Researcher:
Babucci, Melike

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PhD Student

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Melike

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Babucci

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Babucci, Melike

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2015 - 20209

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    Interactions of [BMIM][BF 4] with metal oxides and their consequences on stability limits
    (Amer Chemical Soc, 2016) N/A; N/A; N/A; Department of Chemical and Biological Engineering; Babucci, Melike; Balcı, Volkan; Akçay, Aslı; Uzun, Alper; PhD Student; PhD Student; Master Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 59917
    Interactions between 1-n-butyl-3-methylimidazolium tetrafluoroborate, [BMIM][BF4], and high-surface-area metal oxides, SiO2, TiO2, Fe2O3, ZnO, gamma-Al2O3, CeO2, MgO, and La2O3, covering a wide range of point of zero charges (PZC), from pH = 2 to 11, were investigated by combining infrared (IR) spectroscopy with density functional theory (DFT) calculations. The shifts in spectroscopic features of the ionic liquid (IL) upon coating different metal oxides were evaluated to elucidate the interactions between IL and metal oxides as a function of surface acidity. Consequences of these interactions on the short- and long-term thermal stability limits as well as the apparent activation energy (Ea) and rate constant for thermal decomposition of the supported IL were evaluated. Results showed that stability limits and Ea of the IL on each metal oxide significantly decrease with increasing PZC of the metal oxide. Results presented here indicate that the surface acidity strongly controls the IL surface interactions, which determine the material properties, such as thermal stability. Elucidation of these effects offers opportunities for rational design of materials which include direct interactions of ILs with metal oxides, such as solid catalysts with ionic liquid layer (SCILL), and supported ionic liquid phase (SILP) catalysts for catalysis applications or supported ionic liquid membranes (SILM) for separation applications.
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    Atomically dispersed reduced graphene aerogel-supported iridium catalyst with an iridium loading of 14.8 wt %
    (American Chemical Society (ACS), 2019) Debefve, Louise M.; Boubnov, Alexey; Bare, Simon R.; Gates, Bruce C.; N/A; Department of Chemical and Biological Engineering; Department of Chemistry; Department of Chemistry; Babucci, Melike; Uzun, Alper; Öztuna, Feriha Eylül Saraç; Ünal, Uğur; PhD Student; Faculty Member; Researcher; Faculty Member; Department of Chemical and Biological Engineering; Department of Chemistry; Graduate School of Sciences and Engineering; College of Engineering; College of Sciences; College of Sciences; N/A; 59917; N/A; 42079
    Atomically dispersed iridium complexes were anchored on a reduced graphene aerogel (rGA) by the reaction of Ir(CO)(2)(acac) [acac = acetonylacetonato] with oxygen-containing groups on the rGA. Characterization by X-ray absorption, infrared, and X-ray photoelectron spectroscopies and atomic resolution aberration-corrected scanning transmission electron microscopy demonstrates atomically dispersed iridium, at the remarkably high loading of 14.8 wt %. The rGA support offers sites for metal bonding comparable to those of metal oxides, but with the advantages of high density and a relatively high degree of uniformity, as indicated by the same turnover frequencies for catalytic hydrogenation of ethylene at low and high iridium loadings. The atomic dispersion at a high metal loading- and the high density of catalytic sites per unit of reactor volume, a key criterion for practical catalysts-set this catalyst apart from those reported.
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    Thermal stability limits of imidazolium ionic liquids immobilized on metal-oxides
    (Amer Chemical Soc, 2015) N/A; N/A; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Babucci, Melike; Balcı, Volkan; Akçay, Aslı; Uzun, Alper; PhD Student; PhD Student; Master Student; Faculty Member; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 59917
