Sol-gel vs. impregnation preparation of MgO and CeO2 doped Ni/Al2O3 nanocatalysts used in dry reforming of methane: Effect of process conditions, synthesis method and support composition

摘要

Ni/Al2O3-CeO2 and Ni/Al2O3-MgO nanocatalysts were prepared by impregnation and sol-gel methods and used in CO2 reforming of methane. The research aimed at the effects of cerium and magnesium addition in sol-gel method on the catalytic properties and performance of Ni/Al2O3 catalyst. All the samples were characterized by XRD, FESEM, PSD, EDX, BET, FTIR and TG-DTG techniques. XRD results confirm reinforced impact of sol-gel method on NiO dispersion in the presence of support promoters. Besides, it proves the potential of the sol-gel method in enhancement of metal-support interaction via NiAl2O4 spinel formation. FESEM images demonstrate smaller and more uniform nanoparticles as a result of utilizing the sol-gel method, especially when CeO2 is used. More than 94% of surface nanoparticles lie between 10 and 40 nm with surface average particle size of 23.3 nm. Apart from revealing the suitability of adopted calcination temperatures, TG-DTG analysis supports the higher surface area for sol-gel made samples which was evidenced by BET analysis. Catalytic evaluation revealed that better performance is obtained by employment of sol-gel method and support promotion. Both of the sol-gel synthesized Ni/Al2O3-CeO2 and Ni/Al2O3-MgO nanocatalysts exhibited the superior and stable catalytic activity during 1440 min at 850 degrees C, indicating the synergistic effect of sol-gel method and promoter addition. However, sol-gel synthesized Ni/Al2O3-CeO2 nanocatalyst was found to be the most proper choice for CO2 reforming of methane, exhibiting the H-2/CO ratio of 1 and H-2 yield of 94% at 850 degrees C. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.