粉状白钨酸的研究(Ⅹ)——粉状白钨酸的离子交换性能

通过粉状白钨酸和黄钨酸的离子交换性能的测定,比较了它们之间化学活性的相对大小。用动态法(交换柱法)测得了它们的离子交换容量,计算了与钨原子相联的羟基数目。并用静态法(振荡平衡法)测定了白钨酸对不同阳离子的交换情况及各种鸽酸的pH滴定曲线。     

钨酸催化氧化环己烯合成己二酸

以钨酸/有机酸性添加剂为催化体系, 在无有机溶剂、相转移剂的情况下, 催化30%过氧化氢氧化环己烯合成己二酸. 当钨酸∶有机酸性添加剂∶环己烯∶过氧化氢＝1∶1∶40∶176(摩尔比, 钨酸用量为2.5 mmol)时, 使用有机酸性添加剂考察钨酸的催化性能, 结果表明以钨酸/间苯二酚催化氧化环己烯的催化效果最优, 反应8 h时己二酸分离产率达90.9%、纯度为～100%; 而不使用有机酸性添加剂时, 己二酸分离产率只有72.1%, 产品纯度为96.2%. 当使用磺酸水杨酸、草酸、水杨酸为有机酸性添加剂时, 随反应时间的增加, 己二酸分离产率均升高, 但反应6 h以后, 己二酸分离产率随时间的变化不明显. 当磺酸水杨酸用量为2.5 mmol时, 己二酸分离产率和纯度均较高. 钨酸-磺酸水杨酸催化体系重复使用五次后, 己二酸分离产率仍可达到80.5%.     

钨酸催化氧化环己烯合成己二酸

以钨酸为催化剂,过氧化氢为氧化剂,催化氧化环己烯(1)合成了己二酸（2）,其结构经¹H NMR和IR确证。采用正交实验法研究了过氧化氢浓度、钨酸用量和磷酸用量对2收率的影响。采用单因素法考察了酸性助剂,过氧化氢用量及其加料方式对收率的影响。结果表明：在最佳反应条件［n(H₂O₂)：n(1)：n(钨酸)=4.6 ：1.0：0.06, w(H₂O₂)=27.5%,回流反应1.7 h］下,2收率95.1%,纯度99.2%。     

室温和低酸度条件下钨酸的制备

本文提出了一种在室温(～20℃)和低酸度(～1/V)条件下制备钨酸的新方法,讨论了钨酸的生成机理、化学组成和物理性能。     

活性粉状白钨酸与十聚、六聚及其他多聚钨酸盐的联系和应用

本文扼要总结了作者近年来关于活性粉状白钨酸与十聚、六聚钨酸的工作,包括它们的制备、分离及相互转化。聚钨酸有机铵盐的光敏性,活性粉状白钨酸用于合成众多新化合物,对三价钨的簇合物以及从WO_4~(2-)转变到黄钨酸系列过程的推测等也给予了相应的评述。     

黄、白钨酸制备法的差异,以及粉状白钨酸反应研究的进展

本文扼要总结了作者多年来对钨酸制备方法的研究。与传统方法不同,黄钨酸得自浓盐酸的均相沉淀法。粉状白钨酸是一个活性化合物,乃将Na₂WO₄滴入1 M HNO₃至pH值近于1时制得。此类白钨酸可作为制备偏钨酸、杂多钨酸,包括有机砷多钨酸盐的原始材料。     

粉状白钨酸研究IX: 含W-N键的钨同多酸盐[Py2W12O38]^4^-的合成

通过粉状白钨酸与吡啶水溶液反应成功地制备了一种无色的晶体(C5H5NH)4[(C5H5N)2W12O38].6H2O.从反应混合物中还分离到一个黄色的副产物,其组成经分析为(C5H5N)0.85.WO3.粉状白钨酸在无水吡啶中放置两周后可得到另一种化学式为(C5H5NH)HW4O13.3H2O的吡啶化合物,经IR和DTA研究可初步说明该化合物与粉状白钨酸(微晶态)之间的联系,并因此推测白钨酸的组成可能为H2W4O13.nH2O.     

