Yazar "Saka, Cafer" seçeneğine göre listele

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    CoB doped acid modified zeolite catalyst for enhanced hydrogen release from sodium borohydride hydrolysis
    (ELSEVIER, 2020) Saka, Cafer; Eygi, Mustafa Salih; Balbay, Asım
    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 (H2) 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.
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    Fe doped-CoB catalysts with phosphoric acid-activated montmorillonite as support for efficient hydrogen production via NaBH4 hydrolysis
    (Elsevier Ltd, 2021) Balbay, Asım; Selvitepe, Nuran; Saka, Cafer
    In this study, montmorillonite (MMT) clay was modified with different acids to be used as support material. The modified MMT clay was used to obtain hydrogen in the hydrolysis reactions of NaBH4 (NaBH4-HR) as a support material for the Co–B and Co–Fe–B catalyst. During the activation of MMT clay, the effects of different acids, phosphoric acid (H3PO4) concentration, and impregnation time with H3PO4 were investigated. During the hydrogen generation from the NaBH4-HR, effects of Co loading, Fe loading, NaBH4 concentration, temperature and, catalyst durability were investigated. The maximum HGRs for MMT-H3PO4–CoB and MMT-H3PO4–Co–Fe–B treated with 5 M H3PO4 for 7 days were 1869 and 4536 mL/min/gcatalyst, respectively. The activation energies for MMT-H3PO4–CoB and MMT-H3PO4–Co–Fe–B catalyst samples were 49.5 and 38.90 kJ/mol.
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    Metal-free catalyst fabrication by incorporating oxygen groups on the surface of the carbonaceous sample and efficient hydrogen production from NaBH4 methanolysis
    (ELSEVIER, 2022) Saka, Cafer; Balbay, Asım
    In the present study, metal-free catalysts for efficient H2 generation from NaBH4 methanolysis was produced for the first time from apricot kernel shells with two-step activation. The first stage of the two-stage activation includes the production of activated carbon with the KOH agent (AKOH), and the second stage includes hydrothermally HNO3 activation with oxygen doping (O doped AKOH + N). The hydrogen production rate (HGR) and the activation energy (Ea) of the reaction with the obtained metal-free catalyst (10 mg) were determined as 14,444 ml min?1 g?1 and 7.86 kJ mol?1, respectively. The structural and physical-chemical properties of these catalysts were characterized by XRD (X-ray diffraction), SEM (scanning electron microscopy), elemental CHNS analysis, FT-IR (Fourier transform infrared spectroscopy), and nitrogen adsorption analysis. Also, the reusability results of this metal-free catalyst for H2 production are promising.
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    Oxygen and nitrogen-functionalized porous carbon particles derived from hazelnut shells for the efficient catalytic hydrogen production reaction
    (Elsevier, 2021) Saka, Cafer; Balbay, Asım
    Due to their low cost and high availability, interest in biomass materials in catalytic studies is increasing. It is possible to increase the catalytic activities by the development of metal-free catalysts obtained by adding different atoms to carbon materials. Here, oxygen (O) and nitrogen (N) doped metal-free carbon catalysts (N-AC-N) were synthesized using activated carbon (AC) obtained from hazelnut shells by KOH activation. These metal-free catalysts were used successfully for the first time in the NaBH4 methanolysis reaction (NaBH4-MR). The structural and physical-chemical properties of the metal-free catalysts obtained were analysed by XRD (X-ray diffraction), elemental analysis (CHNS), FT-IR (Fourier transform infrared spectroscopy), SEM (scanning electron microscopy), and nitrogen adsorption surface analyses. N and O doped metal-free catalyst showed very good catalytic performance against NaBH4-MR. The hydrogen production rate (HGR) with 10 mg metal-free catalyst at 30 °C and the activation energy(Ea) of the reaction were calculated as 16250 mL min?1 g?1 and 11.45 kJ mol?1, respectively. At the same time, with favourable reusability results, this metal-free catalyst is a promising candidate for the hydrogen(H2) generation system.