焙烧温度对CO2-CH4重整制合成气NiO/γ-Al2O3催化剂性能的影响

采用水解-沉积法, 在不同焙烧温度下制备了cat-500、cat-600、cat-700和cat-800系列NiO/γ-Al₂O₃催化剂。XRD和H₂-TPR分析表明, 焙烧温度高于700 ℃, 活性组分与载体具有强烈的金属-载体相互作用(SMSI), 具体表现为活性组分前驱体以尖晶石NiAl₂O₄的形式存在。反应后催化剂的XRD、TG-DTG、TPH等表征结果表明, cat-700和cat-800试样的Ni晶粒尺寸分别为9.8和8.7 nm, 小于cat-500和cat-600试样(分别为15.7和13.6 nm), 分散性更好; 且催化剂表面积炭为丝状碳, 其不会导致催化剂失活, 但大量积累会引起床层压降升高, 影响催化剂的反应性能。cat-800试样110 h寿命试验表明, 高温焙烧制备的Ni基催化剂活性和稳定性均较高, CO₂转化率达95%左右, 失活速率仅为0.0536%/h。     

Exploitation of methane in the hydrate by use of carbon dioxide in the presence of sodium chloride

The replacement process of CH4 from CH4 hydrate formed in NaCl solution by using pressurized CO2 was investigated with a self-designed device at temperatures of 271.05,273.15 and 275.05 K and a constant pressure of 3.30 MPa.The mass fraction of the NaCl solution was either 0.5 wt% or 1.0 wt%.The effects of temperature and concentration of NaCl solution on the replacement process were investigated.Experimental results showed that high temperature was favorable to the replacement reaction but high NaCl concentration had a negative effect on the replacement process.Based on the experimental data,kinetic models of CH4 hydrate decomposition and CO2 hydrate formation in NaCl solution were established.The calculated activation energies suggested that both CH4 hydrate decomposition and CO2 hydrate formation are dominated by diffusion in the hydrate phase.     

凝胶网格法制备纳米CdFe_2O_4粉体及其对CH_3SH的气敏性

以无机盐为原料,采用凝胶网格法合成了尖晶石型复合氧化物CdFe2O4的前驱体,并在700°C热处理后得到了纳米尺寸CdFe2O4粉体,利用XRD和TEM对粉体的形貌、结构进行了表征。研究表明,用凝胶网格法制备的CdFe2O4结晶良好,粒度分布均匀,平均粒径为21.3 nm。以CdFe2O4纳米粉体为原料制备了厚膜型气敏元件。CdFe2O4是电子导电型半导体,当加热电压为6.5 V时,该元件对甲硫醇具有较高的灵敏度,较好的稳定性和选择性。     

CH4/CO2 reforming over La2NiO4 and 10%NiO/CeO2–La2O3 catalysts under the condition of supersonic jet expansion via cavity ring-down spectroscopic analysis

CH₄/CO₂ reforming over La₂NiO₄ and 10%NiO/CeO₂–La₂O₃ catalysts under the condition of supersonic jet expansion was studied via direct monitoring of the reactants and products using the sensitive technique of cavity ring-down spectroscopy. Vibration–rotational absorption lines of CH₄, H₂O, CO₂ and CO molecules were recorded in the near infrared spectral region. Our results indicated that La₂NiO₄ is superior to 10%NiO/CeO₂–La₂O₃ in performance. In addition, we observed enhanced reverse-water-gas-shift reaction at augmented reaction temperature. The formation of reaction intermediates was also investigated by means of time-of-flight mass spectrometry and there was the detection of CH_x⁺, OH⁺ and H⁺ species.     

