中北大学磁载钛硅基催化剂制备成功

正中北大学在磁载钛硅基催化剂制备及磁分离反应方面的研究取得突破,开发出具有催化活性且可磁分离功能的复合催化剂,研制了磁分离反应一体化装置,解决了细小催化剂的固液分离难题,并减少了后序固液分离装置和相关配套设施。中北大学该项研究可用于磁性钛硅分子筛催化环己酮氨肟化制环己酮肟、磁性氧化钛光催化降解有机废水、磁性铜硅催化剂催化糠醛加氢制糠醇和磁性固体酸催化烯烃制     

磁性催化剂反应器耦合磁分离装置

反应磁分离耦合装置兼具化学反应和流固相分离的功能,有助于提高反应效率、降低分离能耗、缩短工艺流程和避免催化剂磨损流失。综述近年来反应磁分离耦合装置的研究进展,流化态耦合磁分离装置包括磁稳流化床反应器和流化床耦合旋流磁分离装置,悬浮态耦合磁分离装置包括磁分离耦合悬浮态光催化反应器和釜式反应器耦合磁分离装置。指出磁性催化剂反应器和磁分离耦合装置应用中需要解决的关键问题是:规范生产适用于磁性催化剂反应器耦合磁分离装置的磁性催化剂以及构建磁性催化剂反应器耦合磁分离装置过程中必须引入磁场发生器。     

磁响应分离膜研究进展

随着智能材料和纳米技术的发展,具有刺激响应的新型功能膜材料是膜分离技术发展的主要方向之一。磁响应分离膜是一种由磁性颗粒和聚合物高分子混合制备的,可以对磁场刺激产生响应的分离膜。磁响应分离膜兼具膜分离技术的低能耗、高效率等优点和磁性颗粒的磁性响应和催化性能等。磁性颗粒对磁场的响应不仅会影响膜的结构和分离选择性,还会改变膜材料的润湿性以及提高膜抗污染性能。本文从共混法、涂层法、接枝法和原位生长法对磁响应分离膜的制备方法展开论述,介绍了不同制备方法的优缺点及未来发展方向。从调控膜表面润湿性、调控膜抗污染性、调控膜孔径三部分对磁响应分离膜的磁场响应机理进行了详细阐述。并从过滤、吸附、降解、交换分离四方面对磁响应分离膜的应用领域展开论述。最后对磁响应分离膜的发展进行了总结,并对其发展前景进行了展望。     

高梯度磁除尘的实验研究

对磁性粉尘和非磁性粉尘进行了磁分离实验研究。结果表明,对磁性粉尘,磁除尘效率可达９９％ 以上,而对非磁性粉尘,通过粉尘上磁,磁除尘效率可达９０％ 以上。     

超导磁分离：工业废水处理新途

一项超导磁体应用技术研究表明,超导高梯度磁分离技术可用于造纸、化工、医药工业废水的净化分离。与传统的超导磁分离技术只能分离矿物、煤、高岭土中磁性杂质不同,该技术通过预先加入改性的磁种子颗粒材料,从而分离工业废水中无磁性的有机、无机污染物,实现工业污水的达标排放。     

嗜硫磁性微球特异性分离牛免疫球蛋白G

利用徽悬浮法制各微米级顺磁性聚合物微球,进一步使用嗜硫性配基（2-巯基噻唑啉）进行表面修饰。并利用此嗜硫性聚合物磁性微球对成牛血清的免疫球蛋白G进行特异性分离。结果表明,聚合物徽球的粒径为0．6～20岫,磁性微球的磁含量高于47％,在PH=3．5的柠檬酸缓冲液中可以特异性吸附成牛血清中的免疫球蛋白G,用低盐浓度NaCI（0．6mol／L）实现解吸附,同时分离提纯后抗体活性依然可以高达99％,磁球分离效率达到88％,最高分离量可以达到39．5mg／g。     

