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研究了以Pd(OAc)2为催化剂,H3PMo12O40为助催化剂,空气为氧化剂,在乙酸溶液中于373 K条件下,在500 ml高压釜中由苯液相氧化偶联合成联苯. 结果表明,反应产物中联苯的选择性高达92%以上,并且只有少量的三联苯副产物生成. 分别考察了H3PMo12O40的加入量和O2分压对以空气或纯O2为氧化剂时Pd/HPMo/AcOH催化苯液相氧化偶联合成联苯反应催化性能的影响. 根据反应液颜色的变化以及文献结果推测,在反应过程中通过钯和钼物种的氧化和还原作用使苯氧化生成联苯. 相似文献
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Kirti Patel Sudhir Kapoor Devilal Purshottam Dave Tulsi Mukherjee 《Journal of Chemical Sciences》2005,117(4):311-316
Pt, Pd, Pt-Ag and Pd-Ag bimetallic nanoparticles were synthesized in ethylene glycol and glycerol using the microwave technique
in the presence of a stabilizer poly(N-vinylpyrrolidone) (PVP). It has been observed that PVP is capable of complexing and
stabilizing nanoparticles. Mixed clusters were formed by simultaneous reduction of the metal ions. The clusters were characterized
using UV-Vis spectra, XRD and dynamic light scattering. To understand the mechanism of formation of mixed nanoparticles, several
experimental parameters such asin situ irradiation of mixed metal salts and mixing of individual sols were attempted. 相似文献
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Pd/C催化剂用于苯胺氧化羰基化 总被引:4,自引:0,他引:4
研究了催化剂制备条件、助催化剂对负载型Pd/C催化剂性能的影响及氧分压、原料苯胺中硝基苯的加入对苯胺氧化羰基化反应的影响;用X光电子能谱(XPS)、程序升温还原(TPR)和现场红外(IR)表征钯催化剂;根据实验结果提出在Pd/C-NaI催化剂体系、醇介质中,苯胺氧化羰基化可能的反应机理. 相似文献
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IntroductionElectrontransfer (ET)reactionsarefoundtobeanelementalstepinmanybiologicalprocessesindeed .1 6IthasbeenbelievedthattheexperimentalmeasurementofETreactionsbetweenbiphenyl (Bp)andaseriesofor ganicsystems ,designedbyMilleretal.,isthefirstsuc cessfule… 相似文献
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Tohru Takahashi Masatoshi Yoshimura Hiroyasu Suzuka Tomohiro Maegawa Yoshinari Sawama Yasunari Monguchi Hironao Sajiki 《Tetrahedron》2012,68(39):8293-8299
Palladium catalysts embedded on molecular sieves (MS3A and MS5A) were prepared by the adsorption of Pd(OAc)2 onto molecular sieves with its in situ reduction to Pd0 by MeOH as a reducing agent and solvent. 0.5% Pd/MS3A and 0.5% Pd/MS5A catalyzed the hydrogenation of alkynes, alkenes, and azides with a variety of coexisting reducible functionalities, such as nitro group, intact. It is noteworthy that terminal alkenes of styrene derivatives possessing electron-donating functionalities on the benzene nucleus were never hydrogenated under 0.5% Pd/MS5A-catalyzed conditions, while internal alkenes of 1-propenylbenzene derivatives were readily reduced to the corresponding alkanes. 相似文献
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通过溶胶凝胶法、浸渍法和共沉淀法制备含贵金属Pd的Ce-Zr-Mn-Al-O固溶体材料,并对新鲜和老化样件材料的BET、孔容、孔径、TPR等表征研究,结果表明:采用溶胶凝胶法制备的材料在新鲜和老化条件下具有良好的储氧能力(OSC)和表征特性,将不同制备方法所得的材料制成催化剂样件在发动机台架进行连续空燃比和连续温度实验,台架数据结果表明采用溶胶凝胶法制备的催化剂在处理HC和NOx时表现出优良的特性,催化剂对总碳氢化合物(THC)和NOx的初始转化能力和偏稀条件下NOx的处理具有较强的适应能力,该方法制备的催化剂应用到CNG发动机上也取得了良好的效果。 相似文献
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A new, reusable Pd/MgLa mixed oxide catalyst has been applied successfully in the Suzuki-Miyaura carbon-carbon cross-coupling reaction of aryl halides as well as benzylic bromide with boronic acids in ethanol. The catalyst is air stable, can be stored and handled under an ambient atmosphere and after the reaction it can be recovered by simple filtration and reused without significant loss of activity. 相似文献
