Search

Pd doped Multi-Walled Carbon Nanotubes were prepared via supercritical carbon dioxide deposition method in order to enhance the hydrogen uptake capacity of carbon nanotubes at ambient conditions. A new bipyridyl precursor that enables reduction at moderate conditions was used during preparation of the sample. Both XRD analyses and TEM images confirmed that average Pd nanoparticle size distribution was around 10 nm. Hydrogen adsorption and desorption experiments at room temperature with very low pressures (0 -0.133 bar) were conducted together with temperature programmed desorption (TPD) and reduction (TPR) experiments on undoped and doped materials to understand the complete hydrogen uptake profile of the materials. TPD experiments showed that Pd nanoparticles increased the hydrogen desorption activity at moderate temperatures around at 38 degrees C while for undoped materials it was determined around at 600 degrees C. Moreover, a drastic enhancement of hydrogen storage was recorded from 44 mu mol/g sample for undoped material to 737 mu mol/g sample for doped material through adsorption/desorption isotherms at room temperature. This enhancement, also verified by TPR, was attributed to spillover effect. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

TEZ13242 Tez (Doktora) -- Çukurova Üniversitesi, Adana, 2017. Kaynakça (s. 139-144) var. XXIII, 185 s. :_res. (bzs. rnk.), tablo ;_29 cm. Tez kapsamında süperkritik karbondioksit depozisyon tekniğinde kullanılabilir nitelikte yeni ß-diketonat türevi ligand ve metal kompleksleri (öncül) hazırlanarak SBA-15 temelli silika üzerine Pd depozisyonunda kullanılmıştır. Bu amaçla asetilaseton bileşiği aktif metilen grubuna çeşitli zincir uzunluğuna sahip florlu ve florsuz alkil grupları bağlanmış ve elde edilen ligandların Pd(II) kompleksleri hazırlanmıştır. Sentezlenen ligand ve metal komplekslerin yapıları FT-IR, 1H,19F NMR, elementel analiz, kütle spektroskopisi, manyetik duyarlılık, UV-Vis gibi analitik yöntemlerle aydınlatılmıştır. Bu komplekslerin süperkritik CO2 depozisyonuna uygunluğunu araştırmak amacıyla deney şartlarındaki çözünürlükleri test edilerek TGA analizi ile kararlılığı incelenmiştir. Ardından sentezlenen öncüller kullanılarak süperkritik CO2 depozisyon tekniğiyle hidrojen gazı ile kimyasal indirgeme yöntemi yapılarak Pd/SBA-15 nanopartikülleri hazırlanmıştır. Oluşan metalik nanopartiküller HR-TEM, BET, XRD ve ICP-OES ile analiz edildiğine % 3.5-5.0 Pd içerdiği ve 10-20 nm boyutlarına sahip olduğu belirlenmiştir. Hazırlanan Pd/SBA-15 nanokatalizörleri Suzuki-Miyaura çapraz eşleşme tepkimelerinde katalitik etkinlikleri farklı çözücü ve sıcaklıklarda incelenmiştir. In the thesis, new ß-diketonate derivative ligand and metal complexes (precursors) have been prepared and used for Pd deposition on SBA-15 based silica, which can be used for supercritical carbon dioxide deposition technique. For this purpose, the acetylacetone compound is coupled with fluorine and fluorine-free alkyl groups having various chain lengths to the active methylene group and Pd (II) complexes of the ligands obtained are prepared. The structures of synthesized ligand and metal complexes were elucidated by analytical methods such as FT-IR, 1H, 19F NMR, elemental analysis, mass spectroscopy, magnetic susceptibility, UV-Vis. Their solubility in scCO2 and TGA analysis were tested to determine their suitability for supercritical CO2 deposition technique. Subsequently, Pd/SBA-15 nanoparticles were prepared by chemical reduction with hydrogen gas using supercritical CO2 deposition technique using synthesized precursors. The resulting metallic nanoparticles were analyzed by HR-TEM, BET, XRD and ICP-OES, contained 3.5-5.0% Pd and were found to have dimensions of 10-20 nm. The prepared Pd/SBA-15 nanocatalysts have been investigated for their catalytic activities in Suzuki-Miyaura crosscoupling reactions at different solvents and temperatures. Bu Çalışma Ç.Ü. Bilimsel Araştırma Projeleri Birimi Tarafından Desteklenmiştir. Proje no: FDK-2015-3668.

