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Öğe Environmental issues and social issues with renewable energy(Elsevier Science, 2022) Baykara, Zeynep Sema; Figen, Halit Eren; Elibol, Meltem Karaismailoğlu[Özet yok]Öğe Investigation of a novel & integrated simulation model for hydrogen production from lignocellulosic biomass(2018) Ersöz, A.; Baykara, Zeynep Sema; Elibol, Meltem Karaismailoğlu; Güldal, N. Ö.; Figen, Halit Eren; Yüksel, F.; Turan, A. Z.; Sarıoğlan, A.; Durak Çetin, Y.Process simulation and modeling works are very important to determine novel design and operation conditions. In this study; hydrogen production from synthesis gas obtained by gasification of lignocellulosic biomass is investigated. The main motivation of this work is to understand how biomass is converted to hydrogen rich synthesis gas and its environmentally friendly impact. Hydrogen market development in several energy production units such as fuel cells is another motivation to realize these kinds of activities. The initial results can help to contribute to the literature and widen our experience on utilization of the CO2 neutral biomass sources and gasification technology which can develop the design of hydrogen production processes. The raw syngas is obtained via staged gasification of biomass, using bubbling fluidized bed technology with secondary agents; then it is cleaned, its hydrocarbon content is reformed, CO content is shifted (WGS) and finally H2 content is separated by the PSA (Pressure Swing Adsorption) unit. According to the preliminary results of the ASPEN HYSYS conceptual process simulation model; the composition of hydrogen rich gas (0.62% H2O, 38.83% H2, 1.65% CO, 26.13% CO2, 0.08% CH4, and 32.69% N2) has been determined. The first simulation results show that the hydrogen purity of the product gas after PSA unit is 99.999% approximately. The mass lower heating value (LHVmass) of the product gas before PSA unit is expected to be about 4500 kJ/kg and the overall fuel processor efficiency has been calculated as ?93%.Öğe Investigation of the physicochemical properties of Bi,Ca-doped BaZrO3 perovskites(Mew Journal of Chemistry, 2023) Elibol, Meltem Karaismailoğlu; Akyüz, Serra Melek; Figen, Halit ErenPerovskite oxides, primarily the ones based on BaZrO3, hold significant interest for diverse applications in a variety of disciplines, such as electrocatalysts or electrolytes in fuel cell technologies. This study outlines the synthesis of BaZrO3 perovskite powders via a sol–gel route, and explores the incorporation of bismuth and calcium cations through single doping. Extensive characterization, encompassing X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller analysis, oxygen/hydrogen temperature-programmed desorption/reduction, and scanning electron microscopy/energy-dispersive X-ray spectroscopy, reveals the impact of the metal cation incorporation on physicochemical properties, enhancing oxygen vacancies and lattice oxygen species within the BaZrO3 perovskite structure.Öğe NaBH4'ten Hidrojen Üretimi için Yüksek Yüzey Alanlı Alümina Destekli Katalizörlerin Geliştirilmesi(Afyon Kocatepe University, 2025) Elibol, Meltem KaraismailoğluDeğerli bir enerji taşıyıcısı olan hidrojen, yenilenebilir enerji teknolojilerinde atmosfere sera gazı emisyonunun azaltılmasında önemli bir rol oynamaktadır. Ancak hidrojen gazı doğada mevcut olmayıp hidrojen içeren bileşiklerden elde edilmesi gerekmektedir. Metal hidrürler hidrojen gazı üretimi için mükemmel adaylardır. Karmaşık metal hidrürler arasında sodyum borhidrür (NaBH4), gelişmiş hidrojen depolama kapasitesi ve düşük maliyeti gibi çeşitli avantajlara sahiptir. Bu çalışmada katalitik hidroliz yoluyla NaBH4’ten hidrojen gazı üretilmektedir. Bu amaçla yıkayarak kaplama yöntemi ile yüksek yüzey alanına sahip alümina destekli Ni/Al2O3, NiCo/Al2O3 ve Ru-NiCo/Al2O3 yapılı katalizörler hazırlanmış olup bu katalizörler sürekli akışlı reaktörde test edilmiştir. Elde edilen sonuçlara göre Ru-NiCo/Al2O3 yapılı katalizör başlangıçta en yüksek katalitik aktiviteye sahip olup reaksiyon boyunca aktivitesinde hızlı bir azalma gözlemlenmiştir. NiCo/Al2O3 yapılı katalizörün varlığında ise başlangıçta daha düşük bir katalitik aktivitesi görülmesine rağmen reaksiyon boyunca hidrojen üretimi hızla artmaya devam etmiştir. Bu nedenle NiCo/Al2O3 yapılı katalizör, Ru-NiCo/Al2O3 yapısına göre daha verimli bir katalizör olarak önerilebilir.