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    Hydrogenation reactions of kerosene on nickel-based catalysts
    (Elsevier Ltd, 2023) Kömürcü, Hasan; Yılmaz, Kadir; Gürdal, Savaş; Yaşar, Muzaffer
    The hydrotreating of kerosene was studied to develop a crude kerosene distillate to produce products with specifications suitable for marketing as kerosene and rocket grade fuel. To saturate the aromatic structures from kerosene, hydrogenation experiments were carried out in a batch steel reactor with different amounts (20 ml and 40 ml) of crude kerosene, using silica-supported nickel and kieselguhr supported nickel-sulfur catalysts. The catalysts were analyzed with Brunauer, Emmett ve Teller (BET), Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), and x-ray diffraction analysis (XRD). The aromatic fractions and paraffin structures content of the obtained samples were examined. The experiments were carried out at 200–220 °C temperature with 5 bar hydrogen initial pressure for 2 h. The obtained products were analyzed by performing a 1H NMR analysis. According to proton NMR result, the ratio of paraffinic methylene, beta methyl, epsilon methylene groups of 20 ml crude kerosene with kieselguhr supported nickel-sulfur is more than 4.5 times compared to crude kerosene, and % the percentage of aromatic hydrogen structures of it is two times lower. As a result of hydrogenation experiments with both nickel-based catalysts, aromatic hydrogen structures in crude kerosene were reduced. The total H/C ratio of rocket grade hydrocarbon fuels increased after hydrogenation experiments. For this reason, the scope of ongoing research can be extended to hybrid rocket propellants (SP-1) used in hybrid rocket engines.
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    Öğe
    Investigation of Sodium Borohydride Synthesis from Anhydrous Borax: Impact of Stoichiometry and Alternative Reducing Agents
    (Çanakkale Onsekiz Mart Üniversitesi, 2024) Yılmaz, Kadir; Yaşar, Muzaffer
    The production of sodium borohydride from anhydrous borax using aluminum and sodium hydroxide as reactants was investigated in a bomb-type batch reactor under hydrogen atmosphere. The study evaluated the effects of stoichiometric ratios and the addition of calcium carbide on yield and product composition. Experiments without calcium carbide, employing 100% molar excess of aluminum and sodium hydroxide, increased the yield from 11.31% to 13.28%. However, incorporating calcium carbide redirected the reaction mechanism, leading to the formation of complex phase structures. Structural characterization using FT-IR and XRD confirmed the consistency of products from Experiments 1 and 2 with reference NaBH₄. In contrast, products from Experiments 3, 4 and 5 showed significant deviations, with no NaBH₄-specific peaks observed. These findings underscore the importance of stoichiometric optimization and particle size reduction ( [TR] Susuz borakstan, alüminyum ve sodyum hidroksit kullanılarak sodyum borhidrür üretimi, hidrojen atmosferinde çalışan bomba tipi kesikli bir reaktörde incelenmiştir. Çalışmada, stokiyometrik oranların ve kalsiyum karbür ilavesinin verim ve ürün kompozisyonu üzerindeki etkileri değerlendirilmiştir. Kalsiyum karbür kullanılmayan deneylerde, molce %100 fazla alüminyum ve sodyum hidroksit kullanımı reaksiyon verimini %11.31’ den %13.28’ e çıkarmıştır. Ancak, kalsiyum karbür ilavesi reaksiyon mekanizmasını değiştirerek, kompleks faz yapılarının oluşumuna yol açmıştır. FT-IR ve XRD ile yapılan yapısal karakterizasyon, 1 ve 2 numaralı deneylerde elde edilen ürünlerin referans NaBH₄ ile uyumlu olduğunu doğrulamıştır. Buna karşın, 3, 4 ve 5 numaralı deneylerin ürünleri, NaBH₄'e özgü piklerin gözlemlenmediği önemli farklılıklar göstermiştir. Bu bulgular, reaksiyon verimliliğinin artırılmasında stokiyometrik optimizasyonun ve tanecik boyutunun küçültülmesinin (
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    Öğe
    Uncovering the Hydrocracking Efficiency of Iron-Based Catalysts: A Novel Approach to Asphaltene Transformation in Iranian Heavy Oil
    (2024) Yılmaz, Kadir; Gürdal, Savaş; Yaşar, Muzaffer
    In the quest for optimal asphaltene conversion, this study investigated a range of cost-effective and easily accessible catalyst precursors, targeting both high yields of lighter products and minimal coke formation. The hydrocracking experiments were conducted within a 10 ml bomb-type reactor equipped with a reciprocating stirrer operating at a reciprocation rate of 200 times per minute. The experiments were performed at a temperature of 425°C for a duration of 90 minutes, with an initial hydrogen pressure of 100 bar. The outcomes of each experiment were assessed in terms of liquid products, coke production and C5- gas products. To analyze the Iranian heavy asphaltene, Nuclear Magnetic Resonance (1H NMR), Gel Permeation Chromatography (GPC) and elemental analysis were employed. Gas products were characterized using Gas Chromatography (GC). The investigation aimed to identify the catalyst precursor mixture that would maximize asphaltene conversion while minimizing coke production. A series of catalyst precursors, encompassing FeSO4·H2O, its binary mixtures with metal oxides (Fe2O3, Al2O3, CaO, SiO2), and combinations of Fe2O3, Al2O3, and SiO2 with elemental sulfur, were evaluated. The experimental results demonstrated that the toluene-soluble fraction (TSF), which includes the middle distillate portion, could be increased to a maximum of 56% while concurrently reducing the coke yield to 19%, down from the initial 36.9% when no precursor was used.