Synergistic effect of carbon shell pore volume and core Pd size of Pd@hollow@C-X for synthesis of H2O2

Yolk-shell catalysts Pd@hollow@C-X (X=1.5, 3.2, 4.5 and 6) with Pd as core and porous carbon as shell were prepared by inverse microemulsion method. The carbon shell pore volume and core Pd size were controlled by varying NH3•H2O amounts. Results showed that with the increasing of NH3•H2O amounts, the average particle size of Pd nanoparticles and shell pore volume decreases first and then increased, and when NH3•H2O amounts was 3.2 ml, the prepared catalyst Pd@hollow@C-3.2 had the smallest Pd particle size and the largest shell pore volume, it is 5.54 ±1.37nm and 0.12 m3•g-1 respectively. The smaller Pd particle size can provide more active sites for the adsorption and reaction of reactant H2 and O2, and the larger shell pore volume is beneficial for the adsorption of reactant H2 and O2. This makes the catalyst Pd@hollow@C -3.2 having the highest selectivity and productivity of H2O2 synthesis, reaching 93% and 3197mmol/gPd-1•h-1, respectively at 1bar.