磁稳定床及磁性催化剂的研究进展

对磁稳定床及磁性催化剂在石油化工和生物工程等领域的应用进行了归纳总结。磁稳定床已经应用于催化加氢、烟尘净化、干法选煤、生化分离、固定化生物反应器、细胞培养等过程。与传统工艺相比,磁稳定床兼有固定床和流化床的优点,能强化受传质传热限制的反应过程,提高反应效率,在实际应用中显示出独特的优越性。磁性催化剂的设计与开发是磁稳定床应用的关键,目前磁性催化剂以包覆型催化剂为主,其共同特点是具有适宜的磁性和低温反应活性,利于反应操作。磁稳定床及其磁性催化剂的研究开发是催化剂工业发展的一个新方向。     

磁性种子剂和混凝剂用于废水处理的初步研究

高磁分离技术用于污水处理,是国内外污水处理技术中一项很有发展前途的新技术。它不仅可以去除水中的磁性污染物,包括微米级的弱磁性、顺磁性物质,而且可借助投加磁性种子剂(或称磁性接种剂)和混凝剂,能有效地去除非磁性污染物,甚至细菌与病毒,高磁分离技术在污水处理上,有着广阔的前景,显示了许多独特的优越性。物     

磁性催化剂的研究进展

磁性催化剂是一类具有磁响应特性的催化剂,它不仅具有较高的催化活性,而且在外加磁场作用下,容易分离回收。根据磁载催化剂的核壳之间是否包覆结合层,将其分为直接包覆和非直接包覆催化剂,从上述两个方面综述了近年来可分离磁性催化剂的研究进展,同时提出了目前磁载催化剂研究的热点和发展趋势。     

磁性催化剂的研究进展

磁性催化剂是一种新型的催化剂,它不仅具有催化特性,还具有独特的磁响应性。磁性催化剂在外加磁场的作用下能与反应物和产物分离,实现了催化剂的回收与重复利用,在工业生产得以连续化的同时,也降低了生产的成本。本文简单介绍了磁性催化剂性质与分类,综述了磁性催化剂在不同领域的应用,探讨了影响磁回收率的因素,和未来的磁性催化剂的发展方向。     

氧化铝源对CA6多孔材料相组成和显微结构的影响

用Al(OH)₃、Al₂O₃微粉(uf-Al₂O₃)、工业Al₂O₃粉作为氧化铝源,CaCO₃为钙源,通过高温固相反应合成了六铝酸钙(CA₆)材料,研究了氧化铝原料对材料物相组成、显微结构和性能的影响。结果表明,以Al(OH)₃、Al₂O₃微粉、工业Al₂O₃为氧化铝源的试样在1 300 ℃时开始有CA₆相生成,各试样固相反应结束温度为1 500 ℃,继续提高烧成温度对物相组成没有影响。反应生成的CA₆显微形貌因氧化铝原料不同而不同,以Al(OH)₃为氧化铝源时,CA₆的显微形貌多为片状结构;以工业Al₂O₃为原料时,CA₆的显微形貌多为板片状和颗粒状;但以uf-Al₂O₃为氧化铝源时,CA₆的显微形貌则多为等轴状晶粒。以uf-Al₂O₃为氧化铝源时,制备的材料耐压强度和体积密度最高,气孔率最低;以Al(OH)₃为氧化铝源时,制备的材料耐压强度和体积密度最低,气孔率最高。     

