The reaction conditions were chosen such that CO2 conversion remained far below the thermodynamic limit at all temperatures, ensuring the measurement of intrinsic activity (kinetic regime). In Fig. (a), throughout the explored temperature range, CO2 conversion obtained with catalysts with different Ti loadings follows the trend of Ru/SiO2 < Ru/4%Ti-SiO2 < Ru/8%Ti-SiO2 < Ru/16%Ti-SiO2 < Ru/12%Ti-SiO2. The corresponding CO2 conversion rate at 300 C normalized by the Ru mass measured from ICP-AES is provided in Table . All Ru/x%Ti-SiO2 catalysts exhibit 100% selectivity toward CH4 over the whole temperature range, whereas the level of activity is shown to be greatly affected by the Ti loading. CO2 conversion rate of Ru/12%Ti-SiO2 is 2.3 times higher than that of the non-promoted Ru/SiO2.