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چکیده
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In this study, the effect of synthesis method (impregnation and so-gel) as well as Co and Cu addition on the catalytic and physicochemical properties of Ni/Al2O3-ZrO2 nanocatalyst was evaluated in dry reforming of methane. The XRD, FESEM, PSD, BET and FTIR analysis were used to characterize the nanocatalysts. Highly dispersed Ni and Zr species and no spinel production in the solegel synthesized samples were confirmed by XRD results. The FESEM images showed small and uniform nanoparticles in the solegel synthesized catalyst. Also, after Cu added to Ni/Al2O3-ZrO2, the particles were more compact than others. Moreover, the promoters addition especially Co to Ni/Al2O3-ZrO2 nanocatalyst improved the particles size uniformity. Particle size distribution of solegel synthesized Ni-Co/Al2O3-ZrO2 nanocatalyst represented that the majority of the particles (nearly 95%) lies between 10 and 40 nm with an average size of 27.4 nm. BET analysis showed higher surface area in the solegel samples, especially when it was coupled with Co and Cu addition. The results indicated the remarkable synergetic effect of sol-gel method and Co addition on the surface morphology and elemental dispersion. Activity of nanocatalysts were evaluated as a function of temperature from 550 to 850 C at GHSV=24 l/g h, P=1 atm and CH4/CO2=1. The solegel synthesized nanocatalyst showed better catalytic performance. Moreover, it was observed that, Cu and Co addition improved feed conversion, products yield and better syngas ratio. The comparison between promoters revealed that activity of Co was better than Cu. During the 1440 min time on stream test at 850 C, the sol-gel synthesized Ni-Co/Al2O3-ZrO2 nanocatalyst exhibited the best activity compared to the other samples and produced syngas with approximately stoichiometry ratio.
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