Ultrafine Ru Nanoparticles Supported on Layered Double Hydroxide-Derived MgAl Mixed Oxides for Durable Bi-Reforming of Methane

Abstract

The sustainable conversion of methane and carbon dioxide into syngas via bi-reforming of methane (BRM) represents a promising strategy for greenhouse gas mitigation and carbon resource utilization. However, catalyst deactivation caused by coke accumulation and sintering of active metals remains a major challenge for achieving efficient and durable BRM processes. Herein, ultrafine Ru nanoparticles (NPs) supported on Mg3AlOx mixed oxides derived from layered double hydroxides (denoted as Ru/MAO) were fabricated via an ultrasound-assisted reduction. The optimal 0.2Ru/MAO catalyst exhibits superior catalytic activity and remarkable long-term stability for 250 h at 800 °C. Mechanistic investigations reveal that the ultrafine Ru NPs (∼1.1 nm) possessing electron-deficient characteristics regulate the adsorption strength of CHx intermediates, thereby suppressing excessive methane cracking and the formation of inert carbonaceous species. Meanwhile, the abundant basic sites on the Mg3AlOx support promote CO2 adsorption and activation, facilitating CO2-assisted carbon oxidation and removal during reaction. Furthermore, the strengthened interfacial interaction between Ru NPs and Mg3AlOx effectively inhibits Ru sintering under high-temperature conditions. A synergistic combination of in situ spectroscopic characterization and theoretical calculations further demonstrate the crucial roles of HCOO* and CHO* intermediates in suppressing coke accumulation and mitigating catalyst deactivation.