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Öğe Hydrogen production by catalytic methane decomposition over yttria doped nickel based catalysts(Pergamon-Elsevier Science Ltd, 2019) Karaismailoğlu, Meltem; Figen, Halit Eren; Baykara, Sema ZeynepCatalytic methane decomposition can become a green process for hydrogen production. In the present study, yttria doped nickel based catalysts were investigated for catalytic thermal decomposition of methane. All catalysts were prepared by sol-gel citrate method and structurally characterized with X-ray powder diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and Brunauer, Emmet and Teller (BET) surface analysis techniques. Activity tests of synthesized catalysts were performed in a tubular reactor at 500 ml/min total flow rate and in a temperature range between 390 degrees C and 845 degrees C. In the non-catalytic reaction, decomposition of methane did not start until 880 degrees C was reached. In the presence of the catalyst with higher nickel content, methane conversion of 14% was achieved at the temperature of 500 degrees C. Increasing the reaction temperature led to higher coke formation. Lower nickel content in the catalyst reduced the carbon formation. Consequently, with this type of catalyst methane conversion of 50% has been realized at the temperature of 800 degrees C. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Molybdenum- and vanadium-containing perovskite electrocatalysts for dissociation of H2S(Wiley, 2020) Karaismailoğlu, Meltem; Güldal, Nafi Özgür; Figen, Halit Eren; Baykara, Sema ZeynepCatalytic operations, achieving considerable energy savings, continue getting wider application especially in clean energy systems. Perovskite materials, owing to their chemical and thermal stability, can be conveniently used as catalysts and electrode materials at wide temperature ranges. Hydrogen sulfide (H2S) offers a new and abundant source of hydrogen, the ultimate energy carrier. In the present work, change in electrical conductivity of catalysts obtained by adding molybdenum (Mo) and vanadium (V) as B to the perovskite structure with lanthanum (La) and strontium (Sr) as A and A ', respectively, has been studied within a temperature range of up to 1100 K. Samples La0.75Sr0.25MoO3 and LaSr0.5V0.5O3 demonstrated the highest values of conductivity at 1100 K. At lower temperatures, Cr-added Mo and V catalysts La0.9Sr0.1Cr0.5Mo0.5O3 and La0.9Sr0.1Cr0.5V0.5O3 had higher conductivity, closely followed by LaSr0.5V0.5O3.