Diethanolamine-assisted construction of a hierarchical zeolite framework for enhanced diffusion and transformation of key intermediates in tandem catalysis

Abstract Rational design of metal-acid bifunctional catalysts is crucial for steering selectivity in tandem catalysis, yet conventional metal/zeolite systems often suffer from diffusion-imposed limitations that hinder intermediate transport. Herein, we report a diethanolamine-assisted alkaline treatment (DEA-AT) strategy to reconstruct β zeolite into a hierarchical framework featuring radially aligned, exterior-connected mesoporous channels (β-DEA-AT). This architecture markedly improved the accessibility of intermediate cyclohexene to Brønsted acid sites and strengthened metal-acid cooperation in benzene hydroalkylation. As a result, Ru/β-DEA-AT catalysts delivered markedly enhanced performance, achieving a cyclohexylbenzene yield of 35.2%, benzene conversion of 62.1%, and a formation rate of 49.6 mmolCHB·gcat−1·h−1, surpassing both conventionally alkali-treated Ru/β-AT (30.6% conversion, 11.6% CHB yield, 31.0 mmolCHB·gcat−1·h−1) and pristine Ru/β catalysts (33.1% conversion, 21.6% CHB yield, 30.5 mmolCHB·gcat−1·h−1). Systematic investigations revealed that the DEA-induced hierarchical reconstruction facilitated the rapid migration of cyclohexene intermediates within the zeolite framework, as reflected by an increase in the apparent cyclohexene diffusion coefficient from 1.81 × 10−5 cm2·s−1 for Ru/β100 to 6.42 × 10−5 cm2·s−1 for Ru/β100-DEA-AT, where shortened diffusion pathways and enhanced accessibility of Brønsted acid sites promote intermediate transport and transformation. These findings establish pore-environment engineering as a generalizable strategy to regulate intermediate transformations through metal-acid synergy, providing guidance for the design of next-generation multifunctional tandem catalysts.