Mechanistic Insight in the Ethane Dehydrogenation Reaction over Cr/Al2O3 Catalysts

A Cr/Al₂O₃ alkane dehydrogenation catalyst exhibits a maximum in ethylene yield during an ethane dehydrogenation cycle. Isotopic labelling experiments with monolabelled ¹³C-ethane and deuterium were used to elucidate whether the initial activity increase could be due to formation of an active, larger hydrocarbon intermediate on the surface. The results strongly indicate that this is not the case, and instead point to a traditional reaction cycle involving adsorption of ethane to form an ethyl species, followed by desorption of ethene and hydrogen. Transient kinetic data suggest that ethane adsorption is the rate-determining step of reaction.     

PEN/PTT共混聚酯的熔融行为

利用差示扫描量热仪对不同配比的聚萘二甲酸乙二醇酯/聚对苯二甲酸丙二醇酯(PEN/PTT)共混体系的熔融行为进行了分析,发现在共混体系中两组分形成各自的晶体,PEN和PTT的熔点均随另一组分含量的增加而下降。根据Nishi-Wang方程,按300℃计算,由PEN/PTT共混体系中PEN熔点下降计算所得到的相互作用能密度为-0．214 2 J/cm~3,相互作用参数为-0．006 8,表明PEN/PTY共混体系在熔融态是热力学性质稳定的相容体系。     

Transformation of Crystal Phase of Micron-sized Rutile TiO2 and Investigation on its Sonocatalytic Activity

The partial transformation of crystal phase of micron-sized TiO₂ powder from rutile to anatase was realized utilizing microwave irradiation in hydrogen peroxide solution. Afterwards, the ultrasound of low power was used as an irradiation source to induce the transition crystal TiO₂ powder to perform the sonocatalytic activity through the degradation of azo fuchsine in aqueous solution. The results show that the sonocatalytic activity of the transition crystal TiO₂ powder is obviously higher than that of pure micron-sized rutile and anatase TiO₂ powders. The degradation ratio of azo fuchsine in the presence of the transition crystal TiO₂ powder attains nearly 80% within 80 min ultrasonic irradiation.     

Poly(N-vinyl-2-pyrrolidone) hydrogel production by ultraviolet radiation: new methodologies to accelerate crosslinking

Poly(N-vinyl-2-pyrrolidone) hydrogels produced by high-energy radiation relies on water radiolysis as a primary process leading to crosslinks. Conversely, ultraviolet direct irradiation into PVP leads to crosslinking trough pyrrolidinone moiety photolysis. However, this process showed to be rather inefficient. This work describes the crosslinking of poly(N-vinyl-2-pyrrolidone) based on hydrogen peroxide photolysis, therefore mimicking water radiolysis, using UV-C (e.g. low pressure Hg lamp) or UV-A radiation sources. The process efficiency and the properties of the hydrogel formed are discussed and compared with other methods of hydrogel production.     

纳米TiO2复合铁钛防锈颜料的研制及产业化进展

介绍了纳米TiO2复合铁钛防锈颜料的制备原理、工艺、技术指标;描述了铁钛防锈涂料的配方、性能检验和产业化进展情况.     

4-氟-2-氯苯胺的合成研究

介绍了以 4 氟苯胺为原料 ,通过乙酰化、氯代、水解三步制备 4 氟 2 氯苯胺的方法 ,对主要的影响因素作了考察并得出结论 :乙酰化反应温度应小于 30℃ ;氯代中 2 /SO2 Cl2为 1∶0 9(mol/mol)时较好 ;在水解阶段盐酸浓度控制在 4mol/L较佳 ,4 氟 2 氯苯胺的纯度大于 99% ,总收率达到 70 %     

β-Sialon-Al2 O3-SiC系复相材料的研制和性能

研究了在 15 0 0℃的流动氮气中 ,用Al粉、Si粉、Al2 O3粉、刚玉和SiC的颗粒及细粉直接制备 β Sialon -Al2 O3-SiC系复相材料的氮化烧结技术。XRD和SEM分析表明 ,结合相 β Sialon的显微形貌随刚玉量的增加由纤维状向棱柱状转变 ,发育良好。复相材料的高温抗折强度高于常温抗折强度。抗热震试验结果显示 :添加适量的刚玉对β Sialon -SiC复相材料和添加适量的SiC对β Sialon -刚玉 复相材料都具有良好的增韧效果 ,这是β Sialon的纤维增强及柱状晶体原位自补强增韧和复合弥散相增韧综合作用的结果。抗碱和抗高炉渣试验均显示了该复相材料优良的抗碱和抗铁渣侵蚀能力。     

2-羟基-3-氰甲基-5-甲基苯乙酮的合成

探索黄酮醋酸类化合物中间体的合成方法。通过酰基化、Fries重排、氯甲基化和氰化合成2 -羟基 - 3-氰甲基 - 5 -甲基苯乙酮 ,获得了满意的收率 ( 88.5 % )。采用新方法合成了鲜见文献报道的新化合物 2 -羟基 - 3-氰甲基 - 5 -甲基苯乙酮。该方法具有反应时间短、操作简便、收率好等优点。     

Characterization and Catalytic Properties of Combustion Synthesized Au/CeO2 Catalyst

Ceria-supported Au catalyst has been synthesized by the solution combustion method for the first time and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Au is dispersed as Au⁰ as well as Au³⁺ states on CeO₂ surface of 20-30 nm crystallites. On heating the as-prepared 1% Au/CeO₂ in air, the concentration of Au³⁺ ions on CeO₂ increases at the expense of Au⁰. Catalytic activities for CO and hydrocarbon oxidation and NO reduction over the as-prepared and the heat-treated 1% Au/CeO₂ have been carried out using a temperature-programmed reaction technique in a packed bed tubular reactor. The results are compared with nano-sized Au metal particles dispersed on -Al₂O₂ substrate prepared by the same method. All the reactions over heat-treated Au/CeO₂ occur at lower temperature in comparison with the as-prepared Au/CeO₂ and Au/Al₂O₂. The rate of NO + CO reaction over as-prepared and heat-treated 1% Au/CeO₂ are 28.3 and 54.0 mol g^-1 s^-1 at 250 and 300 °C respectively. Activation energy (E _a) values are 106 and 90 kJ mol^-1 for CO + O₂ reaction respectively over as-prepared and heat-treated 1% Au/CeO₂ respectively.     

SO_4~(2-)TiO_2固体超酸催化合成异丙基萘的研究

用SO2 - 4 TiO2 固体超酸为催化剂合成了二异丙基萘 ,生产过程简单、无污染、无腐蚀。SO2 - 4 TiO2 固体超酸催化剂较为适宜的制备条件是 :浸酸浓度为 0 5 0mol/L、焙烧温度为 5 0 0℃。在催化剂用量为 10 %、反应温度为 160℃、反应时间为 2 5h的条件下连续两次使用SO2 - 4 TiO2 超酸催化萘对丙烯的烷基化反应 ,产品中一异丙基萘、二异丙基萘、三异丙基萘的总含量大于 98%。