铜锰氧化物水煤气变换催化剂的还原与催化性能

以CuSO₄·5H₂O和MnSO₄·H₂O为前驱物,NaOH为沉淀剂,选用共沉淀工艺,添加Al₂O₃、BaO+Al₂O₃、ZrO₂+Al₂O₃或CeO₂+Al₂O₃粉末作为催化助剂,制备了4种铜锰氧化物水煤气高温变换催化剂。X射线衍射分析表明,4种铜锰氧化物催化剂的主要化学成分为氧化铜和氧化锰系化合物以及锰钡、铜锰和铜锰铝复合氧化物;在催化水煤气变换反应(WGSR)后,4种铜锰氧化物的化学成分发生了变化。H2还原实验结果表明,在4种铜锰氧化物中,添加ZrO₂+Al₂O₃的铜锰氧化物H₂还原效率最好;而添加CeO₂+Al₂O₃的铜锰氧化物H2还原效率最小。对WGSR出口气中CO体积分数进行对比分析可知,分别添加Al₂O₃和CeO₂+Al₂O₃铜锰氧化物催化剂的变换活性较好。     

Tribological Properties of a Zr2Al3C4 Ceramic at Ambient Temperature

In this work, reciprocating ball-on-flat sliding friction and wear tests as well as two-body abrasive wear tests were performed on Zr₂Al₃C₄, a new type of ceramic material. In the sliding wear tests, a Si₃N₄ ball and an AISI 52100 steel ball were used as counter materials. When Zr₂Al₃C₄ was slid against an AISI 52100 ball, the coefficient of friction (COF) was as low as 0.20–0.42, being independent of normal loads, and the wear rates of Zr₂Al₃C₄ and AISI 52100 steel were in the range of 10⁻⁴–10⁻⁵ mm³/m. A tribofilm between the tribopair was presumed to be responsible for the low COF and wear rate. According to Raman and energy-dispersive spectroscopy analysis, the tribofilm consists of a mixture of oxides of Zr, Al, and Fe as well as amorphous carbon. When Zr₂Al₃C₄ was slid against a Si₃N₄ ball, a transition from mild wear to severe wear was observed as the normal load increased. The transition occurs under certain contact stresses after a damage-accumulating period. In the two-body abrasive wear test, surface chipping and fragmentation resulting from coalescence of surface and subsurface microcracks were the main material removal mechanisms of Zr₂Al₃C₄.     

Microstructure and Nonlinear Properties of Microwave-Sintered ZnO-V2O5 Varistors: I, Effect of V2O5 Doping

The modification of the densification behavior and the grain-growth characteristics of the microwave-sintered ZnO materials, caused by the incorporation of V₂O₅ additives, have been systematically studied. Generally, the addition of V₂O₅ markedly enhances the densification rate, such that a density as high as 97.9% of the theoretical density and a grain size as large as 10 µm can be attained for a sintering temperature as low as 800°C and a soaking time as short as 10 min. Increasing the sintering temperature or soaking time does not significantly change the sintered density of the ZnO-V₂O₅ materials but it does monotonously increase their grain size. Varying the proportion of V₂O₅ in the range of 0.2-1.0 mol% does not pronouncedly modify such behavior. The leakage current density ( J _L) of these high-density and uniform-granular-structure samples is still large, which is amended by the incorporation of 0.3 mol% of Mn₃O₄ in the ZnO materials, in addition to 0.5 mol% of the V₂O₅ additives. Samples that are obtained using such a method possess good nonohmic characteristics (α= 23.5) and a low leakage current density ( J _L= 2.4 10^-6 A/cm²).     

PA66/POE-g-MAH/纳米SiO_2复合材料的制备及性能

通过熔融共混的方法制备PA66/POE-g-MAH/纳米SiO_2三元共混体系,研究纳米SiO_2、POE-g-MAH对PA66力学性能的影响.研究结果表明:POE-g-MAH与纳米SiO_2对PA66有协同增韧效应,当PA66/POE-g-MAH/纳米SiO_2配比为100/30/0.1时,复合体系的缺口冲击强度达到最大,为纯PA66的10.9倍,为PA66/POE-g-MAH(100/30)二元体系的1.8倍;低温缺口冲击强度也达到最大,为纯PA66的6.3倍.用扫描电镜观察分析冲击断口形态.     

