Ce0.70La0.20Ni0.10O2-delta catalyst for methane dry reforming: Influence of reduction temperature on the catalytic activity and stability

The influence of reduction temperature (450-900 oC) on the catalytic activity of Ce0.70La0.20Ni0.10O2-d sample during methane dry reforming reaction to synthesis gas has been studied. The activity of the sample, prepared by combustion synthesis, has been evaluated at 750 oC under increasing gas hourly space velocity (from 26400 to 105600 h-1) for 50 h of stream. H2-reduction of the sample at 450 oC induces, during reaction, large amount of carbon deposition (21-27%) that increases by increasing the gas hourly space velocity (GHSV), as revealed by TPO analysis on spent catalysts. Stable activity was revealed after reduction at 750 and 900 oC under a GHSV of 26400 h-1. The catalytic activity of the reduced samples, by apparent specific activity, increases by increasing the Ni particles size and by increasing the fraction of Ni sites revealed by H2-TPD peak at high temperature. The catalytic behavior has been discussed on the basis of the samples characterizations derived from X-ray diffraction, UV-vis diffuse reflectance spectroscopy, H2-programmed reduction (TPR) and desorption (TPD), CO pulse chemisorption, X-ray photoelectron spectroscopy (XPS) and Scanning Electron Microscopy-Energy dispersive X-Ray (SEM/EDX).