    Thermal stability limits of 33 imidazolium ionic liquids (ILs) immobilized on three of the most commonly used high surface area metal-oxides, SiO2, gamma-Al2O3, and MgO, were investigated. as were chosen from a family of 13 cations and 18 anions. Results show that the acidity of C2H of an imidazolium ring is one of the key factors controlling the thermal stability. An increase in C2H bonding strength of ILs leads to an increase in their stability limits accompanied by a decrease in interionic energy. Systematic changes in IL structure, such as changes in electronic structure and size of anion/cation, methylation on C2 site, and substitution of alkyl groups on the imidazolium ring with functional groups have significant effects on thermal stability limits. Furthermore, thermal stability limits of ILs are influenced strongly by acidic character of the metal-oxide surface. Generally, as the point of zero charge (PZC) of the metal-oxide increases from SiO2 to MgO, the interactions of IL and metal-oxide dominate over interionic interactions, and metal-oxide becomes the significant factor controlling the stability limits. However, thermal stability limits of some ILs show the opposite trend, as the chemical activities of the cation functional group or the electron donating properties of the anion alter IL/metal-oxide interactions. Results presented here can help in choosing the most suitable ILs for materials involving ILs supported on metal-oxides, such as for supported ionic liquid membranes (SLLM) in separation applications or for solid catalyst with ionic liquid layer (SCILL) and supported ionic liquid phase (SILP) catalysts in catalysis.
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    Tuning the selectivity of single-site supported metal catalysts with ionic liquids
    (American Chemical Society (ACS), 2017) Fang, Chia-Yu; Hoffman, Adam S.; Bare, Simon R.; Gates, Bruce C.; N/A; Department of Chemical and Biological Engineering; Babucci, Melike; Uzun, Alper; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 59917
    1,3-Dialkylimidazolium ionic liquid coatings act as electron donors, increasing the selectivity for partial hydrogenation of 1,3-butadiene catalyzed by iridium complexes supported on high-surface-area gamma-Al2O3. High-energy-resolution fluorescence detection X-ray absorption near-edge structure (HERFD XANES) measurements quantify the electron donation and are correlated with the catalytic activity and selectivity. The results demonstrate broad opportunities to tune electronic environments and catalytic properties of atomically dispersed supported metal catalysts.
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    A model to predict maximum tolerable temperatures of metal-oxide-supported 1-n-butyl-3-methylimidazolium based ionic liquids
    (Elsevier, 2015) N/A; N/A; N/A; Department of Chemical and Biological Engineering; Akçay, Aslı; Babucci, Melike; Balci, Volkan; Uzun, Alper; Master Student; PhD Student; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 59917
    The thermal stability limits of metal-oxide-supported ionic liquids (Its) with 1-n-butyl-3-methylimidazolium cation, [BMIM](+), on most commonly used metal-oxides, SiO2, TiO2, gamma-Al2O3, and MgO are determined. Data show that stability limits of bulk and metal-oxide-supported ILs linearly increase with increasing acidity of C2 proton on imidazolium ring, controlling the inter-ionic interaction strength. Moreover, data also show that the presence of metal-oxide lowers the stability limits considerably. This effect becomes more significant as the surface acidity of the metal-oxide decreases from SiO2 to MgO This decrease in stability limits with increasing point of zero charge (PZC) of metal-oxide indicates that the interaction between IL and metal-oxide becomes the dominant factor rather than the inter-ionic interactions. Based on these findings a simple mathematical expression was developed as a function of PZC and inter-ionic interaction strength probed by nu(C2H) to predict the stability limits of [BMIM](+)-based ILs immobilized on metal-oxides. Performance of the model was tested on several different ILs supported on different metal-oxides, including Fe2O3 and CeO2. Results show that the model successfully predicts the maximum operating or tolerable temperatures of supported-[BMIM](+)-based ILs with an average relative error less than 4.3%. We suggest that the model developed here can help to choose proper ILs that can tolerate the operating conditions of systems including ILs immobilized on metal oxides, such as in solid catalysts with ionic liquid layer (SCILL) or in supported ionic liquid phase (SILP) catalysts. (C) 2014 Elsevier Ltd. All rights reserved.
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    Single-site supported metal complexes: tunable catalytic performance with ionic liquid coatings
    (American Chemical Society (ACS), 2018) Fang, Chia-Yu; Hoffman, Adam; Bare, Simon; Gates, Bruce; N/A; Department of Chemical and Biological Engineering; Babucci, Melike; Uzun, Alper; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 59917
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    Effects of interionic interactions in 1,3-dialkylimidazolium ionic liquids on the electronic structure of metal sites in solid catalysts with ionic liquid layer (SCILL)
