Nanosized cobalt-based catalyst prepared by supercritical phase condition for Fischer-Tropsch synthesis

A series of nanosized Co/Zn/Mn/K composite catalysts for Fischer-Tropsch synthesis (FTS) were prepared by supercritical fluid drying (SCFD) method and common drying (CD) method. The nanosized cobalt-based catalysts were characterized by XRD, TEM and BET techniques. Their catalytic performances were tested in a slurry-bed reactor under FTS reaction conditions. The drying and crystallization were carried out simultaneously during SCFD, therefore, the catalysts prepared by SCFD method have ideal structure and show the FTS performance superior to the others prepared by CD method. The FTS activity and selectivity were improved via adding Zn, Mn and K promoters, and less CH₄ and CO₂ as well as higher yield of C₅₊ products were achieved. The optimal performance of a 92% CO conversion and a 65% C₅₊ product yield was obtained over a catalyst with the component of Co/Zn/Mn/K = 100/50/10/7. Furthermore, the catalytic performance was studied under the conditions of liquid-phase and supercritical phase slurry-bed, and C₅₊ product yield were 57.4% and 65.4%, respectively. In summary, better catalytic performance was obtained using the nanosized catalyst prepared by SCFD method under supercritical reaction conditions, resulting in higher conversion of CO, less CO₂ byproduct, and higher yield of C₅₊ products.     

Enhanced electroluminescence of Eu by Tb in complexes Tb1−xEux(TTA)3Dipy

A series of rare earth ternary compounds of Tb_1−xEu_x(TTA)₃Dipy (HTTA=thenoyltrifluoroacetone, Dipy=2,2′-dipyridyl) have been synthesized, and the characteristics of the compounds have been performed by DTA-TG, IR, UV and fluorescence spectroscopy. Photoluminescence measurements indicated that the complexes of Eu(III) emit strong red luminescence under UV radiation. IR spectra suggest that complexes have been successfully synthesized, and TG curves indicate that the complexes are stable up to a temperature of about 220 °C. The Eu complex was blended with poly(N-vinylcarbazole) (PVK) and spin coated into films, and electroluminescence devices with the structure of Indium Tin Oxide (ITO)/PVK:Tb_1−xEu_x(TTA)₃Dipy/BCP(2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline)/aluminum quinoline (AlQ)/Al were fabricated, the luminescence of Eu³⁺ complexes enhances after doping with Tb³⁺. Therefore, it may be an effective method to improve the EL intensity of the lanthanide complex.     

Effect of Several Anions on Fe-Based Catalyst for Fischer-Tropsch Synthesis

The influence of several anions on Fe-based Fischer-Tropsch catalyst,used in the synthesis of light olefins from synthesis gas,was studied.The results indicated that the addition of anions resulted in the reduction of catalytic activity.When the anion content in the catalyst was 500 ppm,the influence of different anions on the catalysis activity was as follows:S~(2-)>Cl~->SO_4~(2-)>NO_3~-.The addition of S~(2-)improved the selectivity of total hydrocarbons in the products,and Cl~- reduced this selectivity but increased the olefin content in the total hydrocarbons at the same time.When the contents of S~2 and Cl~- in the catalyst were less than 50 ppm,their influence could be ignored.The XRD results indicated that the addition of anions reduced the contents ofα-Fe and Fe_3C,which were the active components in the catalyst.     

808 nm InGaAsP-InP单量子阱激光器热特性研究

从InGaAsP-InP单量子阱激光器结构分析入手,采用自行设计的热封闭系统对808 nm InGaAsP-InP单量子阱激光器热特性进行了研究.实验表明,在23-70℃的温度范围内,器件的功率由1.74 W降到0.51 W,斜率效率由1.08 W/A降到0.51 W/A.实验测得其特征温度T0为325 K.激射波长随温度的漂移dλ/dT为 0.44 nm/℃.其芯片的热阻为3.33℃/W.     

