Molded Nanoporous Ni Catalysts with High Active Metal Utilization for CO₂ Methanation

Nanoporous nickel (NP Ni) catalysts are widely used in the catalytic industry, especially in various unsaturated organic compounds hydrogenation. However, the compatibility of traditional powdered NP Ni catalysts is limited to slurry bed reactors, which hinders their potential applications and the range of reaction systems. Thus, the design of molded NP Ni catalysts to fit various reactors, such as fixed-bed reactors, has garnered increased attention. Herein, a novel alumina-loaded NP Ni molded catalyst (NP Ni@Al2O3) was designed and prepared by sequential coating and dealloying processes, specifically optimized for fixed-bed reactors. The obtained NP Ni@Al2O3 catalyst shows an interlocked core–shell structure; that is, NP Ni is uniformly dispersed across the porous surface of the Al2O3 support. The synthesized NP Ni@Al2O3 catalyst demonstrated superior performance with a CO2 conversion rate of 71%, a CH4 selectivity of 99%, and a CO2 reaction rate of 0.79 molCO2gNi–1h–1, significantly outperforming commercial catalysts with a rate of 0.026 molCO2gNi–1h–1. In addition, the catalytic performance of the NP Ni@Al2O3 catalyst remained stable after a 120 h stability test, further demonstrating the catalysts’ robustness and potential for long-term applications. The developed catalyst formation method substantially improves the utilization of active metals, exhibiting broad applicability to a range of Raney-type catalysts, thereby rendering it a promising candidate for industrial-scale applications.