焦炭反应性与反应后强度的关系及其影响因素探讨

为了很好地预测焦炭在高炉中的反应行为,对大量的焦炭进行了检测及数据的分析,说明焦炭反应性与反应后强度之间有良好的负相关性;对焦炭冷态强度与热态性能之间进行了对比,建议焦化企业在保证焦炭的冷态强度合格的同时,更要关注焦炭的热态性能指标;对影响焦炭反应性与反应后强度的反应温度、碱金属、钝化剂等因素进行了试验,指出在生产中应严格控制高炉操作温度,并在按国标方法测定时,加入一定浓度的碱类,以模拟高炉生产的实际过程。提出熄焦时采用一定浓度的硼砂溶液喷洒焦炭,可改善焦炭的热性能。     

添加剂对焦粉型焦性能的影响

分析了热压成型及冷压成型方法的优劣。选择增强剂、固化防水剂等添加剂对水玻璃粘合剂进行改性,研究了添加剂对型焦性能的影响。实验结果表明,焦粉成型添加剂加入量为:水玻璃粘合剂12%,增强剂0.2%,固化防水剂0.3%,成型焦球生(干)型焦落下强度、生(干)型焦压缩强度、耐水性、热稳定性、反应活性等性能可满足工业生产的工艺要求。     

丙烯酸偕二硝基丙酯与苯乙烯的共聚合及共聚物性质

丙烯酸偕二硝基丙酯(DNPA)与苯乙烯(St)在乙酸乙酯溶液中自由基共聚反应得到DNPA-St共聚物,利用红外光谱法测定了共聚物的组成,从而测得了丙烯酸偕二硝基丙酯与苯乙烯的竞聚率,采用FT-IR、1H NMR、DSC等方法研究了DNPA-St共聚物的结构和热性能.研究结果表明,用Fineman-Ross方法,求得丙烯...     

Effect of CO2 Exposure on the Chemical Stability and Mechanical Properties of BaZrO3‐Ceramics

The reactivity of BaZrO₃ with CO₂ has been addressed as one of the major challenges with BaZrO₃‐based electrolytes in protonic ceramic fuel cells. Here, we present a study of the effect of CO₂ exposure on BaZrO₃‐materials at elevated temperatures. Dense BaZr_1?xY_xO_3?x/2 (x = 0, 0.05, 0.1, 0.2) and BaCe_0.2Zr_0.7Y_0.1O_2.95 ceramics were prepared by sintering of powder prepared by spray pyrolysis. The Vickers indentation method was used to determine the hardness and estimate the fracture toughness of pristine materials as well as the corresponding materials exposed to CO₂. Formation of BaCO₃ on the surface of exposed ceramics was confirmed by X‐ray diffraction and electron microcopy. The reaction resulted in formation of Ba‐deficient perovskite at the exposed surface. The reaction with CO₂ was most pronounced at 650°C compared to the other temperatures applied in the study. The reactivity was also shown to depend on the Y‐content and the grain size and was most pronounced for BaZr_0.9Y_0.1O_2.95. The reaction with CO₂ was observed to have a profound effect on the fracture toughness of the ceramics, demonstrating a depression of the mechanical stability of the materials. The results are discussed with respect to the chemical and mechanical stability of BaZrO₃ materials, with particular emphasis on the composition and grain size.     

Processing of ZrO2 scaffolds coated by glass–ceramic derived from 45S5 bioglass

Three dimensional, highly porous, ZrO₂ scaffolds coated by glass–ceramic derived from 45S5 bioglass were fabricated. The surface reactivity of 45S5 in aqueous solution was investigated as a function of the immersion time. The influence of the solid loading on the rheological behavior of 45S5 aqueous slips with ammonium polyacrylate (NH₄PA) was studied; besides the effect of poly(vinyl)alcohol (PVA) on the relative viscosity was determined. The structure and microstructure of uncoated and coated ZrO₂ scaffolds were characterized. The high ionic exchange capability of 45S5 was demonstrated by the pH rise, the significant weight loss and the amorphous calcium phosphate nucleation, upon its immersion in aqueous solution. The addition of PVA did not affect the dispersion properties of the 45S5 powder, which were basically controlled by its negative surface charge. 30 wt% 45S5 slips with 4 wt% PVA exhibited a yield stress and an adequate viscosity in the low shear rate range, to produce a bioglass coating into the ZrO₂ scaffold. The glass-ceramic coating was distributed along the strut surfaces, forming a thin film without altering the porosity and the strut thickness of the original ZrO₂ scaffold structure.     

