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排序方式: 共有101条查询结果,搜索用时 31 毫秒
1.
Marcella Bonchio Mauro Carraro Martino Gardan Gianfranco Scorrano Enrico Drioli Enrica Fontananova 《Topics in Catalysis》2006,40(1-4):133-140
The incorporation of decatungstate in polymeric membranes provides new heterogeneous photocatalysts for the oxidation of organic
substrates under oxygen atmosphere at 25 °C. Photocatalytic membranes have been prepared yielding polymeric films with a high
thermal, chemical and mechanical stability (PVDF, PDMS, Hyflon). Surface spectroscopy techniques including transmittance and
reflectance UV-Vis and FT-IR have been used to assess the photocatalyst integrity within the polymeric support. Catalyst screening
has been performed under both homogeneous and heterogeneous photooxygenation conditions. The photocatalyst activity has been
evaluated in terms of the substrate conversion, turnover numbers, and recycling experiments. A membrane induced selectivity
behavior has been evidenced by comparison with homogeneous oxidations. 相似文献
2.
通过复分解法合成了3种基于Mo8O4-26阴离子的四烷基铵钼多金属氧酸盐,并将其作为催化剂,质量分数为30%H2O2溶液为氧化剂、1-己基-3-甲基咪唑四氟硼酸盐离子液体([C6MIM]BF4)为萃取剂,用于柴油的催化氧化脱硫。分别考察了催化剂摩尔分数、反应温度、剂油体积比、反应时间、氧化剂用量等条件对模拟油品脱硫率的影响,确定了最优化反应条件,并将其应用于实际油品的脱硫中。结果表明,在60℃反应条件下,反应时间1h,当催化剂摩尔分数为5%、剂油体积比为1∶5、n(氧化剂)/n(硫化物)为6∶1时,该催化氧化-萃取体系对模拟油品(初始含硫质量分数为1 164μg/g)有较高的脱硫率,一次脱硫率可达95%以上。对抚顺石化公司生产的催化裂化柴油(初始含硫质量分数为850μg/g)一次脱硫率约为92%。 相似文献
3.
合成了3种新的多金属氧酸盐(CTMA)5BW12O40·8H2O,(CTMA)4SiW12O40·3H2O,(CTMA)3PW12O40·2H2O,利用元素分析、IR光谱和TG-DTA技术对其进行了表征.IR光谱表明这些化合物不仅含有Keggin型结构,而且存在有机大阳离子的特征吸收峰;TG-DTA曲线显示它们的热行为是一个多步分解过程,首先这些化合物在大约269℃以下脱去水分子,然后它们的无水多金属氧酸盐经历了两步或3步的分解过程,分别脱去CTMA分子及其碎片,并伴随Keggin型结构的塌陷.通过XRD和IR光谱确证其最终分解产物是一个含有WO3与B2O3,SiO2或P2O5的混合物.同时还提出了这些化合物可能的热分解过程. 相似文献
4.
以多金属氧酸盐Na8[PMo7V5O40]为介体,对杨木硫酸盐浆进行了电化学介体脱木素的研究.结果表明,采用钌钛涂层电极为阳极,不锈钢为阴极,以Na8[PMo7V5O40]为介体对杨木硫酸盐浆进行无隔膜电化学处理,能够有效脱除纸浆中的残余木素,而浆的黏度损失不大.Na8[PMo7V5O40]最优的电化学介体脱木素条件为:Na8[PMo7V5O40]浓度5 mmol/L,电压2.5V,温度80℃,时间7h,pH值2.0~3.0,Na2SO4用量0.1mol/L.该条件下,纸浆卡伯值从17.3降至11.4,黏度从1018 mL/g降至846 mL/g.电化学处理后的废液可进行多次循环使用. 相似文献
5.
