Calcium hydroxyapatite（HAp） supported cobalt and cobalt-cerium catalysts were examined for hydrogen production in glycerol steam reforming. The catalysts were synthesized by incipient wetness impregnation method and...Calcium hydroxyapatite（HAp） supported cobalt and cobalt-cerium catalysts were examined for hydrogen production in glycerol steam reforming. The catalysts were synthesized by incipient wetness impregnation method and characterized through X-ray diffraction, adsorption-desorption isotherms of N2 and temperature-programmed reduction of H2. Catalytic properties were examined in terms of glycerol conversion, selectivity toward hydrogen and C-containing products in temperature range of 650-800 ℃.The effect of active metal reduction and residence time（thereby flow feed rate） was analysed. It was found that the growth of residence time increased the hydrogen selectivity in the whole temperatures range whereas the catalyst reduction, before the catalytic process, decreased the hydrogen selectivity at temperatures lower than 750 ℃. The cerium addition improved the catalytic behaviour for hydrogen production via glycerol steam reforming. Cerium oxide suppressed the sintering of cobalt particles and as a result Co-Ce/HAp ensured higher stability and H2 selectivity than Co/HAp. Under reaction conditions investigated in this study, the highest selectivity toward hydrogen at 650 ℃ was obtained for 7.5 Co-Ce/HAp catalyst.展开更多
By plasma transmitting spectrograph,electron energy spectrometry,X-ray diffractometry,transmission electron microscopy and micro-hardometry,the effects of ultrasonic irradiation and rare earth metal cerium on the depo...By plasma transmitting spectrograph,electron energy spectrometry,X-ray diffractometry,transmission electron microscopy and micro-hardometry,the effects of ultrasonic irradiation and rare earth metal cerium on the depositing speed,chemical composition,crystal structure and microhardness of electroless Co-Ni-B alloy coating were inspected and analyzed. The results show that cerium and ultrasonic irradiation can evidently raise the depositing speed of electroless Co-Ni-B alloy. The cerium content of electroless Co-Ni-B-Ce alloy coating also increases after ultrasonic irradiation applied to electroless Co-Ni-B plating process. Under the action of ultrasonic irradiation and rare metal cerium,the chemical composition of electroless Co-Ni-B alloy coating is changed. Electroless Co-Ni-B alloy with amorphous structure is transformed to electroless Co-Ni-B-Ce alloy with microcrystalline in general state and electroless Co-Ni-B-Ce alloy with crystalline structure in ultrasonic irradiation. In this way microhardness of the coatings increases remarkably.展开更多
利用等离子发射光谱仪、电子能谱仪、X射线衍射仪、透射电子显微镜和显微硬度计等考察和分析了引入超声波和稀土金属铈时化学镀Co Ni B合金镀液的沉积速度、Co Ni B合金镀层的化学成分、晶体结构和显微硬度。结果表明 ,超声波和稀土金...利用等离子发射光谱仪、电子能谱仪、X射线衍射仪、透射电子显微镜和显微硬度计等考察和分析了引入超声波和稀土金属铈时化学镀Co Ni B合金镀液的沉积速度、Co Ni B合金镀层的化学成分、晶体结构和显微硬度。结果表明 ,超声波和稀土金属铈的介入明显提高了化学镀Co Ni B合金的沉积速度 ,超声波的介入则提高了化学镀Co Ni B Ce合金镀层中稀土铈的含量。在超声波和稀土铈的共同作用下 ,化学镀Co Ni B合金镀层的化学组成发生了改变 ,镀层结构由非晶态向微晶和晶态转化 。展开更多
文摘Calcium hydroxyapatite（HAp） supported cobalt and cobalt-cerium catalysts were examined for hydrogen production in glycerol steam reforming. The catalysts were synthesized by incipient wetness impregnation method and characterized through X-ray diffraction, adsorption-desorption isotherms of N2 and temperature-programmed reduction of H2. Catalytic properties were examined in terms of glycerol conversion, selectivity toward hydrogen and C-containing products in temperature range of 650-800 ℃.The effect of active metal reduction and residence time（thereby flow feed rate） was analysed. It was found that the growth of residence time increased the hydrogen selectivity in the whole temperatures range whereas the catalyst reduction, before the catalytic process, decreased the hydrogen selectivity at temperatures lower than 750 ℃. The cerium addition improved the catalytic behaviour for hydrogen production via glycerol steam reforming. Cerium oxide suppressed the sintering of cobalt particles and as a result Co-Ce/HAp ensured higher stability and H2 selectivity than Co/HAp. Under reaction conditions investigated in this study, the highest selectivity toward hydrogen at 650 ℃ was obtained for 7.5 Co-Ce/HAp catalyst.
文摘By plasma transmitting spectrograph,electron energy spectrometry,X-ray diffractometry,transmission electron microscopy and micro-hardometry,the effects of ultrasonic irradiation and rare earth metal cerium on the depositing speed,chemical composition,crystal structure and microhardness of electroless Co-Ni-B alloy coating were inspected and analyzed. The results show that cerium and ultrasonic irradiation can evidently raise the depositing speed of electroless Co-Ni-B alloy. The cerium content of electroless Co-Ni-B-Ce alloy coating also increases after ultrasonic irradiation applied to electroless Co-Ni-B plating process. Under the action of ultrasonic irradiation and rare metal cerium,the chemical composition of electroless Co-Ni-B alloy coating is changed. Electroless Co-Ni-B alloy with amorphous structure is transformed to electroless Co-Ni-B-Ce alloy with microcrystalline in general state and electroless Co-Ni-B-Ce alloy with crystalline structure in ultrasonic irradiation. In this way microhardness of the coatings increases remarkably.
文摘利用等离子发射光谱仪、电子能谱仪、X射线衍射仪、透射电子显微镜和显微硬度计等考察和分析了引入超声波和稀土金属铈时化学镀Co Ni B合金镀液的沉积速度、Co Ni B合金镀层的化学成分、晶体结构和显微硬度。结果表明 ,超声波和稀土金属铈的介入明显提高了化学镀Co Ni B合金的沉积速度 ,超声波的介入则提高了化学镀Co Ni B Ce合金镀层中稀土铈的含量。在超声波和稀土铈的共同作用下 ,化学镀Co Ni B合金镀层的化学组成发生了改变 ,镀层结构由非晶态向微晶和晶态转化 。
