NDN-1型氮氧化物脱除催化剂的评价及应用

对NDN-1型氮氧化物脱除催化剂进行了实验室性能评价,并与进口催化剂A及国产催化剂B进行了比较,结果表明,NDN-1型催化剂的化学组成、结构、性能均优于进口催化剂A。介绍了该催化剂在南京帝斯曼东方化工有限公司工业应用的情况。     

Methanol Selective Oxidation to Formaldehyde over Iron-Molybdate Catalysts

This review deals with the important industrial reaction of formaldehyde manufacture by methanol oxidation over iron molybdate catalysts. Detailed reference is made to the used catalyst, preparation techniques (coprecipitation, sol-gel like, mechanical mixing, etc.) including unsupported and supported catalysts, promoters and characterization methods. The controversial active phase assignment (stoichiometric versus Mo rich iron molybdate) is discussed. The proposed reaction mechanisms and kinetic laws for the main and side reactions are examined. The catalyst deactivation processes are reviewed and the role of Mo excess on these processes is underlined. Finally conclusions and perspectives are presented.     

世界碳酸钙工业发展近况

世界碳酸钙工业发展迅速，产能不断增加，首先介绍了近几年来重质研磨碳酸钙（GCC）产业的发展概况，重点介绍了中国、日本、马来西亚、韩国、泰国的GCC产业及国际著名GCC生产公司在中国的经营情况。其次介绍了世界轻质沉淀碳酸钙（PCC）的市场概况及国外大型PCC生产公司的基本情况。最后，重点介绍了中国大陆地区的碳酸钙生产与市场情况，并通过分析近几年中国碳酸钙产品的进出口数量及价格情况指出，开发适合碳酸钙用户需求的新产品、新技术，参与国际竞争是今后中国碳酸钙生产企业的发展方向。     

湿磨干烧生产线料浆脱水工艺的选择

料浆脱水是湿磨干烧的关键工艺，其脱水方法一般有过滤法，喷浆法和混合法三种，其中过滤法包括真空过滤和加压过滤两种，在国外都有应用，国内则大都用前者。南京院在皖维公司1000t/d生产线和白马山厂850t/d生产经上则采用了厢式压滤脱水法，文中就这两种过滤法的过滤工艺特点及其选择进行了分析和探讨。     

提高φ5m×11.5m生料磨产量的措施

针对粘土资源枯竭问题,江苏巨龙水泥集团实施了以粉煤灰和硅石代替粘土的技改工程。但改造后因原料的变更,导致入房物料易磨性变差而影响了φ5m×11.5m生料磨的产质量,并进一步影响察系统的运行。因此该厂在工艺分析的基础上,采取了调整钢球级配、用高铬球替代合金刚球、改造选粉机、加强石灰石二破的管理和减少系统是否是“漏风”等技术措施,效果显著。改造后的生料磨台时产量比调整前提高了12t/h,且节电效果显著。     

SLS工艺制造的高分子原型材料选择

面向快速铸造工艺的激光选择性烧结（SLS）工艺制造可以制造可烧蚀的高分子快速原型，结合熔模铸造工艺能够实现金属零件的无模快速铸造。选择既适合激光烧结工艺又满足铸造要求的高分子材料是快速铸造工艺的前提。在系统地比较和分析了常用高分子材料的特性．并进行了粉末激光烧结实验后，选择了聚苯乙烯（PS）材料作为快速铸造用SLS原型的粉末原材料。     

CGA560增强助磨剂在水泥粉磨中的应用研究

研究了CGA560增强助磨剂在水泥粉磨中对台时产量和水泥质量的影响。试验结果表明:在磨机状况不改变的条件下,CGA560增强助磨剂的加入可提高磨机产量10%-30%;同时可有效减少过粉磨现象,优化水泥颗粒级配,提高了水泥粉磨细度及比表面积;因而使水泥强度等性能得到了明显改善和提高。     

2,2,6,6-四甲基-4-甲氧基哌啶氮氧自由基制备方法的改进

阐述了一种制备 4 -甲氧基 -2 ,2 ,6 ,6 -四甲基哌啶氮氧自由基的改进方法 :以四氢呋喃为溶剂 ,0℃时 ,在N2 的保护下和NaH的存在下 ,2 ,2 ,6 ,6 -四甲基 -4 -羟基哌啶氮氧自由基与MeI在室温反应 5h。分离混合物 ,得到粘稠状红色液体 ,加入正己烷 ,在 -2 0℃条件下储存 ,结晶出针状深红色的晶体。熔点 :4 2～ 4 3℃ ,产率 70 %以上     

Structural characterization of Ti centres in Ti-silicalite and reaction mechanisms in cyclohexanone ammoximation

The main results obtained by means of many physical methods (IR, Raman, UV-Vis and XAFS spectroscopies) concerning the structure of the Ti centre in titanium silicalite and the reaction intermediates in the ammoximation of cyclohexanone are concisely reviewed.

The Ti is in tetrahedral coordination in vacuo and expands its coordination sphere upon interaction with adsorbates. In the presence of H₂O and H₂O/H₂O₂ solutions one of the SiOTi bridges is hydrolyzed with formation of (SiO)₃L₂TiOH (LH₂O) and (SiO)₃L₂TiOOH species, respectively. When NH₃ is dosed on (SiO)₃L₂TiOOH structures (SiO)₃L₂TiOO⁻NH₄⁺ species are formed. These species are thought to play an important role in the ammoximation reaction. The geometries of the peroxidic species (open or bridged) are discussed also on the basis of ab initio calculations.     

Kinetics of the selective catalytic reduction of NO by NH3 on a Cu-faujasite catalyst

The kinetics of the selective catalytic reduction (SCR) of NO by NH₃ in the presence of O₂ has been studied on a 5.5% Cu-faujasite (Cu-FAU) catalyst. Cu-FAU was composed of cationic and oxocationic Cu species. The SCR was studied in a gas phase-flowing reactor operating at atmospheric pressure. The reaction conditions explored were: 458<T_R<513 K, 2503 (ppm) < 4000, 12 (%) < 4. The kinetic orders were 0.8–1 with respect to NO, 0.5–1 with respect to O₂, and essentially 0 with respect to NH₃. Based on these kinetic partial orders of reactions and elementary chemistry, a wide variety of mechanisms were explored, and different rate laws were derived. The best fit between the measured and calculated rates for the SCR of NO by NH₃ was obtained with a rate law derived from a redox Mars and van Krevelen mechanism. The catalytic cycle is described by a sequence of three reactions: (i) Cu^I is oxidized by O₂ to “Cu^II-oxo”, (ii) “Cu^II-oxo” reacts with NO to yield “Cu^II-N_xO_y”, and (iii) finally “Cu^II-N_xO_y” is reduced by NH₃ to give N₂, H₂O, and the regeneration of Cu^I (closing of the catalytic cycle). The rate constants of the three steps have been determined at 458, 483, and 513 K. It is shown that Cu^I or “Cu^II-oxo” species constitute the rate-determining active center.