Autothermal steam reforming of ethanol over La2Ce2−xRuxO7 (x = 0–0.35) catalyst for hydrogen production

Pyrochlore phases solid solutions, La2Ce2−xRuxO7 (x = 0–0.35) were prepared with a sol–gel process and used as catalysts for the autothermal steam reforming of ethanol. The samples as prepared were characterized with powder X-ray diffraction (PXRD), X-ray photoelectron spectra (XPS), and temperature-programmed reduction (TPR). The XPS and TPR spectra revealed the effect of doped Run+ to oxidation states of La and Ce sites. The low temperature reduction ability and relative concentration of Ce4+ ions are increased as the cell-dimension decreased. Tests of catalytic activity showed that the reforming performance of La2Ce2−xRuxO7 catalysts was affected by the Ru/Ce loading ratio. For all catalysts, partial oxidation was favored at a large C/O composition; incomplete ethanol conversion was observed for C/O ≥ 0.7. The optimized catalyst was La2Ce1.8Ru0.2O7 with hydrogen production rate (rH2rH2) 2.01 × 10−3 mol s−1 gcat−1 (autothermal temperature ∼600 °C and 97% ethanol conversion at C/O = 0.6). The catalyst exhibited stable rH2rH2 over 26 h of the reaction with ethanol conversion >95%. rH2rH2 of the catalyst gradually decreased thereafter because LaAlO3 started to formed and affected catalytic process. For the catalyst, the Ru ions remained well dispersed before and after the AESR reaction.

Graphical abstractPyrochlore phase La2Ce1.8Ru0.2O7 is a new catalyst for autothermal steam reforming reaction. The catalyst as prepared shows stable hydrogen production rate 2.01 × 10−3 mol s−1 gcat−1.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Pyrochlore phases La2Ce2−xRuxO7 (x = 0–0.35) were prepared by sol–gel method. ► The metal–metal interaction between Ru and La ions was observed on XPS analyses. ► La2Ce1.8Ru0.2O7 revealed the better activity on autothermal steam reforming of ethanol. ► The amount of Ru loading was reduced while the catalytic activity was maintained. ► The catalysts as prepared kept evenly distributed Ru ions before and after the tests.