Au-Cu-K三组元无汞催化剂活性下降原因

采用浸渍法制备Au-Cu-K三组元无汞催化剂,在中试单管固定床反应器中考察了Au-Cu-K催化剂用于乙炔氢氯化反应制取氯乙烯的催化效能,并采用微结构分析仪、扫描电镜、透射电镜、红外光谱、电感耦合等离子体发射光谱等对反应前后的无汞催化剂进行了对比分析表征。结果表明,Au-Cu-K催化剂在反应温度170℃、常压、空速20h?1、v(HCl)∶v(C2H2)=1.1的条件下,乙炔转化率从初始的98%缓慢下降到1600h后的89%,氯乙烯选择性在整个反应期间始终大于99%;Au-Cu-K无汞催化剂的活性下降主要是表面生成了类聚乙烯化合物。     

BF3催化1-癸烯制备聚α-烯烃合成润滑油基础油

低黏度聚α-烯烃（PAO）合成技术主要为国外所垄断,国内少有研究报道。为了解决这一技术问题,本文以1-癸烯为原料,在1L高压反应釜中进行聚合实验,考察反应压力、反应温度、引发剂、反应时间对转化率及聚合产物组成分布的影响,并以优化后的工艺条件在200L低黏度PAO中试试验装置上进行中试放大试验。结果表明,在反应压力为0.2MPa、反应温度为20℃、催化剂加入量为850g、引发剂加入量685mL（与1-癸烯质量比为0.5%）、反应时间2h的条件下,转化率大于95%,产品关键组分三聚体和四聚体含量大于80%,反应放热量约为6.3×10⁴kJ。以此条件获得的产品100℃运动黏度4.3mm²/s,黏度指数132,-40℃低温动力黏度2318 mm²/s,倾点-60℃,与国外产品主要性能指标相当。     

阿卡波糖发酵过程的放大研究

研究了阿卡波糖产生菌游动放线菌A-56在30 m3罐上的发酵放大策略。首先通过摇瓶分批补料发酵,考察了补料培养基中麦芽糖和葡萄糖配比对阿卡波糖合成的影响,结果表明,麦芽糖和葡萄糖的配比对阿卡波糖的生物合成具有显著的影响,且麦芽糖和葡萄糖的配比为3∶1最利于阿卡波糖合成;在此基础上,在100 L发酵罐上进一步考察了碳源控制对阿卡波糖发酵的影响,结果表明,补料阶段的发酵液总糖和还原糖浓度分别控制在75～80 g/L和45～50 g/L时,最利于阿卡波糖合成。因此,筛选出总糖和还原糖(麦芽糖和葡萄糖)这两个关键参数作为放大因子,成功地实现了阿卡波糖从100 L罐到30 m3罐的工业化发酵放大,最终(168 h)的阿卡波糖产量达到4 327 mg/L。     

反应器类型对流动影响的数值模拟

在油-氢气体系中使用欧拉-欧拉双流体模型考察了温度703.15 K和压力11 MPa下气升式环流反应器和鼓泡床反应器对气液两相流动的影响. 结果表明,环流反应器中气含率和轴向液速沿导流筒径向存在突增现象,环流反应器中气含率在径向0~0.5和0.75~1时明显大于鼓泡床反应器,在径向0.5~0.75处前者的平均气含率比后者高约6%;环流反应器中上升管内环流液速明显大于鼓泡床反应器,且在下降区有所增强,环流反应器平均轴向液速比鼓泡床反应器高约21%;反应器尺寸较小时环流反应器和鼓泡床反应器的流动特性相差不大,反应器体积放大过程中前者的流动特性优于后者的趋势逐渐明显.     

微通道反应器的一维放大及气液传质特性

微通道反应器能有效增强气液间传质,但处理能力受限。为了提高微通道的处理量,对微通道反应器的一维放大及气-液传质特性进行了研究。以乙醇胺（MEA）和甲基二乙醇胺（MDEA）混合水溶液吸收CO₂为研究物系,在通道深度恒定时,考察了微通道宽度、气液流速对传质特性的影响。结果表明,传质系数和体积传质系数均随通道宽度先增大后缓慢减小,在通道宽度为1000 μm时达到最大值。比表面积随通道宽度的增大而降低。因此,合理增大微通道宽度,可在提高处理能力的同时,仍然保持良好的传质特性。     

XJM-S系列浮选机的研发及展望

浮选是目前细粒煤泥处理最有效、应用最广泛的方法.XJM-S系列浮选机在我国煤泥浮选设备中占有率最高,达70％以上.为使选煤同仁全面了解XJM-S系列浮选机技术特色、应用及发展,简述了 XJM-S系列浮选机的工作原理、设计思路及其结构特点,回顾了该设备的研发历程,介绍了指导大型设备参数设计的放大准则,以及采用流场数值模拟...     

