Oxidative steam reforming of ethanol over M: XLa2- xCe1.8Ru0.2O7- δ (M = Mg, Ca) catalysts: Effect of alkaline earth metal substitution and support on stability and activity

Ho Chen Hsieh, Ping Wen Tsai, Yuan Chia Chang, Sheng Feng Weng, Hwo Shuenn Sheu, Yu Chun Chuang, Chi Shen Lee*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Alkaline earth metal substitutions on the A-site of pyrochlore oxide MxLa2-xCe1.8Ru0.2O7-δ (M = Mg, Ca) were studied as catalyst materials for oxidative/autothermal steam reforming of ethanol (OSRE/ATR). The as-prepared oxides were synthesized by a combustion method and characterized using powder X-ray diffraction (PXRD), and X-ray photoelectron and absorption spectroscopy (XPS and XAS). PXRD Rietveld analysis and elemental analysis (ICP-AES) support the formation of a pyrochlore-type structure (space group Fd3m) with a distorted coordination environment. The substitution of Mg2+ and Ca2+ ions affects the oxidation states of Ce4+/3+ and Run+ ions and creates oxygen vacancies, which leads to enhanced catalytic activity and reduced ethylene selectivity. A long-term stability test showed optimized catalysts Mg0.3La1.7Ce1.8Ru0.2O7-δ and Ca0.2La1.8Ce1.8Ru0.2O7-δ with SH2 = 101(1)% and SH2 = 91(2)% under OSRE conditions. The initial operation temperatures were lower than that of the unsubstituted catalyst La2Ce1.8Ru0.2O7-δ. Catalysts supported on La2Zr2O7 showed stable OSRE/ATR performance and low carbon deposition compared to catalysts supported on Al2O3. We ascribe the enhanced activity to well-dispersed alkaline earth metal and Ru ions in a solid solution structure, synergistic effects of (Mg, Ca)2+/Ce3+/4+/Run+ ions, and a strong catalyst-support interaction that optimized the ethanol conversion and hydrogen production.

Original languageEnglish
Pages (from-to)39932-39944
Number of pages13
JournalRSC Advances
Volume9
Issue number68
DOIs
StatePublished - 2 Dec 2019

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