Insights into Ni and (Ce)SBA-15-CTA interaction and syngas formation rate

Abstract

• A low initial activation reaction temperature of CH 4 and CO 2 at a high syngas formation rate was verified via TPSR analysis. • XANES analysis confirmed CeO 2 plays a key role in regulating the valence state of Ni species and stabilizing their metallic state. • Ni/30CeO 2 -SBA-15-CTA gave low coke deposition rate at 4.9% over 12 h dry reforming reaction at 700 °C. Our SBA-15-CTA mesoporous materials developed in citric acid (CTA), instead of traditional HCl intermediate, were used to support CeO 2 doped nickel catalysts in methane dry reforming reaction. Results revealed that SBA-15-CTA had a high capacity for hosting CeO 2 (up to 30 wt.%), which had strong interaction with Ni species, leading to a high reduction temperature of NiO at 442 °C. XANES analysis verified that Ni species were much more stable over Ce doped SBA-15-CTA than un-doped ones, which helped the Ni species maintain their metallic state. As demonstrated through TPSR analysis, CH 4 and CO 2 was converted to syngas at a high rate at a low initiation temperature over Ce doped Ni/SBA-15-CTA catalysts. Despite both catalysts having similar performance, Ni/30CeO 2 -SBA-15-CTA yielded a much lower coke deposition rate (4.9% vs 22.4% on Ni/10CeO 2 -SBA-15-CTA). A desirable endurance to metal sintering and carbon elimination rate was achieved over 5Ni/15CeO 2 -SBA-15-CTA catalyst, owing to the high concentration of oxygen vacancy coupled with the high amount of Ce 3+ . CeO 2 played a key role in regulating valence states and stabilizing the metallic state of Ni species over Ni/SBA-15-CTA catalyst, with a narrow Ni particle size distribution.