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载体对负载型TiO2催化剂光催化性能的影响 总被引:22,自引:0,他引:22
以活性碳(AC)和镁铝尖晶石(MA)为载体,采用真空吸附水解法制备了负载型光催化剂TiO2/AC和TiO2/MA,并采用TiO2溶胶负载法制备了活性碳负载催化剂TiO2(C)/AC.以氯仿为探针分子研究了其在催化剂上的吸附及光催化降解反应性能.结果表明,催化剂的制备方法、TiO2负载量与载体的吸附性能对光催化活性有明显的影响.通过优化制备条件,TiO2/AC催化剂的催化活性可提高到纳米TiO2的2.5倍.氯仿在AC上的饱和吸附量较高,但吸附强度较弱;在纳米TiO2上的吸附情况则正好相反.氯仿在AC和TiO2上吸附性质的差异有利于吸附在TiO2/AC上的氯仿分子从活性碳载体向TiO2光催化活性中心迁移.镁铝尖晶石载体对光催化反应没有明显的促进作用,与其基本上不吸附氯仿分子有关.与TiO2胶体负载法相比,真空吸附水解法是一种较好的负载型TiO2光催化剂制备方法. 相似文献
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高度分散的Pt/TiO2的制备及光催化活性 总被引:7,自引:2,他引:7
用柠檬酸作为空穴捕获剂和分散剂,在温和条件下用光催化还原法将3nm金属铂沉积在7nm的锐钛矿相及介孔二氧化钛纳米晶表面,TEM观察显示铂的负载量为w=1.0%时,多数二氧化钛纳米晶表面沉积了岛状的铂团簇,XPS和电子衍射结果表明铂以游离态存在.负载w=1.0%~2.0%铂的TiO2在苯酚光氧化反应中活性显著提高,Pt/TiO2在氨气中经550℃氮化,可制得氮掺杂的Pt/TiO2可见光光催化剂,氮化过程中铂团簇没有烧结和显著长大。 相似文献
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Au/TiO2光催化剂的制备及其催化性能 总被引:2,自引:0,他引:2
采用改进的等体积浸渍法、光化学沉积法分别制备了不同Au担载量的Au/TiO2光催化剂,以甲基橙的光催化降解反应作为模型反应,考察了金的担载量、预处理条件、制备方法等因素对其光催化性能的影响,以漫反射紫外一可见光谱(DRS)分析了不同金担载量的Au/TiO2光催化剂的光谱特征。结果显示,适当担载量的Au可显著提高TiO2的光催化活性,以改进的等体积浸渍法制备的0.8%Au/TiO2催化剂的光催化活性最高。DRS结果显示,金的担载对TiO2的光谱特征没有影响。 相似文献
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无氧条件下Pt/TiO2光催化重整降解一乙醇胺水溶液制氢 总被引:2,自引:0,他引:2
以一乙醇胺(以下简称乙醇胺)为电子给体,在无氧条件下进行了Pt/TiO2光催化重整制氢的研究.详细讨论了诸多因素如催化剂表面Pt化学状态、Pt担载量、溶液pH值、乙醇胺溶液浓度等对产氢效率的影响,并用XRD、HNMR、XPS等进行了深入表征,探讨了Pt/TiO2光催化重整降解乙醇胺和产氢的反应, 实验表明,利用所制备的光催化剂, 可实现在消除水中有机污染物的同时制取氢气的目标.催化剂表面的Pt以Pt0的化学状态存在, 有利于析氢;溶液pH值和浓度的变化对产生速率也有一定的影响.同时发现Pt/TiO2光催化重整乙醇胺制氢反应的最佳条件是:Pt的最佳担载量约为0.5%~1.0%;乙醇胺溶液最佳浓度约为0.05 mol•L-1;最佳溶液pH值范围为4~10;氨基取代的羰基类化合物是其主要中间产物. 相似文献
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B掺杂TiO2/AC光催化剂的制备及活性 总被引:13,自引:1,他引:13
以硼酸和钛酸丁酯为主要原料,以活性炭(AC)为载体。用溶胶-凝胶法制备了B掺杂TiO2/AC光催化剂.用X射线衍射(XRD)、紫外可见漫反射吸收光谱(UV—VIS)对制得的光催化剂进行了表征.以甲基橙水溶液的光催化脱色反应和氧化乐果水溶液的光催化降解反应。考查了不同B掺杂TiO2/AC光催化剂的活性.结果表明,所有B掺杂TiO2/AC光催化剂均为锐钛矿晶相.B的掺杂未导致TiO2/AC光催化剂的吸收带边发生明显的移动.当B-TiO2质量分数分别为2.0%和2.5%时,TiO2/AC光催化剂的活性有明显的提高.B-TiO2质量分数2.0%时活性最高.但是,当B-TiO2质量分数分别为1.5%和3.0%时。TiO2/AC光催化剂的活性降低.B的缺电子特性可能改变了TiO2能带中的电子密度,使光催化反应中光生电子和空穴的俘获方式发生变化;同时。B的缺电子特性也会使光催化剂表面的Lewis酸强度增强,导致表面吸附OH-数量和目标反应物的吸附方式发生变化.这些可能是B-TiO2/AC光催化剂活性发生变化的主要原因. 相似文献
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RE/TiO2用于NO2-光催化氧化的研究 总被引:73,自引:0,他引:73
以稀土盐和钛酸丁酯为原料,采用溶胶-凝胶法制备了掺杂稀土\r\n光催化剂RE/TiO2(RE=La,Ce,Er,Pr,Gd,Nd,Sm),并用XRD,\r\nDRS和IR等手段对RE/TiO2进行了表征;以NO-2为目标降解物,考察了\r\n其光催化氧化活性.结果表明,适量RE的掺入,可有效扩展TiO2的光谱\r\n响应范围,有利于NO-2的吸附,使光催化活性均有不同程度的提高.\r\n其中掺杂Gd样品的光催化活性最高.掺杂量是影响光催化活性的重要因\r\n素,一般最佳掺杂量为w(RE)≈0.5%. 相似文献
