Cost-effective thermal energy storage materials are vital to the application of solar thermal power plants . One focus of this paper is improving thermal and mechanical properties of the thermal energy storage materials; the second focus lies in reducing the investment cost. On the basis of aluminate cementitious composites with 1 wt% nano-SiO 2 , 1 wt% nano-Cu and 15 wt% Cu powders, we introduced different wt% (0, 5, 10, and 15) of Fe powders to gradually replace 15 wt% Cu powders. The samples were heated at 105, 350, and 900 °C, respectively. As a result, when the content of Fe powders substitution was 10 wt%, volume heat capacity, thermal conductivity and compressive strength of the composites after heat-treatment at 900 °C were up to 2.38 MJ m −3 K −1 , 1.45 W m −1 K −1 , and 73.8 MPa respectively, which were 26.6%, 26.1%, and 24.0% higher than those of the composites with 15 wt% Cu powders. At the same time, the investment of the composites with 10 wt% Fe powders substitution was reduced almost 62.0%, compared with that of the composites with 15 wt% Cu powders. In addition, XRD and MIP were employed to characteristic the mineral phases and the pore structures of the aluminate cementitious composites, respectively.
Zhang Haochen,Li Chunsong,Liu Wenxuan,Luo Guangsheng,Goddard William A.,Cheng Mu-Jeng,Xu Bingjun,Lu Qi
Light alkane activation under mild conditions remains a substantial challenge. Here we report an aqueous reaction system capable of selectively converting light alkanes into corresponding olefins and oxygenates at room temperature and ambient pressure using Cu powder as the catalyst and O 2 as the oxidant. In ethane activation, we achieved a combined production of ethylene and acetic acid at a rate of 2.27 mmol g Cu −1 h −1 , with a combined selectivity up to 97%. Propane is converted to propylene with a selectivity up to 94% and a production rate up to 1.83 mmol g Cu −1 h −1 , while methane is converted mainly to carbon dioxide, methanol and acetic acid. On the basis of catalytic experiments, isotopic labelling experiments, spectroscopic insights and density functional theory calculations, we put forward mechanistic understandings in which the C–H bond is activated by the surface oxide species generated during the oxidation process, forming alkyl groups as key reaction intermediates.
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