Preparation of double perovskite-type oxide LaSrFeCoO_6 for chemical looping steam methane reforming to produce syngas and hydrogen

• Published in: 中国稀土学报：英文版 Vol. 34; no. 10; pp. 1032 - 1041
• Main Author: 赵坤 沈阳 何方 黄振 魏国强 郑安庆 李海滨 赵增立
• Format: Journal Article
• Language: English
• Published: 2016
• Subjects: 制备; 化学链; 合成气; 氢气; 甲烷重整; 蒸汽; 钙钛矿型复合氧化物; 钙钛矿结构
• ISSN: 1002-0721; 2509-4963

Double-perovskite type oxide LaSrFeCoO_6 was used as oxygen carrier for chemical looping steam methane reforming（CL-SMR） due to its unique structure and reactivity. Solid-phase, amorphous alloy, sol-gel and micro-emulsion methods were used to prepare the LaSrFeCoO_6 samples, and the as-prepared samples were characterized by means of X-ray diffraction（XRD）, hydrogen temperature-programmed reduction（H_2-TPR）, X-ray photoelectron spectroscopy（XPS）, Brunauer-Emmett-Teller（BET） surface area. Results showed that the samples made by the four different methods exhibited pure crystalline perovskite structure. The ordered double perovskite LaSrFeCoO_6 was regarded as a regular arrangement of alternating FeO_6 and CoO_6 corner-shared octahedra, with La and Sr cations occupying the voids in between the octahedral. Because the La~（3＋） and Sr~（2＋） ions in A-site did not take part in reaction, the TPR patterns showed the reductive properties of the B-site metals. The reduction peaks at low temperature revealed the reduction of adsorbed oxygen on surface and combined with the reduction of Co~（3＋） to Co~（2＋） and to Co~0, while the reduction of Fe~（3＋） to Fe~（2＋） and the partial reduction of Fe~（2＋） to Fe~0 occurred at higher temperatures. From the point of view of the oxygen-donation ability, resistance to carbon formation, as well as hydrogen generation capacity, the sample made by micro-emulsion method exhibited the best reactivity. Its redox reactivity was very stable in ten successive cycles without deactivation. Compared to the single perovskite-type oxides LaFeO_3 and LaCoO_3, the double perovskite LaSrFeCoO_6 exhibited better syngas and hydrogen generation capacity.