Wenjing Zheng Licong Yang Xiuying Qin Yanhui Zhou 《Science and Technology of Advanced Materials》2014,15(3)
Tumor growth depends on angiogenesis, which can furnish the oxygen and nutrients that proliferate tumor cells. Thus, blocking angiogenesis can be an effective strategy to inhibit tumor growth. In this work, three typical nanoparticles based on polyoxometalates (POMs) have been prepared; we investigated their capability as antitumor and anti-angiogenesis agents. We found that Mo POM nanoparticles, especially complex 3, inhibited the growth of human hepatocellular liver carcinoma cells (HepG2) through cellular reactive oxygen species levels’ elevation and mitochondrial membrane potential damage. Complex 3 also suppressed the proliferation, migration, and tube formation of endothelial cells in vitro and chicken chorioallantoic membrane development ex vivo. Furthermore, western blot analysis of cell signaling molecules indicated that Mo POMs blocked the vascular endothelial growth factor receptor 2-mediated ERK1/2 and AKT signaling pathways in endothelial cells. Using transmission electron microscopy, we demonstrated their cellular uptake and localization within the cytoplasm of HepG2 cells. These results indicate that, owing to the extraordinary physical and chemical properties, Mo POM nanoparticles can significantly inhibit tumor growth and angiogenesis, which makes them potential drug candidates in anticancer and anti-angiogenesis therapies. 相似文献
6.
Alexander M. Khenkin Ronny Neumann Alexander B. Sorokin Alain Tuel 《Catalysis Letters》1999,63(3-4):189-192
The impregnation of H5PV2Mo10O40 polyoxometalate onto MCM‐41 and amino‐modified MCM‐41 materials provided mesoporous active catalysts with large surface areas
for aerobic hydrocarbon oxidation using isobutyraldehyde as a reducing agent. The results of the oxidation of alkenes and
alkanes gave product selectivities similar to those observed in the corresponding homogeneous reaction although catalytic
activity was somewhat reduced. Under appropriate experimental conditions there was no leaching and the solid catalyst could
be recovered and reused without loss in activity.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
This paper is a choral personal account on a longstanding and fruitful collaboration of organic and inorganic chemists to develop new hybrid polyoxometallic systems. .We explain our motivation and the context of our work that led to polyoxometalates with highly functional and reactive organic groups. Our approach yielded catalytically, biologically, and photochemically active systems. 相似文献
8.
Oxana A. Kholdeeva 《Topics in Catalysis》2006,40(1-4):229-243
The similarity in the catalytic behaviour of titanium-monosubstituted Keggin type polyoxometalates [PTi(L)W11O39]n- (Ti-POMs) and heterogeneous titanium single-site catalysts in selective oxidations with H2O2 is demonstrated. Recent achievements in the application of Ti-POMs as soluble molecular models for studying mechanisms of
oxidation catalysis are reviewed. 相似文献
9.
İlhan Küçük Sema Vural Süleyman Köytepe 《Polymer-Plastics Technology and Engineering》2019,58(13):1445-1460
The aim of this study was to synthesis, characterization and investigation of the influence of the polyoxometalate concentrations (1, 3, 5 and 10 wt%) on chemical, thermal, physical and morphological properties of nickel-based polyoxometalate/polyurethane composite (Ni-POM/PU) materials. Firstly, nickel-based polyoxometalate (Ni-POM) compound has been synthesized and characterized through various spectroscopic techniques. Synthesized Ni-POM compounds have been used for preparation of polyurethane composites as a reinforcement. Three different Ni-POM/PU composites containing Ni-POM were prepared by solution mixing and casting techniques. The chemical structure and morphology of prepared Ni-POM/PU composite samples were confirmed by Fourier transform infrared spectroscopy (FTIR), elemental analysis and SEM techniques. Effects of Ni-POM on thermal stability, glass transition temperature, optical transparency, hydrophilicity and physical properties of polyurethane composites were examined. Thermal stabilities and glass temperatures of the materials have been checked by differential thermal analysis (DTA), thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). The SEM results confirmed the highly porous structure and the formation of Ni-POM structures in the polymer matrix. Synthesized composites showed high chemical stability, good processability, and low Tg values. The dielectric properties of the prepared Ni-POM/polyurethane composites were also investigated at room temperature. These results displayed that the dielectric constant of the POM/polyurethane composites decreased with the increase of the Ni-POM content in polymeric matrix. 相似文献