Support Induced Effects on the Ir Nanoparticles Activity, Selectivity and Stability Performance under CO2 Reforming of Methane

• Published in: Nanomaterials (Basel, Switzerland) Switzerland), 2021-10, Vol.11 (11), p.2880
• Main Authors: Nikolaraki, Ersi, Goula, Grammatiki, Panagiotopoulou, Paraskevi, Taylor, Martin J., Kousi, Kalliopi, Kyriakou, Georgios, Kondarides, Dimitris I., Lambert, Richard M., Yentekakis, Ioannis V.
• Format: Article
• Language: English
• Subjects: Aging; Alternative energy sources; alumina-ceria-zirconia mixed oxides; Aluminum oxide; Ammonia; Atoms & subatomic particles; Biogas; Carbon dioxide; Catalysis; Catalysts; Cerium oxides; coking-resistant catalysts; Deposition; dry reforming of methane; Electricity; Energy technology; Gases; greenhouse gases; Iridium; iridium nanoparticles; Low temperature; Material properties; Metal oxides; Metals; Methane; Nanoparticles; Oxidation resistance; Oxygen; Oxygen enrichment; Physicochemical properties; Reaction mechanisms; Reforming; Renewable energy technologies; Selectivity; Sintering; Solid oxide fuel cells; Stability; Storage capacity; Synthesis gas; Transitional aluminas; Zirconia; Zirconium dioxide
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano11112880

The production of syngas (H2 and CO)—a key building block for the manufacture of liquid energy carriers, ammonia and hydrogen—through the dry (CO2−) reforming of methane (DRM) continues to gain attention in heterogeneous catalysis, renewable energy technologies and sustainable economy. Here we report on the effects of the metal oxide support (γ-Al2O3, alumina-ceria-zirconia (ACZ) and ceria-zirconia (CZ)) on the low-temperature (ca. 500–750 ∘C) DRM activity, selectivity, resistance against carbon deposition and iridium nanoparticles sintering under oxidative thermal aging. A variety of characterization techniques were implemented to provide insight into the factors that determine iridium intrinsic DRM kinetics and stability, including metal-support interactions and physicochemical properties of materials. All Ir/γ-Al2O3, Ir/ACZ and Ir/CZ catalysts have stable DRM performance with time-on-stream, although supports with high oxygen storage capacity (ACZ and CZ) promoted CO2 conversion, yielding CO-enriched syngas. CZ-based supports endow Ir exceptional anti-sintering characteristics. The amount of carbon deposition was small in all catalysts, however decreasing as Ir/γ-Al2O3 > Ir/ACZ > Ir/CZ. The experimental findings are consistent with a bifunctional reaction mechanism involving participation of oxygen vacancies on the support’s surface in CO2 activation and carbon removal, and overall suggest that CZ-supported Ir nanoparticles are promising catalysts for low-temperature dry reforming of methane (LT-DRM).