La-doped supported Ni catalysts for steam reforming of methane

Abstract

Ni-La/α-Al2O3 catalysts at different Ni/La ratio of respectively 7/3, 8/2 and 9/1 to obtain a material with total loading of 10 wt% as used in industrial methane steam reforming field are prepared with incipient wetness impregnation method. Various techniques including TGA-DTA, XRF, XRD, particles size, H2-RTP and BET are used to characterize materials and their catalytic performance is evaluated during the steam reforming reaction at different temperatures ranging from 500 to 800 °C. Only NiO and α-Al2O3 phases are evidenced by DRX indicating probably the presence of small lanthanum crystallites in high dispersion state. Addition of La may cause strong change at the surface of NiO sites. Substitute Ni by La leads to smaller and well dispersed NiO particles sizes with strong metal support interaction (SMSI). TPR analysis reveals the reduction of Ni species with high Ni-La-Al interactions particularly well observed with 3 wt%La catalyst. The small Ni particles sizes highly dispersed on the support enhance the dissociative adsorption of CHx species. The highest H2 yield is obtained with 7Ni-3La/Al catalyst reaching 94% at 800 °C.