Fig. 3

Effect of carbon supports on catalytic performance. The bar graph shows the selectivity to HCALD at 10% CALD conversion for Pd supported on the PS support and on PS defunctionalized at 200–800 °C (blue). The values correspond to the average selectivity calculated for three independent experiments ± the corresponding standard deviation (s.d.). The selectivity to HCALD was found to increase with the annealing temperature although the average particle size, metal loading, and normalized reaction rate were within error for the five samples. This trend was consistent with changes in the active metal phase revealed by hydrogen chemisorption (ratio of reversibly to irreversibly chemisorbed hydrogen H_R/H_I, orange) and by XPS (ratio of the Pd 3d5/2 peaks for the metal to δ + phase, Pd⁰/Pd^δ+, green)