Study on Segregation Process and Equilibrium Distribution Coefficients of Impurities during Zone Refining of Bibenzyl

The purification of commercial Bibenzyl by zone refining has been investigated with a view to establishing operational parameters and optimum processing conditions. Three factors are inspected, which are zone passing number, translation rate, and zone length. The axial profiles of product purity are determined. Meanwhile, the axial concentration profiles of four main impurities, which are Cyclohexylbenzene, Diphenylmethane, 1,1-Diphenylethane, and 1,2-Diphenylpropane have been also determined. The equilibrium distribution coefficients of the four impurities in Bibenzyl are calculated by measuring their effective distribution coefficients at zone travel rate of 4.97, 8.80, 11.89, and 17.43 mm/h. The results indicate that zone refining of Bibenzyl is very successful. The product purity can increase from 98.3466% to 99.8353% after 8 zone passes. The each additional zone pass and slower translation rate are helpful to purification of Bibenzyl. For 1 pass, longer zone length is better for purification of Bibenzyl. The equilibrium distribution coefficients of Cyclohexylbenzene, Diphenylmethane, 1,1-Diphenylethane, and 1,2-Diphenylpropane are 0.3917, 0.3677, 0.1687, and 3.8148, respectively.     

镁质挡渣墙的研制、生产与应用

以高纯烧结镁砂和电熔镁砂为主要原料研制出了具有良好物理性能、施工性能、抗爆裂性能和使用性能的挡渣墙用镁质浇注料。探讨了养护温度、养护时间和环境湿度对坯体性能的影响。在某钢厂 4 8t中间包中的实际使用结果表明 ,镁质挡渣墙对钢水中CaO、SiO2 和A2 O3夹杂物具有明显的吸附作用     

1，2-二苯乙烷的合成工艺进展

1,2-二苯乙烷是一种重要的有机合成中间体,本文对其多种合成工艺进行了总结和讨论。其中包括FriedelCrafts烷基化反应、苄基氯偶联反应、苯偶姻还原反应、苯和环氧乙烷的烷基化反应、甲苯氧化缩合反应及乙炔芳香化法。最后对1,2-二苯乙烷的应用和发展现状进行了简要介绍。     

提升二氯乙烷产品质量的技术研究与优化

利用化工流程模拟软件Aspen Plus2007,对聚氯乙烯装置二氯乙烷(EDC)精制单元(1300单元)的实际工况进行深入研究,针对实际生产中EDC纯度不达标的现状,提出可行的有效提升产品纯度的方案.研究结果表明,自氯乙烯精制单元返回的粗EDC中含有的大量杂质对产品纯度有着至关重要的影响,其中,三氯甲烷、苯和三氯乙烯为关键组分,控制这三种组分的含量可大大提升产品的纯度.此外,控制脱轻塔的进料量和在脱轻塔顶加入氮气进行吹扫也能解决产品质量不达标的问题.针对这三个方面对工艺设备进行调控和改进,产品纯度高达99.6％左右.     

熔盐法合成氧化物陶瓷粉体的研究进展

简要介绍了在熔盐介质中合成氧化物陶瓷粉体的方法、特点以及目前的进展。以该方法合成氧化物陶瓷粉体,具有操作简单、合成温度较其它方法低,合成产物的纯度高,各组分配比准确,无偏析等特点。通过调整原料与盐的比例以及合成温度可以控制粉体颗粒的形貌与尺寸。该方法在合成高纯复杂氧化物陶瓷粉体方面具有很广阔的应用前景。     

Effect of Titanium Carbide Heat Exchanger Block and Retort on Oxygen Impurities in Mc-Silicon: Numerical Modelling

Primarily, mc-Silicon growth is undertaken by directional solidification (DS) process. Reduction of non-metallic impurities such as oxygen, carbon and nitrogen in DS produced mc-Si ingots is a challenging task and strong contaminations come from inner parts of the DS system. In conventional DS system heat exchanger block and retort are made of graphite. In our present work, we have used a heat exchanger block and retort made by titanium carbide (TiC). The simulation has been done for using both graphite and TiC as Heat exchanger block and retort. The simulation results were compared and analysed. The numerical simulation of oxygen impurity distributions in melt and crystal has been investigated. When we used TiC as Heat exchanger block and retort, it gives lower melt convection in the molten stage, more uniform temperature distribution in x- axis and lower temperature gradient in y-axis at the end of solidification. The lower melt convection can reduce the oxygen impurities and results in uniform oxygen distribution. So, TiC based DS system gives better results compared with the graphite-based system.