聚烯丙硫醇/丙烯酸甲酯羰基铑(Ⅰ)配合物的分子内取代反应

合成了一种新的含有S、O未配位原子的高分子顺二羰基铑配合物 ,用IR和XPS数据研究了其分子内羰基取代反应 ,结果表明在遇热且无CO保护下S、O与铑形成的弱的S→Rh、O→Rh键可取代强的Rh→Cπ键 ,形成稳定的四配位结构 ,从而保护了铑不因末端羰基脱落而分解 ,提高了它的稳定性 ;其分子内取代反应是可逆的 ,在CO气氛下该结构又能够回复到二配位结构     

Controllable growth of well-aligned ZnO nanorod arrays by low-temperature wet chemical bath deposition method

Well-aligned ZnO nanorod arrays were synthesized by low-temperature wet chemical bath deposition (CBD) method on Si substrate under different conditions. Results illustrated that dense ZnO nanorods with hexagonal wurtzite structure were vertically well-aligned and uniformly distributed on the substrate. The effects of precursor concentration, growth temperature and time on nanorods morphology were investigated systematically. The mechanism for the effect of preparation parameters was elucidated based on the chemical process of CBD and basic nucleation theory. It is demonstrated that the controllable growth of well-aligned ZnO nanorods can be realized by readily adjusting the preparation parameters. Strong near-band edge ultraviolet (UV) emission were observed in room temperature photoluminescence (PL) spectra for the samples prepared under optimized parameters, yet the usually observed defect related deep level emissions were nearly undetectable, indicating high optical quality ZnO nanorod arrays could be achieved via this easy process chemical approach at low temperature.     

微机控制实现检测数据的彩色图象显示

计算机控制实现探测数据的彩色图象显示是一种新型的显示技术。在如压力、温度、速度等大面积物理参数的自动探测与彩图显示方面都有广泛应用。做为这种技术的一个应用实例,本文介绍了黑白图象伪彩色编码的实验工作,对实验所采用的方法、设备的特点以及在流动显示等其它方面的应用进行了讨论。     

半浮区液桥振荡对流的微重力实验

利用日本微重力中心８００ｍ落井装置，完成了半浮区液桥振荡对流的微重力实验，对振荡对流的典型物理量诸如内部温度、流场、自由面边缘变化及表面波进行了综合测量。实验结果给出了振荡对流由地球重力环境向微重力环境的过渡，以及不同几何参数半浮区液桥的振荡特征，并首次获得了微重力环境下热毛细对流的表面波位形及边缘振荡特征．     

氯化钙在粗孔硅胶上的单层分散及其氨吸附——乙醇溶液浸渍法的影响

利用乙醇溶液浸渍法将氯化钙担载于粗孔硅胶上,通过焙烧或微波加热使氯化钙在载体表面分散,研究了不同条件下氯化钙在粗孔硅胶上的单层分散及其氨吸附量的影响,并将结果与水溶液浸渍法进行了比较.结果表明,乙醇溶液浸渍样品的适宜焙烧温度为500℃,对应的氯化钙单层分散阈值在0.4-005g/g之间,而水溶液浸渍样品的最大单层分散容量小于0.4g,g,乙醇溶液浸渍法较水溶液浸渍法更适合在粗孔硅胶上担载氯化钙.乙醇浸渍微波法与焙烧法相比,微波法能显著提高氯化钙在硅胶上的单层分散.氨吸附实验进一步验证了上述结论,担载量为0.5g/g的乙醇浸渍微波样品的氨吸附量最大,在35℃达到0.654g,g.乙醇溶液浸渍样品的氨吸附分离能力明显大于水溶液浸渍样品.     

Effect of different annealing temperature on Sb-doped ZnO thin films prepared by pulsed laser deposition on sapphire substrates

Influence of annealing temperature on the properties of Sb-doped ZnO thin films were studied. Hall measurement results indicated that the Sb-doped ZnO annealed at 950 °C was p-type conductivity. X-ray diffraction (XRD) results indicated that the Sb-doped ZnO thin films prepared at the experiments are high c-axis oriented. It was worth noting that p-type sample had the worst crystallinity. The measurements of low-temperature photoluminescence (PL) spectra indicate that the sample annealed at the temperatures of 950 °C showed strong acceptor-bound exciton (A⁰X) emission, and confirmed that it is related to Sb-doping by comparing with the undoped ZnO low-temperature PL spectrum.