Increasing the catalytic performance of erionite by hierarchization

Abstract

Abstract The texture and acidity of a parent synthetic erionite zeolite (ERI structure) are modified by a two-step top-down treatment involving acid (HNO3) and base (NaOH) biased leaching as well as an unbiased HF/NH4F leaching. These zeolites are compared to a bottom-up prepared nanosized ERI, UZM-12. The structural (XRD, 29Si MAS NMR), textural (N2 adsorption-desorption, STEM) and acidic (FT-IR spectroscopy of adsorbed probe molecules) properties of the parent and hierarchical ERI are also carefully monitored. Among all top-down hierarchization strategies applied for 8-ring ERI structure, the sequential leaching in acid (HNO3) and caustic (NaOH) solutions is the most efficient to add mesoporosity to the native microporosity. The catalytic performances of the hierarchical materials and their parent are assessed in the dealkylation of 1,3,5-triisopropylbenzene (TiPBz); they are in line with the mesoporous external surface area and the external surface acid site density for all samples. The best top-down hierarchical ERI has similar catalytic properties as the nanosized ERI, UZM-12.