     

双温区合成法制备ZnGeP_2多晶材料

合成高纯及化学计量比的ZnGeP2多晶材料是生长高质量ZnGeP2单晶的关键。但由于P在高温下蒸气压高,Zn和P易挥发等因素,使合成化学计量比ZnGeP2多晶材料存在一定困难。采用双温区合成法制备了ZnGeP2多晶材料,用X射线粉末衍射分析了反应过程中在炉内温度梯度区间生成的中间产物和在高温区末端石英管壁上的少量沉淀。结果表明:温度梯度区间生成的中间产物中ZnP2含量为95.45%(体积分数,下同),Zn3P2含量为4.55%。高温区末端石英管壁上的沉淀中ZnP2含量为40%,ZnGeP2含量为60%,Zn和P的挥发导致合成的ZnGeP2多晶体中富含Ge。通过调节高温区的温度和降温速率,可有效地控制组分挥发,得到化学计量比的ZnGeP2多晶材料。     

高纯氧化铥的分离制备研究

用ＣＬ－Ｐ５０７－ＨＣｌ体系柱色层法分离原料氧化铥中铒、镱等稀土和非稀土杂质。讨论了树脂粒度、温度、淋洗剂浓度１负载量、进样比等条件对铥、镱 分离的影响,观没蛭铥、镱之间存在萃取抑制现象。选择合适分离条件以９９．９％氧化铥 为原料制备出９９．９９５％的高纯氧化铥产品,其主要稀土杂质铒,镱 均小于５μｇ／ｇ,非稀土杂质铁小于２μｇ／ｇ,钙小于５μｇ／ｇ。     

EFFECT OF MAGNESIUM AND SULFATE IONS ON KCl CRYSTALLIZATION IN A CONTINUOUS COOLING MSMPR CRYSTALLI2:ER

Crystallizations of KCl from water and reagent grade potassium chloride solution with and without magnesium sulfate and magnesium chloride as impurities were conducted in a one liter continuous MSMPR cooling crystallizer. A series of experiments at a constant operating temperature, various feed temperatures and magnesium and sulfate ions concentrations were carried out to investigate the effect of the type and concentration of impurities on the width of the meta-stable zone, crystal size distribution, crystal habit, crystal purity, growth rate, nucleation rate, and aggregation index. The width of the meta-stable zone increased with impurity concentrations of both magnesium and sulfate ions alike. Sulfate ion increased the mean crystal size at all concentrations, whereas the initial increase in mean crystal size at low magnesium concentrations was moderated at higher concentrations. Polycrystals formation was significant with and without impurities. The crystal surface became irregular at higher sulfate ion concentrations. The impurity incorporation within KCl crystals decreased with crystal size and was much higher in the case of magnesium sulfate. Secondary nucleation rate was unaffected and growth rate was altered in the presence of both impurities, and the influence was apparently independent of the effect upon the meta-stable zone width. The effect of impurities was suppressed with increase in suspension density.     

新型聚醚酮熔体过滤装置的设计与应用

聚醚酮合成反应时产生细小胶体杂质,原料、精制及干燥过程会带入诸如灰尘等杂质,另外熔体挤出造粒中,聚醚酮因长时间塑化和加热产生碳化。这些杂质进入挤出模具中,会造成流道堵塞或制品残缺,不同程度地影响聚醚酮的应用范围。采用挤出机熔融、加压,经熔体泵加压,再经过高目数过滤网,成功实现了聚醚酮熔体的连续过滤。由于产量扩大,原有过滤设备已满足不了生产需要。经过放大原有设备,生产运行表明:由于网片区域空间过大,难控制网片表面的温度。温度过高会使物料出现变性;网片面积大易变形,杂质逃逸,不能实现聚醚酮预定过滤目标。根据已成功实现过滤的经验,设计一种新型过滤装置,采用双柱,每柱双网。过滤条件为:加料速度175 kg/h;挤出机加热温度375℃;出口压力12 MPa;熔体泵出口压力22～40 MPa;过滤网304材质;网块直径200 mm、网区直径180 mm、网孔最小直径5μm;换网次数1次/55分针。测试结果为过滤后杂质粒径小于5μm,纯物料收率91.4%。     

聚醚酮熔体过滤装置的建立与改进研究

针对聚醚酮的合成反应会产生细小固体杂质,原料、精制及干燥过程会带入灰尘等杂质,熔体挤出造粒时聚醚酮因长时间塑化和加热会产生残渣等问题,设计、建立了聚醚酮连续过滤生产装置,采用挤出机熔融、加压,再经熔体泵加压,经过高目数过滤网对其进行过滤。对装置试运行后出现的问题进行了改进,确定了适宜的操作条件,加料速度40 kg/h,挤出机加热温度375℃;出口压力12 MPa,熔体泵出口压力22～45 MPa,过滤网304材质,网块直径200 mm、网直径180 mm,网孔直径5μm,换网次数1次/h。测试结果表明,过滤后Ф5μm的颗粒杂质个数<6个/cm2,纯物料收率90.5%。     

Steady melting of rectangular thermoplastic bars induced by hot contacting surfaces

The steady melting of rectangular thermoplastic bars in contact with hot surfaces is analyzed by solving a simplified set of the momentum and energy balance equations, assuming a temperature and shear-rate dependent melt viscosity. A numerical model is developed for predicting the flow field and the temperature distribution in the solid and molten regions of the bar and the location of the solid/melt interface. Computer simulations show that the steady melting rate of the thermoplastic solid is mainly affected by the temperature sensitivity of the melt viscosity, by the pressure applied on the end of the bar, and by a balance between heat conduction and the convection of colder material into the molten region. For the amorphous and semicrystalline polymers considered, heat convection in the outflow direction of the molten material, viscous dissipation, and shear-thinning of the melt viscosity have a much smaller effect on the melting process. These results provide an insight into conduction-induced melting with forced melt removal caused by pressure-induced flow; they also provide a basis for developing a transient model for the hot-tool welding process.     

