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    CoB doped acid modified zeolite catalyst for enhanced hydrogen release from sodium borohydride hydrolysis
    (Pergamon-Elsevier Science Ltd, 2020) Saka, Cafer; Eygi, Mustafa Salih; Balbay, Asim
    Cobalt-boron (CoB) catalyst supported on zeolite modified with hydrochloric acid (CoB-zeolite-HCl) and zeolite modified with acetic acid (CoB-zeolite-CH3COOH) is prepared for the hydrogen (H-2) release from sodium borohydride (NaBH4). The supported catalyst samples were characterized by X-ray diffraction spectroscopy (XRD), scanning electron microscope (SEM), Fourier transforms infrared spectroscopy (FTIR), nitrogen adsorption and, inductively coupled plasma optical emission spectroscopy (ICP-OES). The effects of Co metal loading, NaBH4 concentration, NaOH concentration, temperature, and reusability on the catalytic performance of the CoB-zeolite-HCl catalyst were investigated. The completion time of the reaction using the raw zeolite supported CoB catalyst was about 265 min. However, the completion time of the reaction using the CoB-zeolite-HCl catalyst was decreased to about 80 min. BET surface area values showed that there is a 7-fold increase in the specific surface area for the zeolite activated with HCl compared to the BET surface area for the raw zeolite. The activation energy (Ea) of the catalyzed reaction was 42.45 kJ mol(-1). (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Cobalt loaded organic acid modified kaolin clay for the enhanced catalytic activity of hydrogen release via hydrolysis of sodium borohydride
    (Pergamon-Elsevier Science Ltd, 2021) Saka, Cafer; Eygi, Mustafa Salih; Balbay, Asimm
    Inorganic acids such as hydrochloric acid (HCl), nitric acid (HNO3) and sulphuric acid (H2SO4) are generally used in the acid modification of clays. Here, CoB catalyst was synthesized on the acetic acid-activated kaolin support material (CH3COOH -kaolin- CoB) with an alternative approach. This prepared catalyst, firstly, was used to catalyze the hydrolysis of NaBH4 (NaBH4-HR). The structure of the raw kaolin, kaolin-CH3COOH, and CH3COOH-kaolin-CoB samples were characterized by X-ray diffraction spectroscopy (XRD), Fourier transforms infrared spectroscopy (FTIR), scanning electron microscope (SEM), and nitrogen adsorption. At the same time, this catalyst performance was examined by Co loading, NaBH4 concentration, NaOH concentration, temperature and reusability parameters. The end times of this hydrolysis reaction using raw kaolin-CoB and CH3COOH-kaolin-CoB were found to be approximately 140 and 245 min, respectively. The maximum hydrogen generation rates (HGRs) obtained at temperatures 30 degrees C and 50 degrees C were 1533 and 3400 mL/min/g(catalyst), respectively. At the same time, the activation energy was found to be 49.41 kJ/mol. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Öğe
    Flotation chemistry of a rare earth mineral: bastnasite
    (2017-11-01) Karataş, Deniz; Karaağaçlıoğlu, İbrahim Ethem; Eygi, Mustafa Salih; Çelik, Mehmet Sabri
    Bastnasite is the primary valuable mineral in two of the world’s largest rare earth (RE) mineral deposits and also found in Beylikova, Sivrihisar Rare Earth Oxide (REO) deposit. Although many technical studies were conducted on flotation of a number of industrial deposits in the last 30 years, the fundamentals on surface chemistry of REO are relatively modest. In this work, the fundamentals and literature on RE mineral flotation is outlined along with a review on electrokinetics and other surface chemistry issues. In particular, specific flotation reagents, i.e. those of hydroxamates developed for selective flotation of REO minerals are highlighted to illustrate their advantages together with an update on so called Beylikova thorium containing bastnasite ore.