Öğe Nickel oxide decorated halloysite nanotubes as sulfur Host materials for lithium–sulfur batteries(2023) Elibol, Meltem Karaismailoğlu; Jiang, Lihong; Xie, Dongjiu; Cao, Sijia; Pan, Xuefeng; Härk, Eneli; Lu, YanLithium–sulfur batteries with high energy density still confront manychallenges, such as polysulfide dissolution, the large volume change of sulfur,and fast capacity fading in long-term cycling. Herein, a naturally abundantclay material, halloysite, is introduced as a sulfur host material in the cathodeof Li–S batteries. Nickel oxide nanoparticles are embedded into the halloysitenanotubes (NiO@Halloysite) by hydrothermal and calcination treatment toimprove the affinity of halloysite nanotubes to polysulfides. TheNiO@Halloysite composite loaded with sulfur (S/NiO@Halloysite) isemployed as the cathode of Li–S batteries, which combines the physicalconfinements of tubular halloysite particles and good chemical adsorptionability of NiO. The S/NiO@Halloysite electrode exhibits a high dischargecapacity of 1205.47 mAh g?1at 0.1 C. In addition, it demonstrates enhancedcycling stability, retaining?60% of initial capacity after 450 cycles at 0.5 C.The synthesized NiO@Halloysite can provide a promising prospect andvaluable insight into applying natural clay materials in Li–S batteriesÖğe Physicochemical characterization of calcium-doped barium zirconate perovskites for hydrogen-induced systems and their life cycle assessment(Elsevier Ltd, 2025) Yılmaz, Enes Emre; Koşma, Elvan Burcu; Figen, Halit Eren; Elibol, Meltem KaraismailoğluBaZrO3 perovskites attract considerable attention in electrocatalytic applications. This study offers a comprehensive overview of synthesizing BaZrO3 perovskite material via the sol-gel method and investigates the impact of Ca-doping on its physicochemical properties. The hydrogen temperature-programmed reduction profiles and X-ray photoelectron spectroscopy analyses demonstrate that Ca-doping effectively enhanced the concentration of oxygen vacancies, which makes the material a candidate for hydrogen-induced electrocatalytic applications. Additionally, life cycle analysis results indicate the synthesis of Ba0.6Ca0.4ZrO3 perovskite with the most concentrated oxygen vacancies among synthesized perovskites caused the highest environmental impact, with marine and freshwater ecotoxicity being the primary environmental concern. © 2025 Hydrogen Energy Publications LLCÖğe Solar-hydrogen coupling hybrid systems for green energy(Wiley, 2023) Coşkuner, Filiz Bilge; Balkanlı Ünlü, Esra; Civelek Yörüklü, Hülya; Elibol, Meltem KaraismailoğluGreen hydrogen production coupled with solar energy became a universal concept to provide more efficient energy caring for the environment within the 2030 sustainable development goals target. The green energy concept provides energy systems without negative impact on the environment, economy, and society. At this point, hydrogen became a suitable energy and energy carrier for the green to green (G2G) concept, which evaluates green resources and green systems together. Producing hydrogen energy using solar radiation lowers greenhouse emissions. It allows people to participate in environmental improvements actively, makes the energy supplied cycles more sustainable, and protects the right to life of future generations. Solar energy is a primer source that can be directly adapted to provide steady power for the G2G system. Nowadays, recent trends on fuel cell, electrolyzer, and photovoltaic and photoelectrochemical technology within solar energy systems as a hybrid combination have a critical approach to realize G2G systems based on hydrogen and solar energy. This chapter focuses on G2G system, the combination of solar energy – hydrogen, fundamentals on electrolysis, photovoltaic panel, fuel cell, and electrolyzer or their hybrid combinations used for green hydrogen production from solar energy; also, thermochemical, photobiological, and photoelectrochemical production methods have been briefly introduced compared and outlined the future remarks.Öğe title Fe sub2/sub O sub3/sub /Y sub2/sub O sub3/sub catalystsupported on alumina and halloysite/title(2018) Elibol, Meltem Karaismailoğlu; Figen, Halit Eren; Baykara, Zeynep Sema[Özet yok]
