Structurally Engineering Multi-Shell Hollow Zeolite Single Crystals via Defect-Directed Oriented-Kinetics Transformation and Their Heterostructures for Hydrodeoxygenation Reaction

Abstract

Single-crystalline multi-shell hollow porous materials with high compartment capacity, large active surface area, and superior structural stability are expected to unlock tremendous potential across diverse critical applications. However, their synthetic methodology has not yet been well established. Here, we develop a defect-directed oriented-kinetics transformation approach to prepare multi-shell hollow aluminosilicate ZSM-5 zeolite (MFI) crystals with single-crystalline feature, hierarchical macro-/mesoporosity, controllable shell number, and high structural stability. The methodology lies in the creation of zeolite precursors consisting of multiple inhomogeneous layers with gradient-distributed defects along the [100] and [010] directions and irregularly discrete defects-rich regions along the [001] direction via continuous epitaxial growth. Subsequently, the locations with more defects could be preferentially etched to form voids or mesopores, meanwhile oriented recrystallization interconnects the nanoshells into a unified architecture along the [001] direction. Benefiting from the easily accessible bifunctional metal/acid sites and the capability for reactant accumulation, the resultant multi-shell hollow Ni-loaded zeolite catalysts show significantly enhanced catalytic activity in the hydrodeoxygenation of stearic acid into liquid fuels. The insight gained from this systematic study will facilitate the rational design and synthesis of diverse multi-shell hollow structured single-crystalline porous materials for a broad range of potential applications.