Modulating the methanation activity of Ni by the crystal phase of TiO2

Abstract

We demonstrate that the methanation activity of Ni catalysts is modulated by the crystal phase of the TiO₂ support. The rutile TiO₂ (r-TiO₂)-supported Ni catalyst gives a turnover frequency almost two orders of magnitude higher than the anatase TiO₂ (a-TiO₂)-supported catalyst although the two catalysts exhibit a similar mean Ni particle size. Characterization by H₂-TPR, H₂-TPD, XPS and IR reveals a stronger interaction between Ni and r-TiO₂, leading to a higher capability of CO activation and hydrogenation activity of Ni although Ni is partially covered by TiO_x overlayers during reaction. Interestingly, the modulating effects of the titania crystal phases are much more pronounced on the activity of Ni in CO₂ methanation.