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We report an alternative hydrogenation of aromatic aminoketones by heterogeneous catalyst of palladium on carbon (Pd/C) in which nitro, in particular carbonyl groups in the ketones, could be selectively transformed to corresponding amino ketone, secondary alcohol, or methylene compound. 相似文献
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使用不同浓度(0~67%)的硝酸对活性炭载体进行预处理,以H2PdCl4为前驱体,用浸渍法制备理论负载量为5%的Pd/C催化剂.浸渍过程中的吸附实验表明,Pd前驱体的平衡吸附量随预处理硝酸浓度的增加而逐渐减小,尤其是浓硝酸预处理的活性炭载体,其上仅有62.54%的Pd前驱体吸附,而37.46%的Pd前驱体仍在水浆液中.分析发现,Pd前驱体的平衡吸附量主要取决于活性炭的零电荷点,表面电荷模型能较好地描述Pd前驱体的吸附规律.当使用浓度≤5%的硝酸进行预处理时,Pd的粒径随硝酸浓度的增加而减小;当硝酸浓度继续增加时,Pd粒径急剧增大.Pd前驱体的平衡吸附量与Pd粒径的大小无直接关系,而Pd前驱体在活性炭表面上吸附物种及数量的不同也对Pd粒径的大小产生影响.活性炭表面基团的增加抑制了PdClyx-吸附物种的生成.当使用≤5%的硝酸处理活性炭时,Pd前驱体的吸附形态主要为PdClxy-和Pd0;当硝酸浓度>5%时,没有检测到PdClyx-的存在. 相似文献
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《高等学校化学学报》2001,22(Z1):1-4
用溶剂化金属原子浸渍法制备了不同钯含量的高分散Pd/γ-Al2O3催化剂,XRD和化学吸收测定结果表明,随着钯含量的增加,钯颗粒度增大,但直径都在2.0~6.0nm范围内.XPS研究表明,钯处于金属态.Pd/γ-Al2O3在较低温度下就显示出CO氧化催化活性,在453K时CO的转化率都可达到1∞%,随着钯粒度减小,催化活性升高,钯颗粒度为2.1nm的Pd/γ-Al2O3催化剂活性最高 相似文献
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研究了一系列联苯衍生物和SO3在二氯甲烷中进行的磺化反应。联苯的磺化产物为4-磺酸取代物,进一步反应得到4,4′-、2,4,4′-及少量的2,4,2′,4′-多取代物。甲氧基取代的联苯体现了较高的反应活性,3,3′-二甲氧基联苯的彻底磺化得到五磺酸取代产物,2-甲氧基联苯的单磺化主要发生在5位上,4-甲氧基联苯的单磺化先在3位上进行。 相似文献
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Thermal behavior of polarized Pd/D electrode, prepared by the co-deposition technique, serving as a cathode in the Dewar-type electrochemical cell/calorimeter is examined. It is shown that: (i) excess enthalpy is generated during and after the completion of the co-deposition process; (ii) rates of excess enthalpy generation are somewhat higher than when Pd wires or other forms of Pd electrodes are used; (iii) positive feedback and heat-after-death effects were observed; and (iv) rates of excess power generation were found to increase with an increase in both cell current and cell temperature, the latter being higher. 相似文献
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XinHuaXU‘ HongYiZHOU DaHuiWANG 《中国化学快报》2003,14(7):700-703
Chlorobenzene was dechlorinated by Pd/Fe bimetallic system in water through catalytic reduction. The dechlorination rate increases with increase of bulk loading of Pd due to the increase of both the surface loading of the Pd and the total surface area. For conditions with 0.005% Pd/Fe, 45% dechlorination efficiency was achieved within 5 h. The dechlorinated reaction is believed to take place on the bimetal surface in a pseudo-first-order reaction, with the rate constant being 0.0043 min^-1. 相似文献
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《液相色谱法及相关技术杂志》2012,35(14):2679-2685
Abstract Residues of the fungicide biphenyl in citrus fruits have been determined by direct scanning of spots on phosphor-impregnated high performance silica gel TLC plates under UV light. Biphenyl was separated from fruit tissue by steam liquid-liquid extraction. Recoveries from spiked samples ranged from 92–99% at 100, 50, and 10 ppm levels. The precision of the TLC determination and overall procedure are shown to be adequate for residue analysis. 相似文献