    (Elsevier Science Bv, 2016) N/A; Department of Chemical and Biological Engineering; Babucci, Melike; Uzun, Alper; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; College of Engineering; N/A; 59917
    Well-defined gamma-Al2O3-supported Ir(CO)(2) complexes were coated with various 1,3-dialkylimidazolium ionic liquids (ILs) to elucidate the ligand effect of ILs. Variations in electron density of iridium sites when coated with ILs were probed by the infrared (IR) fingerprints of carbonyl ligands. Results presented here illustrate that IL layer strongly controls the electron density of metal sites; and there is a strong correlation between the interionic interactions in ILs and the degree of electron donation to the metal. These results create opportunities to tune the electronic structure of active metal sites by tailoring the structure of IL for optimum catalytic performance. (C) 2015 Elsevier B.V. All rights reserved.
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    Unraveling the individual influences of supports and ionic liquid coatings on the catalytic properties of supported iridium complexes and iridium clusters
    (Elsevier, 2020) Hoffman, Adam S.; Debefve, Louise M.; Bare, Simon R.; Gates, Bruce C.; N/A; N/A; Department of Chemical and Biological Engineering; Babucci, Melike; Öztulum, Samira Fatma Kurtoğlu; Uzun, Alper; PhD Student; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; 384798; 59917
    Supported iridium complexes were synthesized by the reaction of Ir(CO)(2) (acac) (acac = acetylacetonato) with SiO2, gamma-Al2O3, and MgO. Extended X-ray absorption fine structure (EXAFS) and infrared (IR) spectra demonstrate that the iridium was present as atomically dispersed species anchored to each support. The samples were treated in flowing H-2 at 673 K to form supported iridium clusters. EXAFS spectra and highangle annular dark-field scanning transmission electron microscopy images demonstrate that the average diameter of the iridium clusters on each support was approximately 1.2 nm. The catalysts before and after cluster formation were coated with each of a family of 1,3-dialkylimidazolium ionic liquids (ILs) having varying electron-donor tendencies probed by their nu(C2H) frequencies determined by IR spectroscopy. The coated and uncoated samples were tested as catalysts for partial hydrogenation of 1,3-butadiene in a flow reactor at 333 K, with turnover frequencies determined from differential conversions. The individual influences of the IL coatings and supports on the catalyst performance were found to depend strongly on whether the iridium was site-isolated complexes or present in clusters. The IL coatings as ligands exerted dominant effects on the clusters as catalysts, whereas the supports exerted dominant effects on the isolated iridium atoms. The results indicate how to tune the effects of metal nuclearity, IL coatings, and supports on the electronic environments and catalytic properties of the metals. (C) 2020 Elsevier Inc. All rights reserved.
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    Controlling catalytic activity and selectivity for partial hydrogenation by tuning the environment around active sites in iridium complexes bonded to supports
    (Royal Society of Chemistry (RSC), 2019) Fang, Chia-Yu; Perez-Aguilar, Jorge E.; Hoffman, Adam S.; Boubnov, Alexey; Guan, Erjia; Bare, Simon R.; Gates, Bruce C.; Department of Chemical and Biological Engineering; Babucci, Melike; Uzun, Alper; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); College of Engineering; N/A; 59917
    Single-site Ir(CO)(2) complexes bonded to high-surface-area metal oxide supports, SiO2, TiO2, Fe2O3, CeO2, MgO, and La2O3, were synthesized by chemisorption of Ir(CO)(2)(acac) (acac = acetylacetonate) followed by coating with each of the following ionic liquids (ILs): 1-n-butyl-3-methylimidazolium tetrafluoroborate, [BMIM][BF4], 1-n-butyl-3-methylimidazolium acetate, [BMIM][Ac], and 1-(3-cyanopropyl)-3-methylimidazolium dicyanamide, [CPMIM][DCA]. Extended X-ray absorption fine structure spectroscopy showed that site-isolated iridium was bonded to oxygen atoms of the support. Electron densities on the iridium enveloped by each IL sheath/support combination were characterized by carbonyl infrared spectroscopy of the iridium gem-dicarbonyls and by X-ray absorption near-edge structure data. The electron-donor/acceptor tendencies of both the support and IL determine the activity and selectivity of the catalysts for the hydrogenation of 1,3-butadiene, with electron-rich iridium being selective for partial hydrogenation. The results resolve the effects of the IL and support as ligands; for example, the effect of the IL becomes dominant when the support has a weak electron-donor character. The combined effects of supports and ILs as ligands offer broad opportunities for tuning catalytic properties of supported metal catalysts.