氚气透过高纵横比空心玻璃微球的实验研究

为了测试用于激光聚变实验的高纵横比空心玻璃微球（HGM）对D2气保气性能及计算HGM内D2剩余量，对3种常用配方HGM及其用0.5MNH4F 0.1MHNO3洗液在90℃下处理后的HGM分别在573K下分三步热扩散充D2气，然后在290K下分别在0h、72h、144h时用气泡法测量HGM内的D2气压，由此测定了D2气体透过HGM的充气速率和漏气速率及其表观扩散活化能，并给出它们对D2保气半时间或充气半时间随HGM直径、壁厚和温度变化的计算式。     

氧化亚铁硫杆菌在气升式反应器中培养条件对其生长特性的影响

构建了一种用于菌体培养-矿物浸取的气升式反应器. 分别采用Leathen和9K培养基研究了不同条件下氧化亚铁硫杆菌在气升式反应器中的生长、Fe2+氧化速率、溶氧随培养时间的变化及其相互关系. 通过测定溶氧和Fe2+氧化速率可了解培养条件对微生物生长特性的影响.     

PS-PVA-CH塑料空心微球充D2

研究了激光惯性约束聚变靶用PS-PVA-CH三层塑料空心微球采用热扩散法高温高压充氘气技术。实验研究表明,对于直径300 μm、PS壁厚5～7 μm、PVA壁厚3～5 μm、CH层厚4～6 μm的塑料微球,50℃充气的平衡时间为20～40 h,70℃的平衡时间为7～12 h,90℃的平衡时间为2～4 h。在室温25℃时,微球的气体渗透系数为（3.0～4.2）×10^-19 mol·m^-1·s^-1·Pa^-1,对应的保气半寿命为28～37 h。对于参数接近的微球,如果充气时间相同,充气外压与微球内压基本呈正比。当外压达到6.0 MPa时微球开始出现破损。     

泰国轮胎工业标准将强制执行

正9月16日,泰国工业部工业标准学会(TISI)分别发布3个通报,拟将机动车、商用车和摩托车等主要轮胎品种的工业标准作为强制性标准执行。3个通报的评议时间为60天,批准和生效日期待定。3个轮胎产品的标准分别是机动车及其拖车充气轮胎工业标准,涵盖用于机动车类型M1、N1、O1和O2的充气轮胎,不适用于老式设备和竞赛用机动车轮胎;商用车辆及其拖车充气轮胎工业标准,涵盖用于机动车类型M2、M3、N、O3和O4的充气轮胎,不适用于速度种类标志低于80 km/h的轮胎;摩托车与轻型摩托     

Fe-TiO_2光催化涂层材料的制备及在可见光下清除甲醛的性能表征

用Fe3+的丙酮溶液对商品锐钛型TiO2光催化剂PC-500进行浸渍改性,制得Fe-TiO2光催化剂。将该光催化剂作为功能性组分加入到耐光催化氧化的硅酸钾无机涂料体系中,得到了一种光催化功能性建筑涂料。使用自行设计的间歇式气-固相反应器,测定了该功能性涂料在可见光下对甲醛的降解性能。实验表明,该涂料最初3h内对甲醛的平均降解速率达到20 3mg/(m2·h);参加过反应的涂料在洁净空气中再生24h后对甲醛的降解性能几乎没有变化;在人工加速老化仪中老化480h后,该涂料3h内对甲醛的平均降解速率仍能达到16 2mg/(m2·h)。     

阴离子交换树脂对磺基水杨酸的吸附解吸性能

用阴离子交换树脂(D201)吸附的方法研究了磺基水杨酸的富集及回收。测定了溶液的pH值、温度、吸附时间等因素对吸附的影响,探讨了吸附的热力学和动力学特性。结果表明:D201树脂在pH=2—11时,吸附能力最好,等温吸附服从Freundlich经验式,吸附动力学符合Lagergren一级速率方程,颗粒内扩散是速率控制步骤之一,膜扩散也共同影响着吸附过程。在295—313 K条件下,磺基水杨酸吸附质量分数为380—420 mg/g的吸附焓变为-13.73—-8.422 kJ/mol,自由能变为-19.89—-21.45 kJ/mol,吸附熵变为20.88—41.62 J/(K.mol),吸附速率常数为0.025 3—0.056 5 min-1,吸附活化能为34.04 kJ/mol。315 K下用质量分数10%NaCl+2%NaOH溶液可定量洗脱,洗脱率达99%。     

