High accessibility to active sites of hierarchical nanocrystalline Zr-β zeolite in ethanol–acetaldehyde conversion to 1,3-butadiene

Hierarchical Zr-β zeolite is a promising catalyst in the conversion of ethanol to 1,3-butadiene owing to the improved accessibility of active sites inside the zeolite to bulky substrates. Accordingly, hierarchical nanocrystalline Zr-β zeolite with sufficient intercrystalline mesoporosity and microporosity was prepared in this work via silanization-based hydrothermal synthesis. A systematic investigation was conducted to determine the effect of the secondary porosity on the textural, acidic and catalytic properties. The results suggested that neither acid amount, strength nor location varied with the additional secondary porosity. However, an appropriate proportion of micropores and mesopores would provide significant contributions to enhanced catalytic performance, arising from the available confined environment around the active sites inside the micropores, enhanced accessibility of such sites and improved diffusion of reactants and products due to mesopores.