Promotional Effects of Ni and Mg on the Preferential Oxidation of CO over Carbon Nanotube-Supported Pt Catalyst

采用共浸渍法制备了nI和Mg促进的碳纳米管载PT催化剂(PT-nI-Mg/CnT),考察了其对CO优先氧化的催化性能.结果表明,PT,nI和Mg在CnT表面发生了相互作用,可能存在合金纳米粒子,从而显著改善了催化剂CO优先氧化的催化性能.添加适量nI可提高CO的转化率,而加入适量Mg则有助于改善CO2的选择性.当PT,nI和Mg同时负载时,优化后所得的催化剂5%PT-5%nI-5%Mg/CnT在100°C对富H2气体中CO选择氧化的转化率为100%,CO2的选择性为53.7%;该催化剂在140°C下连续反应24H,催化活性稳定.A carbon nanotube-supported Pt catalyst promoted by Ni and Mg(Pt-Ni-Mg/CNT) was prepared by the co-impregnation method for preferential oxidation of CO in H2-rich gas.The results of X-ray diffraction, H2 temperature-programmed reduction, transmission electron microscopy, and energy dispersive spectroscopy indicated that Pt interacted with Ni and Mg on CNT surface and might form alloy nanoparticles to some extents, which in turn markedly improved the catalytic performance of preferential oxidation of CO in H2-rich gas.The results of performance tests showed that CO conversion at low temperatures could be effectively enhanced by adding a proper amount of Ni, while the selectivity was improved by adding a proper amount of Mg.When Ni and Mg were added simultaneously, the 5%Pt-5%Ni-5%Mg/CNT catalyst showed CO conversion of 100% and selectivity for CO2 of 53.7% in a H2-rich stream at 100 °C.The catalytic performance did not change obviously during 24 h of run at 140 °C.国家重点基础研究发展计划(973计划;2009CB939804);福建省科技重大专项前期项目(2009HZ10102

星系中心大质量黑洞及潮汐瓦解恒星事件

黑洞潮汐瓦解恒星事件(Tidal Disruption Events,TDE)是星系中心黑洞瓦解进入其潮汐瓦解半径内的恒星并吸积恒星碎片物质而产生的一种剧烈辐射耀发现象.TDE的能谱和光变特征中蕴含了中心黑洞和被瓦解的恒星的信息,为我们证实和普查宁静星系中的黑洞,研究其参数、吸积过程和喷流产生、以及核区星际介质等提供了可能.TDE还可能提供中等质量黑洞和双黑洞存在的证据.TDE的观测和理论已成为一个新开辟的天体物理研究领域,但目前的进展受制于探测到事件太少(尤其是在X射线波段),且观测数据普遍质量不高.TDE的发生率很低,要探测大样本的事例需要监测足够大的空间体积.爱因斯坦探针卫星(Einstein Probe,EP)覆盖了0.5–4 keV的软X射线波段(接近TDE耀发时的辐射峰值能段),具有大视场以及高灵敏度,非常利于对TDE的探测.预期爱因斯坦探针卫星每年可以发现约几十至上百例TDE,其中有约10例或更多具有相对论性喷流特征.这将使我们可以获得较为完备、具有统计意义的TDE的样本,为进一步研究黑洞的存在和统计性质、增长和演化、发现中等质量黑洞和大质量双黑洞等提供了新的途径.中国科学院空间科学战略性先导科技专项(编号:XDA15052100);;北京大学“985工程”建设项目“星团环境对双黑洞形成演化过程的干扰及其对引力波探测的影响”资

Promotional Effects of Ni and Mg on the Preferential Oxidation of CO over Carbon Nanotube-Supported Pt Catalyst

A carbon nanotube-supported Pt catalyst promoted by Ni and Mg (Pt-Ni-Mg/CNT) was prepared by the co-impregnation method for preferential oxidation of CO in H-2-rich gas. The results of X-ray diffraction, H-2 temperature-programmed reduction, transmission electron microscopy, and energy dispersive spectroscopy indicated that Pt interacted with Ni and Mg on CNT surface and might form alloy nanoparticles to some extents, which in turn markedly improved the catalytic performance of preferential oxidation of CO in H-2-rich gas. The results of performance tests showed that CO conversion at low temperatures could be effectively enhanced by adding a proper amount of Ni, while the selectivity was improved by adding a proper amount of Mg. When Ni and Mg were added simultaneously, the 5%Pt-5%Ni-5%Mg/CNT catalyst showed CO conversion of 100% and selectivity for CO2 of 53.7% in a H-2-rich stream at 100 degrees C. The catalytic performance did not change obviously during 24 h of ran at 140 degrees C

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本发明涉及生物化工中对酶进行固定化的工艺，具体地说是载体 ZH-HA固定化粪产碱杆菌青霉素G酰化酶的方法，固定化粪产碱杆菌青霉素G酰化酶的载体为ZH-HA，于缓冲溶液体系中，以ZH-HA进行固定化时，酶浓度为为180-240mg/ml，固定化时间12-18h，缓冲溶液pH 7.5 -10.0，反应体系中盐的1.0-1.5M，载体与缓冲溶液的重量体积比例为1g 载体：4-6ml缓冲溶液。本发明固定化酶的温度、pH稳定性都比自由酶有了改善。经过连续多批水解青霉素G钾盐，固定化粪产碱杆菌青霉素G 酰化酶显示出良好的操作稳定性，表现出比自由酶的优势。带填

巨大芽孢杆菌青霉素G酰化酶在新型环氧载体ZH-HA上的固定化

巨大芽孢杆菌青霉素G酰化酶共价结合在新型环氧-氨基型载体ZH-HA上，通过对酶浓度、固定化时间、pH以及缓冲液浓度等条件的考察，确定了最优固定化条件：50mg比活力6000U／g的巨大芽孢杆菌青霉素G酰化酶蛋白和1g ZH-HA悬浮于pH9．01mol／L磷酸缓冲液，室温搅拌6h，制得固定化巨大芽孢杆菌青霉素G酰化酶，活力2126U／g湿载体，活力回收率7．67％。比较研究了固定化酶与原酶性质，原酶最适温度45℃，最适pH为8．0。固定化酶则分别是50℃和9．0，分别比溶液酶偏移5℃、1．0个pH单位。经过40批连续水解青霉素G钾盐，固定化巨大芽孢杆菌青霉素酰化酶仍保持80％的活力，显示出良好的工作稳定性