Photodegradation of a herbicide derivative, 2,4-dichlorophenoxy acetic acid in aqueous suspensions of titanium dioxide

The photocatalytic degradation of a herbicide derivative, 2,4-dichlorophenoxy acetic acid (2,4-D, 1), has been investigated in aqueous suspensions of titanium dioxide. The degradation was studied by monitoring the change in substrate concentration employing UV spectroscopic analysis and decrease in Total Organic Carbon (TOC) content as a function of irradiation time in the presence of UV light source. The degradation kinetics was investigated under a variety of conditions, such as different types of TiO₂, pH, catalyst and substrate concentrations. Higher photonic efficiencies were observed with Degussa P25 as compared with other photocatalysts. The degradation products were analysed by GC-MS and probable pathways for the formation of different products were proposed.     

TiO2/PtO-Pt复合膜和SnO2/PtO-Pt复合膜氢敏性能的研究

将PtO-Pt纳米粒子膜与TiO2，SnO2纳米粒子膜复合，利用PtO-Pt纳米粒子膜作 为插入电极和催化剂，设计并研制出一类新型双层结构复合膜气体传感器。采用 TEM和SEM对薄膜的显微结构进行了表征，对空气中4.0H2的氢敏性能研究表明： 200℃时，TiO2/PtO-Pt复合膜对氢气的灵敏度为70％，而TiO2纳米粒子膜无响应。 100℃时，SnO2/PtO-Pt复合膜的灵敏度为92％，同样条件下，SnO2纳米粒子膜的灵 敏度仅为4％。说明PtO-Pt纳米粒子膜的催化作用能够显著提高TiO2和SnO2的膜氢 敏性能。另外，TiO2/PtO-Pt复合膜和SnO2/PtO-Pt复合膜均对空气中H2有很高的选 择性。     

配合物3AgNO3·2[C3H7S(CH2)2SC3H7]的晶体结构

本文测定了配合物3AgNO3·2BPrTE的晶体结构, 该晶体属三斜晶系, 空间各为PI,晶胞参数: a=0.8945(1), b=1.2355(2), c=1.3572(5)nm; α=98.69(2)°, β=92.74(2)°, γ=90.45(1)°; V=1.480nm^3; Z=2, 分子中三个Ag原子的配位数均为5, 但它们的配位多面体各不相同, Ag(3)为四方锥体, Ag(2)为三角双锥, Ag(1)则介于两者之间, NO3^-以单齿、不等长双齿和等长双齿两种形式配位于Ag原子。配体BPrTE也具有两种构象, 反式构象具有C1对称性, 并以两种形式和Ag原子配位, 偏转式构象不具有C4对称性, 与Ag原子形成五元螯合环, 分子为三维无限长链结构。     

Experimental study of photocatalytic oxidation of formaldehyde and its by-products

Formaldehyde is one of the most harmful pollutants that endanger occupants' health and the way of its effective removal has become a focus in the field of air quality. This paper studies the static photocatalytic removal of formaldehyde experimentally and finds out that carbon monoxide, which is more harmful to occupants' health than the formaldehyde itself, is one of the by-products in the process of photocatalytic oxidation of formaldehyde. The increase of carbon monoxide concentration should be taken into consideration in the photocatalytic application. The photocatalyst surface at room temperature can weakly adsorb CO and CO₂, which can deactivate the photocatalysts.     

聚-4-氧杂0-6，7-二甲硒基庚基硅氧烷钯（0）配合物的合成及其催化性能研究

4-氧杂-6，7-二氯庚基三甲氧基硅烷依次与气相法二氧化硅、甲硒基钠、氯化 钯作用，然后用水合肼还原，合成了二氧化硅负载的聚-4-氧杂，6，7-二甲硒基庚 基硅氧烷钯(O)配合物．该配合物是苯乙烯及丙烯酸的Heck芳基化反应的有效催化 剂，为立体选择性地合成各种取代的反式-1，2-二苯乙烯及反式肉桂酸提供了简便 且实用的新方法     

Titanium-dioxide-mediated photocatalysis reaction of three selected pesticide derivatives

