Effect of Ti/Al ratio on the performance of Ni/TiO2-Al2O3 catalyst for methane reforming with CO2

Abstract

A series of mesoporous nanocrystalline TiO2-Al2O3 supports containing 0 to 100% alumina were synthesized via improved evaporation-induced self-assembly (EISA) strategy. The surface of the mixed oxide supports was decorated with nickel nanoparticles (10 wt%) via urea deposition-precipitation method. The catalysts containing different Ti/Al ratio were examined for methane reforming with CO2 regarding their activity and stability. Catalysts in both calcined, as well as in spent stages, were comprehensively characterized by various techniques like N2-physisorption analysis (BET), XRD, H2-TPR, NH3-TPD, TGA/DTG, SEM, ICP-MS, and TEM. The results show that a synergy between TiO2 and Al2O3 exist, and the doping of alumina with titania enhanced the catalytic activity and stability for an optimum doping ratio. The deactivation of pure titania supported catalyst was probably due to the sintering of Ni crystallites, partial coverage of Ni active sites by the TiOx species and the shrinkage of titania structure, however, it presents a high coke resistive catalyst. Doping up to 25% of alumina with titania was shown to retard the crystal growth of titania and redox characteristics of titania suppressed the deposition of coke over the catalyst surface. Different characterization techniques confirm the increase in coke deposition in TAL catalysts with an increase in alumina content. © 2019 Elsevier B.V.