Hybrid Self-Assembling Nanoparticles Encapsulating Zoledronic Acid: A Strategy for Fostering Their Clinical Use

Self-assembling nanoparticles (SANPs) promise an effective delivery of bisphosphonates or microRNAs in the treatment of glioblastoma (GBM) and are obtained through the sequential mixing of four components immediately before use. The self-assembling approach facilitates technology transfer, but the complexity of the SANP preparation protocol raises significant concerns in the clinical setting due to the high risk of human errors during the procedure. In this work, it was hypothesized that the SANP preparation protocol could be simplified by using freeze-dried formulations. An in-depth thermodynamic study was conducted on solutions of different cryoprotectants, namely sucrose, mannitol and trehalose, to test their ability to stabilize the produced SANPs. In addition, the ability of SANPs to deliver drugs after lyophilization was assessed on selected formulations encapsulating zoledronic acid in vitro in the T98G GBM cell line and in vivo in an orthotopic mouse model. Results showed that, after lyophilization optimization, freeze-dried SANPs encapsulating zoledronic acid could retain their delivery ability, showing a significant inhibition of T98G cell growth both in vitro and in vivo. Overall, these results suggest that freeze-drying may help boost the industrial development of SANPs for the delivery of drugs to the brain.     

Animal cell bioreactors — recent advances and challenges to scale-up

The demand for animal cell derived products has stimulated the development of bioreactors in the last decade. Most of those developments allow a higher cell concentration to be achieved in the bioreactor than in the past, primarily by means of the continuous flow of culture medium and a mechanism of cell retention. The advantages and technological challenges of some of these developments are discussed. Lagging behind the bioreactor developments is the strategy for culture operation and optimization. The need for suitable kinetic models to describe animal cell growth is emphasized.     

Scale-up of liquid-liquid dispersions in stirred tanks

A study of local drop size, drop size distribution and holdup fraction was conducted for liquid-liquid dispersions in three geometrically similar stirred tanks of standard configuration over a range of stirrer speeds and dispersed phase volume fractions. The tanks had diameter ratios 1:2:4, the smallest diameter being 11 cm. Two liquid-liquid systems were used: n-heptane-water and n-heptane containing different concentrations of di-(2-ethylhexyl) phosphoric acid dispersed in an aqueous sulphate solution. No significant local variations of the three parameters investigated were observed at constant stirrer speed and constant dispersed phase volume fraction. Measurements in the three tanks indicated that the rule of equal impeller tip speed provides the best scale-up criterion for equal interfacial areas per unit volume of dispersion. A correlation was also proposed for the Sauter mean diameter.     

Scale-up of a cyclone bioreactor

The operation of a cyclone bioreactor differs from conventional stirred tanks since the agitation is accomplished by means of a pumped reciculation loop. Oxygen transfer can occur across the swirling gas—liquid interface in the cyclone or from bubbles entrained in the recirculation loop. A cyclone bioreactor was scaled-up from a 1 dm³ bench top unit to a 75 dm³ Process Development Unit (PDU). A reduction in the aspect ratio was compensated for by extending the length of the recirculation loop and providing additional aeration. Performance of the two reactors for the production of microbial poly-β-hydroxybutyrate (PHB) was compared under various operation conditions. The culture used for PHB production was Alcaligenes eutrophus DSM 545, grown on a mineral salts medium limited by the supply of nitrogen. The levels of dissolved oxygen obtained in the PDU were strongly dependent on the location at which the air was introduced into the reactor. However, with aeration balanced between two injection points and a similar level of power input, 17 J s^?1 dm^?3, the PDU was able to provide at least as much oxygen transfer capability as the laboratory-scale reactor. Under all conditions tested, the PHB accumulation by A. eutrophus was in excess of 80% of the biomass dry weight, although the yield on glucose was lower in the PDU than in the laboratory-scale reactor.