低灰熔点无烟煤煤焦与CO_2催化气化特性研究

利用碱金属碳酸盐作催化剂,对低灰熔点无烟煤煤焦与CO2的催化气化反应活性进行研究.结果表明,反应活性主要受温度、催化剂种类及担载量的影响,催化活性顺序为:K2CO3Na2CO3Li2CO3,煤焦的反应活性随着催化剂担载量的增加而提高;在反应过程中,催化剂与煤焦中的物质会发生一定程度的反应,生成不溶性盐;煤焦的比表面积会随着催化剂担载量的增大而减小,但催化活性反而增强,其主要受到催化剂提供的反应活性中心的影响.     

铂催化硅氢加成反应研究进展

硅氢加成反应是合成有机硅材料最重要的途径之一,铂催化剂作为其应用最广的催化剂,具有重要的意义。本文首先介绍了硅氢加成反应机理的研究现状;分析了聚合物长链段铂配合物、含多个铂原子铂簇化合物及N-杂环卡宾铂配合物均相铂催化剂的研究进展,致力于改善均相催化剂催化选择性差、催化活性难以控制等缺点;分别阐述了不同铂催化剂载体如无机二氧化硅、炭载体、金属氧化物、有机高分子、固载液等作为铂催化剂载体的优点,负载铂催化剂具有可回收、产物选择性好的优点,有效解决了工业上铂损失的问题;最后对铂催化硅氢加成反应的发展趋势进行了展望分析,铂负载能力的提高、铂负载催化剂的分离、硅氢加成反应的原理、催化范围的扩大等均是今后研究的重要方向。     

酯交换法合成碳酸甲乙酯催化剂的研究进展

碳酸甲乙酯（EMC）是一种环境友好型的不对称碳酸酯,因其独特的结构性质被广泛用作溶剂或有机合成中间体,特别是随着锂离子电池的迅猛发展,其作为电池电解液主要成分市场需求量急增。文中简单介绍了光气法、氧化羰化法和酯交换法合成碳酸甲乙酯的研究进展。重点针对最具发展前景的酯交换法合成EMC工艺路线中所用催化剂进行了综述;讨论和分析了该路线所用催化剂的类型、结构、性质及性能,并对当前研究中存在的问题进行了归纳和分析总结。最后本文分析并展望了酯交换法合成EMC催化剂的研究方向及新型合成工艺发展趋势,提出研发经济、高效、稳定且制备工艺简单的非均相催化剂,并与反应精馏技术耦合是今后的主要发展趋势,期望为EMC的高效合成提供参考和借鉴。     

水淬渣的胶凝活性及其形成机理

采用重新熔融水淬的方法制备不同水淬矿渣样品,综合进行净浆强度实验和碱溶出实验研究,借助XRD,DTA, TEM, SEM和EDX等分析手段,研究了矿渣形成过程、形成结构和胶凝性能之间的关系,并在此基础上探讨了矿渣潜在胶凝活性的形成机理. 研究表明,在合适的排渣温度和冷却速度条件下,水淬渣能够形成分相结构,对水淬渣胶凝活性产生重要影响. 分相矿渣具有富钙相和富硅相,富钙相的迅速溶解和富硅相的缓慢溶解是水淬渣水化过程中产生足够早期强度和发挥稳定后期强度的主要原因. 由于玻璃分相的影响,排渣过程存在最佳工艺条件,即最佳的排渣过程能使水淬渣形成玻璃分相结构,从而具有最好的活性.     

双酚A的酶联免疫检测方法的建立

将双酚A(BPA)半抗原与牛血清白蛋白(BSA)共价偶联后,制备兔抗双酚A多克隆抗体,建立了双酚A间接竞争酶联免疫(icELISA)检测方法,并对其进行了方法学评价。结果表明:最佳的抗体稀释度为1∶1600,双酚A竞争标准曲线在0.3～100μg·mL-1之间具有良好的线性关系,最低检测浓度为0.001μg·mL-1,重现性实验变异系数均小于10%。交叉反应实验中,与双酚酸和双酚B的交叉反应率分别为20.0%和10.0%;与双酚E和4-枯基苯酚的交叉反应率均在5%以下。水样的添加回收实验,回收率范围为92.5%～107.7%。