Purification process of phosphoric acid by vertical zone‐melting technique

The efficiency of vertical zone‐melting technique as a function of molten‐zone length, number of zone passes, molten‐zone velocity and phosphoric acid concentration on the purification process of phosphoric acid is studied. The results showed that adopting a relatively long molten‐zone length in the initial passes to effect a rapid movement of impurities and a short molten‐zone length in the later passes to obtain greater purification; additional zone‐passes cannot be made as impurities redistribution approaches limiting distribution; for stirring mechanism is not adopted in the present study and as diffusion is the only mixing process, slow molten‐zone velocity 3–6 mm h^?1 is better; the purification efficiency increases with phosphoric acid concentration, and 94–99.8% concentration of phosphoric acid is better. © 2012 Canadian Society for Chemical Engineering     

The melting of polymer granules through the use of a fluid medium

A process of melting individual polymer granules and then combining them into a homogeneous molten mass is examined. The granules are introduced into a high temperature fluid bath, heated as they move due to the polymer-fluid density difference and finally coalesce under the action of surface and gravity forces into a uniform polymer melt which can be used for extrusion, injection molding or other melt processing techniques. Theoretical models and analyses are presented to predict the time required to melt a granule in a particular polymer-fluid system and to have the molten granule coalesce into the developing mass of molten polymer. This latter time includes the time for the continuous phase fluid to drain between the approaching granule and the molten polymer-fluid interface and the time for the granule, once in contact with the interface, to be deposited to some specified depth in the bulk molten polymer. Design parameters for a particular embodiment of the process are presented. Experimental results obtained with a prototype device using mercury as the heat transfer medium are discussed.     

A Low-Temperature Molten Salt Synthesis of LiNiVO4 Cathode Material for Lithium Ion Batteries

A newly developed molten salt method was applied at a temperature as low as 350°C to successfully synthesize an inverse spinel LiNiVO₄ cathode by reacting lithium nitrate, nickel nitrate, and ammonium vanadate. As shown in XRD and TEM, the resultant product was a pure phase of LiNiVO₄ without any other impurities. The powders showed a narrow particle size distribution with an average particle size of about 80 nm. No organic materials were introduced in the whole process.     

利用熔融结晶法进行芴的提纯

以工业芴为原料，实验研究了利用熔融结晶法制备精芴的工艺过程，考察了结晶降温速率、结晶终温、发汗升温速率及发汗终温对产品纯度及收率的影响，得到了利用熔融结晶方法分离提纯芴的优化工艺条件，产品纯度可达97.4%。同时根据实验结果，对芴与2-甲基氧芴两元物系的固液平衡相图进行了推测分析。     

己二酸交联木薯醋酸酯淀粉的制备与性能研究

以木薯淀粉为原料,用己二酸二乙烯酯做交联剂,醋酸乙烯酯做酯化剂制备了交联醋酸酯淀粉;确定了最佳反应条件;并测定了产物糊化温度、粘度、冻融稳定性等特性.结果表明,经过交联酯化的淀粉具有较高粘度和冻融稳定性.     

已二酸交联木薯醋酸酯淀粉的制备与性能研究

以木薯淀粉为原料，用己二酸二乙烯酯做交联剂，醋酸乙烯酯做酯化剂制备了交联醋酸酯淀粉；确定了最佳反应条件；并测定了产物糊化温度、粘度、冻融稳定性等特性。结果表明，经过交联酯化的淀粉具有较高粘度和冻融稳定性。     

Particle Shape and Purity in Membrane Based Crystallization

Well‐controlled crystallization is the best method for preparing materials that are uniform in shape, size, structure and purity. The driving forces for crystallization are local gradients of supersaturation as the source and desupersaturation as the drain. Very high local supersaturation causes a high growth rate and represents a limiting factor for unstable modifications and product impurities. Hybrid membrane technology provides an interesting tool for controlling and limiting the maximum level of supersaturation due to defined mass transfer across the membrane. In this paper, the level of crystal growth rate in the system NaCl/KCl/water is varied by using different crystallization techniques. Vacuum evaporation crystallization (high growth rate) is compared to membrane based evaporation crystallization (low growth rate) and the results are interpreted in terms of product purity, particle shape and size. Membrane based crystallization in combination with effective solid/liquid separation as well as high performance analytics is suggested as a significant ultrapurification methodology.     

酶法7-ACA酰化液的除杂工艺研究

7-ACA是合成头孢菌素的关键中间体,其生产工艺已逐渐由化学法被酶法所取代。因酶法工艺较化学法酰化液存在蛋白、色素等杂质多的问题,需结晶前进行除杂。介绍了炭脱、超滤、萃取等各种除杂方法,将各种除杂方法及其各种组合方式对产品质量的影响进行了比较,确定双膜法除杂工艺为最佳方式。该除杂工艺能有效去除蛋白、色素等杂质,产品纯度、色级、内毒素等质量指标明显提高。