Akademik Veri Yönetim Sistemi
International Journal of Hydrogen Energy, cilt.45, sa.60, ss.34547-34556, 2020 (SCI-Expanded)
© 2020 Hydrogen Energy Publications LLCSupported nickel-iron catalysts with core/shell structures (Ni,Fe/SiO2, and Ni/SiO2, Fe (Imp.)) were synthesized by sol-gel microencapsulation and sol-gel microencapsulation-impregnation methods, respectively. Sol-gel microencapsulation resulted in the formation of Ni and Fe containing alloys, where both Fe and Ni were in the core (Ni,Fe/SiO2). In the case of combined microencapsulation-impregnation Ni was placed in the center where Fe was on the shell side (Ni/SiO2, Fe (Imp.)). BET, XRD, SEM, TGA and Raman Spectroscopy techniques were used for catalysts characterization. Catalysts were tested in dry reforming of methane (DRM) reaction which was specially selected to provide a comprehensive utilization of methane and carbon dioxide. The catalytic activity tests were carried out at 750 °C and atmospheric pressure, using stainless steel, temperature-controlled tube reactor. After 3 h of reaction, Ni,Fe/SiO2 bimetallic core-shell microsphere catalysts with Ni/Fe ratio of 4/1 and 2/1 indicated the highest CH4 conversions (74% and 68%, respectively) and H2/CO (0,72 and 0,69) ratios. Ni,Fe/SiO2 catalysts showed higher activity compared to Ni/SiO2, Fe (Imp.) catalysts and an activity increase for both types of catalysts were observed due to increasing Ni amount in catalyst structure. Ni,Fe/SiO2 catalysts were also determined to be highly resistant against coke formation. A significant resistance against coke formation on active sites was achieved via SiC formation during reaction. The catalyst with best performance (4Ni,1Fe/SiO2) was regenerated after use and tested on following three successive cycles under identical experimental conditions. Results indicated similar activity values with negligible deactivation.