稻壳基SiO2的提取及其含量对铜基摩擦材料性能的影响

采用K₂CO₃溶液提取稻壳气化炭中的SiO₂（RHC-SiO₂）,再以RHC-SiO₂/晶体SiO₂（C-SiO₂）/两种SiO₂等比例混合（RC-SiO₂）为摩擦组元,电解铜粉为基体,石墨和二硫化钼为固体润滑剂,制备铜基摩擦材料,并考察RHC-SiO₂/C-SiO₂/RC-SiO₂的添加对铜基摩擦材料密度、表面硬度及摩擦系数的影响,通过打磨及腐蚀制备金相,观察材料表面的物质分布状态,结果表明,RHC-SiO₂的比表面积为135.532m²/g,其5nm左右的中孔非常发达且在950℃烧结4h后,其表面收缩团聚,出现烧结颈,有结晶化的趋势;随着RHC-SiO₂/C-SiO₂/RC-SiO₂添加量的增大,铜基摩擦材料的密度逐渐降低,但RHC-SiO₂使其降低的幅度更显著;当RHC-SiO₂添加量为10%时,其表面硬度为64.6HV,较无摩擦组元的基础材料显著提高（43.33%）;C-SiO₂在材料中钉扎摩擦副,阻止摩擦运动以及提高摩擦系数而RHC-SiO₂起钉扎作用。本研究以期为RHC-SiO₂在铜基摩擦材料中的应用提供理论依据。     

Enhanced Fracture Toughness in Layered Microcomposites of Ce-ZrO2 and Al2O3

Laminar composites, containing layers of Ce-ZrO₂ and either Al₂O₃ or a mixture of Al₂O₃ and Ce-ZrO₂, have been fabricated using a colloidal method that allowed formation of layers with thicknesses as small as 10 μm. Strong interactions between these layers and the martensitic transformation zones surrounding cracks and indentations have been observed. In both cases, the transformation zones spread along the region adjacent to the layer, resulting in an increased fracture toughness. The enhanced fracture toughness was observed for cracks growing parallel to the layers as well as for those that were oriented normal to the layers.     

无机纳米粒子/PA66/POE-g-MAH复合材料研究

用POE-g-MAH对PA66进行增韧,分别再添加纳米SiO2和纳米CaCO3,研究了两种无机纳米粒子在PA66/POE-g-MAH共混体系中的作用。结果表明,PA66/POE-g-MAH/纳米SiO2三元共混体系质量比为100/30/0.1时,共混体系的缺口冲击强度是纯PA66的10.9倍;质量比为100/20/0.1时,缺口冲击强度是纯PA66的4.4倍。PA66/POE-g-MAH/纳米CaCO3三元共混体系配比为100/20/1时,共混体系的缺口冲击强度是纯PA66的3倍。冲击断口的微观形态观察表明,纳米SiO分散均匀,团聚现象少,纳米SiO在体系中的增韧效果优于纳米CaCO。     

Lithium Storage Performance of Hollow and Core/Shell TiO2 Microspheres Containing Carbon☆

TiO2 microspheres containing carbon have been synthesized viaa one-pot hydrothermal process using CTAB as the mesoporous template and nanoparticle stabilizer and Ti(SO4)2 and sucrose as titanium and ca...     

Tetragonal Tungsten Bronze Niobate, K0.2Sr0.4NbO3: A New Material for Capacitors with Flat Dielectric Curves

A new ceramic for capacitors, which exhibits flat dielectric curves with relative permittivity values (ɛ) as high as 3000 (Y7R or X7R class), has been synthesized. Use of a niobate, K_0.2Sr_0.4NbO₃ (KSN), with a tetragonal tungsten bronze structure (TTB), as a major phase for the fabrication of such ceramics is shown for the first time. Nevertheless, the addition of perovskites as minor agents—PbMg_1/3Nb_2/3O₃ (PMN)—is necessary to obtain stable temperature. Moreover, the use of lithium salts as sintering agents has been shown to be important for the fabrication of these ceramics.