A comparative study of zirconia and yttria promoted mesoporous carbon-nickel-cobalt catalysts in steam reforming of ethanol for hydrogen production

Abstract

Steam reforming of ethanol process was evaluated over unpromoted / yttria and zirconia-promoted mesoporous carbon-Ni-Co catalysts. The nickel and cobalt ions were added during the synthesis of mesoporous carbon support and then yttrium and zirconium promoters loaded by the wet impregnation method. The catalysts were characterized by BET, XRD, HR-TEM, TPR, TG-DTA, and FE-SEM methods. XRD and HR-TEM results indicated that the yttria-promoted MC-Ni-Co catalyst has a smaller particle size (the higher dispersion) compared to zirconia-promoted MC-Ni-Co catalyst. Furthermore, TPR analysis confirmed an easier reduction of oxide nanoparticles in the yttria-promoted catalyst compared to the zirconia-promoted catalyst. By adding promoters, the activity of catalysts increased significantly. The catalytic activity of yttria-promoted catalyst (ethanol conversion ̴ 56% at 375 °C) was higher than zirconia-promoted catalyst (ethanol conversion ̴ 46% at 375 °C). Also, it was revealed that increasing the feed ratio could improve catalytic activity. FE-SEM and HR-TEM images indicated the deposited carbon with the filamentous nature on the surface of spent catalysts. The TG analysis showed the highest and lowest amount of carbon deposition for the unpromoted and zirconia-promoted catalysts after the stability test, respectively.