回收灯用钨丝在H2O2催化氧化环己酮合成己二酸中的应用

以回收灯用钨丝为催化剂前驱物,30％H2O2为氧源,催化氧化环己酮合成了己二酸,反应体系中无须使用有机溶剂、酸性助剂和相转移剂。 IR和TG分析表明,钨丝与H2O2反应生成的新生态过氧钨酸是催化活性成分,合成己二酸后转化为钨酸。 钨丝为催化剂前驱物合成己二酸适宜反应条件为：100 mmol环己酮,50 mL 30%H2O2,钨丝的摩尔用量为环己酮摩尔数的1.5%,回流反应6 h,己二酸收率63.7%。 比相同反应条件下用钨酸和WO3为催化剂的收率高10%~18%。     

La séparation et le dosage du tungstène et du molybdène au moyen du chlorure de calcium

A rapid and simple method is described for the separation and the determination of molybdenum and tungsten. Both metals are extracted as their soluble salts, sodium molybdate and sodium tungstate, by means of an alkaline fusion (Na₂CO₃ + Na₂O₂), after which they are separated by precipitation with calcium chloride as reagent. The precipitates of calcium molybdate and calcium tungstate are filtered, washed and then decomposed by concentrated hydrochloric acid. Calcium molybdate passes completely into the filtrate while calcium tungstate leaves a precipitate of tungstic acid. By calcining this precipitate, tungstic trioxide is obtained and weighed. The tungsten content is calculated therefrom.The filtrate from tungstic acid serves for reprecipitation of calcium molybdate on making the solution alkaline and by boiling. Calcium molybdate is filtered by means of a porcelain crucible filter and then calcined. When the weight of the calcined precipitate is constant, the molybdenum content is obtained by multiplying the weight of the precipitate by the conversion factor. Results are satisfactory, separation and determination of both metals not taking more than a day's work.     

On key factors for the fabrication of mesoporous tungsten oxide films from tungstic acid

Thermally stable mesoporous tungsten oxide films (TOFs) were prepared by surfactant templated sol–gel method using tungstic acid as tungsten oxide source. Influence of various experimental conditions on the obtained mesostructures was investigated, including the solvent compositions, addition of hydrogen peroxide, substrates, and aging time, heat treatment, etc. It has been found that the addition of hydrogen peroxide has a significant influence on the flexibility of formed meso-frameworks, and just a small amount can regenerate the degraded coating sol. TOFs were also found to crystallize on ITO coating easier than on bare glass, indicating that the different interactions with the substrates influence the crystallinity of obtained meso-structured TOFs. Film thickness can be adjusted by simply changing the solvent compositions while keeping mesostructures intact. This work clarified several key parameters in delivering well-defined mesostructured TOFs from cheap, moisture-insensitive tungstic acid precursor via the process developed.     

H2WO4/GO的制备及其超声-氧化脱除模拟油中的硫化物

以钨酸和氧化石墨烯为原料,利用浸渍法将钨酸负载到氧化石墨烯上制得H₂WO₄/GO。采用XRD、FT-IR、SEM、BET表征确定H₂WO₄/GO的形态及其结构。以H₂WO₄/GO作为催化剂,H₂O₂作为氧化剂,乙腈作为萃取剂超声氧化脱除模拟油中的二苯并噻吩（DBT）。实验表明,在模拟油为5 mL,钨酸的负载量为30%（质量分数）,催化剂为0.02 g,乙腈为1 mL,H₂O₂/S（mol ratio）为8,反应温度为50℃,超声功率为150 W的最佳反应条件下,二苯并噻吩（DBT）、4,6-二甲基二苯并噻吩（4,6-DMDBT）、苯并噻吩（BT）的脱除率分别达到96.6%、81.2%、72.8%。同时,考察了催化剂的循环使用性能,并对超声氧化脱硫机理进行了研究。     

The Research on the Stability of TiO2， MoO3， PEO Doped Four-member Tungstic Acid Sols

The TiO2, MoO3, PEO doped four-member tungstic acid sols were prepared for the first time. The stability of different doped content sols were investigated and optimized with rotational viscometer. The four-member doped tungstic acid sol was very stable which could be stored more than two months at room temperature. The WO3 electrochromic film prepared from this doped four-member tungstic acid sol had excellent performance and longevity of service.     

粉状白钨酸的制备

钨酸的颜色有黄有白,并有粉状与胶状的区别。其中黄色胶状物是黄色粉状与白色胶状的混合物。一般制得的白色粉状钨酸,又或多或少地杂有胶状物,不易定其组成。所以长时期来,只把黄色粉状钨酸作为钨酸的代表,并作为制备金属钨及其他钨化合物的基本原料。黄色粉状钨酸和白色钨酸的生成机理不同,但二者在生成时每易交织在一起。黄色粉状钨酸是均相沉淀的产物,即是含钨络阴离子的分解产物。     

Heterogenized tungsten complex: an efficient and high yielding catalyst for the synthesis of structurally diverse tetra substituted pyrrole derivatives via four-component assembly

An efficient, high yielding, and expeditious method has been developed for the synthesis of diversity oriented pyrrole derivatives via a four component, one-pot cyclocondensation reaction of amines, aldehydes, α-methylene ketones, and nitroalkanes using silica supported tungstic acid as a heterogeneous catalyst for the first time. The scope of the domino reaction is successfully explored toward synthesis of highly aryl-substituted pyrroles. The reaction was conveniently promoted by silica supported tungstic acid and the catalyst could be recovered easily after the reaction and reused without any loss of its catalytic activity. The advantageous features of this methodology are high atom-economy, operational simplicity, shorter reaction time, convergence, and facile automation.     

