In the chemical looping with oxygen uncoupling(CLOU)process,CuO is a promising material due to the high oxygen carrier capacity and exothermic reaction in fuel reactor but limited by the low melting point.The combusti...In the chemical looping with oxygen uncoupling(CLOU)process,CuO is a promising material due to the high oxygen carrier capacity and exothermic reaction in fuel reactor but limited by the low melting point.The combustion rate of carbon is faster than the decoupling rate of oxygen carrier(OC).Hence,high temperature tolerance and rapid oxygen release rate of CuO modified by three different ores were investigated in this study.The kinetics analysis of oxygen decoupling with Cu-based oxygen carriers was also evaluated.Results showed that CuO modified by chrysolite had faster oxygen release rate than that of CuO.Limestone showed obvious positive effect on the oxidization process.The selected OCs could keep stable in at least 20 cycles,for about 1200 min.Shrinking core model(SCM)fitted well for the decoupling process in the temperature range of 1123-1223 K.Reduction rate kinetic information may aid in the development of chemical looping with oxygen uncoupling(CLOU)technologies during reactor design and process modeling.Ternary doped copper oxide with chrysolite and limestone could improve the reactivity of CuO in decoupling and coupling process and also improve the high temperature tolerance.展开更多
Variability and long-term trends of sunshine duration(SSD) and total cloud cover(TCC) were studied based on surface observations from 10 meteorological stations over East China in the first half of the 20 th century. ...Variability and long-term trends of sunshine duration(SSD) and total cloud cover(TCC) were studied based on surface observations from 10 meteorological stations over East China in the first half of the 20 th century. The correlation coefficients between SSD and diurnal temperature range(DTR), as well as TCC, were analyzed. SSD experienced a significant increasing trend(0.16 h d-1 per decade) from 1908 to 1936, and the maximum brightening was in autumn(0.33 h d-1 per decade). The good agreement between the variability of SSD and DTR, supported by the correlation coefficient between them of 0.72, implies that the SSD measurements were reliable. TCC showed a decreasing trend(-0.93% per decade) and was significantly inversely related to SSD(-0.74), indicating the variation of SSD was attributable to changes in cloud cover. The result was obviously different to that since the 1960 s, when clouds could not account for the decadal trend of surface solar radiation in China.展开更多
化学链氧解耦(CLOU)是基于化学链燃烧(CLC)技术的一种新型燃烧方式,具有CO2内分离的优良特性。具有良好吸氧释氧性能的氧载体是CLOU技术的关键,其宏观层面的反应性决定于其微观层面的晶格氧传输机理,但目前对这种微观机理的研究非常缺...化学链氧解耦(CLOU)是基于化学链燃烧(CLC)技术的一种新型燃烧方式,具有CO2内分离的优良特性。具有良好吸氧释氧性能的氧载体是CLOU技术的关键,其宏观层面的反应性决定于其微观层面的晶格氧传输机理,但目前对这种微观机理的研究非常缺乏。本文采用量子化学计算方法——密度泛函理论(DFT)研究Cu O氧载体释氧的微观机理,构建了Cu O团簇及Cu O平板模型,模拟团簇及表面的释氧过程。Cu O平板模型释氧包括O原子在Cu O内部扩散、表面O2的形成及释放过程。结果表明:Cu O(111)表面释氧过程的最高能量势垒为3.16 e V,与实验值3.39 e V接近,低于Cu O团簇模型的释氧能量势垒3.51 e V;此外,O原子在Cu O(111)内部的扩散势垒仅为0.87 e V,说明Cu O(111)释氧的限制步骤是表面O2的形成过程。展开更多
基金financial support by the Fundamental Research Funds for the Central Universities(xjh012019019)the National Natural Science Foundation of China(51606087)。
文摘In the chemical looping with oxygen uncoupling(CLOU)process,CuO is a promising material due to the high oxygen carrier capacity and exothermic reaction in fuel reactor but limited by the low melting point.The combustion rate of carbon is faster than the decoupling rate of oxygen carrier(OC).Hence,high temperature tolerance and rapid oxygen release rate of CuO modified by three different ores were investigated in this study.The kinetics analysis of oxygen decoupling with Cu-based oxygen carriers was also evaluated.Results showed that CuO modified by chrysolite had faster oxygen release rate than that of CuO.Limestone showed obvious positive effect on the oxidization process.The selected OCs could keep stable in at least 20 cycles,for about 1200 min.Shrinking core model(SCM)fitted well for the decoupling process in the temperature range of 1123-1223 K.Reduction rate kinetic information may aid in the development of chemical looping with oxygen uncoupling(CLOU)technologies during reactor design and process modeling.Ternary doped copper oxide with chrysolite and limestone could improve the reactivity of CuO in decoupling and coupling process and also improve the high temperature tolerance.
基金supported by National Natural Science Foundation of China (41175031)
文摘Variability and long-term trends of sunshine duration(SSD) and total cloud cover(TCC) were studied based on surface observations from 10 meteorological stations over East China in the first half of the 20 th century. The correlation coefficients between SSD and diurnal temperature range(DTR), as well as TCC, were analyzed. SSD experienced a significant increasing trend(0.16 h d-1 per decade) from 1908 to 1936, and the maximum brightening was in autumn(0.33 h d-1 per decade). The good agreement between the variability of SSD and DTR, supported by the correlation coefficient between them of 0.72, implies that the SSD measurements were reliable. TCC showed a decreasing trend(-0.93% per decade) and was significantly inversely related to SSD(-0.74), indicating the variation of SSD was attributable to changes in cloud cover. The result was obviously different to that since the 1960 s, when clouds could not account for the decadal trend of surface solar radiation in China.
文摘化学链氧解耦(CLOU)是基于化学链燃烧(CLC)技术的一种新型燃烧方式,具有CO2内分离的优良特性。具有良好吸氧释氧性能的氧载体是CLOU技术的关键,其宏观层面的反应性决定于其微观层面的晶格氧传输机理,但目前对这种微观机理的研究非常缺乏。本文采用量子化学计算方法——密度泛函理论(DFT)研究Cu O氧载体释氧的微观机理,构建了Cu O团簇及Cu O平板模型,模拟团簇及表面的释氧过程。Cu O平板模型释氧包括O原子在Cu O内部扩散、表面O2的形成及释放过程。结果表明:Cu O(111)表面释氧过程的最高能量势垒为3.16 e V,与实验值3.39 e V接近,低于Cu O团簇模型的释氧能量势垒3.51 e V;此外,O原子在Cu O(111)内部的扩散势垒仅为0.87 e V,说明Cu O(111)释氧的限制步骤是表面O2的形成过程。