LNG卸料管道预冷工艺仿真优化

针对LNG卸料管道预冷工艺,建立了气液分层流模型和动态仿真操作平台。在满足目前现场安全规范的前提下,对当前常用BOG和LNG阶梯式预冷工艺进行优化;其LNG用量为264t,耗时30h。基于此,设计了三种典型预冷方案并利用本文动态仿真操作平台对其优化:低温BOG预冷至153K后用LNG预冷;低温BOG预冷至173K后用LNG预冷、直接LNG预冷。分别可节省LNG用量112t、154t和210t,节省能源成本42%、58%、80%,耗时增加24h、25h和52h。仿真计算表明:对于国内常用的LNG卸料管道系统,控制卸料管道降温速率,即可保证预冷过程安全可靠。     

稻壳在水蒸气中气化实验研究

在流化床实验装置上以水蒸气为气化剂,对稻壳进行热解气化的实验研究,分别考察单因素反应温度(500~700℃)、蒸气流量(7~11kg/h)和进料速率(1.2~3.6kg/h)对产气率及其主要组分(H2、CO、CH4、CO2)的影响。实验结果表明:温度的升高可提高气化气产率及气体组分中CH4和H2的含量,同时降低了CO2的含量,随温度升高,CO的含量呈先增加再降低的趋势。蒸气流量和进料速率的增加对产气率影响分别在500℃和700℃呈现出了不同的规律,说明了在不同反应温度下床内起主导作用的反应不同。在700℃,随蒸气流量和进料速率增加,气化气中H2、CO和CO2的含量都有小幅度变化,CH4体积分数稳定在12%左右。在条件考察范围内,当反应温度为700℃、蒸气流量为7kg/h、进料速率为1.2kg/h时,产气率和H2体积分数分别有最大值,为725L/h和18.05%。     

液滴法制备空心玻璃微球中初始液滴的定量形成

通过对液滴法制备激光聚变靶丸空心玻璃微球（HGM）中液滴形成过程予以分析,导出了射流初始速率、液滴直径及目标HGM直径分别与进为压力、小孔板孔径、射流振荡频率、溶液浓度及密度等因素的定量表达式,并在进料压力为13．7、18．7、23．6、28．5、33．4、38．3、43．2kPa和溶液中玻璃形成物浓度为1％、2％、4％、6％、8％、12％、16％下,测量了孔直径分别为108μm、142μm和168μm的小孔板的流量及流动系数,给出了射流初始速率、液滴直径及目标HGM中玻璃形成物含量的定量控制条件,实验结果符合定量表达式。     

面向中温储热的D-半乳糖醇/肌糖醇二元共晶相变材料热稳定性研究

相变材料的热稳定性在实际相变储热应用中至关重要。通过熔融共混的方法制备了可用于中温储热的D-半乳糖醇（69%（mol））/肌糖醇二元共晶相变材料,使用真空管式炉分别在463、473、483和493 K温度下将该共晶混合物加热5、10、15和20 h。然后采用差示扫描量热仪测量试样的熔化焓,并采用基于焓值变化的恒温动力学模型分析其焓值热降解特性,从而对其热稳定性进行评价。此外,采用添加抗氧化剂1010（1.0%（质量））的方法提高共晶糖醇的热稳定性。结果表明,在463 K温度下加热20 h后,共晶糖醇焓值下降24.9%;添加抗氧化剂后,其焓值仅下降8.25%。采用恒温动力学模型计算发现,共晶糖醇在463 K温度下焓值下降一半所用的时间为154 h,添加抗氧化剂1010后,其热降解时间增加约4倍。当加热温度升高至473、483、493 K时,热降解时间分别提高约2.6、1.6、1.1倍,热降解速率 k值分别降低62.65%、40.42%、6.51%。结果表明添加抗氧化剂可有效提高共晶糖醇的热稳定性。     

TiO2薄膜光催化剂的性能研究

采用溶胶-凝胶法在玻璃管上制备了透明的TiO₂薄膜，并利用XRD、Raman、UV-Vis和XPS技术对薄膜进行了表征。结果表明,在773 K焙烧的TiO₂样品在290～330 nm处的吸收明显强于573 K焙烧的样品。在573 K焙烧的情况下，薄膜基本为非晶态，但却表现出良好的光催化活性，并随着负载层数的增加，薄膜的光催化活性逐渐增加。在573 K以上，随焙烧温度的升高，TiO₂薄膜的光催化活性逐渐降低。     

Methanol decomposition over supported palladium and platinum

Methanol decomposition over supported Pt and Pd catalysts was investigated in the temperature range from 453 to 573 K with the partial pressure of methanol up to 0.8 arm. The specific activity of Pd was higher than that of Pt, and alumina-supported Pd was more active than silicasupported Pd, although aluminasupported catalysts produced dimethyl ether as a by-product. A silica-supported Pd catalyst prepared from a tetraamine salt solution with a proper pH exhibited higher activity than the other silica-supported Pd catalysts. Dependence of the decomposition rate on the partial pressure of methanol was similar regardless of the metal, the support or the preparation method. The apparent reaction orders were near 0.3 at low pressures below about 0.4 atm and became near zero or slightly negative at higher pressures. The apparent activation energies were about the same for most of the catalysts and were in the range from 66 to 77 kJ/g-mol.     