A study of the tungsten-hydroquinone color: Spectrophotometric determination of tungsten in tungsten steels

The red color produced by tungsten and hydroquinone in a concentrated sulfuric acid medium was studied. Various factors affecting the color were examined including the effects of phosphoric acid, water, hydrochloric acid, tin(II) chloride, and wavelength of measurement. The interferences from iron, molybdenum, vanadium, and titanium were studied. A method is described for the determination of tungsten in tungsten steels that involves precipitation of the tungsten with cinchonine. ignition to tungstic oxide, dissolution of the tungstic oxide in sodium hydroxide, and development of the tungsten hydroquinone color on an aliquot of the solution.     

新型WO3/HMS催化剂的制备及其对环戊烯选择氧化反应的催化性能

 采用草酸络合方法将WO3固载到六方介孔全硅分子筛HMS上,制得新型WO3/HMS非均相催化剂. 利用SEM,TEM,N2吸附,XRD及激光拉曼光谱等手段对催化剂进行了表征,研究了催化剂在环戊烯选择性氧化合成戊二醛反应中的催化性能. 结果表明,在WO3/HMS催化下环戊烯和H2O2的转化率均可达100%,戊二醛的选择性可达72%. WO3以高分散状态存在于催化剂表面. 单次反应后钨的溶脱量(5.5 μg/ml)很小,对反应几乎没有影响. 催化剂具有较高的稳定性,可以重复套用6次. 失活后的催化剂可通过简单焙烧的方式再生.     

Micro-heterometric determination of molybdic acid with α-benzoin oxime

1 mg of molybdenum as molybdic acid in 20 ml solution can be titrated heterornetrically with a-benzoin oxime in the presence of ~ 99% of most bivalent or tri valent cations as well as in excesses of tungstic or vanadic acids. Error: 0–2%.     

Spectroscopic and DFT study of tungstic acid peroxocomplexes

The catalytic system formed by tungstic acid and its complexes with H2O2 and phenylphosphonic acid has been analyzed from the experimental and theoretical points of view. Previous structural studies by XRD proved the validity of the DFT proposed models and methodology. Hydrogen peroxide reacts with tungstic acid to form a peroxo complex. Vibrational and electronic spectra showed significant changes upon interaction with H2O2. The DFT and TD-DFT for IR and UV-vis calculations not only are in agreement with experimental data but also allow for a deeper characterization of the species formed in in situ conditions. A SCRF/PCM methodology was chosen to account for the solvent effect. The solvent effect of water was considered for geometry re-optimization of the structure and for the TD-DFT calculations.     

白钨酸研究——Ⅶ.K3W2Cl9的制备及反应

用粉状白钨酸作原针,在一般条件下制备K₃W₂Cl₉,产率达53%,证明白钨酸是比黄钨酸优越的钨化学试剂。研究了K₃W₂Cl₉经离子又换转化为酸的形态后与Ndz₂(C0₃)₃的反应。得到了新的化合物NdW₂Cl₉,提出了一条新的制备溶解度大的各种金属离子与W₂Cl₉^3-的化合物的途径。 对K₃W₂Cl₉和NdW₂Cl₉进行了紫外可见尤谱和X针线粉末衍射的测定。     

Crystallographically oriented mesoporous WO3 films: synthesis, characterization, and applications.

Mesoporous semiconducting films consisting of preferentially orientated monoclinic-phase nanocrystals of tungsten trioxide have been prepared using a novel version of the sol-gel method. Transformations undergone by a colloidal solution of tungstic acid, stabilized by an organic additive such as poly(ethylene glycol) (PEG) 300, as a function of the annealing temperature have been followed by means of a confocal Raman microscope. The shape and size of WO3 nanoparticles, the porosity, and the properties of the films depend critically on preparation parameters, such as the tungstic acid/PEG ratio, the PEG chain length, and the annealing conditions. Well-crystallized WO3 films combine excellent photoresponse to the blue region of the solar spectrum, up to 500 nm, with good transparency at wavelengths larger than 550 nm. Particular applications of these nanocrystalline WO3 films include photoelectrochemical and electrochromic devices.