TiCl4水解法制备纳米TiO2粉体

以TiCl4为原料,采用低温液相水解法制备了纳米TiO2粉体,着重研究了Ti4 的浓度和添加聚乙烯吡咯烷酮(Polyvinylpyrrolidone,PVP)对产物的晶相、颗粒大小和表面形貌的影响.使用XRD,TEM,SEM,激光粒度测试仪对样品进行了表征.结果表明,Ti4 浓度影响TiO2粉体的相转变温度,随着Ti4 浓度的升高金红石相的含量逐渐升高,但粉体分散性变差;添加PVP提高了所得TiO2粉体的分散性,粒径降低为40～50 nm左右,并改善了粉体的形貌.     

尿素分解水热合成Ni-Al类水滑石的研究

采用尿素分解水热合成Ni-Al类水滑石,其中使Ni2 /Al3 /尿素的摩尔比为2:1:10和3:1:10.用XRD、SEM、TG检测,结果表明,合成出的类水滑石结晶度高,具有规整的片状晶体形貌,延长反应时间和提高反应温度有利于提高类水滑石的结晶度和颗粒的分散性.     

Synthesis of Nickel Sulfide Powders by Thioacetamide in the Presence of Urea

Additions of urea were found to increase the yield of nickel sulfide formation from acidic solutions of thioacetamide. Two precipitation mechanisms were identified: hydrolysis and direct reaction between nickel and thioacetamide. Hydrolysis-controlled precipitation is evident with low initial pH. The direct reaction is dominant at high initial pH. Nucleation proceeds by a direct reaction between nickel and thioacetamide. The role of urea in precipitation of nickel was found to be twofold. Urea increases the rate of thioacetamide decomposition, thus increasing the concentration of H₂S form. Secondly, decomposition increases the pH of the solution, which in turn increases the relative concentration of S⁼ ions. Agglomeration of particles was more evident in the powders obtained in the presence of urea.     

Preparation of Zirconia-Alumina Powders by Zirconium Alkoxide Hydrolysis

Zirconia-alumina powders were prepared by controlled hydrolysis of zirconium propoxide in a dispersion of a-alumina powder in anhydrous 100% ethanol. Transmission electron micrographs show a "fluffy" zirconia coating on the alumina particles. Chemical analyses by four methods demonstrated that the procedure is reproducible and introduces only low impurity levels.     

钨掺杂M型二氧化钒粉体的水解法制备与结构分析

采用水解法制备不同W掺杂量的VO2(M)粉体。借助于X射线衍射仪、Fourier变换红外谱、差示扫描量热仪、X射线光电子谱仪和X射线精细结构谱对粉体的成分和结构进行表征。结果表明,W6+进入VO2晶格,形成固溶体V4+1-3xV3+2xWxO2。W掺杂降低了VO2(M)的相变温度,相变温度与W掺杂量在一定范围内成线性关系,掺杂效率约为18℃/1%(摩尔分数)。掺杂的大半径W原子部分替换了VO2(M)晶格中的V原子,晶格膨胀畸变产生的压应力通过共享顶点O,沿着W—O—V链传递到邻近的次晶格,造成V—O键键长变化,促使V周围的氧分布对称性随W掺杂量的增加而增大。当W掺杂量增大至2.5%时,单斜结构中的V—O1键和V—V1a键伸长,V—O2键和V—V1b键缩短,V—O1和V—O2峰合并成金红石结构的V—O峰,V—V1a峰和V—V1b峰合并成金红石结构的V—V1峰,即样品已转变为金红石结构。     

蛇纹石/La复合粉体的制备及其摩擦性能

分别采用水溶液沉淀法和乙醇溶液沉淀法制备了蛇纹石/La复合粉体,并分别在120℃（脱除吸附水）和700℃（蛇纹石脱除羟基）对复合粉体进行了干燥和煅烧热处理。利用X射线衍射法、扫描电子显微镜、能谱分析表征了复合粉体的物相组成、微观形貌。利用MM-10W型多功能摩擦磨损试验机对复合粉体的摩擦性能进行了评价。结果表明：蛇纹石/La复合粉体中,La化合物呈纳米颗粒,并包覆在蛇纹石表面;700℃煅烧将导致蛇纹石/La复合粉体物相变化和摩擦性能变差;120℃干燥处理的蛇纹石/La复合粉体具有良好的减摩-抗磨性能,摩擦因数较未添加者降低22.48%以上。     

