Influence of Ru-substitution on the performance of pyrochlore catalysts in oxidative steam reforming of ethanol

• Published in: Sustainable energy & fuels Vol. 8; no. 9; pp. 214 - 2114
• Main Authors: Huang, Yu-Hsuan, Hsieh, Ho-Chen, Wang, Yun-Hsin, Weng, Sheng-Feng, Lee, Chi-Shen
• Format: Journal Article
• Language: English
• Published: London Royal Society of Chemistry 30.04.2024
• Subjects: Aggregation; Aluminum oxide; Catalysts; Electrons; Ethanol; Photoelectron spectroscopy; Photoelectrons; Pyrochlores; Raman spectroscopy; Reforming; Spectroscopy; Stability tests; Substitution reactions; Transitional aluminas; X ray photoelectron spectroscopy; X rays; X-ray diffraction
• ISSN: 2398-4902; 2398-4902
• DOI: 10.1039/d3se01585h

This study introduces a series of Ru-substituted pyrochlore catalysts, achieved by using La 2 Zr 2− x Ru x O 7− δ (LZRO-00-04, x = 0.0-0.4) during the oxidative steam reforming of ethanol reaction (OSRE). The samples were characterized using X-ray diffraction (XRD), temperature programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS). The reduction behavior and catalytic performance correlate directly with the Ru content. The 5 wt% LZRO02 catalytic system outperforms the supported Ru-based catalyst (5 wt% RuO 2 /LZO), boasting lower Ru concentrations (2.66 wt%). The enhancement is attributed to the uniform dispersion of Ru ≥ 4+ ions embedded within the pyrochlore structure, as convincingly supported by the XPS result. This underscores notable distinctions between the internal and external structures of the two systems. On the other hand, our extensive long-term testing of LZRO02 across γ-Al 2 O 3 and lab-made LZO carriers, coupled with meticulous mapping and Raman analysis, revealed a significant observation: the catalyst exhibits notably reduced aggregation tendencies and enhanced activity when utilized on the LZO carrier. The La 2 Zr 1.8 Ru 0.2 O 7− δ catalyst supported on LZO demonstrated selectivity of hydrogen S H 2 = 86.4(1)%; Y H 2 = 2.55(3) (mol/mol EtOH) for long-term stability tests at T = 400 °C, C/O = 0.6, and O 2 /C 2 H 5 OH = 1.5. This discovery underscores the catalyst's remarkable stability and activity, making it a promising candidate for catalytic applications. This study reveals that La 2 Zr 2− x Ru x O 7− δ optimizes hydrogen production and ethanol conversion, particularly at a 2.66% Ru concentration, outperforming traditional 5 wt% Ru catalysts through superior long-term stability and efficiency.