Direct synthesis of hydrogen peroxide over Pd nanoparticles embedded between HZSM-5 nanosheets layers

Direct synthesis of hydrogen peroxide (DSHP) was studied over Pd loaded on HZSM-5 nanosheets (Pd/ZN). Pd nanoparticles with average size of co. 4.3 nm were introduced into the adjacent nanosheet layers (thidcness of cu. 2.9 nm) by impregnation method. Pd/ZN with theoretical Si/AI molar ratio of 25 showed the highest selectivity for H2O2 among the prepared catalysts, together with highest formation rate of H2O2 (38.0 mmol.(g cat)(-1).h(-1)), 1.9 times than that of Pd supported on conventional HZSM-5 zeolite (Pd/CZ-50). Better catalytic performance of nanosheet catalysts was attributed to the promoted Pd dispersion which promoted H-2 dissociation, more Bronsted acid sites and stronger metal-support interaction which inhibited the dissociation of O-O bond in H2O2. The embedded structure sufficiently protected the Pd nanoparticles by space confinement which restrained the Pd leaching, leading to a better catalytic stability with 90% activity retained after 3 cycles, which was almost 3 times than that of Pd/CZ-50 (30.4% activity retained). (C) 2020 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.