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    A Comprehensive Review on Red Mud-Based Catalysts: Modification Methods and Applications in Thermal- and Photocatalysis
    (Wiley-V C H Verlag Gmbh, 2025) Sekizkardes, Busra; Soyer-Uzun, Sezen; Uzun, Alper; Kuhn, Simon; Kaya-Ozkiper, Kardelen; Kurtoglu-Oztulum, Samira F.
    Red mud (RM), waste of the Bayer process for aluminum production, is mostly stored in landfill areas, creating serious environmental and economic problems. It offers substantial potential for catalytic applications, primarily because of its cost efficiency and rich chemical composition, including Fe, Si, Al, and Ti oxides. Using RM as a catalyst not only contributes to environmental protection but also offers economic advantages as it can potentially reduce the reliance on expensive noble metals typically used in solid catalyst formulations. RM is predominantly used in thermal- and photocatalysis, serving as a bulk catalyst, support material, promoter, additive, or as a host material for heterojunction catalysts. Before use, RM is generally modified to enhance its textural properties and tailor its composition. This review provides a comprehensive analysis of the utilization of RM in catalytic applications. The structural changes resulting from various pretreatments and their impact on catalytic properties are discussed. Key thermal- and photocatalytic reactions involving RM-based catalysts are presented to highlight their industrial and environmental significance. Potential pathways for further optimization of RM-based catalysts are also proposed, offering a broad perspective on future directions in the field.
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    Modified Fly Ash: An Eco-Friendly, Cost-Free, and Efficient Iron-Based Catalyst for Ammonia Decomposition to COx-Free Hydrogen
    (Wiley-V C H Verlag Gmbh, 2024) Sekizkardes, Busra; Kurtoglu-Oztulum, Samira F.
    Fly ash (FA), an industrial waste produced in large amounts, is rich in metal oxides such as Al2O3, SiO2, and Fe2O3, making it an ideal candidate for use as a catalyst in ammonia decomposition. However, FA's surface area is very low (<1.0 m(2) g(-1)), limiting its potential. This study investigates the modification of FA by calcination at various temperatures (550, 700, and 1000 degrees C), HCl treatment, and HCl treatment followed by calcination at 500 degrees C to convert FA into a catalyst by utilizing its iron content as active sites. The catalyst obtained by treating FA with HCl at 220 degrees C, calcining at 500 degrees C, reducing in H-2 at 700 degrees C, and activating in ammonia at 700 degrees C achieved 86.0% ammonia conversion at a reaction temperature of 700 degrees C and a space velocity of 30,000 mL NH3 h(-1) gcat(-1), remaining stable for 140 h following an induction period of 30 h. Enhanced textural properties (18.5 m(2) g(-1)), elimination of S and Cl impurities, and the formation of relatively small Fe crystallites (23.8 nm determined by Scherrer equation and 24.0 nm measured by transmission electron microscopy (TEM)) when reduced in H-2 were responsible for this performance.
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    Reactive capture and electrochemical conversion of CO2 with ionic liquids and deep eutectic solvents
    (Royal Soc Chemistry, 2024) Dongare, Saudagar; Zeeshan, Muhammad; Aydogdu, Ahmet Safa; Dikki, Ruth; Kurtoglu-Oztulum, Samira F.; Coskun, Oguz Kagan; Munoz, Miguel
    Ionic liquids (ILs) and deep eutectic solvents (DESs) have tremendous potential for reactive capture and conversion (RCC) of CO2 due to their wide electrochemical stability window, low volatility, and high CO2 solubility. There is environmental and economic interest in the direct utilization of the captured CO2 using electrified and modular processes that forgo the thermal- or pressure-swing regeneration steps to concentrate CO2, eliminating the need to compress, transport, or store the gas. The conventional electrochemical conversion of CO2 with aqueous electrolytes presents limited CO2 solubility and high energy requirement to achieve industrially relevant products. Additionally, aqueous systems have competitive hydrogen evolution. In the past decade, there has been significant progress toward the design of ILs and DESs, and their composites to separate CO2 from dilute streams. In parallel, but not necessarily in synergy, there have been studies focused on a few select ILs and DESs for electrochemical reduction of CO2, often diluting them with aqueous or non-aqueous solvents. The resulting electrode-electrolyte interfaces present a complex speciation for RCC. In this review, we describe how the ILs and DESs are tuned for RCC and specifically address the CO2 chemisorption and electroreduction mechanisms. Critical bulk and interfacial properties of ILs and DESs are discussed in the context of RCC, and the potential of these electrolytes are presented through a techno-economic evaluation.