Influence of Particle Size on Reaction Selectivity in Cyclohexene Hydrogenation and Dehydrogenation over Silica-Supported Monodisperse Pt Particles

The role of particle size during the hydrogenation/dehydrogenation of cyclohexene (10 Torr C₆H₁₀, 200–600 Torr H₂, and 273–650 K) was studied over a series of monodisperse Pt/SBA-15 catalysts. The conversion of cyclohexene in the presence of excess H₂ (H₂: C₆H₁₀ ratio = 20:60) is characterized by three regimes: hydrogenation of cyclohexene to cyclohexane at low temperature (<423 K), an intermediate temperature range in which both hydrogenation and dehydrogenation occur; and a high temperature regime in which the dehydrogenation of cyclohexene dominates (>573 K). The rate of both reactions demonstrated maxima with temperature, regardless of Pt particle size. For the hydrogenation of cyclohexene, a non-Arrhenius temperature dependence (apparent negative activation energy) was observed. Hydrogenation is structure insensitive at low temperatures, and apparently structure sensitive in the non-Arrhenius regime; the origin of the particle-size dependent reactivity with temperature is attributed to a change in the coverage of reactive hydrogen. Small particles were more active for dehydrogenation and had lower apparent activation energies than large particles. The selectivity can be controlled by changing the particle size, which is attributed to the structure sensitivity of both reactions in the temperature regime where hydrogenation and dehydrogenation are catalyzed simultaneously.     

Solubility of propylene in semicrystalline polypropylene

Gas solubilities and polymer swelling in propylene and semicrystalline polypropylene system at temperatures of 323.2 and 348.2 K and pressures up to propylene's vapor pressure were measured. Pressure, specific volume, and temperature (PVT) measurements of polypropylene were carried out at temperatures from 313 to 573 K and pressures up 200 MPa. Two kinds of polypropylenes, which had different stereoregularities, were used for both solubility and PVT measurements. The solubilities were correlated with the Sanchez–Lacombe equation of state (EOS) with temperature‐dependent binary interaction parameters to within 5% average relative percentage deviation. Swelling ratios estimated with Sanchez–Lacombe EOS coupled with optimized interaction parameters were 20% lower than the experimental values. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1134–1143, 2001     

微波场中生物炭还原褐铁矿反应动力学实验及模型计算

采用微波失重在线检测装置和XRD分别分析了褐铁矿与生物炭升温至923 K的失重变化及微波焙烧前后的矿相变化;同时基于褐铁矿微波还原焙烧升温失重曲线,采用Achar-Brindley-Sharp-Wendworth微分法和Coats-Redfern积分法,计算了褐铁矿在不同温度段的反应动力学参数. 结果表明,褐铁矿与生物炭在923 K的还原温度下转变为磁铁矿,同时生成少量的硅酸亚铁(Fe2SiO4);其微波还原焙烧过程分为3个阶段进行,在366~470 K,反应的表观活化能(E1)分别为30.7和26.3 kJ/mol,反应机理符合反应级数函数,属于化学反应控制;在470~650 K,表观活化能(E2)分别为40.3和33.1 kJ/mol,反应机理符合Avrami-Erofeer函数,是随机成核和随后生长的化学反应控制;在650~825 K,表观活化能(E3)分别为52.4 和52.9 kJ/mol,反应机理符合Zhuralev-Lesokin-Tempelman函数,属于三维扩散控制.     