尿素水解装置问题分析

水解装置是将要排放的工艺冷凝液中的尿素分解成NH3和CO2,再进行解吸,将氨和CO2从工艺冷凝液中分离出来,回收至生产系统,使处理后的水中氨氮值低于环保规定值,并且可送往锅炉作为给水或送往三胺装置的氨洗涤塔。本文通过对尿素深度水解装置的运行情况与以往问题的总结,对出现的负荷过高、压力不易控制,外送精致水无法达标等问题进行分析和研究。     

Synthesis and Characterization of Hydroxyapatite–Wollastonite Composite Powders by Sol–Gel Processing

Composites of hydroxyapatite–wollastonite were synthesized by a sol–gel route using calcium acetate and triethyl phosphate as precursors of hydroxyapatite and high-purity natural wollastonite added in ratios of 20, 50, and 80 wt%. These composites were characterized by thermal analysis, X-ray diffraction, FT-IR and Raman spectroscopy, and scanning and transmission electron microscopic techniques. Formation of hydroxyapatite occurs at a relatively low temperature, about 420°C, accompanied by calcium carbonate; wollastonite remains unreacted. The composites were purified by heat treatment to a higher temperature and washed with hydrochloric acid and distilled water, to produce B-type carbonated hydroxyapatite–wollastonite composites as final products.     

醇盐水解法制备亚微米球形氧化铝粉体

以仲丁醇铝为铝源,以乙腈与正丁醇作溶剂,通过醇盐水解法制备了亚微米球形氧化铝粉体.研究了溶剂配比、水加入量及煅烧温度对产物相结构及微观形貌的影响.结果表明,乙腈与正丁醇的体积比及去离子水的加入量是影响产物的成球性以及粒径大小的关键因素,随着乙腈与正丁醇体积比增大,产物成球性变好;去离子水加入量的变化,影响了产物粒径的大小.经不同温度煅烧后,产物发生了由γ-Al2O3转化为α-Al2O3的相变,但仍保持着球形形貌.     

核-壳型方解石/磷灰石复合微粉的微波辅助合成

从材料设计的角度出发,探讨一种具有核-壳型结构方解石/磷灰石复合微粉的合成方法.对通过溶液结晶制备的类球状聚晶型碳酸钙微粉,进一步借助微波辐射使晶体表面快速磷酸化,并利用ESEM,XRD和EDS等进行表征.实验制得的复合微粉为类球形颗粒,粒度集中在25μm左右,其结构特征是骨架核体为实心的聚晶型方解石,表面壳层为绒毛状的羟基磷灰石活性层.其制备方法简单,易于操作.     

尿素水解方法的简述及展望

综述了现今国内外尿素水解技术的研究现状,对各种水解技术的优点和存在的不足进行了梳理与总结。并展望其发展前景,提出了需进一步研究及解决的问题。     

尿素水解技术应用总结

在我国中小型尿素装置原设计中,对尿素装置产生的工艺冷凝液和其他含氨氮废水的处理方式是在解吸塔处理后直接排放。由于解吸残液中氨含量的质量分数为0.07%,尿素含量的质量分数为0.8%~1.2%,不仅增加了产品消耗,提高了成本,而且造成环境污染。四川美丰化工股份有限公司1 000 t/     

Simulation of a Urea Thermal Hydrolysis Reactor

In this work, the removal of urea from industrial wastewater by thermal hydrolysis was studied. The performance of the hydrolyzer was investigated using an equilibrium-based model. This model incorporates two sets of important equilibrium reactions and takes into account the effects of liquid nonideality on the reaction equilibria. It provides outlet temperature, concentration, and flow rate of different components in the reactor. The predicted data of the model were consistent with the plant data, indicating the validity of the model. The impact of different parameters on the performance of urea hydrolyzer was examined. The result of this work showed that an increase in inlet wastewater temperature and steam flow rate would improve the urea removal efficiency.     

