Harnessing Na-Promoted Zeolite–Binder Synergy for One-Step Shaping of Highly Para -Selective ZSM-5 Catalysts

Shaping zeolite powders is essential for industrial catalysts, yet the interactions between binders, additives, and zeolite frameworks during shaping remain poorly understood. These interactions critically influence the external surface acid property, which governs catalytic performance, particularly in shape-selective reactions. For the toluene alkylation with methanol, achieving high para -xylene selectivity typically requires complex post-treatment to passivate external acid sites. Here, a previously unrecognized synergistic effect is identified, enabling catalyst shaping and surface passivation to be accomplished in a single extrusion step. Specifically, Na species not involved in charge balancing of the zeolite framework, often viewed as detrimental, are found to act as promoters that facilitate the uniform dispersion of oxide binders across the external surface of ZSM-5. This uniform binder coverage, in turn, protects the zeolite framework by mitigating Na-induced degradation during high-temperature calcination. This powerful synergy enables a decoupled regulation of bulk and external acid property, selectively eliminating the external Brønsted acid sites responsible for undesired isomerization while preserving the internal acid sites crucial for alkylation. Consequently, this one-step strategy directly yields catalysts with a para -xylene selectivity exceeding 95% without additional post-treatment. The approach is general across different oxide binders, highlighting its broad applicability. These findings provide fundamental understanding of zeolite–binder interactions during shaping and establish a practical, scalable route for industrially relevant, high-performance, shape-selective ZSM-5 catalysts.