Hydrothermal Annealing of Hierarchical ZSM‐5 Zeolites Improves Catalytic Performance

Abstract Engineering next‐generation zeolite catalysts requires state‐of‐the‐art synthesis techniques to tailor the properties of materials along with robust methods to evaluate their catalytic performance. Here, we introduce hydrothermal annealing as a facile and highly effective method to improve the activity and lifetime of zeolite catalysts. This post‐synthesis treatment uses a siliceous growth solution at approximate solubility of zeolite crystals with high temperature to alter the physicochemical properties of as‐synthesized materials. We employ the methanol‐to‐hydrocarbons (MTH) process as a benchmark reaction, along with a wide range of characterization techniques, to assess the impact of annealing on four nanosized and hierarchical ZSM‐5 materials compared to a commercial sample. Our findings reveal that annealing significantly increased cumulative MTH turnover without appreciably altering product selectivity, despite non‐obvious changes to zeolite structure as a result of the annealing process. Comparisons of catalyst performance are made under identical reaction conditions using a descriptor that correlates cumulative turnovers to compositional, mass transport, and textural properties of each material – in line with growing efforts to increase rigor and reproducibility in the field of catalysis. The collective approach used in this study serves as a guideline for establishing structure‐composition‐performance relationships for zeolite‐based catalysts across wide‐ranging applications.