Preparation of double perovskite-type oxide LaSrFeCoO₆ for chemical looping steam methane reforming to produce syngas and hydrogen

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• 作者：Kun ZHAO (赵 坤)^a ; ^b ; ^c ; Yang SHEN (沈 阳)^c ; Fang HE (何 方)^a ; ^{hefang@ms.giec.ac.cn" class="auth_mail" title="E-mail the corresponding author} ; Zhen HUANG (黄 振)^a ; Guoqiang WEI (魏国强)^a ; Anqing ZHENG (郑安庆)^a ; Haibin LI (李海滨)^a ; Zengli ZHAO (赵增立)^a
• 关键词：double-perovskite ; CL-SMR ; micro-emulsion ; oxygen species ; redox ; rare earths
• 刊名：Journal of Rare Earths
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：34
• 期：10
• 页码：1032-1041
• 全文大小：1663 K

文摘

Double-perovskite type oxide LaSrFeCoO₆ 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 LaSrFeCoO₆ samples, and the as-prepared samples were characterized by means of X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H₂-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 LaSrFeCoO₆ was regarded as a regular arrangement of alternating FeO₆ and CoO₆ corner-shared octahedra, with La and Sr cations occupying the voids in between the octahedral. Because the La³⁺ and Sr²⁺ 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 Co³⁺ to Co²⁺ and to Co⁰, while the reduction of Fe³⁺ to Fe²⁺ and the partial reduction of Fe²⁺ to Fe⁰ 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 LaFeO₃ and LaCoO₃, the double perovskite LaSrFeCoO₆ exhibited better syngas and hydrogen generation capacity.