Preparation of Ni/MgxTi1-xO catalysts and investigation on their stability in tri-reforming of methane

Ni/MgxTi1-xO catalysts were prepared through a wet impregnation method by dispersing Ni on MgxTi1-xO composite oxides obtained via a sol-gel technique. The Ni/MgxTi1-xO catalysts were characterized by various means including ICP-OES, BET, XRD, H2-TPR, SEM, and TG. No free NiO peak was found in all XRD patterns of the Ni/MgxTi1-xO catalysts. The H2-TPR and chemisorption results indicated that adding Ti to the NiO-MgO system obstructed the formation of solid solution, and thus increased the reducibility of the catalysts. The prepared MgxTi1-xO composite oxides had the same ability to disperse Ni as TiO2 and MgO. The tri-reforming (simultaneous oxygen reforming, carbon dioxide reforming, and steam reforming) of methane over Ni/MgxTi1-xO catalysts was carried out in a fixed bed flow reactor. The conversions of CH4 and CO2 can respectively be achieved as high as above 95% and 83% over Ni/Mg0.75Ti0.25O catalyst under the reaction conditions. The activity of Ni/Mg0.75Ti0.25O and Ni/Mg0.5Ti0.5O did not decrease for a reaction period of 50 h, indicating their rather high stability. The experimental results showed that the nature of support, the interaction between metal and support, and the ability to be reduced played an important role in improving the stability of catalysts. (author)