An as-constructed Al penta 3+ site-rich and boron-doped Al 2 O 3 -supported Ru nanocatalyst exhibited a better catalytic performance in CO 2 methanation along with a higher methane yield of 81.2% under reaction conditions (i.e., 350 °C, 0.1 MPa pressure, and gas hourly space velocity of 6000 mL·g cat –1 ·h –1 ), compared to other supported Ru ones over commercial alumina and defect-free alumina. It was demonstrated that the high catalytic performance was closely associated with the coexistence of surface-defective Al penta 3+ sites and B–O species, thereby facilitating the accommodation of active hydrogen species on the support during CO 2 hydrogenation as well as the activation adsorption of CO 2 at the medium-strength basic sites originating from surface B–O–Al structures. This work provides a new strategy to construct high-performance and stable supported noble metal catalysts through engineering alumina support with special defective structures and surface modification for the applications in advanced heterogeneous catalytic systems.

Topics & Concepts