Ni/La_2O_3 catalysts for dry reforming of methane: Effect of La_2O_3 synthesis conditions on the structural properties and catalytic performances

摘要

10 wt%Ni/La2O3 catalysts for dry reforming of methane (DRM) were synthesized by wetness impregnation of lanthana supports prepared using sol-gel citric method with and without NH3 addition (Ni-La CA-NH3 and Ni-La CA, respectively). The support preparation conditions affect the nature, phase composition, and distribution of Ni phases (LaNiO3, NiO and La3Ni2O6). The gradient temperature DRM tests (400-800 degrees C) reveal higher catalytic activity of Ni-La CA (at 650 degrees C, X(CO2) = 65.7%, X(CH4) = 54.6%, H-2/CO = 0.71). The Ni-La CA-NH3 shows higher stability (at 650 degrees C and 24 h, X(CO2): 73.7% = 76.4%, X(CH4): 64.7% = 64.6%, H-2/CO: 0.77 = 0.72). For both catalysts, La2O2CO3 phase is formed after long run tests at 650 degrees C 24 h, with the greater TGA weight loss and stronger deactivation being observed for Ni-La CA. The H-2-reduced Ni La CA-NH3 features ultrasmall (1-2 nm) Ni NPs strongly interacting with the support. Catalyst nature affects the amount of carbon coke formed. (c) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.