Enhanced CO2 Methanation Activity of Ni/Anatase Catalyst by Tuning Strong Metal-Support Interactions

Strong metal-support interaction (SMSI) has been widely recognized for platinum-group metals on reducible oxide supports. Herein we report that the catalytic activity of Ni catalyst in CO2 methanation is significantly suppressed over conventional anatase (a-TiO2) support due to the SMSI-induced formation of a titania overlayer around the Ni nanoparticles. Furthermore, CO is the only product . In contrast, the NH3-treatment and H-2-treatment of the a-TiO2 support enhance remarkably the activity of Ni, i.e., CO2 conversion increases by 1 order of magnitude and CO2 is hydrogenated almost exclusively to CH4. X-ray photoelectron spectroscopy (XPS), H-2 and CO chemisorption, and low temperature electron paramagnetic resonance (EPR) reveal that the enhanced CO2 methanation activity may be related with the Ti3+ species in the bulk that are generated by reduction treatment, which likely have altered the SMSI between Ni and a-TiO2 support. This simple reduction treatment approach may be applicable to modulate the SMSI of other reducible oxide-supported metal catalysts