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An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions. 相似文献
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An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction. 相似文献
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The Diels-Alder reactivity of 1,2-heteroborines (H4C4B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed. 相似文献
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Xi-Liu YunWen-Ying Bi Jian-Hui HuangYu Liu Daisy Zhang-NegrerieYun-Fei Du Kang Zhao 《Tetrahedron letters》2012,53(38):5076-5080
A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd2(dba)3-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring. 相似文献
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Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles. 相似文献
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An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C60 and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C60, followed by SET from the amine to the triplet excited state of C60. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C60 radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared. 相似文献
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Viktor A. Dmitriev Mariia M. Efremova Alexander S. Novikov Vladimir V. Zarubaev Alexander V. Slita Anastasia V. Galochkina Galina L. Starova Andrey V. Ivanov Alexander P. Molchanov 《Tetrahedron letters》2018,59(24):2327-2331
The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities. 相似文献
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A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields. 相似文献
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Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl3-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction. 相似文献
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M. Saeed Abaee Atefeh Hadizadeh Mohammad M. Mojtahedi Mohammad R. Halvagar 《Tetrahedron letters》2017,58(14):1408-1412
An efficient four-component reaction was developed to take advantage of the reactivity of the 2-aminothiophene-3-carbonitrile functionality, which is obtained during the classical three-component Gewald reaction. Various α-methylene bearing ketones were reacted with malononitrile, elemental sulfur, and aryl/heteroarylnitrile derivatives in t-BuOH/NaOH to afford 2-arylthieno[2,3-d]pyrimidin-4-amines in high yields. Preliminary studies revealed the photophysical properties of the products and their potential for use as metal sensors. 相似文献