Promotion effect of the S-1 zeolite microenvironment on confined Pd nanoparticles for the selective hydrogenation of nitrile

Zeolite-tailored encapsulation of metal nanoparticles exhibits prominent catalytic performance in many fields especially for selective hydrogenation reaction due to the modulation effect of the zeolite microenvironment. Here, Pd nanoparticles encapsulated in MFI zeolite by an in-situ encapsulation method were first used in the selective hydrogenation of nitrile into a primary amine. After introducing KOH for mediating the acid-base property of zeolite microenvironment, the as-synthesized Pd@S-1-K manifested an improved selectivity in the synthesis of primary amine from nitrile, while outperformed both commercial catalysts and conventional Pd supported on zeolite catalyst. The remarkable performance of Pd@S-1-K could be attributed to both the basic property of the S-1-K zeolite for inhibiting the side reactions and the highly dispersed and ultrasmall Pd clusters for superior catalytic activity. Besides, the best yield of 81% was achieved at 80 degrees C, 5 bar H-2, 2 h in ammonia solution via optimization experiments, and the moderate applicability of Pd@S-1-K catalyst was obtained by substrate scope test.