Well-dispersed Ni nanoclusters on the surfaces of MFI nanosheets as highly efficient and selective catalyst for the hydrogenation of naphthalene to tetralin

One of the challenges in material science has been to design and prepare highly efficient and selective catalysts for target reactions. Here we demonstrate a one-pot hydrothermal synthesis of hierarchical MFI nanosheets with nickel species chemically bonded on the outer surfaces. It turns out that the growth and morphologies of self-pillared MFI nanosheets are affected by Ni content, and the thickness of MFI nanosheets are determined to be 2.3 nm or 3.0 nm. Specially, the bonded Ni on the outer surfaces can effectively prevent adjacent nanosheets from forming new Si-O-Si bonds, and in conjunction with the self-pillared structure, can hamper complete collapse of Ni-MFI-NSs during calcination. In naphthalene hydrogenation, the separated Ni species are previously reduced to highly-dispersed metallic Ni nanoclusters with size below 1.6 nm, which are highly active for hydrogenation. And the hierarchical porosity of Ni-MFI-NSs significantly enhances the diffusion of substrates and the accessibility of active sites. As a result, Ni-MFI-NSs achieve 100% selectivity for tetralin and 84.9% conversion of naphthalene with Ni content of only 4.2 wt%. Furthermore, the gradually enlarged Ni nanoparticles cause the decline of catalytic activities of catalysts. (C) 2017 Elsevier B.V. All rights reserved.