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Effect of the addition of rare earths on the activity of alumina supported copper cobaltite in CO oxidation, ch_4 oxidationand NO decomposition

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Journal of Rare Earths 2015年第4期33卷 382-390页

作者： B.Ivanov I.Spassova M.Milanova G.Tyuliev M.Khristova Institute of General and Inorganic chemistry Bulgarian Academy of Sciences Faculty of chemistry and Pharmacy Sofia University Institute of Catalysis Bulgarian Academy of Sciences

The effect of the addition of small amounts of rare earths （Ln=La, Ce, Nd and Gd） to alumina supported copper-cobalt spinel oxide on the catalysts efficiency in CO and ch4 oxidation and in NO decomposition was investigated. Samples of Ln/CuCo/AI catalyst were prepared and characterized by X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, atomic absorption spectroscopy （AAS）, scanning electron mieroscopy-energy dispersive spectroscopy （SEM-EDS）, H2-temperature-programmed reduc- tion （H2-TPR）, electron paramagnetic resonanee （EPR） spectroscopy and low temperature nitrogen adsorption, The results showed that the addition of rare earths changed the surface state of the alumina supported copper-cobalt spinel catalyst. As a result, partial re- duction of copper species was observed as well as migration of these species between the surface and the bulk. The Ln/CuCo/A1 catalysts behaved differently in oxidation and reduction processes. In oxidation processes where oxide structure was important, Ce/CuCo/A1 and Nd/CuCo/A1 were the most active catalysts. The catalyst Ce/CuCo/AI was the most active in the oxidation reactions because of the availability and favorable surface distribution of the redox couples Cu＋/Cu2＋ and Ce3＋/Ce4＋. In NO decompostion, Ln-modified catalysts significantly improved the selectivity of the process to N2.

关键词： copper cobaltite NO decomposition CO oxidation ch4 oxidation rare earths

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Straw Application Altered ch_4 Emission,Concentration and ^(13)C-Isotopic Signature of Dissolved ch_4 in a Rice Field

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Pedosphere 2012年第1期22卷 13-21页

作者： ZHANG Xiao-Yan ZHANG Guang-Bin JI Yang MA Jing XU Hua CAI Zu-Cong State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008(China) Graduate University of chinese Academy of Sciences Beijing 100049(China)

ch4 emission and the concentration of dissolved ch4 in soil solution and floodwater in a rice field and their stable carbon isotopic signatures as affected by straw application were investigated in 2009 in a field experiment at Jurong, Jiangsu Province, china. Straw application increased ch4 emission and ch4 concentration in the soil solution and floodwater. A positive seasonal correlation was also observed in the variation between ch4 flux and ch4 concentration in soil solution. The seasonal total ch4 emission （51.6 g ch4 m^-2） in Treatment WS （straw applied） was about 168% higher than that in Treatment CK （without straw）. The emitted ch4 and ch4 in soil solution were initially relatively enriched, then depleted and finally enriched again in 13C in both treatments, while ch4 in floodwater became isotopically heavier. The carbon isotopic signature of emitted ch4 and ch4 in floodwater averaged around -62%o and -45%0 for both treatments, respectively, and was not significantly influenced by the application of straw. However, straw application caused the ch4 in soil solution to be significantly depleted in lac during the middle of the rice season, and the mean δ13C value was lower in WS （-57.5‰） than in CK （-49.9‰）. Calculation from the isotopic data showed that straw application increased the fraction of ch4 oxidized, causing no significant difference in the δ13C value of the emitted ch4 between the two treatments.

关键词： δ13ch4 ch4 flux ch4 oxidation floodwater soil solution

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Effect of Structural Properties of Mesoporous Co3O4 Catalysts on Methane Combustion

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chemical Research in chinese Universities 2016年第5期32卷 808-811页

作者： JIA Yongchang WANG Shuyuan LU Jiqing LUO Mengfei Key Laboratory of the Ministry of Education for Advanced Catalysis Materials Institute of Physical Chemistry Zhejiang Normal University Jinhua 321004 P R. China

Highly ordered 2D and 3D-Co3O4 catalysts were prepared using SBA-15 and KIT-6 as templates. Na- no-Co304 catalyst was obtained by calcination of cobalt nitrate as a comparison. The BET surface area of nano- CO304, 2D-Co3O4 and 3D-Co3O4 catalysts was 16.2, 63.9 and 75.1 mE/g, respectively. All the catalysts were tested for the total combustion of methane and their catalytic performance was in the order of 3D-Co3O4（T90=355℃）〉 2D-CoaO4（T90=383℃）〉nano-Co3O4（T90=455℃）. It was also found that the order of the areal specific reaction rates for the combustion of methane followed the same order of total activity. The characterization result demonstrates that enhanced catalytic performance of methane of the 2D-Co3O4 and 3D-Co3O4 catalysts is due to their pronounced reducibility and abundant active Co3O4 species, which was caused by the preferential exposure of {220} crystal planes in 3D-Co3O4 and 2D-Co3O4 catalysts compared to the nano-Co3O4.

关键词： Mesoporous Co3O4 Hard template ch4 oxidation KIT-6 SBA-15

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Variations of Stable Carbon Isotopes of ch4 Emission from Three Typical Rice Fields in china

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Pedosphere 2017年第1期27卷 52-64页

作者： ZHANG Guangbin MA Jing YANG Yuting YU Haiyang SHI Yaping XU Hua State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008(China) University of chinese Academy of Sciences Beijing 100049(China)

Little is known about the stable carbon isotopes of methane （ch4） emitted （δ13ch4elnitted） from permanently flooded rice fields and double rice-cropping fields. The ch4 emission and corresponding （δ13ch4emitted under various field managements （mulching, water regime, tillage, and nitrogen （N） fertilization） were simultaneously measured in three typical chinese rice fields, a permanently flooded rice field in Ziyang City, Sichuan Province, Southwest china, a double-rice cropping field in Yingtan City, Jiangxi Province, Southeast china, and a rice-wheat rotation field in Jurong City, Jiangsu Province, East china, from 2010 to 2012. Results showed different seasonal variations of δ13ch4emitted among the three fields during the rice-growing season. The values of （δ13ch4emitted were negatively correlated with corresponding ch4 emissions in seasonal variation and mean, indicating the importance of ch4 production, oxidation, and transport associated with isotopic fractionation effects to the δ13ch4emitted. Seasonal variations of δ13ch4emltted were slightly impacted by mulching cultivation, tillage, and N application, but highly controlled by drainage. Meanwhile, tillage, N application, and especially mulching cultivation had important effects on seasonal mean ch4 emissions and corresponding δ13ch4emitted with low emissions accompanied by high values of δ13ch4emitted. Seasonal mean values of （δ13ch4emitted from the three fields were similar, mostly ranging from -60‰ to -50‰ which are well in agreement with previously published data. These demonstrated that seasonal variations of （δ13ch4emitted mainly depended on the changes in ch4 emission from rice fields and further indicated the important effects of methanogenic pathways, ch4 oxidation, and ch4 transport associated with isotope fractionation effects influenced by field managements on δ13ch4emitted.

关键词： ch4 oxidation ch4 transport isotope fractionation methanogenic pathways nmlching N application tillage

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