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    Öğe
    Ag-Nb-Pt Bazlı SCR Katalizör Karakterizasyonu
    (Çukurova Üniversitesi, 2018) Keskin, Ali; Yaşar, Abdulkadir; Keskin, Zeycan; Akar, M. Atakan; Reşitoğlu, İ. Aslan; Özarslan, Himmet; Aydın, Kadir
    Seçici Katalitik İndirgeme (SCR), dizel motorlarda NOx emisyonlarını azaltmak için kullanılan bir emisyon kontrol sistemidir. Bu çalışmada, SCR sistemi için gümüş esaslı katalizörün sentezlenmesi deneysel olarak incelenmiştir. Bu amaçla, kordiyerit (2Al2O3-5SiO2-2MgO) yapısını daldırma yöntemiyle kaplamak amacıyla gümüş nitrat (AgNO3), niyobyum (V) klorür (NbCl5) ve tetra amin platin (II) nitrat (Pt (NH3)4 (NO3)2) katalizörleri kullanılmıştır. Katalizörün kimyasal ve fiziksel özelliklerini belirlemek için XRF, SEM ve BET analizleri gerçekleştirilmiştir. Sonuçlar, kaplama malzemelerinin gözeneklerin tüm yüzeyine nüfuz ettiğini göstermiştir. Üretilen katalizör ve kordieritin BET yüzey alanlarının sırasıyla 0,2918 m2/g ve 0,4568 m2/g olduğu belirlenmiştir. Yüzey alandaki azalmanın, yüksek sinterleme sıcaklığında meydana gelen kimyasal reaksiyonlarla kristalizasyon artışına bağlı olduğu düşünülmektedir. Ayrıca, XRF analizi sonuçları, kordierit yapısındaki Ag içeriğinin %0,03 olmasına karşın katalizörde Ag, Pt ve Nb içeriğinin sırasıyla %3,67, %0,19 ve %0,12 oranlarında olduğunu ortaya koymuştur. 
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    Öğe
    Properties of ethyl alcohol-water mixtures as a reductant in a SCR system at low exhaust gas temperatures
    (Taylor & Francis Inc, 2024) Ahmad, Mohamad Al Cheikh Mohamad; Keskin, Ali; Ozarslan, Himmet; Keskin, Zeycan
    In this experimental study, effects of ethyl alcohol-water mixtures as reducing agents in the presence of Ag/Cu-based catalyst on NOx conversion efficiency were investigated. The Ag/Cu-based catalyst was synthesized with the impregnation method. In this method, cordierite structure was immersed into the solution including nanoparticle materials and then the solvent was evaporated. The analysis done by SEM and XRD revealed the structural and chemical properties of the catalyst. In order to obtain information on how the addition of water affects the activity of the NOx conversion in the SCR exhaust test performance system, tests were carried out depending on a temperature window of 170-260 degrees C, two different space velocities (20000 h(-1), and 40000 h(-1)), and three different reductants (100% Ethyl alcohol (E), 4% water + 96% Ethyl alcohol (E4 W), and 8% water + 92% Ethyl alcohol (E8 W)). The increase in the engine load showed a little increase in the NOx conversion rates. Taking into account the space velocity, the NOx conversion rates were higher at 20000 h(-1) in comparison at 40000 h(-1). The highest NOx conversion rate recorded in the tests was 68% at 4 kw engine load, 100% ethyl alcohol spraying, and 20000 h(-1). However, the results of the tests showed that when the water content of the reductants increased from 4% to 8%, the NOx conversion rates decreased at both 20000 h(-1) and 40000 h(-1) SV. The highest NOx conversion rates of the tests conducted with E4 W and E8 W reductants were 62.75% and 61.78%, respectively, at 4 kw engine load and 20000 h(-1). Also, the highest NOx conversion rates of the same reductants were 55.8% and 55.01%, respectively, at 4 kw engine load and 40000 h(-1). It was concluded that the water added to ethyl alcohol has a negative effect on NOx reduction.
  • [ X ]
    Öğe
    The effects of Fe2O3 based DOC and SCR catalyst on the exhaust emissions of diesel engines
    (Elsevier Sci Ltd, 2020) Resitoglu, Ibrahim Aslan; Altinisik, Kemal; Keskin, Ali; Ocakoglu, Kasim
    The effects of Fe2O3 based DOCs (Diesel Oxidation Catalyst) and SCR (Selective Catalytic Reduction) catalysts on the exhaust emissions of diesel engine were investigated in this experimental study. The investigated catalysts, Al2O3 - TiO2/CeO2/Fe2O3 (ATCF) and Al2O3- Nb2O5/CeO2/Fe2O3 (ANCF), were produced with impregnation method and aged for 6 h at 600 degrees C. FE-SEM (Field Emission Scanning Electron Microscopy), XRD (X-Ray Diffraction), XRF (X-Ray Fluorescence) and BET (Brunauer-Emmett-Teller) Surface Area analyzes were carried out to determine the specifications of catalysts. The catalytic performances of the DOCs were tested for the oxidation of CO, HC, PM, NO while SCR catalysts were tested for SCR of NOx using NH3. An individual exhaust system was built up and mounted to the engine for tests of catalysts. An electronic control system and a software were developed to control the SCR system. After the completion of experimental setup, catalysts placed inside the exhaust system were subjected to the engine tests to determine their effects on the exhaust emissions. Tests were carried out under actual working conditions with a single cylinder direct injection diesel engine. In conclusion, the catalysts made significant decrease in pollutant emissions while brake specific fuel consumption (BSFC) increased slightly. ANCF released better conversion efficiency in all pollutant emissions compared to the ATCF. Maximum decreases in CO, HC and NOx emissions, which are resulted from ANCF catalyst, were obtained at a rate of 83.51%, 80.83% and 80.29% respectively.