Insights into Photothermocatalytic Dry Reforming of Methane on Ru/La‐Al2O3 using Carbonate Species and Reactive Oxygen Species to Enhance the Fuel Production Rates and Completely Prevent Coking

Abstract

AbstractPhotothermocatalytic dry reforming of methane (DRM) offers a promising strategy for converting solar energy into fuel. However, the high light intensity required for high fuel production rates and thermodynamically more favorable coking side reactions limit this strategy. Herein, a nanocomposite of La‐doped Al2O3 supporting Ru nanoparticles (NPs) (Ru/La‐Al2O3) is synthesized. At relatively low light intensity (80.2 kW m−2), Ru/La‐Al2O3 obtains high production rates of CO and H2 per gram of Ru (rRu, CO and rRu, H2, 8410.19 and 7181.94 mmol gRu−1 min−1) with light‐to‐fuel efficiency (η, 26.6%), and completely prohibits coking. In striking contrast, the reference catalyst without La doping (Ru/Al2O3) exhibits lower rRu, CO, rRu, H2, η and produces large amounts of coke. The improved photothermocatalytic performance stems from the fact that reactive oxygen species and carbonate species are involved in the oxidation of carbon species (rate‐determining steps of DRM) through two different reaction pathways, which significantly increases catalytic activity and prevents the carbon species from polymerizing into coke. Additionally, light not only enhances the DRM on Ru NPs and the oxidation reaction between carbonate species and carbon species but also promotes the dissociation of CH4 and desorption of H2, which improves the catalytic activity and product selectivity of Ru/La‐Al2O3.