Kinetics and reaction pathway of the CO2 reforming of methane on Rh supported on lanthanum-based solid

Rh/La2O3 catalysts are very stable for the dry reforming of methane. To understand this catalytic behavior, this system was thoroughly characterized using a battery of instrumental techniques: XRD, LRS, DRIFTS, and XPS. The data obtained with the fresh calcined and reduced solids during reaction and after use, at both the volumetric and surface levels, led to a satisfactory description of the working catalyst that in turn suggested a possible reaction mechanism. It is proposed that the slow steps are both the decomposition of methane (C + 2H2) and the reaction of the carbon species left on the surface with the oxycarbonates present in the working catalyst. The kinetic data obtained by varying the reactant partial pressures between 2.5 and 40 kPa in the temperature range of 823–903 K is well fitted by the kinetic equation derived from the proposed reaction mechanism.