Synthesizing supercritical carbon dioxide (scCO2) soluble precursors would be helpful for many processes of material syntheses based on scCO2. Ligand (amphi-(1Z, 2Z)-N-(2-fluoro-3-(trifluoromethyl) phenyl)-N'-hydroxy-2-(hydroxyimino) were synthesized from chloro glyoxime and flourus aniline and Pd(II) complex (precursor) prepared. For scCO2 deposition method, organometallic precursor was dissolved in scCO2 and impregnated onto the SBA-15 at 90 °C and 3000 psi. Then the organometallic precursor was reduced with H2 in the CO2 mixture (150 psi H2 + 2850 psi CO2). Pd deposited support material was characterized by ICP-OES, XRD, FE-SEM, TEM and EDX analyses. The Pd loading of the prepared catalyst, measured by ICP-OES showed a value of about 1.64% mol/g Pd of catalyst. Average particle size was found 5.3 nm. The catalytic activity of prepared catalyst was investigated over Suzuki-Miyaura C-C coupling reaction in different solvent with K2CO3 at 50 oC. The conversion ratio was determined by gas chromatography., {"references":["Y. Zhang, C. Erkey, \"Preparation of supported metallic nanoparticles using supercritical fluids: a review,\" J. Supercrit. Fluids, vol. 38, pp. 252, 2006.","C. Erkey, \"Preparation of metallic supported nanoparticles and films using supercritical fluid deposition,\" J. Supercrit. Fluids, vol. 47, pp. 517, 2009.","X.R. Ye, Y. Lin, C.M. Wai, \"Decorating catalytic palladium nanoparticles on carbon nanotubes in supercritical cabon dioxide,\" Chem. Commun., vol. 5, pp. 642, 2003.","S.E. Bozbag, C. Erkey, \"Supercritical deposition: Current status and perspectives for the preparation of supported metal nanostructures\" J. Supercrit. Fluids, vol. 96, pp. 298, 2015.","Lin, Chi-Kai, \"Novel synthesis and characterization of precious-metal nanocatalysts for clean energy applications,\" N. IL. Uni., pp. 128, 2011.","S.K. Morley, P.C. Marr, P.B. Webb, A.R. Berry, F.J. Allison, G. Moldovan, P.D. Brown, S.M. Howdle, \"Clean preparation of nanoparticulate metals in porous supports: a supercritical route,\" J. Mater. Chem., vol. 12, pp. 1898, 2002.","A. Bayrakceken, U. Kitkamthorn, M. Aindow and C. Erkey, \"Decoration of multi-wall carbon nanotubes with platinum nanoparticles using supercritical deposition with thermodynamic control of metal loading\" Scripta Materialia, 56, 101–103, 2007","J. Baoa, H. Tianb, R. Tang, \"Synthesis and characterization a novel europium(III)-β-diketonate complex with carbazole and triphenylamine moieties\" Inorganica Chimica Acta, vol.401, pp.19–23, 2013.","A.L. Dantas, P.D. Alves, D. Arando, M. Schmal, \"Characterization of carbon supported Pd catalysts: Influence of electronic and particle size effects using reaction probes\" Appl. Catal., vol 277, pp. 71-81, 2004.\n[10]\tHunt A. J., Budarin V. L., Comerford J. W., Parker H. L., Lazarov V. K., Breeden S.W., Macquarrie D. J., Clark J. H.. \"Deposition of Palladium Nanoparticles in SBA-15 Templated Silica Using Supercritical Carbon Dioxide\" Materials Letters vol.116, pp. 408–411, 2014.\n[11]\tCotugno, P., M. Casiello, A. Nacci, P. Mastrorilli, M. M. Dell'Anna and A.Monopoli. \"Suzuki coupling of iodo and bromoarenes catalyzed by chitosan-supported Pd-nanoparticles in ionic liquids\" Journal of Organometallic Chemistry vol. 752: pp.1-5, 2014."]}

WOS: 000379514000101 …

TEZ9000 Tez (Yüksek Lisans) -- Çukurova Üniversitesi, Adana, 2013. Kaynakça (s. 93-101) var. xv, 118 s. : res. ; 29 cm. Vic-dioxime derivative metal complexes were synthesized in order to determine their solubility in a scCO2 medium and their use as precursors in the deposition of metal nanoparticles. Their structures were determined and their use in deposition onto silicagel and ?-alumina in scCO2 was tested in this study. Pd(II) and Cu(II) metal complexes with vic-dioxime ligands and were synthesized for this purpose. The ligands were made by reacting various aniline derivatives with antimonochloro glyoxime. In order to increase the solubility of the complexes in scCO2, some of the ligands were synthesized from aniline derivatives with long fluorous chains. All ligands and complexes were synthesized and characterized via various analyses including FT-IR, 1H, 19F NMR, UV-Vis and magnetic susceptibility. The solubility of the metal complexes in supercritical medium was also determined. The synthesized metal complexes were used as precursors for the deposition of the metals on solid supports in a scCO2 medium resulting in the synthesis of nano-sized metal catalysts. The size of the synthesized nanocatalysts was analyzed by TEM and XRD. The Pd particles ranged from 2-16nm and the Cu nanoparticles ranged from 3-20nm. The activity of these catalysts in a hydrogenation reaction of olefins was analyzed using GC. Tez kapsamında süperkritik karbondioksit çözücü ortamında yapılan depozisyon işlemlerinde kullanılabilir nitelikte vic-dioksim türevi metal kompleksleri (öncül) sentezlenmiş, yapıları aydınlatılmış, süperkritik karbondioksit ortamında silikajel ve ?-alümina üzerine depozisyon işleminde kullanılabilirliği denenmiştir. Bu amaçla anilin türevleri ile anti-monokloro glioksimin ile vic-dioksim ligandları ve bu ligandların Pd(II), Cu(II) kompleksleri sentezlenmiştir. Ligand sentezinde süperkritik karbondioksitte çözünürlüğü arttırmak amacıyla uzun zincirli anilin türevleri seçilmiştir. Bu metal öncüllerin süperkritik çözücü ortamındaki çözünme miktarları belirlenmiştir. Sentezlenen bileşiklerin yapıları FT-IR, 1H,19F NMR, elementel analiz, manyetik süsseptibilite ve UV-Vis ile aydınlatılmıştır. Elde edilen metal kompleksleri scCO2 ortamında katı destek üzerine metal depozisyonunda öncül olarak kullanılmış olup nano boyutta metal katalizörler elde edilmiştir. Elde edilen katalizörlerin boyutları TEM ve XRD ile analiz edilmiştir. Buna göre Pd taneciklerinin boyutu 2-16nm ve Cu taneciklerinin boyutu 3-20nm arasında değişmektedir. Bu katalizörlerin olefinlerin hidrojenasyon reaksiyonundaki katalitik aktiviteleri belirlenmiş ve bu amaçla GC kullanılmıştır. Bu çalışma Ç.Ü. Bilimsel Araştırma Projeleri Birimi tarafından desteklenmiştir. Proje No: FEF2012YL27.