Unravelling the Descriptors of Intracrystalline Diffusion and Al Location on Hollow Zeolite Nanosheets for Target Acid-Base Co-Catalyzed Reaction

Rational design of zeolites with improved diffusion properties and desirable acid-base densities is vital in relevant heterogeneous catalysis process. Herein, an effective protocol is developed to achieve the synchronous modulation of intracrystalline diffusion and Lewis acid-base sites distributions via constructing hollow zeolite nanosheets. We disclose the significant application of the desired catalyst in the reaction of toluene side-chain alkylation. The reaction results demonstrate that the platelike zeolite after alkali-treatment (CsZ5-U-AT) exhibits a higher toluene conversion (12.1%) and styrene selectivity (80.2%), accompanied by an extended catalytic stability (> 100 h) than conventional catalyst. Structure-performance relationships in side-chain alkylation are established for optimal catalyst in comparison with other catalysts using an experimentally derived descriptor that takes into account two critical physicochemical properties: mass transport and acid-base site densities. The explanations are as follows: (i) The hollow structure and short b -axis of desired catalysts synergistically facilitate the intracrystalline diffusivity, thereby improving the utilization of active sites; (ii) Partial framework Al sites are transformed to EFAL species (LASs) and “acid-free” Al(OH) ₄ ⁻ during alkali-treatment process, which modulating the Lewis acid-base sites; (iii) The Si-zoned external surface constructed during “desilication and recrystallization” process could improve shape-selective capability. In this case, the synchronous modulation of desirable intracrystalline diffusion and acid-base distributions can be achieved, and the ideal catalysts for acid-base catalyzed reactions can be designed.