The photocatalysis reaction of three selected pesticide derivatives, namely methoxychlor (1), chlorothalonil (2) and disulfoton (3), has been investigated in an acetonitrile/water mixture in the presence of titanium dioxide and oxygen. The change as a function of irradiation time has been monitored using the UV spectroscopic analysis technique. An attempt has been made to identify the product formed during the photooxidation process through GC/MS analysis technique. The photolysis of methoxychlor (1) led to the formation of methoxychlor olefin (4) and 4,4-dimethoxybenzophenone (9), whereas chlorothalonil (2) gave rise to 2,3,4,5-tetrachlorophenol (17) as the only product. On the other hand, the photolysis of disulfoton (3) under analogous conditions gave disulfoton sulfoxide (25) and phosphorodithioic acid (21). All the products have been identified by comparing the molecular ion and mass fragmentation peaks of the products with those reported in the library. A probable mechanism for the formation of the products has been proposed.     

1,2,4-三嗪类化合物的研究 VIII: 3-甲硫基-5-羟基-1,2,4-三嗪-6-羧酸乙酯和N^2-[5'-(3'-甲硫基-6'-乙氧羰基)-1',2',4'-三嗪基]-3-甲硫基-5-氧代-1,2,4-三嗪-6-羧酸乙酯的氧化及其取代反应

本文报道3-甲硫基-5-羟基-1,2,4-三嗪-6-羧酸乙酯(4)及N^2-[5'-(3'-甲硫基-6'-乙氧羰基)-1',2',4'-三嗪基]-3-甲硫基-5-氧代-1,2,4-三嗪-6-羧酸乙酯(8)分子内,甲硫基的氧化及其就地与取代芳胺进行亲核取代反应.3-甲砜基和N^2-[5'-(3'-甲硫基-6'-乙氧羰基)-1',2',4'-三嗪基]作为离去基,其离去能力相近.     

导电高聚物修饰纳米尺度TiO~2多孔膜电极的光电化学研究

用光电化学方法研究了用导电高聚物修饰的纳米晶TiO~2多孔膜电极在不含氧化还原对和含不同氧化还原对体系电解质溶液中的光电转换过程。TiO~2/导电高聚物多孔膜电极为双层n型半导体结构,内层TiO~2多孔膜的禁带宽度为3.26eV,外层聚吡咯(PPy)膜的禁带宽度为2.23eV,而聚苯胺(PAn)膜的禁带宽度为2.88eV。用导电高聚物修饰半导体电极能使其在可见光区的光吸收增加,光电流增强,且起始波长红移至>600nm,使宽禁带半导体电极的光电转换效率得到明显改善。     

磁铅石型复合氧化物LaNi_xCo_(1-x)Al_(11)O_(19+δ)催化剂上CH_4和CO_2重整反应的研究

考察了磁铅石型复合氧化物LaNi_(0.5)M_(0.5)Al_(11)O_(19 + δ) (M = Co, Fe, Mn, Cu)和LaNi_xCo_(1-x)Al_(11)O_(19+δ)催化剂在CH_4与CO_2重整制合成 气反应中的催化活性，并应用XRD，TPR，UV-DRS技术着重表征LaNi_xCo_(1-x)Al_ (11)O_(19+δ)催化剂的结构和性能。研究结果表明该系列催化剂具有相同的晶体 结构和相似的还原稳定性。对不同过渡金属取代的催化剂来说，以LaNi_(0.5)Co_ (0.5)Al_(11)O_(19+δ)催化剂具有最好的反应活性。而对于LaNi_xCo_(1-x)Al_ (11)O_(19+δ)系列催化剂，当x ≤ 0.375时，随x值的增大，催化活性明显提高， 但在0.375 ≤ x ≤ 1.0范围内，催化活性几乎保持不变。由此得到结论，对于此 反应来说，控制Ni量在0.375 ≤ x ≤ 0.50范围内比较合适。     

二氧化碳: 一种同时提供亲核中心保护和亲电中心活化的试剂 XI:2-取代四氢噻唑的新合成方法

四氢噻唑和正丁基锂反应生成的N-锂代四氢噻唑(2)与二氧化碳作用生成N-羟酸锂盐3; 3然后在叔丁基锂作用下失去2-位质子形成相应的2-位碳阴离子4; 该碳阴离子和一系列亲电试剂反应, 并在酸性条件下除去保护基团得产物-2-取代四氢噻唑7. 在此过程中, 二氧化碳既是氨基的保护基团, 同时又活化了2-位亲电中心.此方法不需分离各步中间体, 产率中等.