Steam reforming and carbon deposition evaluation of phenol and naphthalene used as tar model compounds over Ni and Fe olivine-supported catalysts

Iron and nickel-based catalysts over an olivine support were prepared by different methods (thermal fusion (TF) and wetness impregnation (WI)), and the effect of steam reforming of phenol and naphthalene on those catalysts was tested. The structure of catalysts synthesized by the TF method exhibited obvious differences compared with the WI method. During the thermal fusion process, part of Fe and Ni was migrated into the olivine framework to form (Mg,Fe) Fe2O4 and Ni2SiO4(NiFe2O4), respectively. In this structure, Fe and Ni acted as active metal, and Si, Mg, O acted as dispersed phases, so Fe and Ni can be dispersed more uniformly and exhibit more stable catalytic activity. However, The Fe and Ni presented as Fe2O3 and NiO-MgO in the wetness impregnation process which was easily sintered and consumed duo to attrition during the catalytic reaction. The catalysts prepared by the two methods both performed well for phenol steam reforming (Fe-containing catalysts reached more than 93% and Ni-containing catalysts reached more than 99%) and carbon deposition resistance (carbon deposition rates were both lower than 7%), while the carbon deposits from the steam reforming of naphthalene were difficult to eliminate by steam. After analysis, it was found that the carbon deposits from phenol catalytic cracking was mainly C-alpha, which was easy to react with steam, and that those from naphthalene were mainly C-beta and C-gamma which had poor reactivity. (C) 2018 Energy Institute. Published by Elsevier Ltd. All rights reserved.