Seed-assisted synthesis of a nanosheet-assembled hierarchical SSZ-13 zeolite by coupling a small amount of TMAdaOH with TPOAC

Abstract

The synthesis of a hierarchical SSZ-13 zeolite with mesopores and micropores is one of the most effective strategies to overcome the diffusion limitation imposed by the micropores of SSZ-13 in reactions involving bulky reactants or intermediates. A zeolite with nanosheet morphology possesses the advantages of large inter-sheet mesopore volume, more accessible acid sites and short diffusion path lengths. Nevertheless, only a few works focused on the synthesis of the nanosheet-assembled SSZ-13 zeolite. In this work, a nanosheet-assembled hierarchical SSZ-13-TP_0.03 (thickness of 20 nm) zeolite was synthesized in a seed-assisted synthesis system by coupling a small amount of N, N, N-trimethyl-1-adamantylammonium hydroxide (TMAdaOH) with octadecyl-(3-trimethoxysilylpropyl)-ammonium chloride (TPOAC). In this strategy, the Si/Al ratio of the initial gel, seed, TPOAC and TMAdaOH amount in the synthesis system and the synergistic effects among them lead to the synthesis of SSZ-13 samples with various textural properties and morphologies. The distinct textural properties and morphologies of SSZ-13 result in the preparation of Pt/SSZ-13 catalysts with varied Pt dispersions. The catalyst, Pt supported on the nanosheet-assembled hierarchical SSZ-13 (Pt/SSZ-13-TP_0.03), exhibits higher hydrogenation ability than its corresponding catalyst, Pt supported on microporous or hierarchical SSZ-13 in the hydrogenation of naphthalene.