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    Structure of ruthenium nanocatalysts of bismuth, investigation of its effect on hydrolysis performance and kinetic studies
    (Wiley, 2021) Avci Hansu, Tulin; Caglar, Aykut; Demir Kivrak, Hilal; Sahin, Omer
    In this study, a new nanocatalyst, RuBi/carbon nanotube, was synthesized to be used in the hydrolysis reaction of sodium boron hydride. The sodium boron hydride hydrolysis performance was investigated by adding bismuth to the structure of ruthenium nanocatalysts. Hydrolysis experiments were carried out by adding bismuth at different atomic proportions to ruthenium. The best atomic ratio was determined to be 90:10. These catalysts are characterized by scanning electron microscopy with energy-dispersive X-ray analysis, X-ray diffraction, and transmission electron microscopy. The parameters affecting hydrolysis such as temperature, catalyst amount, sodium hydroxide concentration, and sodium borohydride concentration were examined. The reusability of the catalyst was tested five times. In the calculations, the reaction order was calculated as n, 0.73, and activation energy E-a, 49657 kJ/mol.
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    Untangling the cobalt promotion role for ruthenium in sodium borohydride dehydrogenation with multiwalled carbon nanotube-supported binary ruthenium cobalt catalyst
    (Wiley-Hindawi, 2021) Avci Hansu, Tulin; Sahin, Omer; caglar, Aykut; Demir Kivrak, Hilal
    In the present study, multiwalled carbon nanotube-supported Ru (Ru/MWCNT) and RuCo (RuCo/MWCNT) nanocatalysts with 3 wt% Ru loading were synthesized via sodium borohydride (SBH) reduction method for the dehydrogenation of SBH (R-SBH)(.) These nanocatalysts were characterized with XRD, XPS, SEM-EDX, and TEM. Ru/MWCNT and Ru:Co/MWCNT catalysts with varying Ru:Co atomic ratios were prepared successfully, and electronic state of Ru:Co altered compared to Ru. R-SBH activities of these Ru/MWCNT and RuCo/MWCNT were examined in alkaline environment. RuCo/MWCNT at 80:20 atomic ratio exhibits superior H-2 evolution. Further experiments were performed with RuCo/MWCNT at 80:20 atomic ratio to determine how NaOH concentration (C-NaOH), reaction temperature (T-rxn), SBH concentration (C-SBH), and amount of nanocatalyst (M-c) affect R-SBH activities. Activation energy (Ea) was calculated using the Arrhenius equation. RuCo/MWCNT at 80:20 atomic ratio exhibits superior H-2 evolution activities compared to the literature values. Initial rate (IR) for this nanocatalyst was found as 123.9385 mL H-2 g(cat)(-1) min(-1). As a result of these kinetic calculations, the Ea of the nanocatalysts was calculated as 35.978 kJ/mol. The degree of reaction (n) was found to be 0.53 by trial and error. RuCo/MWCNT at 80:20 atomic ratio is a promising nanocatalyst for R-SBH.