WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article New Bifunctional Catalysts for the Synthesis of Dimethyl Ether Via Carbon Dioxide Utilization(Y H Mammadaliyev inst Petrochemical Proc, Natl Acad Sci, Baku, Azerbaijan, 2025) Guliyev, Bilal, V; Zahidova, Aysel; Tuncer, Bashak; Sheker, Erol; Nasirov, Fizuli A.; 01. Izmir Institute of TechnologyThe increasing demand for sustainable energy sources has intensified research into carbon dioxide (CO2) utilization for the synthesis of clean alternative fuels such as dimethyl ether. This study investigates the direct synthesis of dimethyl ether from CO2 using bifunctional copper-based hybrid catalysts (SCR-A, SCR-B, and SCR-C) synthesized via the sol-gel method. These catalysts integrate oxidative and acidic functionalities within a single system, enabling methanol synthesis and subsequent dehydration into dimethyl ether in a one-step process. Experimental evaluations were conducted under varying pressures ranging from atmospheric to 40 bar and temperatures between 200-350 degrees C, using both low-and high-pressure reactors to assess performance. The results indicate that under atmospheric conditions, methanol conversion reached 87%, with 82% dimethyl ether selectivity, demonstrating the bifunctional character of the catalysts. Among them, SCR-A exhibited the most favorable performance in terms of conversion and product distribution. Under high-pressure conditions (5 and 7 bar), CO2 conversion remained constant at 50%, while selectivity was influenced by temperature and reactor pressure. At 40 bar and 300 degrees C, dimethyl ether selectivity reached its peak at 60%, confirming this range as the optimal operational window for maximizing dimethyl ether yield. However, a notable decrease in selectivity was observed at 350 degrees C, likely due to catalyst deactivation or the promotion of undesired side reactions. These findings underline the thermodynamic and operational benefits of direct dimethyl ether synthesis over the conventional two-step route, as it simplifies process design, enhances CO2 utilization, and reduces energy and cost demandsArticle Citation - WoS: 59Citation - Scopus: 67Design and Thermodynamic Analysis of a Novel Methanol, Hydrogen, and Power Trigeneration System Based on Renewable Energy and Flue Gas Carbon Dioxide(Pergamon-Elsevier Science LTD, 2021) Nazerifard, Reza; Gökçen Akkurt, Gülden; Mohammadpourfard, Mousa; Mohammadi-Ivatloo, Behnam; Gökçen Akkurt, Gülden; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this paper, a new trigeneration system is proposed to decrease atmospheric carbon dioxide emission and produce methanol, hydrogen, and power. The system is composed of an organic Rankine cycle, a direct methanol fuel cell, a carbon capture unit, a proton exchange membrane electrolyzer, and a methanol synthesis unit. A flue gas stream with a defined composition, solar energy, and the atmospheric air are the system?s inlets. In the design step, special attention is paid to heat and mass integration between different components so that its waste can be lowered as much as possible. Then, mass balance law, energy conservation principle, exergy relations, and auxiliary equations are applied for each subsystem to investigate the system's thermodynamic performance. Also, the effect of changing operating parameters on the performance of each subsystem is studied. The obtained results show that the proposed system has the energy and exergy efficiencies of 66.84% and 55.10%, respectively. Furthermore, 94% of the total exergy destruction rate belongs to the water electrolyzer, while the contribution of the organic Rankine cycle is negligible. The performance of the methanol synthesis reactor depends strongly on its inlet temperature. Maximum equilibrium methanol concentration and carbon dioxide conversion are achieved at the inlet temperature of 210 degrees C. The parametric studies reveal that there is an optimum fuel cell current density in which its produced power density is maximized.Article Citation - WoS: 2Catalytic Activity of Heteropolytungstic Acid Encapsulated Into Mesoporous Material Structure(Walter de Gruyter GmbH, 2007) Gündüz, Gönül; Yılmaz, Selahattin; Dimitrova, Rayna P.; Yılmaz, Selahattin; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe paper presents a spectroscopic and catalytic study of encapsulated Keggin type heteropoly acid (12-tungstophosphoric acid, HPW) in the mesopores of MCM-41 molecular sieves. Nitrogen physisorption, FTIR, SEM, XRD and catalytic methods have been used to characterize and compare the properties of the samples. Methanol conversion, alpha-pinene isomerization and ethyl acetate oxidation have been applied as model reactions for the evaluation of acid site activity. The combined physicochemical and catalytic investigations clearly show that the introduction of 12-tungstophosphoric acid into MCM-41 causes significant changes in the properties of the sample.Article Citation - WoS: 36Citation - Scopus: 44Assessment of Elliptic Flame Front Propagation Characteristics of Iso-Octane, Gasoline, M85 and E85 in an Optical Engine(Elsevier Ltd., 2014) Ihracska, Balazs; Korakianitis, Theodosios P.; Ruiz, Paula; Emberson, David Robert; Crookes, Roy James; Diez, Alvaro; Wen, Dongsheng; 01. Izmir Institute of TechnologyPremixed fuel-air flame propagation is investigated in a single-cylinder, spark-ignited, four-stroke optical test engine using high-speed imaging. Circles and ellipses are fitted onto image projections of visible light emitted by the flames. The images are subsequently analysed to statistically evaluate: flame area; flame speed; centroid; perimeter; and various flame-shape descriptors. Results are presented for gasoline, isooctane, E85 and M85. The experiments were conducted at stoichiometric conditions for each fuel, at two engine speeds of 1200. rpm (rpm) and 1500. rpm, which are at 40% and 50% of rated engine speed. Furthermore, different fuel and speed sets were investigated under two compression ratios (CR: 5.00 and 8.14). Statistical tools were used to analyse the large number of data obtained, and it was found that flame speed distribution showed agreement with the normal distribution. Comparison of results assuming spherical and non-isotropic propagation of flames indicate non-isotropic flame propagation should be considered for the description of in-cylinder processes with higher accuracy. The high temporal resolution of the sequence of images allowed observation of the spark-ignition delay process. The results indicate that gasoline and isooctane have somewhat similar flame propagation behaviour. Additional differences between these fuels and E85 and M85 were also recorded and identified.Article Citation - WoS: 30Citation - Scopus: 34Authentication of a Turkish Traditional Aniseed Flavoured Distilled Spirit, Raki(Elsevier Ltd., 2013) Yüceesoy, Dila; Özen, Banu; Özen, Fatma Banu; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyConsumption of traditional aniseed alcoholic beverage, raki, adulterated with methanol results in deaths, therefore, its detection is an important issue. In this study, mid-infrared spectra of pure and methanol adulterated (0.5-10% (vol/vol)) raki samples were collected with an attenuated total reflectance attachment of a Fourier-transform infrared spectrometer. Principal component analysis was used to discriminate pure and adulterated raki samples, then, a partial least square model was constructed to determine the adulterant methanol content in raki using mid-IR spectral data. A minimum threshold level of 0.5% methanol in raki samples was successfully detected. A good prediction model for determination of methanol adulteration ratio in raki samples was also constructed (R2 = 0.98 and RPD = 8.35).