Effects of cerium and lanthanum on Ni-based catalysts for CO2 reforming of toluene

Abstract

The dry reforming of toluene (DRT) has been studied on Cerium and Lanthanum-promoted Ni–Al catalysts derived from hydrotalcites precursors in the temperature range 300–800 °C. X-ray powder diffraction (XRD) and thermogravimetric and differential thermal analyses (TGA-DSC) of as-prepared samples confirmed the formation of the hydrotalcite structure. Temperature programmed reduction (TPR) and desorption (CO2-TPD) indicated that Ni phase reducibility and basicity of the catalysts were influenced by the presence of the promoters. Ce-promoted catalyst was reducible at lower temperatures and had higher total basicity than the La-promoted and non-promoted catalysts. Furthermore textural property of solid was modified after cerium incorporation. These factors played a key role in the enhancement of the catalytic activity and suppression of carbon deposition. Post-reaction characterization of the catalysts by Temperature Programmed Oxidation (TPO) and TGA-DSC evidenced a better resistance towards carbon deposition for the Ce and La promoted catalysts. The promoted and non-promoted catalysts showed similar toluene conversion but promoted catalysts presented lower carbon deposition after test. Benefit effect of Cerium promotion catalyst was related by its characteristic which greatly influenced the activity. Lanthanum promoted exhibited a similar textural and physico-chemical characteristic than non-promoted catalyst but showed a higher performance than this latter. Promotion-activity relationship of the La containing catalyst was related by the presence of La2O3 on Ni based catalyst which could influence the transport and the adsorption of the CO2 onto the active sites surface.