A spectroscopic study on the 12-heteropolyacids of molybdenum and tungsten (H3PMo12−nWnO40) combined with cetylpyridinium bromide in the epoxidation of cyclopentene

The epoxidation of cyclopentene with hydrogen peroxide catalyzed by 12-heteropolyacids of molybdenum and tungsten (H₃PMo_12−nW_nO₄₀, n = 1–11), 12-tungstophosphoric acid and 12-molybdophosphoric acid combined with cetylpyridinium bromide as a phase transfer reagent was carried out in acetonitrile. Among 13 heteropolyacids investigated, catalyst of H₃PMo₆W₆O₄₀ showed the highest activity, giving a conversion of 60% and a selectivity of 95% in the epoxidation of cyclopentene. The fresh catalysts and the catalysts under reaction condition were characterized by UV–vis, FT-IR and ³¹P NMR spectroscopy, which has revealed that all of the molybdotungstophosphoric acids were degraded in the presence of hydrogen peroxide to form a considerable amount of phosphorus-containing species. The active species resulted from H₃PMo₆W₆O₄₀ are new kinds of phosphorus-containing species, which is different from {PO₄[WO(O₂)₂]₄}³⁻.     

耐硫催化剂上合成混合醇的研究

通过改进制备方法和添加助剂，用浸渍－热分解法制得了具有高活性和高选择性的MoS2-K-C型耐硫低碳混合醇催化剂。在8.0-11.0MPa,290-340℃，6000-12000h^-1,H2 S 浓度为100ppm 左右的条件下，在直流反应器中对催化剂进行了性能测试，结果表明，醇得率为0.14-0.47gROH(gcat·h)^-1，选择性为89-98%。同时，考察了操作条件对催化剂性能的影响。1042h的试验，证明催化剂具有很好的稳定性。     

Synthesis of polypiperazine-amide thin-film membrane on PPESK hollow fiber UF membrane

A new interfacial polymerization (IP) procedure is developed in order to synthesize polypiperazine-amide thin-film membrane on the inner surface of poly(phthalazinone ether sulfone ketone) (PPESK) hollow fiber ultrafiltration (UF) membrane.A hollow fiber composite membrane with good performance was prepared and studied by FT-IR and scanning electron microscopy.     

Stable, reproducible nanorecording on rotaxane thin films

Stable, reversible conductance transitions and memory effects were observed in solid-state rotaxane-based Langmuir-Blodgett (LB) thin films. Taking advantage of the switching property, we have achieved reproducible nanometer-scale recording dots on rotaxane LB films via voltage application using a scanning tunneling microscope probe. The stable and easily controlled conductance switching makes the rotaxanes a hopeful candidate for nanorecording.     

聚电解质与相反电荷表面活性剂的相互作用

通过透光度测定、电导滴定和粘度法考察了阳离子聚电解质聚苯乙烯 4 乙烯基吡啶硫酸甲酯盐与阴离子表面活性剂十二烷基硫酸钠 (SDS)的相互作用。研究表明 ,在表面活性剂未过量时 ,二者之间的静电作用占主导地位 ,并且当二者电荷总量相等时 ,生成的复合物沉淀最多 ;在表面活性剂过量后 ,复合物可部分溶解 ,溶解的原因是疏水相互作用。本文初步阐述了二者的作用机理     

反对数微分简易示波伏安法的研究

在获得微分简易地波伏安图的实验线路中,增加了反对数装置,提出了反对数微分简易示波伏安法。该方法被应用于铝合金中微量铜和分子筛中微量钴的测定,获得了满意结果。     

甲醇催化分解动力学之研究

甲醇的裂解产物为H_2与CO,故甲醇被视为一种方便、安全的贮氢材料,可作为汽油的代用燃料;其裂解气作为保护气氛可广泛应用于热处理工业。甲醇裂解有两种方法,高温热裂解(约930℃)与低温催化裂解(约300℃)由于低温催化裂解有诸多优点,在工业上的应用正在发展。     

壁喷电池在流动注射阳极溶出伏安法中的应用

在流动注射阳极溶出伏安法中应用壁喷电池,探讨了非稳定态电积过程的溶出峰电流理论方程,预言了峰电流正比于R~(3/4)(R为工作电极半径),并对有关参数进行了实验验证。对5×10~(-7)mol/L Cd(Ⅱ)连续测定40次,表明相对标准偏差为0.94％。     

锌试剂分光光度法测定壳聚糖含量

利用锌试剂与壳聚糖在一定酸度条件下的特异性显色反应，即其复合物在465nm处吸光度与壳聚糖含量在0～O．04g／L范围内呈现良好的线性关系(R=0．996)，基于此建立了一种简便快速的分光光度法。平均回收率为99．68％。     

有机硅耐磨透明涂层的固化分析

ＦＴＩＲ、ＴＧ、ＴＢＡ等对有机硅耐磨涂料（有机硅溶胶）的热固化过程研究表明有机硅胶体中缔合羟基间的脱水缩合速率很高；羟基脱水程度与固化温度有关，温度越高，达平衡时羟基的浓度越低，在１０５～１３０℃间羟基的浓度变化最大，加入适当的固化剂，对羟基的脱水交联有促进作用，在较高的固化温度下，反应体系中出现了环氧环异构化产生的酮羰基的吸收峰