Temperature and hydrogen pressure dependences in the ring opening of methylcyclobutane over Pt/SiO2 catalyst

The temperature and hydrogen pressure dependences in the ring-opening reactions of methylcyclobutane were studied over Pt/SiO₂ catalyst. The temperature dependence of the ring opening revealed that the reaction rate vs. temperature curves passed through a maximum. On the basis of this information two temperatures were selected for hydrogen pressure studies: 573 K, close to the lowest temperature at which any reaction took place at all, and 623 K, where the ring opening of methylcyclobutane exhibited the highest rate. The initial formation rate vs. hydrogen pressure dependence curves are of bimodal type at 573 K, but they increase monotonously at 623 K. Over the working catalyst, no significant changes were observed at 573 K, but the curve for pentane formation changed to a large extent at 623 K. At 573 K, the selectivity of ring opening was close to statistical, with little excess of isopentane (sterically less hindered direction) over both the clean and the working catalyst. This was also observed at 623 K, however, over the working catalyst as the hydrogen pressure increased the selectivity of the ring opening increased as well. Moreover, at the highest hydrogen pressures studied excellent selectivity for the formation of isopentane was observed. The mechanisms over the initial and the working catalysts are discussed on the basis of these experimental findings.     

Electrical Conductivity of Zirconia Stabilized with Scandia and Yttria

Electrical conductivity of zirconia stabilized with scandia and yttria (Sc₂O₃+Y₂O₃= 8 mol%) has been measured by the complex impedance method in the temperature range 573 to 1173 K. With increasing Sc₂O₃ concentration, electrical conductivity increases at temperatures above 640 K, but it decreases below this temperature. Electrical conductivity in the electrolytes examined is a result of two processes: an activation energy of 59 to 79 kJ·mol⁻¹ predominant at high temperatures and an activation energy of 109 to 125 kJ·mol⁻¹ predominant at low temperatures.     

Kinetic analysis of spinel formation from powder compaction of magnesia and alumina

A kinetic investigation into the formation of spinel from alumina (Al₂O₃) and magnesia (MgO) powder compaction with a stoichiometric mixing molar ratio of 1:1 was conducted in the temperature range of 1573 K to 1773 K over a certain time interval up to 25 h. The samples were pressed at pressures of 125, 375 and 750 MPa. The progress of the reaction was evaluated by monitoring the expansion ratio instead of the thickness of the spinel layer that was generated. The expansion ratio increases with increasing pressing pressure and holding time, and high temperature favored spinel formation. However, densification was observed at temperatures above 1673 K due to the occurrence of sintering between the powders. A kinetic model taking electrochemical potential as the driving force of the reaction was established, and the apparent activation energy was calculated to be 310.6 kJ/mol in the temperature range between 1573 K and 1673 K. The reaction was controlled by the inter-diffusion of Al³⁺ and Mg²⁺ ions in the spinel layer that was formed.     

Kinetics of alkylation of phenol with methanol over Ce-exchanged NaX zeolite

The alkylation of phenol with methanol was investigated in vapor phase over a series of cerium-exchanged NaX zeolite with Ce loadings ranging from 0 to 10.43 wt%. The catalyst MX-4 with 8.86 wt% cerium was found to be the best one with total cresols selectivity of 72% at a temperature of 573 K and MeOH to phenol mole ratio of 4:1. The catalyst was also found to be quite stable in the operating range investigated. It was established that the stronger acid sties are required for C-alkylation compared to O-alkylation. From the study of the effects of various parameters, the optimum operating condition for highest cresols selectivity were determined as: MeOH to phenol mole ratio, 4:1; temperature, 623 K; space-time, 10.2 kg h/kgmole under atmospheric pressure. From the kinetic analysis of the experimental data, the apparent activation energy for the reaction was determined as 57.2 kJ/mole.     

Vapor Pressure, Enthalpy, Evaporation Coefficient, and Enthalpy of Activation of the Beryllium Nitride (Be3N2) Decomposition Reaction

Beryllium nitride (Be₃N₂) vaporizes congruently in the range 1640° to 1960°K by the reaction Be, N₂( c ) = 3Be( g ) + N₂( g ). The equilibrium nitrogen partial pressure, in atmospheres, at the composition for congruent sublimation is given by the expression log P _N2= [(–1.952 ± 0.038) × 10⁴] T ⁻¹+ (6.509 ± 0.207). The measured enthalpy of decomposition (370 ± 5 kcal at 298° K) yields an enthalpy of formation for Be₃N₂( c ) of –136 ± 6 kcal/mole. The upper limit to the evaporation coefficient at 1600° to 2000°K can be set as 10^–4 by comparison of equilibrium data to Langmuir data obtained with a sample of 18% porosity. The apparent enthalpy of activation for the reaction is 409 ± 7 kcal/mole at 1800°K for the porous Langmuir specimen. An expression is developed to predict the temperature dependence of the reduced apparent pressures in Knudsen studies of substances with low evaporation coefficients in terms of the enthalpy of activation. The variation in temperature dependence of the Langmuir measurements and Knudsen measurements with three different-sized orifices is consistent with predictions from this expression.