Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
Browse
Search Results
Article Citation - WoS: 100Citation - Scopus: 116The Effect of Char Properties on Gasification Reactivity(Elsevier Ltd., 2014) Duman, Gözde; Uddin, Md Azhar; Yanık, JaleIn this study, CO2 gasification of raw and acid-washed chars obtained from various types of lignocellulosic biomasses (woody and agricultural waste biomasses) was studied under isothermal conditions (850 C) using thermal gravimetric analysis. The effect of surface area and alkali/earth alkali metals on the reactivity of the chars was investigated. The different kinetic models were used to fit with the reactivity data by using least square method. The gasification of chars with higher surface area was found to be faster than that of chars having lower surface area. The acid treatment decreased the overall gasification rate for each raw chars. However, although the AI (alkali index) values of chars obtained from agricultural biomasses had equal or higher than that of woody biomass chars, their initial rates were considerably lower. It was concluded that indigenous alkali metals of chars have a remarkable influence of gasification reactivity but an adequate surface area should be provided to react with CO2.Article Citation - WoS: 34Citation - Scopus: 37Steam Gasification of Safflower Seed Cake and Catalytic Tar Decomposition Over Ceria Modified Iron Oxide Catalysts(Elsevier Ltd., 2014) Duman, Gözde; Watanabe, Taichi; Uddin, Md Azhar; Yanık, JaleCatalytic steam gasification of safflower seed cake was carried out using a double-bed microreactor in a two-stage process in the presence of ceria oxide (CeO2) modified iron oxide (Fe2O3) catalysts with different CeO2-Fe2O3 ratios. The effects of both catalyst and the temperature of catalytic bed on the tar decomposition and the overall gaseous product yield were investigated comparatively. It was found that ceria modified iron oxide catalysts had higher reactivity than that of the individual Fe2O3 and CeO2 for the catalytic tar decomposition in safflower seed cake steam gasification. The CeO2-Fe2O3 catalyst with 50 wt.% of Fe 2O3 exhibited the excellent performance for tar conversion at 700 °C. A comparison of tar decomposition from thermal run and catalytic run showed that in thermal run tar decomposition was progressed via steam reforming only. However, in the presence of catalyst, tar decomposition occurred via both steam reforming and water gas shift reaction. As a conclusion, ceria promoted iron catalysts were found to be active for both hydrogen production and tar decomposition in steam gasification of lignocellulosic biomass.Article Citation - WoS: 149Citation - Scopus: 180Hydrogen Production From Algal Biomass Via Steam Gasification(Elsevier Ltd., 2014) Duman, Gözde; Uddin, Md. Azhar; Yanık, JaleAlgal biomasses were tested as feedstock for steam gasification in a dual-bed microreactor in a two-stage process. Gasification experiments were carried out in absence and presence of catalyst. The catalysts used were 10% Fe2O3-90% CeO2 and red mud (activated and natural forms). Effects of catalysts on tar formation and gasification efficiencies were comparatively investigated. It was observed that the characteristic of algae gasification was dependent on its components and the catalysts used. The main role of the catalyst was reforming of the tar derived from algae pyrolysis, besides enhancing water gas shift reaction. The tar reduction levels were in the range of 80-100% for seaweeds and of 53-70% for microalgae. Fe2O3-CeO2 was found to be the most effective catalyst. The maximum hydrogen yields obtained were 1036cc/g algae for Fucus serratus, 937cc/g algae for Laminaria digitata and 413cc/g algae for Nannochloropsis oculata.