High-shear stirring assisted synthesis of Ni nanoparticles confined in H-ZSM-5 for hydrodeoxygenation of palmitic acid

In this study, H-ZSM-5 molecular sieves loaded with metallic Ni are successfully synthesized by high-shear stirring assisted in situ precipitation encapsulation method. During the synthesis process, the nickel complexes synergize with zeolite precursor solution to combine Ni species with molecular sieve skeleton via a self-assembly strategy, which result in the formation of molecular sieve-limited nano-sized Ni clusters (with the size of about 12 nm) after calcination and reduction in H₂/N₂ atmosphere. The high dispersion and small size of Ni species in the ZSM-5 skeleton are confirmed by a series of experimental characterizations. Palmitic acid is used as a model compound to evaluate the performance of the catalyst for the hydrodeoxygenation reaction of long-chain fatty acids, and the results show that the Ni clusters in the confined domain of the molecular sieve significantly inhibit the metal migration and sintering due to the spatial confinement effect of the skeleton, and exhibit higher catalytic activity (89 %) and stability in the reaction compared with the surface-loaded Ni nanoparticles. This study provides a new strategy for the design of metal-zeolite catalysts with high catalytic activity, which has potential applications especially in the preparation of aviation paraffin from bio-oil.