Simulation of a Urea Thermal Hydrolysis Reactor

In this work, the removal of urea from industrial wastewater by thermal hydrolysis was studied. The performance of the hydrolyzer was investigated using an equilibrium-based model. This model incorporates two sets of important equilibrium reactions and takes into account the effects of liquid nonideality on the reaction equilibria. It provides outlet temperature, concentration, and flow rate of different components in the reactor. The predicted data of the model were consistent with the plant data, indicating the validity of the model. The impact of different parameters on the performance of urea hydrolyzer was examined. The result of this work showed that an increase in inlet wastewater temperature and steam flow rate would improve the urea removal efficiency.     

不同种类碳源对TiC–TiB_2复合粉末合成的影响

以二氧化钛、硼酸和不同碳源(炭黑、蔗糖、葡萄糖)为原料,用碳热还原法合成了TiC–TiB_2复合粉末。研究了不同种类碳源及反应温度对TiC–TiB_2复合粉末的影响。用X-射线衍射仪、激光粒度分析仪和扫描电子显微镜对样品的物相组成、晶粒尺寸及颗粒形貌进行了分析。结果表明:以炭黑、葡萄糖为碳源合成TiC–TiB_2复合粉末的适宜宜条件为在1400℃保温2h;以蔗糖为碳源合成TiC–TiB_2复合粉末的适宜条件为在1350℃保温2h。在最适宜反应温度下,以炭黑为碳源合成的TiC–TiB_2复合粉末样品粒径最小,且颗粒之间相互团聚较少,大部分颗粒尺寸在100nm左右。     

Synthesis of CoO/Ni Composite Powders for Molten Carbonate Fuel Cells

CoO/Ni composite particles were prepared by the advanced mechanical-coating method called Mechanofusion™. These composite particles were composed of nickel particles uniformly covered with fine CoO particles. A new cathode structure for molten carbonate fuel cells (MCFCs), where the NiO core was coated with an outer layer of lithiated cobalt and nickel solid-solution oxide (Li(Co,Ni) oxide), was formed by oxidation and lithiation using these CoO/Ni composite particles. The solubility of nickel in this Li(Co,Ni) oxide layer into carbonate melt decreased to two-thirds of that of NiO when used as a cathode for MCFCs.     

改造水解系统回收尿素工艺冷凝液

结合我公司生产实际，对尿素工艺冷凝液不能回收的原因进行分析，通过增设板式换热器及电导分析仪解决问题，并针对改造后运行中存在问题及解决措施进行了总结。     

尿素水解工艺改造的理论分析

通过对尿素水解工段的计算机模拟和结果分析发现：在竖式水解塔现有条件下,决定最终尿素浓度的控制因素是板效率,从而为大型氮肥厂尿素水解水解工段的技术改造提供了理论依据。     

尿素解吸-水解系统改造小结

从工艺设备的角度,分析了尿素解吸—水解系统中解吸塔、水解槽、水解泵等存在的问题;介绍了系统工艺设备的技改措施和实施注意事项;从节电、环保、设备选材和安装方面总结了技改效果和经验。     

水热法制备球形二氧化锆粉体的研究

以氯氧锫为前躯体通过水热法制备出了粒径在5μm左右,粒度分布均匀的球形二氧化锆粉体.研究结果表明水热温度、水热时间以及醇水比例对产物的微观结构均有影响.140℃水热处理24h获得产物为无定型态的氢氧化锆粉体,而200℃水热处理24h可获得单斜和四方混相的二氧化锆粉体.随水热时间的延长,产物相结构经历了由无定型氢氧化锆向单斜与四方混相的二氧化锆转变,相转变机制则经历了由均匀饱和析出机制到溶解沉淀为主、原位结晶为辅机制再到原位结晶为主、溶解沉淀为辅机制的变化过程.