The catalysts are characterized (3Flex, Micromeritics) by N2 physisorption, H2 chemisorption, CO2 chemisorption and H2 temperature programmed reduction (H2-TPR) measurements. For the H2-TPR experiments samples are dried under flowing Ar at 120 °C for 30 min, cooled down to 50 °C and then the feed is switched to 10 % H2 in Ar. After the TCD baseline signal stabilizes, the temperature is increased to 1000 °C with a heating rate of 10 K/min. The chemisorption experiments are conducted with the volumetric method. Circa 100 mg of each sample are reduced with H2 at 200 °C for 4 h and degassed at 300 °C for 6 h. The adsorption isotherms are then recorded at 50 °C. After degassing for 1 h, a repeat measurement is taken. Both chemisorption isotherms are measured and the Sinfelt method is applied to calculate the adsorbed amount by conducting a linear fit through both isotherms and subtracting the y-intercepts.