载体对Co-Cu催化剂催化CH4-合成气梯阶转化反应的影响

以钴、铜为活性金属,采用等体积浸渍法制备Co-Cu双金属催化剂,考察了不同载体的Co-Cu双金属催化剂对CH4-合成气梯阶转化直接合成C2+含氧化合物的影响,并进行了XRD、NH3-TPD和H2-TPR表征及相应的分析。实验结果表明,载体对催化剂催化性能有较大的影响,不同载体的催化剂对CH4-合成气两步梯阶转化反应的活性高低顺序为Co-Cu/TiO2＞Co-Cu/Al2O3＞Co-Cu/SiO2,Co-Cu/TiO2催化剂对C2+含氧化合物的选择性为79.9%。这归因于TiO2载体与活性金属Co、Cu之间适宜的相互作用及载体对Co-Cu良好的分散性能。此外,Co-Cu/TiO2催化剂还具有反应所需的表面酸量及适度的中强酸度。     

WC/C制备条件对甲醇电氧化特性的影响研究

以钨酸铵为前躯体,采用程序升温控制还原法（TPR）制备了WC／C纳米颗粒,在碳载体存在的情况下,研究了钨源前躯体碳化过程中CH4与H2流量比对单-WC晶相以及Pt／WC／C电催化氧化甲醇性能的影响。XRD测试结果发现：仅在CH4：H2流量比为2时可获得单一WC多晶,其平均粒径为11．3nm。循环伏安实验结果证实：10wt％Pt-10wt％WC／C电催化氧化cH,OH的比质量活性达到875mA·mg^-1,远远高于10wt％Pt／C的658mA·mg^-1,且起始氧化电位负移80mV。计时电流法实验表明Pt／WC／C在酸性介值中稳定性高于Pt／C催化剂。     

基于ATmega128和CH374的USB接口设计

针对嵌入式MCU的USB接口需求,提出了以ATmega128为微处理器,采用USB控制器CH374,用SPI串口方式设计了一款USB接口,以解决嵌入式MCU与PC机进行通讯问题。文中介绍了该接口的硬件电路和软件设计方法,充分利用南京沁恒公司提供的资源,大大降低了软件设计的难度,提高了工作效率。在1KW碟式斯特林太阳能热发电装置中得到了应用,实践证明,该USB接口工作稳定、可靠,成本较低,取得了良好的应用效果。     

14C labelling of lignins of normal and bm3 maizes for fermentation studies

[U-¹⁴C] phenylalanine (phe*) and [O¹⁴CH₃] sinapic acid (sin*) were infused into the cut ends of normal and bm3 maizes (anthesis stage) under or above the last node or at mid-internode, with or without the leaf, in light or in darkness. Radioactivity was measured in the organs, and in phenolic constituents of the cell wall and saponified residues of the bases and tops of the apical inter-node. In both maize genotype labelled under the node the radioactivity was distributed more evenly in the organs with sin* than with phe*. Infusion above the node and at mid-internode greatly increased radioactivity in the bases and tops, respectively. Removal of the leaf only slightly increased the radioactivity, mainly in the bases, and no clear-cut effect of darkness was observed. Phe* labelled the phenolic acids and the three lignin units, but the syringyl units of bm3 maize were only slightly labelled. Sin* specifically labelled the syringyl units, which represented the least condensed fraction of lignins. Both the native and labelled lignins were highly alkali soluble. There were differences in lignin biogenesis between the bases and tops, and between normal and bm3 maizes. The newly formed lignins were slightly different from the native lignins but had similar types of heterogeneity, with variations in the internode and between genotypes similar to those in native lignins. Provided due allowance is made for the distinguishing characteristics of newly formed lignins, the [¹⁴C-lignin] cell walls, which are strongly labelled on complementary structures, seem suitable model substrates for fermentation studies.     

C02，CH4在全硅MFI型沸石中吸附的分子模拟

采用巨正则蒙特卡洛（GCMC）分子模拟方法研究了CO2,CH4分子在全硅MFI型沸石中的吸附行为,计算得到了纯组分和两组分的混合物在不同温度时的吸附等温线;分析了全硅MFI型沸石对混合组分的选择性吸附;模拟还得到了COz,CHt分子在全硅MFI型沸石中的吸附位。